WO2012024243A1

WO2012024243A1 - Minimally invasive low level light therapy for neurological disorders

Info

Publication number: WO2012024243A1
Application number: PCT/US2011/047808
Authority: WO
Inventors: Luis De Taboada; Jackson Streeter
Original assignee: Photothera, Inc.
Priority date: 2010-08-16
Filing date: 2011-08-15
Publication date: 2012-02-23

Abstract

Minimally invasive devices and methods for treating neurological disorders with low level light therapy are disclosed. A light therapy apparatus for therapeutically treating a subject's brain can include a substantially flat, biocompatible base sheet configured to be implanted between the subject's scalp and the subject's skull and configured to be anchored to an outer surface of the subject's skull and one or more light sources mechanically coupled to the base sheet.

Description

MINIMALLY INVASIVE LOW LEVEL LIGHT THERAPY FOR

NEUROLOGICAL DISORDERS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application Serial No. 61/374,200 filed on August 16, 2010, the entire content of which is hereby expressly incorporated herein by reference.

FIELD

[0002] This disclosure relates in general to low level light therapy for treatment of neurological disorders, and more particularly, to novel implantable apparatuses and minimally invasive methods for delivering therapeutic amounts of low level light to neural tissue.

BACKGROUND

[0003] Neurological disorders are disorders that can affect the central nervous system (brain and spinal cord), the peripheral nervous system, or the autonomic nervous system. Numerous neurological disorders exist, affecting individuals both young and old. Within this category of disorder are included but not limited to behavioral/cognitive syndromes (e.g., dementia, depression), speech and language disorders (e.g., dysarthria and dysprosody), sleep disorders ((e.g., insomnia, parasomnias), psychiatric disorders (e.g. anxiety and depression, schizophrenia, obsessive compulsive disorders, addictions), motor disorders (e.g., epilepsy, stroke, Parkinson's and Huntington's Disease), and neurodegenerative diseases, among others. Neurological disorders can be characterized as acute or chronic and are often categorized based on the area affected or the etiology of clinical symptoms.

[0004] The progressive and long-term decline in cognitive function of an individual more rapidly than expected for that individual's age is broadly known as dementia. Affected areas of cognition may include memory, attention, language, and problem solving. Thus, this class of disease actually includes other disorders such as Alzheimer's and Parkinson's disease, discussed more below.

[0005] Depression is a neurological psychiatric disorder, typically recognized by its impact on an affected individual's behavior. Numerous brain areas show altered metabolic or neuronal activity in depressed patients; the most well studied areas include the frontal cortex (FCx), suprachiasmatic nucleus (SCN), the hypothalamic-pituitary-adrenal (HPA) axis, the ventral tegmental area (VTA), the nucleus accumbens (Nac), and the anterior cingulate cortex (ACC). Due to the variation in affected brain regions, determination of a defined etiology has been difficult, if not impossible. A prevailing hypothesis regarding depression does, however, suggest abnormalities or deficits in certain neurotransmitters (particularly monoamine neurotransmitters like serotonin, norepinephrine, and dopamine).

[0006] Neurodegenerative disorders result from loss of or functional deterioration of neurons over time or with aging, which leads to disability or dysfunction. The neurons themselves may die or become dysfunctional, or may experience degradation in their myelin sheath (the "conductive insulation" of a neuron), either of which reduces the transmission of neural signals from the nervous system to peripheral target tissues or organs. Neurodegenerative diseases can affect cognition, movement, strength, and coordination, for example. Neurodegenerative diseases include, but are not limited to, Alzheimer's disease, Parkinson's disease, Huntington's disease, dementia with Lewy bodies or Lewy body disease, corticobasal degeneration, Prion disorders, amyotrophic lateral sclerosis, hereditary spastic paraparesis, Friedreich's ataxia, spinocerebellar atrophies, amyloidoses, demyelinating diseases (e.g., multiple sclerosis, Charcot Marie Tooth), encephalitis, hydrocephalus, cranial nerve palsies (e.g., progressive supranuclear palsy), traumatic brain injury, stroke, epilepsy and spinal cord injury.

[0007] As of late, the neurodegenerative disorders have been the subject of much interest, due to the substantial emotional and financial impact on those suffering from neurodegenerative disorders, their families, caregivers and society. For example, it has been recently estimated that the health care costs of Alzheimer's disease patients are more than triple those of other older people. Compared with people aged 65 and older without Alzheimer's, those with Alzheimer's disease are much more often hospitalized and treated in skilled-nursing centers.

[0008] The mechanisms causing neurodegenerative diseases are varied, depending on the disease in question. As stated above, there may be loss of the neurons themselves, or degradation or dysfunction of the neuron, in terms of the transmission of neural signals. Biomedical research is presently ongoing in relation to many neurodegenerative diseases in order to determine molecular mechanisms involved, thereby leading to improved treatment of the diseases themselves, as well as the symptoms.

[0009] Studies have revealed that particular neurodegenerative diseases involve particular areas of the brain. For example, Alzheimer's disease is believed to primarily affect the neurons in the entorhinal cortex. The entorhinal cortex is a deep brain region, positioned in front of the hippocampus. This region of the brain is involved in memory consolidation, and its deterioration leads to the hallmark symptoms of Alzheimer's disease, memory loss and forgetfulness.

[0010] Parkinson's disease is typified by motor symptoms (e.g., tremor, rigidity, postural instability, gait disturbances) and speech disturbances. These symptoms are caused by loss of dopaminergic nerve cells in the pars compacta region of the substantia nigra. For reasons not fully understood, these neurons are particularly sensitive to damage of various types (e.g., disease-related, drug-related, or trauma-related). Recent research suggests that dysfunctional molecular transport machinery within these neurons may lead to protein build-up that is toxic to the neuron.

[0011] Despite learning a great deal about various neurological disorders, true cures for these disorders remain as long-term targets for researchers and physicians. Some mechanistic understanding has led to therapies that address symptoms via molecular targets. In depression, for example, correlations between the symptoms presented and the known effects of a particular neurotransmitter deficit are used to guide therapy. For example, if a patient shows signs of anxiety, obsessions, and compulsions, which are correlated with lack of serotonin, a physician may use an antidepressant that prolongs the activity of serotonin. Other treatment modalities are available, such as psychotherapy or electroconvulsive therapy. In many cases, however, therapies remain directed largely to alleviation and slowing the rate of progression of symptoms

[0012] Pharmacological therapy is a first-line therapy for neurodegenerative disorders such as Alzheimer's and Parkinson's disease. In regards to Alzheimer's, the focus of drug treatment is to improve cognitive abilities and attempt to slow the progression of these symptoms, e.g., memory and thinking. Alzheimer's drugs are typically either cholinesterase inhibitors (slow the breakdown of acetylcholine, a neurotransmitter important in nerve communication) or compounds that reduce the excitatory activity of glutamate on brain cells, as glutamate overexposure is thought to be toxic to certain neurons. Parkinson's is currently treated with drugs that work directly or indirectly to increase the level of dopamine in the brain. These drugs include dopamine precursors, such as levodopa, that cross the blood-brain barrier and are thereafter metabolized into dopamine. Other drugs mimic dopamine or prevent or slow its breakdown. Certain symptoms are related to other neurotransmitters. For example, anticholinergic drugs help reduce tremors and muscle stiffness.

[0013] While pharmaceuticals currently offer some relief from symptoms for patients, there are several drawbacks to pharmaceutical therapy. Many pharmaceuticals are associated with side effects, which reduce patient compliance. In some instances, patients are not equipped to self-medicate with the frequency required to maintain therapeutically effective drug levels. In particular, with neurodegenerative diseases, such as Alzheimer's, a patient's loss of memory may impact her ability to remember to take medication. Thus, a high level of interest and clinical need remains in finding new and improved therapeutic interventions for treatment of neurologic disorders that continue to cause significant morbidity and mortality and involve tremendous burden to society, families and caregivers.

SUMMARY

[0014] In some embodiments, an apparatus adapted to provide light therapy to a subject experiencing symptoms associated with one or more neurological disorders or a subject who has been diagnosed with one or more neurological disorders is implanted below the scalp of the subject. The apparatus can comprise a controller that can operate in a standalone, independent manner, or in response to a signal from a remote control. The controller can activate one or more light sources adapted to deliver light to the subject's neural tissue.

[0015] In some embodiments, a light therapy apparatus for therapeutically treating a neurological condition (e.g., a chronic neurodegenerative disorder) comprises a substantially flat, biocompatible base sheet configured to be implanted between the subject's scalp and the subject's skull and configured to be anchored to an outer surface of the subject's skull and one or more light sources mechanically coupled to the base sheet. In some embodiments, the one or more light sources are positioned to irradiate at least a portion of the subject's brain with light transmitted through the subjet's skull. The base sheet can comprise substantially flexible material (e.g., mylar, polytetrafluoroethylene (PTFE)) or a substantially rigid material. In some embodiments, the one or more light sources are one or more light emitting diodes, one or more vertical cavity surface-emitting laser diodes, woven optical fibers, combinations of the same, or other coherent or non-coherent light sources. In some embodiments, the one or more light sources are variably positionable within the base sheet. In some embodiments, the one or more light sources are aligned with one or more sutures of the skull.

[0016] In some embodiments, at least one of the light sources is configured to emit pulsed light beams comprising a plurality of pulses. In some embodiments, the temporal pulse width of the pulses is within a range between 0.1 milliseconds and 150 seconds. In some embodiments, the light beams (pulsed or continuous) stimulate, excite, induce, or otherwise support one or more intercellular or intracellular biological processes involved in the survival, regeneration, or restoration of performance or viability of neurons or brain cells irradiated by the light. The pulsed light can have a temporal pulse width and duty cycle sufficient for the pulsed light beam to penetrate the subject's skull to modulate membrane potentials, thereby enhancing cell survival, cell function, or both, of the neurons or brain cells irradiated by the pulsed light beam.

[0017] In accordance with some embodiments, an implantable light therapy apparatus for treating at least a portion of a subject's brain comprises a substantially flat, biocompatible base sheet and one or more light sources mechanically coupled to the base sheet. Upon the light therapy apparatus being implanted below an inner surface of the subject's scalp and being anchored to an outer surface of the subject's skull, the one or more light sources can be positioned to irradiate at least a portion of the subject's neural tissue with light having a wavelength between about 640 nm and about 2000 nm (e.g., between about 780 nm and about 840 nm), the light having an irradiance configured to therapeutically treat a neurological condition of the brain. In some embodiments, the irradiance is between about 0.01 mW/cm and

2 2 2

about 10 W/cm (e.g., between about 0.01 mW/cm and about 1 W/cm , between about 0.1 mW/cm² and about 100 mW/cm², between about 1 mW/cm² and about 500 mW/cm²) at the irradiating surface of the light sources. In some embodiments, the irradiated light has a wavelength greater than 1300 nm. In some embodiments, the irradiance is less than 10 W/cm² at the outer surface of the subject's skull. In some embodiments, the irradiance delivered by the one or more light sources is configured such that the irradiance at the cortical surface of the

2 2 2 2 subject's brain is between 0.01 mW/cm and 1 W/cm or between 0.5 mW/cm and 10 mW/cm .

[0018] A method for treating a patient with a neurological condition can include providing an implantable light therapy apparatus, implanting the light therapy apparatus below the scalp of the patient and outside the skull of the patient, and anchoring the light therapy apparatus to an outer surface of the skull of the patient. The light therapy apparatus can comprise a substantially flat, biocompatible base sheet, one or more light sources mechanically coupled to the base sheet, a controller mechanically coupled to the base sheet and operatively coupled to the one or more light sources, and a power source operatively coupled to the controller and to the one or more light sources. The one or more light sources can be positioned to target a particular target site (e.g., a particular region or component of the brain) or to irradiate the entire brain. For example, target sites can include, but are not limited to, the amygdala, the substantia nigra, the entorhinal cortex, and the hippocampus.

[0019] In some embodiments, the method comprises identifying at least one suture of the skull and aligning at least one of the one or more light sources with the at least one suture of the skull. In some embodiments, anchoring the light therapy apparatus comprises inserting one or more bone anchors into the skull of the patient. In other embodiments, anchoring the light therapy apparatus comprises applying a bioadhesive to the skull and positioning the light therapy apparatus over the bioadhesive.

[0020] In accordance with several embodiments, the apparatuses and methods described herein can be used to treat, or otherwise improve the resultant effects of neurological conditions, such as chronic neurodegenerative diseases, or the symptoms associated with such neurological conditions. In some embodiments, the apparatus and methods described herein can be used to treat or otherwise improve the symptoms or effects associated with neurological degenerating diseases, such as cognitive impairment, deterioration in movement or motor skills, decreased strength, and deterioration in coordination. In accordance with several embodiments, the apparatuses and methods described herein are used to treat or otherwise address subjects having, or experiencing symptoms of, but not limited to, behavioral/cognitive syndromes (e.g., dementia, anxiety and depressive conditions including major depressive disorders and the like, age-related cognitive impairment, learning and memory disorders), speech and language disorders (e.g., dysarthria and dysprosody), sleep disorders (e.g., insomnia, parasomnias), psychiatric disorders (e.g., attention deficit disorder, schizophrenia, bipolar disorder, obsessive- compulsive disorders, phobias), compulsive disorders (e.g., excessive or dysfunctional eating disorders such as anorexia, bulimia, as well as sexual or gambling), addictive disorders such as substance abuse, (e.g., nicotine, heroin, methamphetamine, cocaine, alcohol), developmental disorders (e.g., autism), epilepsy, schizophrenia, and neurodegenerative diseases (e.g., Alzheimer's disease, Parkinson's disease, Huntington's disease, Pick's disease, myasthenia gravis, multiple sclerosis, Guillain-Barre syndrome, hereditary spastic paraplegia). Categories are generally determined based on the area affected or on the etiology and it should be appreciated that some disorders, diseases, or conditions can overlap or be comorbid between two or more categories.

[0021] In some embodiments, implanting the light therapy apparatus below the scalp of the subject (e.g., subdermal) but above the skull of the subject reduces penetration issues of delivering light through hair or through skin of different pigmentations and colorations but does not require invasive surgery to the skull or brain. In some embodiments, subdermal implantation may reduce the incident power level to be provided by the light sources. In some embodiments, the light therapy apparatuses and methods described herein can advantageously be used to address chronic neurological conditions and/or chronic neurodegenerative diseases or disorders or the symptoms associated with such conditions, diseases or disorders to facilitate neuroprotection and counteract neurodegeneration.

[0022] For purposes of summarizing the disclosure, certain aspects, advantages and novel features of the inventions have been described herein. It is to be understood that not necessarily all such advantages can be achieved in accordance with any particular embodiment of the inventions disclosed herein. Thus, the inventions disclosed herein can be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as can be taught or suggested herein.

BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1A schematically illustrates a light therapy apparatus for administration of light therapy for subdermal implantation in accordance with several embodiments described herein.

[0024] FIG. IB schematically illustrates another light therapy apparatus for administration of light therapy for subdermal implantation in accordance with other embodiments described herein.

[0025] FIG. 2A schematically illustrates a cross-sectional view of a light therapy apparatus placed within the subdermal space of the head of a patient according to several embodiments described herein. [0026] FIG. 2B schematically illustrates an additional cross-sectional view of a light therapy apparatus placed within the subdermal space of the head of a patient according to several embodiments described herein.

[0027] FIG. 3 shows a diagrammatic representation of a portion of a light therapy apparatus for administration of light therapy for subdermal implantation, in accordance with several embodiments described herein.

[0028] FIGS. 4A and 4B schematically illustrate alignment of a plurality of light sources with sutures of the skull.

[0029] FIG. 5 schematically illustrates the interconnection and activity of the components of a light therapy apparatus according to several embodiments described herein.

[0030] FIGS. 6A and 6B schematically illustrate the diffusive effect of a light source on the light emitted.

[0031] FIG. 7 is a block diagram of a control circuit comprising a programmable controller for controlling a light source according to embodiments described herein.

[0032] FIG. 8A is a graph of the transmittance of light through blood (in arbitrary units) as a function of wavelength.

[0033] FIG. 8B is a graph of the absorption of light by brain tissue.

[0034] FIG. 8C shows the efficiency of energy delivery as a function of wavelength.

[0035] FIG. 9 shows measured absorption of 808 nanometer light through various rat tissues.

[0036] FIGS. 10A-10D schematically illustrate example pulses in accordance with certain embodiments described herein.

[0037] FIG. 1 1 is a graph of the power density versus the depth from the dura for an input power density of 10 mW/cm² with the light bars corresponding to predicted values of the power density and dark bars corresponding to an estimated minimum working PD of 7.5 μ\¥/ϋπι², as described below.

[0038] FIG. 12 shows the effect of light therapy on Αβ amyloid deposition in a murine brain with mean ± SEM for each treatment group.

[0039] FIG. 13A shows the effects of light therapy on latency time to find hidden platform (Morris water maze) with mean ± SEM for each treatment group. [0040] FIG. 13B shows the effects of light therapy on distance to find hidden platform (Morris water maze) with mean ± SEM for each group.

[0041] FIGS. 14A- 14C show the effects of light therapy on inflammatory mediators in the brain of APP transgenic mice with mean ± SEM for each group.

[0042] FIGS. 15A and 15B show the effects of light therapy on Αβ peptide levels in the brain of APP transgenic mice with mean ± SEM for each group.

[0043] FIGS. 16A and 16B show the effects of light therapy on Αβ peptide levels in the plasma of APP transgenic mice at 13 and 26 weeks, respectively, with mean ± SEM for each group.

[0044] FIGS 17A and 17B show the effects of light therapy on sAPPa and CTF levels, respectively, in the brain of APP transgenic mice with mean ± SEM for each group.

[0045] FIG. 18 shows the effect of light therapy on CSF Αβ peptide levels in APP transgenic mice with mean ± SEM for each group.

DETAILED DESCRIPTION

[0046] Low level light therapy ("LLLT") or phototherapy involves therapeutic administration of light energy to a subject (e.g., a human or animal) at lower irradiances than those used for cutting, cauterizing, or ablating biological tissue, resulting in desirable biostimulatory effects while leaving tissue undamaged. In non-invasive phototherapy, it is desirable to apply an efficacious amount of light energy to the internal tissue to be treated using light sources positioned outside the body. (See, e.g., U.S. Patent Nos. 6,537,304 and 6,918,922, both of which are incorporated in their entireties by reference herein.)

[0047] Studies have shown that laser-generated infrared radiation is able to penetrate various tissues, including the brain, and to modify function. In addition, laser-generated infrared radiation can induce effects including, but not limited to, angiogenesis, modify growth factor (transforming growth factor-β) signaling pathways, and enhance protein synthesis.

[0048] However, absorption of the light energy by intervening tissue can limit the amount of light energy delivered to the target tissue site, while heating the intervening tissue. In addition, the intervening tissue may scatter the applied light energy and can limit the irradiance (otherwise known as power density) or energy density delivered to the target tissue site. Attempts to circumvent these effects by increasing the irradiance applied to the outside surface of the body can result in damage (e.g., burning) of the intervening tissue. Thus, non- invasive phototherapy treatment parameters are developed within specified limits so as to preferably avoid damaging the intervening tissue.

[0049] Despite the clear benefits of efficacious non-invasive phototherapy methods, in certain instances, non-invasive phototherapy may not be an optimal choice for all patient populations. For example, certain neurological disorders may require irradiation of deep or central neural tissue. While adjustments to light parameters can be developed to limit the energy loss due to tissue (or blood) scattering and to limit tissue heating, it may be beneficial to, through a minimally invasive procedure, implant a light source closer to the target tissue. Moreover, for some patients suffering from chronic diseases, particularly neurological conditions that require frequent (e.g., daily) therapy, invasive phototherapy methods may be a preferable therapeutic regimen. For example, some patients suffering from neurological disorders may have limited capacity to remember to institute treatment or may not physically be able to administer treatment. Similarly, patients who suffer from severe motor disorders (e.g., tremors or tics) may be unable to remain sufficiently stationary to properly receive treatment with a non-invasive phototherapy apparatus. In such instances, as well as others, invasive methods of phototherapy, administered via an indwelling apparatus, are viable alternatives. In some embodiments, the indwelling apparatus can be coupled to a programmable controller that controls the administration of the therapy, thereby removing the need to visit the doctor for daily treatment. In some embodiments, the indwelling apparatus can function as a standalone unit without user interaction after implantation.

[0050] In many cases, even with an invasive approach, there will remain some amount of intervening tissue between the light source and the target tissue. Thus, the concerns of tissue-based light scattering and heating of intervening tissue of phototherapy, are unlikely to be wholly ameliorated by invasive methods. Certain embodiments, as described herein, provide devices and methods which advantageously treat neurological conditions or disorders using a set of undamaging, yet efficacious, parameters for the phototherapy.

[0051] Such embodiments may include selecting a wavelength of light at which the absorption by intervening tissue is below a damaging level. Such embodiments may also include setting the power output of the light source at low, yet efficacious, irradiances (e.g., between approximately 100 μ\¥/ϋπι² to approximately 10 W/cm²) at the target tissue site, setting the temporal profile of the light applied to the head (e.g. , temporal pulse widths, temporal pulse shapes, duty cycles, pulse frequencies), and time periods of application of the light energy at hundreds of microseconds to minutes to achieve an efficacious energy density at the target tissue site being treated. Other parameters can also be varied in the use of phototherapy. These other parameters contribute to the light energy that is actually delivered to the treated tissue and may play key roles in the efficacy of phototherapy.

[0052] In certain embodiments, the target area of the subject's brain includes the area of injury, e.g., to neurons within the "zone of danger." In other embodiments, the target area includes portions of the brain not within the zone of danger. Information regarding the biomedical mechanisms or reactions involved in phototherapy is provided by U.S. Patent Application Publication No. 201 1/0144723 to Streeter et al; Tiina I. Karu in "Mechanisms of Low-Power Laser Light Action on Cellular Level", Proceedings of SPIE Vol. 4159 (2000), Effects of Low-Power Light on Biological Systems V, Ed. Rachel Lubart, pp. 1-17; and Michael R. Hamblin et al, "Mechanisms of Low Level Light Therapy," Proc. of SPIE, Vol. 6140, 614001 (2006), each of which is expressly incorporated in its entirety by reference herein. For example, U.S. Patent Application Publication No. 201 1/0144723 to Streeter et al discusses cellular mechanisms of action and includes descriptions of studies or phototherapy examples regarding the effects of phototherapy.

[0053] In some embodiments, low level light therapy involves therapeutic administration of light energy to a patient at lower power outputs than those used for cutting, cauterizing, or ablating biological tissue, which, in several embodiments, results in desirable biological (e.g., biostimulatory) effects while leaving tissue undamaged.

[0054] As described in U.S. Patent Application Publication Nos. 2004/0138727A1 , 2007/0179570A1 , and 2007/0179571A1 , each of which is incorporated in its entirety by reference herein, this discovery has been particularly applicable with respect to treating and saving surviving but endangered neurons after stroke (e.g., in a zone of danger surrounding the primary infarct after a stroke or cerebrovascular accident). Without being bound by theory or by a specific mechanism, it is believed that, in some embodiments, light energy delivered within a certain range of power densities and energy densities provides the desired biostimulative (or other biological) effect on the intracellular environment, such that proper function is returned to previously nonfunctioning or poorly functioning mitochondria in neurons which are at risk due to stroke. The biological effect may include interactions with chromophores within the target tissue, which facilitate production of ATP thereby feeding energy to injured cells which have experienced decreased blood flow due to the stroke. Because strokes correspond to blockages or other interruptions of blood flow to portions of the brain, effects of increasing blood flow of said blocked vessels by phototherapy, in some embodiments, may be of less importance in the efficacy of phototherapy for stroke victims. In other embodiments, treating vessels with interrupted flow may be beneficial. Further information regarding the role of power density and exposure time is described by Hans H.F.I, van Breugel and P.R. Dop Bar in "Power Density and Exposure Time of He-Ne Laser Irradiation Are More Important Than Total Energy Dose in Photo-Biomodulation of Human Fibroblasts In Vitro," Lasers in Surgery and Medicine, Volume 12, pp. 528-537 (1992), which is incorporated in its entirety by reference herein.

[0055] In certain embodiments, the apparatuses and methods of phototherapy described herein are used to treat neurological disorders. As used herein, the term "neurological disorder" refers to at least one characteristic or symptom of a neurological, psychiatric, mood, movement, pain, epilepsy, behavioral, addiction, attention, consciousness, psychological, developmental, or other central or peripheral nervous system disorder. A neurological disorder can also be a thought processes disorder, a memory disorder, a neurodegenerative disorder, an age-related disorder, a cognitive disorder, a motor disorder, a sleep disorder, a speech or language disorder, or other disorder having a neural origin or neural component.

[0056] In certain embodiments, the apparatuses and methods of phototherapy described herein are used to treat physical trauma (e.g., TBI or ischemic stroke) or other sources of neurodegeneration or aid in rehabilitation of the neurodegenerative effects caused by the physical trauma (e.g., TBI or stroke). As used herein, the term "neurodegeneration" refers to the process of cell destruction resulting from primary destructive events such as stroke or CVA, as well as from secondary, delayed and progressive destructive mechanisms that are invoked by cells due to the occurrence of the primary destructive event. Primary destructive events include disease processes or physical injury or insult, including stroke, but also include other diseases and conditions such as multiple sclerosis, amyotrophic lateral sclerosis, myasthenia gravis, Guillain-Barre syndrome, hereditary spastic paraplegia, heat stroke, epilepsy, Alzheimer's disease, dementia resulting from other causes such as AIDS, cerebral ischemia including focal cerebral ischemia, and physical trauma such as crush or compression injury in the CNS, including a crush or compression injury of the brain, spinal cord, nerves or retina, or any acute injury or insult producing neurodegeneration. Secondary destructive mechanisms include any mechanism that leads to the generation and release of neurotoxic molecules, including but not limited to, apoptosis, depletion of cellular energy stores because of changes in mitochondrial membrane permeability, release or failure in the reuptake of excessive glutamate, reperfusion injury, and activity of cytokines and inflammation. Both primary and secondary mechanisms contribute to forming a "zone of danger" for neurons, wherein the neurons in the zone have at least temporarily survived the primary destructive event, but are at risk of dying due to processes having delayed effect.

[0057] In certain embodiments, the apparatuses and methods described herein are used to provide neuroprotection. As used herein, the term "neuroprotection" refers to a therapeutic strategy for slowing or preventing the otherwise irreversible loss of neurons due to neurodegeneration after a primary destructive event, whether the neurodegeneration loss is due to disease mechanisms associated with the primary destructive event or secondary destructive mechanisms.

[0058] In certain embodiments, the apparatuses and methods described herein are used to improve neurologic function, to provide neurologic enhancement, or to regain previously lost neurologic function. The term "neurologic function" as used herein includes both cognitive function and motor function. The term "neurologic enhancement" as used herein includes both cognitive enhancement and motor enhancement. The terms "cognitive enhancement" and "motor enhancement" as used herein refer to the improving or heightening of cognitive function and motor function, respectively.

[0059] Certain embodiments described herein for low level light therapy methods for enhancing neurologic function are based in part on the new and surprising discovery that power density (i.e., power per unit area or irradiance) of the light energy applied to tissue appears to be a very important factor in determining the relative efficacy of low level light therapy, and particularly with respect to enhancing the function of neurons in both healthy and diseased states.

[0060] Certain embodiments described herein provide methods directed toward the enhancement of neurologic function in a subject. The methods include delivering a neurologic enhancing effective amount of a light energy having a wavelength in the visible to near-infrared wavelength range to at least one area of the brain of a subject. In certain embodiments, delivering the neurologic function enhancing effective amount of light energy includes delivering a predetermined power density of light energy through the skull to the target area of the brain and/or delivering light energy through the skull to at least one area of the brain of a subject, wherein the wavelength, power density and amount of the light energy delivered are sufficient to cause an enhancement of neurologic functioning.

[0061] The term "cognitive function" as used herein refers to cognition and cognitive or mental processes or functions, including those relating to knowing, thinking, learning, perception, memory (including immediate, recent, or remote memory), and judging. Symptoms of loss of cognitive function can also include changes in personality, mood, and behavior of the subject. The term "motor function" as used herein refers to those bodily functions relating to muscular movements, primarily conscious muscular movements, including motor coordination, performance of simple and complex motor acts, and the like.

[0062] Diseases or conditions affecting neurologic function include, but are not limited to, Alzheimer's disease, dementia, AIDS or HIV infection, Creutzfeldt-Jakob disease, head trauma or traumatic brain injury (including single-event trauma and long-term trauma such as multiple concussions or other traumas which may result from athletic injury), Lewy body disease, Pick's disease, Parkinson's disease, Huntington's disease, myasthenia gravis, multiple sclerosis, Guillain-Barre syndrome, hereditary spastic paraplegia, drug or alcohol abuse, brain tumors or brain cancer, hydrocephalus, encephalitis, kidney or liver disease, stroke, depression, age-related cognitive impairment, dyskinesias, dystonias, autism, epilepsy, and other mental diseases which cause disruption in cognitive or motor function, and neurodegeneration.

[0063] In other embodiments, the apparatuses and methods described herein are used to treat speech and language disorders. The term "speech disorder" as used herein, refers to an inability of a person to produce speech sounds correctly or fluently or when a person has problems with his or her voice. The term "language disorder" as used herein can refer to a disorder characterized by an inability to understand others or to put words together to communicate ideas to others. Speech and language disorders include, but are not limited to, apraxia, dysarthria, stuttering, aphasia, and dysprosody.

[0064] In other embodiments, the apparatuses and methods described herein are used to treat sleep disorders. The term "sleep disorder" as used herein refers to conditions resulting in a disruption of the sleep patterns of a subject. Sleep disorders include, but are not limited to, insomnia, bruxism, narcolepsy, night terror, cataplexy, parasomnias, restless legs syndrome, obstructive sleep apnea, somnambulism (sleepwalking), periodic limb movement disorder, hypersomnia, circadian rhythm sleep disorders, and nocturia.

[0065] In other embodiments, the apparatuses and methods described herein are used to treat psychiatric disorders. The term "psychiatric disorder" as used herein is to be given its ordinary and customary meaning to a person of ordinary skill in the art in the medical context and also can refer to any pattern of psychological or behavioral symptoms that causes a subject significant distress or otherwise impairs the subject's ability to function in life. Psychiatric disorders include, but are not limited to, anxiety disorders (e.g., panic disorder, obsessive- compulsive disorder, phobias, nightmares, flashbacks, fears of social contacts, separation anxiety disorder, acute stress disorder, post-traumatic stress disorder (PSTD)), depressive disorders (e.g., depression, major depressive disorder, dysthymia, bipolar disorder, seasonal affective disorder, cyclothymia, postnatal depression), personality disorders (e.g., borderline personality disorder), dissociative disorders, mood disorders, somatoform disorders, factitious disorders, sexual and gender identity disorders, adjustment disorders, behavioral disorders (e.g., attention deficit disorder, attention deficit hyperactivity disorder, autism, Asperger's syndrome, Rett's syndrome, drug abuse, alcohol abuse or alcoholism, other substance abuse disorders, addictions such as gambling or sexual addictions), eating disorders (e.g., anorexia, bulimia, binge eating disorder, eating addictions), and psychotic disorders (e.g., schizophrenia, delusional disorder, shared psychotic disorder).

[0066] In some embodiments, the apparatuses and methods described herein are used to treat a disorder in which mitochondrial transport (or axonal transport) is diminished by at least 20%, 25%, 50%, 75% or more. In some embodiments, the apparatuses and methods described herein are used to treat mitochondrial myopathies. In some embodiments, the apparatuses and methods described herein are used to treat peripheral or optical neuropathy based on mitochondrial dysfunction.

[0067] For example, a prominent feature of early Parkinson's disease is the damage to the neuronal processes (e.g., axons and their synapses) that communicate with other neurons. Axons are thin, cylindrical processes that extend so far from the neuronal cell that they require an axonal transport system to supply vital nutrients and important organelles like mitochondria and synaptic vesicles. One recent hypothesis to explain why axons and synapses are damaged in Parkinson's disease patients is a failure in the axonal transport system in dopaminergic neurons.

[0068] To determine if axonal transport is defective, two different models of sporadic Parkinson's disease have been previously used in studies by Dr. Patricia Trimmer et al. of the University of Virginia Department of Neuroscience. In these studies, axonal transport of mitochondria was found to be significantly reduced in processes of Parkinson's disease cybrids (unique human neuronal cell lines that contain the mitochondrial DNA of individual Parkinson's disease patients and which share many important attributes with injured dopaminergic neurons in the brains of Parkinson's disease patients) and similar human neuronal cells exposed to rotenone (a pesticide that damages neurons in a manner that resembles Parkinson's disease). These findings suggest that reduced axonal transport plays an important role in the early stages of Parkinson's disease.

[0069] In several embodiments, axonal transport is altered. For example, studies which are described in more detail below have exposed Parkinson's disease cybrid cells and/or rotenone -treated neuronal cells to LLLT and determined that axonal transport of mitochondria was restored. According to several embodiments, LLLT improves the supply of vital nutrients and/or organelles to axons and synapses in neurological diseases (such as Parkinson's) to compensate at least in part for the reduced axonal transport. In other embodiments, LLLT improves the removal of toxins in, for example, axons and synapses in neurological diseases (such as Parkinson's).

[0070] In several embodiments, axonal transport is enhanced by the administration of light to a neuron. In some embodiments, the neuron has reduced axonal transport, while in some embodiments, the neuron has normal axonal transport. In some embodiments, the neurons have impaired dopaminergic function and/or transport of dopamine-containing vesicles. In some embodiments wherein the neuron has reduced axonal transport, the reduction is caused by disease or injury (as discussed herein). In some embodiments, the neuron has reduced axonal transport, and said reduction is purposefully induced by chemical, physical, or other means, in order to simulate or model a disease state (e.g., rotenone induced damage to model Parkinson's disease or genetic over-expression of Amyloid proteins to model Alzheimer's disease).

[0071] In some embodiments, axonal transport can be altered by at least about 10%, 20%, 30%, 40%, 50%, or more. Axonal transport can be modified, for example, to alter transport velocity (fast axonal flow; FAF) distance, mitochondrial membrane potential, neuronal excitability, or transport of quantity of elements such as substances, such as neurotransmitters, neurotoxins, or mitochondria.

[0072] The various mechanisms involved in altering axonal transport are dependent, in some embodiments, on the wavelength of light administered. In some embodiments, the power of light is important in determining the effect and/or mechanism involved in altering axonal transport. In some embodiments, the overall energy density of light administered is important in determining the effect and/or mechanism involved in altering axonal transport In some embodiments, combinations of two or more of these parameters, as well as time and tissue heating (as discussed above) determine the effect on axonal transport.

[0073] In several embodiments, LLLT is applied to affect different cell types differentially. In some embodiments, LLLT is used to selectively affect neurons that are predisposed to, or already have, reduced axonal transport (e.g., impaired cells). In some embodiments, LLLT selectively affects neurons based on morphology. In some embodiments, LLLT selectively affects cells having long axons (e.g. sensory neurons). In some embodiments, neurons with a defined cell body (a neuritic morphology as opposed to a more non-neural morphology) are selectively affected by LLLT.

[0074] In some embodiments, light administration at different parameters can reduce, slow, or even stop (reversibly or irreversibly depending on the embodiment) axonal transport. In several embodiments, administering light having a power density greater than a first threshold level, but less than a second threshold level greater than the first threshold level will increase axonal transport with respect to a patient's pre-light treatment baseline, while administering light having a power density above the second threshold level will decrease axonal transport below a patient's pre-light treatment baseline. In some embodiments, the first threshold level at the target tissue surface is less than or equal to about 200, 150, 100, 75, 50, 25, 10, or less mW/cm². In some embodiments, the second threshold level at the target tissue surface is greater than or equal to about 150, 200, 250, 300, 350, 400, or greater mW/cm . In several embodiments, the thresholds above are representative of the average irradiance at the target tissue, while in other embodiments, the thresholds are representative of the peak irradiances at the target tissue. In some embodiments, the light can be administered continuously or alternatively in pulses for a total of no more than about 240, 200, 160, 120, 90, 60, 50, 40, 30, 20, 10, 5 seconds, or less. [0075] As such, low energy light therapy can be used to alter axonal transport in either a positive or a negative fashion, depending on the desired clinical result. Clinical presentation of a patient may suggest that administration of light to enhance axonal transport is necessary (e.g., to treat or ameliorate a reduction in axonal transport). In some embodiments, light is administered to treat neuronal degeneration, including degeneration of motor, sensory, or cortical neurons. In some embodiments, light is administered to treat impaired dopaminergic function.

[0076] In contrast, clinical symptoms may suggest that administration of light is needed to reduce axonal transport. For example, light administration could be used in order to reduce axonal transport and neuronal function in sensory neurons, thereby functioning as an anesthetic or analgesic. Certain such embodiments are particularly advantageous if patients requiring anesthesia are sensitive to normal anesthetic agents. In some embodiments, light administration reduces axonal transport in order to modulate nociception (for example in patients with a hyperactive pain response or having phantom pain due to trauma or amputation of limbs). Thus, several embodiments disclosed herein are useful for as a non-drug alternative for management of pain, including chronic pain. Moreover, light administration at parameters that reduce axonal transport are used, in some embodiments, to reduce the activity of hyperactive neurons.

[0077] Several embodiments described herein advantageously provide low energy laser treatment to combat a reduction of transport of desired compounds (e.g., nutrients, organelles) and/or enhance the transport of undesired compounds (e.g., toxins) in and out of a cell. In some embodiments, delivering electromagnetic radiation to brain cells, the spinal cord, and/or peripheral nerves causes an improvement of mitochondrial function in irradiated cells (e.g., neurons). Delivering electromagnetic radiation to peripheral nerves can also modulate axonal transport and mitochondrial function, depending on the desired clinical result. In some embodiments, increasing axonal transport can be also used to treat Alzheimer's disease, Huntington's disease, amyotropic lateral sclerosis, myasthenia gravis, multiple sclerosis, Guillain-Barre syndrome, or hereditary spastic paraplegia, for example. Increasing axonal transport can also be useful to clear substances such as neurotoxins, including botulinum, or neuropathic side effects from chemotherapeutic agents, such as taxanes, vinca alkaloids, or platinum-based agents for example. [0078] In certain embodiments, the apparatus and methods of phototherapy described herein increase the cerebral blood flow of the patient. In certain such embodiments, the cerebral blood flow is increased by at least about 10%, 15%, 20%, or 25% immediately post-irradiation, as compared to immediately prior to irradiation.

[0079] In certain embodiments, it is advantageous to decrease axonal transport, such as by decreasing axonal transport velocity, distance, or quantity of mitochondria traveled along an axon by at least about 10%, 20%, 30%, 40%, 50%, or more in some embodiments. In some embodiments, decreasing axonal transport can inhibit neurons, such as hyperactive neurons, or promote or prevent release or uptake of a substance, such as a neurotransmitter. Reducing axonal transport could result, for example, in increased production of serotonin, increased synthesis of endorphins, increased synaptic activity of acetylcholinesterase, or inhibition of the sodium-potassium ATPase responsible for maintaining the resting potential of nerves. While any wavelength of light, such as those described elsewhere in the application can be used, in certain embodiments, light having a wavelength of from about 780-930 nm, such as between about 810-830 nm is used. In some embodiments, light having a wavelength between about SOS- SIS nm (e.g., 808 nm, 810 nm) is at least 10%, 25%, 50%, 75% or more efficacious than light at other wavelengths according to parameters disclosed herein.

[0080] Modulating axonal transport could be particularly advantageous to treat psychiatric conditions, such as schizophrenia, mania, anxiety, or attention deficit disorder for example. Decreasing axonal transport could be beneficial for analgesia to treat acute or chronic pain disorders, including neuropathic pain (such as trigeminal neuralgia, diabetic or post herpetic neuropathy, complex regional pain syndrome, or fibromyalgia, for example), joint disorders such as osteoarthritis or rheumatoid arthritis, or to prevent withdrawal from drug or substance dependence, such as opiate or benzodiazapene withdrawal, for example. Inhibiting hyperactive neurons could be beneficial in treating disorders such as tremors or seizures. Decreasing axonal transport via light therapy may also be beneficial as a primary or adjunctive local or general anesthetic. Additional details regarding the use of phototherapy in treating disorders or conditions in which mitochondrial transport (or axonal transport) is diminished (including in vitro and in vivo studies) can be found in U.S. Patent Application Publication No. 201 1/0144723, the entire content of which is incorporated herein by reference. [0081] The term "treat" as used herein is to be given its ordinary and customary meaning to a person of ordinary skill in the art in the medical context and also can refer to the curing, improvement, maintenance, or reduction in rate of progression of neurological conditions, disorders, diseases or syndromes and/or the slowing, maintenance, reduction, or removal of the symptoms or effects associated therewith. The terms "subject" and "patient" are used interchangeably herein to refer to the person or animal being treated or examined.

[0082] As used herein, the terms "therapeutic regimen" and "treatment regimen" refer to a protocol and associated procedures used to provide a therapeutic treatment that includes one or more periods during which light is irradiated to one or more neural target regions. As used herein, the terms "target," "target area," and "target region" refer to a particular neural area, region, location, structure, population, or projection (e.g., within the brain or spinal cord) to be irradiated by light in association with the treatment of a particular type of neurologic condition, disease, disorder, or injury. In certain embodiments, the irradiated portion of the brain can comprise the entire brain. In other embodiments, the irradiated portion of the brain can comprise a targeted region of the brain, such as the hypothalamic region, the prefrontal cortex, the cerebellum, or the brainstem.

Implantable Light Therapy Apparatus

[0083] The phototherapy methods for the treatment of neurologic conditions described herein may be practiced and described using various light delivery systems. Such light delivery systems may include a low level laser therapy apparatus based on, though modified for use as an implantable apparatus, those shown and described in U.S. Pat. Nos. 6,214,035; 6,267,780; 6,273,905; 6,290,714; and 7,303,578 and in U.S. Pat. Appl. Publ. Nos. 2005/0107851 , 2007/0179571 , 2009/0254154, and 2010/0067128, the contents of each of which is hereby incorporated by reference in its entirety herein.

[0084] As disclosed in several embodiments, invasive methodologies may be varied in their degree of invasiveness. As used herein, "invasive" is to be given its ordinary and customary meaning to a person of ordinary skill in the art in the medical context and also may mean a method that comprises breaking the plane of a subject's skin in order to administer phototherapy. In some embodiments, invasive procedures employ the use of an indwelling light therapy apparatus, at least temporarily. In certain embodiments, the light therapy apparatus is permanently implanted in a subject. In other embodiments, the light therapy apparatus is resident within a subject for an extended period of time, ranging from several weeks to several years.

[0085] In some embodiments, the invasive procedures comprise minimally invasive procedures. As used herein, "minimally invasive" may mean a method that comprises breaking the plane of a subject's skin but not breaking the plane of internal bone or neural tissue. For example, a minimally invasive method can comprise delivering phototherapy via an indwelling light therapy apparatus positioned beneath the inner surface of the scalp but above the outer surface of the skull. Implantation below the scalp removes the scattering of the light caused by blood and/or skin pigmentation in the scalp tissue. Implantation above the skull reduces the trauma and injury to the skull or neural tissue and reduces the risk of disease or infection to the internal tissue. Minimally invasive procedures may be more acceptable to subjects and can have reduced recovery times. Accordingly, the phototherapy is applied without penetrating the skull and/or the brain, thereby reducing trauma or damage to the internal tissue.

[0086] FIGS. 1A and IB illustrate two different embodiments of an implantable light therapy apparatus 5. The light therapy apparatus 5 comprises a base sheet, or mat 10 formed of a biocompatible material. The light therapy apparatus 5 further comprises one or more light energy sources 20 variably positioned and retained on or within the base sheet 10, each capable of emitting light energy having a wavelength in the visible to near-infrared wavelength range, a programmable controller 30 operative ly coupled to the one or more light sources 20, and a power source 40 operatively coupled to the one or more light sources 20 and to the programmable controller 30. In various embodiments, the light sources 20 are mechanically coupled to, on, or within, the base sheet 10. The light sources can be variably positioned on or within the base sheet 10 according to any pattern as desired and/or required.

Base Sheet

[0087] Any biocompatible material may be used to form the base sheet 10. In some embodiments, the base sheet 10 is made of a flexible material, thereby allowing the base sheet 10 to conform to the contour of the skull. In other embodiments a partially flexible, substantially rigid, or rigid material is used. In some embodiments, the base sheet 10 is made of mylar. In other embodiments, the base sheet 10 is made of polytetrafluoroethylene (PTFE), nylon-backed polychloroprene, silicone, SILASTIC (available from Dow Corning Corp.), titanium mesh, and/or the like. Other suitable biocompatible materials include, but are not limited to composite materials, carbon fiber, metals, collagen, polymers and/or plastics. The biocompatible materials can be compatible with the ISO 10993 biocompatibility standard. The base sheet 10 can be made of reabsorbable polymers (e.g., polylactic acid membranes) such that the light sources 20 eventually become fixed to the surrounding tissue. In certain embodiments, combinations of materials are used. In certain embodiments, the materials combined have varying degrees of flexibility. In some embodiments, porous materials may be used (e.g., non-rigid, macroporous membranes or protective sheets), such that tissue surrounding the base sheet 10 grows into the pores to maintain the positioning of the light therapy apparatus 5. In other embodiments, the base sheet 10 comprises porous materials, such as porous SILASTIC (available from Dow Corning Corp.) sheets. The base sheet 10 can comprise an electroluminescent material and not incorporate discrete light sources. The base sheet 10 can advantageously comprise thermally conductive materials.

[0088] The base sheet 10 can be any geometric shape that is amenable to providing the light sources 20 in a desired arrangement for a particular treatment regimen. In several embodiments, the base sheet 10 is shaped and dimensioned to retain one or more light sources 20 so as to enable administration of light to a single or a plurality of treatment sites. For example, in some embodiments, a circular or oval base sheet 10 is used, as schematically illustrated in FIG. 1A. Certain such embodiments can be used, for example, when administering light to one or more regions of the brain. In other embodiments, rectangular or other substantially linear shapes are employed for the base sheet 10, as schematically illustrated in FIG. IB. Such embodiments can be used, for example, when administering light to one or more regions of the brainstem or spinal column.

[0089] In various alternative embodiments, the base sheet 10 can comprise an H- shape, an L-shape, a V-shape, a T-shape, or an I-shape. In still other embodiments, the base sheet 10 can comprise a ring shape or S-shape. For example, the H-shaped implant can be configured to align with the sutures of the brain, as will be described in more detail below. The shape and dimensions of the base sheet 10 can be selected based on the particular disease or condition and/or the target zone to be treated, the number and type of light sources used, and/or the parameters of light used for the light therapy. The size of the base sheet 10 can range from covering the entire bony area of the skull (e.g., approximately 22 cm long (from forehead to occiput), approximately 18 cm wide, and having an average circumference of 54-57 centimeters) down to being just large enough to accommodate a single light source configured to emit a beam of light having a thermally-safe irradiance, or any size in between. In some embodiments, the base sheet 10 is manufactured in a large simple shape, for example a square, and is trimmed to a particularly desired shape prior to implantation. In some such embodiments, the light sources 20 are positioned after the base sheet 10 is trimmed.

[0090] In certain embodiments, the base sheet 10 is dimensioned such that it may be implanted under the scalp of a subject, but external to the skull (e.g., sub-dermal implantation). This is schematically illustrated in FIGS. 2A and 2B. Accordingly, the base sheet is dimensioned to be substantially flat. In FIG. 2A, the base sheet 10 is positioned under the scalp 15, but outside the skull 25 of the subject, resulting in a minimally invasive procedure. The light sources 20 may be placed at advantageous points in the base sheet 10 such that the illumination, 50a in FIG 2B, passes through the skull 25 of the subject and into the brain tissue 35. In other embodiments, the base sheet 10 is dimensioned to be implanted subdermally and positioned to irradiate the brainstem, the cerebellum, the spinal column, or other components of the nervous system. For example, the base sheet 10 can be positioned at a posterior region of the skull to irradiate the brainstem and/or the cerebellum.

[0091] While the subdermal space surrounding the skull or other neural tissue may be expanded by placement of the light therapy apparatus 5, in some embodiments, the thickness of the base sheet 10 is less than about 7mm thick. In some embodiments, the thickness of the base sheet 10 ranges from about 3 mm to about 5 mm. In some embodiments, the base sheet 10 is of uniform thickness. In other embodiments, the base sheet 10 is thicker in some areas relative to other areas. In such embodiments, the thicker areas may house additional light sources 20, or other components of the light therapy apparatus 5 which may benefit from being placed in a thicker portion of the base sheet 10. For example, in some embodiments, a microcontroller (e.g., programmable controller 30) or power supply (e.g., power source 40) may be positioned in a thicker region of the base sheet 10. In some embodiments, thicker portions of the base sheet 10 may be positioned at anchoring, or attachment, points, discussed in more detail below.

[0092] In several embodiments, the base sheet 10 is affixed to an underlying body structure, thereby enhancing the accuracy and precision of the light therapy. For example, in some embodiments, the base sheet 10 is affixed to the outer surface of the skull 25. In some embodiments, the base sheet 10 is adhered to the outer surface of the skull 25 through the use of a biocompatible adhesive or bioadhesive. In other embodiments, anchoring screws, staples, or other physical anchoring or fastening mechanisms, such as anchoring techniques used during plastic surgery (e.g., facelifts) and hair transplant procedures, can be used to affix the base sheet 10 to the skull 25. Osseointegration can occur between the anchoring, or fixation, mechanisms and the bone over time to facilitate anchoring. In still other embodiments, combinations of adhesives and physical mechanisms can be used. The anchoring, or fixation, mechanisms can be permanent, semi-permanent or temporary.

[0093] In some embodiments, the base sheet 10 can be anchored to one, two, or more vertebrae. In some such embodiments, the base sheet 10 may also comprise extensions, or "wings," that are used to attach the base sheet 10 to one or more transverse processes of the vertebrae. In other embodiments, the base sheet 10 is attached to the spinous process of one or more vertebrae. Besides improving the accuracy and precision of the light therapy, which results in more effective treatment, anchoring the light therapy apparatus 5 can advantageously prevent irradiation of healthy, non- targeted regions of neural tissue.

Light Sources

[0094] As used herein, "light sources" is to be given its ordinary and customary meaning to one of ordinary skill in the art and may also mean an element of the light therapy apparatus 5 that is configured to provide optical output (e.g., transmits light from the light therapy apparatus 5 to the neural tissues of the subject). Although the embodiments disclosed herein contemplate light sources, the light sources could be replaced with, or used in combination with, non-light energy sources, such as magnetic energy sources, radio frequency sources, DC electric field sources, ultrasonic energy sources, microwave energy sources, mechanical energy sources, electromagnetic energy sources, and the like. For example, the phototherapy could be combined with transcranial magnetic stimulation therapy. As shown in FIG. 3, the light source 20 is disposed within the base sheet 10. The light source 20 comprises an emission surface 22 that directs light emitted from the light source 20 towards the subject's neural tissue. The light source 20 can optionally comprise a lens, diffuser, waveguides, and/or other optical elements. [0095] Any type of light source that is biocompatible may be used. In certain embodiments, one or more light emitting diodes (LED) are used. In other embodiments, one or more laser diodes are used. The one or more laser diodes can be gallium-aluminum-arsenic (GaAlAs) laser diodes and/or vertical cavity surface-emitting laser (VCSEL) diodes, for example. In certain arrangements where multiple light sources are used, the light sources can be coupled to one or more optical fibers. Other light sources that generate or emit light with an appropriate wavelength and irradiance can also be used. In some embodiments, a combination of multiple types of light sources can be used.

[0096] In several embodiments, the light sources 20 are dimensioned such that they may be housed in the base sheet 10, as described above, and implanted under the scalp 15 of a subject, but external to the skull 25 (e.g., minimally invasive implantation). In other embodiments, the light sources 20 are dimensioned to be housed in a longitudinal, or other shaped base sheet 10, and placed along or around the spinal column. In various embodiments, the light sources are mechanically coupled to and/or within the base sheet 10.

[0097] In some embodiments, the light sources 20 range from about 2 mm to about 7 mm thick. In some embodiments, the light sources 20 are between about 3 mm and about 5 mm thick. In some embodiments, the light sources 20 are between about 4 mm and about 6 mm thick. In certain embodiments, the light sources 20 are about 2, 3, 4, 5, 6 or 7 mm thick. In certain embodiments with a plurality of light sources, the light sources 20 may be of different or the same thickness as other light sources 20. In some embodiments, the light sources 20 range from about 2 mm to about 7 mm in length and/or width. In some embodiments, the light sources 20 are between about 3 mm and about 5 mm in length and/or width. In some embodiments, the light sources 20 are between about 4 and about 6 mm in length and/or width. In certain embodiments, the light sources 20 are about 2, 3, 4, 5, 6 or 7 mm in length and/or width. The light source can comprise a single light source that covers substantially the entire base sheet. In certain embodiments with a plurality of light sources, the light sources 20 may be of different or the same length and/or width as other light sources. In still other embodiments with a plurality of light sources, combinations of light sources 20 of varied dimension (from one another) are used to provide optimal dimensions for the position of a given light source 20 on the base sheet 10 and as implanted in the subject. [0098] In certain embodiments, the irradiance of the light beam is selected to provide a predetermined irradiance at the target neural tissue. The target neural tissue may be an area of the brain affected by disease or trauma that has been identified using standard medical imaging techniques, it may be a portion of the brain that is known to be affected by a particular disease, it may be a portion of the brain that is known to control certain functions or process, or it may be any section of the brain. The selection of the appropriate irradiance of the light beam emitted from the emission surface 22 to use to achieve a desired irradiance at the level of the target neural tissue preferably includes, among other factors, the wavelength of light selected, the type of disease (if any), the clinical condition of the subject, skull thickness, and the distance to the target region.

[0099] In some embodiments with a plurality of light sources, certain light sources emit light at a higher or lower power as compared to other light sources. Power output of the light source can thus be tailored depending on the thickness of the skull, bone, or other intervening tissue between the emission surface 22 of the light source 20 and the target neural tissue. The parameters of the light emitted by the light sources 20 are discussed in greater detail below.

[0100] The light sources 20 are variably positionable in the base sheet 10 depending on the neurological disorder to be treated. In such embodiments, the light sources 20 are removably attached to the base sheet 10 so that they may be placed in the position needed for treatment of any target region of the brain. In several embodiments, the light sources 20 are uniformly positioned within the base sheet 10 in a grid pattern. In such embodiments, the distance between the light sources 20 on the base sheet 10 is a distance allowing the fields of neural tissue irradiated by the emitted light to abut one another (e.g., there are no gaps in the irradiated field). In other embodiments, the light sources 20 are strategically placed within the base sheet 10 such that a target region of neural tissue is irradiated from multiple light sources 20 (e.g., via triangulation). In other embodiments, the light sources 20 are placed within the base sheet 10 such that two or more light sources 20 irradiate the same portion of neural tissue. In certain such embodiments, the light sources 20 may be activated alternately or in series such that the target neural tissue is irradiated, but the tissue closest to the emission surface is not constantly irradiated, and thus experiences less temperature increase during treatments. In other embodiments, the light sources 20 can advantageously be positioned within the base sheet 10 so as to align with one or more sutures of the skull 25, as shown in FIG. 4, thereby enhancing the delivery of light to the target neural tissue.

Programmable Controller

[0101] To tailor one or more of the light energy emission, light energy intensity, light energy duration, frequency, area or sequence of application of light energy to a subject's neural tissue, or other treatment parameters, several embodiments comprise a programmable controller 30. In general, the programmable controller 30 executes a set of program instructions that are stored in memory to accomplish tasks or operations such as, but not limited to, operating the one or more light sources 20 according to a particular therapeutic regimen, communicating with external devices, monitoring the condition of elements such as the light sources 20 and the power source 40, storing parameters or program instructions in the memory, and the like. For example, the programmable controller 30 can be used to transmit light to specific target regions of the brain according to a therapeutic regimen. For example, the programmable controller 30 can execute a treatment program that includes a set of activation times or periods during which each of the light sources is in an emitting state and a set of inactivation times or periods during which the light source is in a non-emitting state. In certain embodiments, the programmable controller 30 comprises a general or a special purpose microprocessor. The programmable controller 30 can comprise an application-specific integrated circuit (ASIC) or Field Programmable Gate Array (FPGA).

[0102] The programmable controller 30 can communicate with internal memory to retrieve and/or store data and/or program instructions for software and/or hardware. In certain embodiments, the programmable controller 30 comprises a central processing unit (CPU). The programmable controller 30 can further include memory, such as random access memory (RAM) for temporary storage of information and/or flash memory, read only memory (ROM), EPROM memory, and/or EEPROM memory for permanent storage of information. In certain embodiments, the memory can be reprogrammable after the initial programming. Additionally, the programmable controller 30 can include a real time clock, one or more timers, an analog to digital (A D) converter, a digital to analog (D/A) converter, a serial communications interface, such as PC or Serial Peripheral Interface, a communications interface, and/or a pulse width modulation (PWM) generator. As depicted in FIG. 5, the power source 40 can provide power to the programmable controller 30, which in turn can drive the one or more light sources 20. In certain embodiments, the programmable controller 30 drives the one or more light sources 20 through a light source driver (not shown). The light source driver can provide an appropriate current or voltage level to energize the one or more light sources 20. When the programmable controller 30 generates a control signal to drive a light source 20, light 50a is emitted from the emission surface 22. In contrast, when the light source 20 is not receiving a control signal from the programmable controller 30 to generate light, the emission surface 22 is in a non-emitting state. The light sources 20 can be configured to emit light continuously or periodically in accordance with various therapeutic regimens.

[0103] In some embodiments, the programmable controller 30 is preprogrammed (e.g., prior to implantation) with a desired set of treatment parameters for a given subject (e.g., patient). For example, a desired frequency of light energy emission (e.g., every 24 hours), duration of light energy emission (e.g., for 20 minutes), irradiance of light energy emission (e.g., from about lmW to about 10 mW), irradiation pattern or order of light source activity (e.g., a sequence of emission of light energy in those embodiments comprising more than one light source), and other parameters can be preprogrammed into the programmable controller 30. For pulsed light dosimetry, the treatment parameters can also include duty cycle, pulse shape, repetition rate, pulse width and/or irradiance per pulse for pulsed light dosimetry.

[0104] In embodiments comprising a plurality of light sources, the programmable controller 30 can be programmed to activate a subset of the light sources 20 to focus on a particular target region. In other embodiments, the programmable controller 30 can be programmed to activate the light sources 20 according to a predetermined treatment regimen, order, template, or sequence. For example, the treatment regimen can follow a pattern similar to the sequences described in paragraphs [0203]-[0228] of U.S. Patent Application Publication No. 2009/0254154, the entire contents of which are hereby expressly incorporated by reference herein. The treatment regimen can also be adjustable by a physician (e.g., via telemetry or a wireless and/or wired network interface).

[0105] In other embodiments, the programmable controller 30 can be reprogrammed dynamically via the communications interface. The communications interface can comprise an antenna configured to receive RF communication from an external telemetry unit. The communications interface can also be configured to transmit information to the external telemetry unit. Other types of wireless communication links can also be used without departing from the spirit and/or scope of the disclosure. For example, treatment parameters of the phototherapy can be adjusted after implantation in order to optimize the phototherapy based on observed subject response to prior treatments or to adjust the therapy based on a change of conditions or to account for individual subject characteristics. In other embodiments, a physician can adjust treatment parameters in response to an alarm or warning generated by the light therapy apparatus 5. The physician can reprogram the programmable controller 30 wirelessly via the communications interface.

[0106] In still other embodiments, the programmable controller 30 can automatically reprogram itself and/or recalibrate its treatment parameters in response to control signals received from feedback sensors. The sensors can provide feedback regarding the parameters of the light treatment and/or the physiological parameters of the subject (e.g., patient). The sensors can include biomedical sensors, biochemical sensors, temperature sensors, and the like. In some embodiments, the sensors can be invasive sensors and can be implanted within the body at least temporarily. In other embodiments, the sensors can comprise noninvasive or minimally invasive sensors. The sensors can be used to measure, for example, adenosine triphosphate (ATP) levels or activity, brain waves (e.g., using an electroencephalography (EEG) sensor system), mitochondrial activity (e.g., by measuring NADH or NADPH levels), nitric oxide (NO) production or consumption, serotonin (5-HT) or selective serotonin reuptake inhibitor (SSRI) activity, cytokines (such as IL-6 interleukins and tumor necrosis factors (TNF)), apoptotic markers (such as Bax and Bcl-2 ), evoked response optical scanning (EROS) responses, oxygen consumption levels, membrane potential, cholinergic molecule concentration, glycolysis activity, and/or pH levels. For example, increases in cellular ATP concentration and a more reduced state within the cell are both related to cellular metabolism and are considered to be indications that the cell is viable and healthy. The increased concentration of NADH within the targeted neural tissue and a corresponding improvement in the redox state of the targeted neural tissue reflects both the metabolic activities and the health of cells.

Power Source

[0107] In several embodiments, the light sources 20 and the programmable controller 30 are powered by a power source 40 implanted in the subject. In some embodiments, the power source 40 is housed within the base sheet 10. In other embodiments, the power source 40 is placed at a position remote from the base sheet 10. For example, the power source 40 may be placed in a subdermal space formed in the subject's pectoral region and electrically coupled (via a cord, cable or the like) to the programmable controller 30 and the light sources 20 housed in the base sheet 10. The power source 40 may comprise one or more electronic components, including, for example, capacitors, diodes, resistors, inductors, transistors, regulators, batteries, fuel cells, and/or any other suitable energy storage device. It is contemplated that the power source 40 may use any type of device, component, or system configured to store electromagnetic energy, including those now existing and those to be developed in the future. In some embodiments, the power source 40 comprises a zinc air battery, similar to those used in hearing aids.

[0108] In certain embodiments, the power source 49 is rechargeable. For example, the power source 49 can comprise a lithium vanadium pentoxide battery, a manganese dioxide lithium battery, a nickel cadmium battery, a nickel-metal hydride battery, a lithium ion battery, or a battery of any other suitable rechargeable battery chemistry. In some embodiments, the power source 40 may comprise an inductive coil and charging circuit that can be charged inductively by an external charging station. In other embodiments, the power source 40 may be an RF-powered device that can be charged by radio frequency (RF) energy. In still other embodiments, the power source 40 may be positioned sufficiently close to the surface of the subject's skin that it may be directly connected to an external power source for recharging. In certain such embodiments, the external power source may optionally be used to power the device.

[0109] In several embodiments employing a rechargeable power source, the charge capacity of the power source 40 is sufficient to last through at least one treatment session. Duration and frequency of the treatment required varies with the severity of the neurodegenerative disease involved. In some embodiments, the charge capacity need only be sufficient to power the programmable controller 30 and light sources 20 for about 10 minutes to about 30 minutes. In other embodiments, the treatment period is about 20 minutes. In those subjects requiring treatment for long periods and/or at high frequencies, some embodiments employ two, three, or more power sources 40 that are coupled to the programmable controller 30 and light sources 20 and provide sufficient power for the longer or more frequent treatment sessions. In other embodiments, a single high capacity power source can be used. In still other embodiments, the power source 40 can include a combination of one or more capacitors and one or more batteries.

Cooling Elements

[0110] In some embodiments, the light delivery apparatus 5 can irradiate a portion of the subject's skull while cooling the irradiated portion of the skull. For example, the light delivery apparatus 5 can include a thermoelectric assembly and/or heat sink thermally coupled to the one or more light sources 20, similar to those described in U.S. Patent Application Publication No. 2009/0254154, filed on March 13, 2009, the contents of which is hereby expressly incorporated by reference herein. In other embodiments, no cooling mechanisms for cooling either the scalp or the skull are employed.

[0111] The light source 20 can be configured to maintain the temperature of the emission surface 22 to be in a range of 18 degrees Celsius to 25 degrees Celsius under a heat load of 2 Watts. In certain other embodiments, the irradiated portion of the subject's skull is not cooled while irradiating the portion of the skull. In certain embodiments in which pulsed light is used, the rate of heat removal can be less, or cooling may not be utilized for certain ranges of pulsed dosimetries and timing. In some embodiments, the neural tissue irradiated is the brainstem or the spinal column.

[0112] In certain embodiments, the emission surface 22 is adapted to conform to the curvature of the skull. The emission surface 22 of certain embodiments is concave (e.g., generally spherical with a radius of curvature of about 100 millimeters). By fitting to the curvature of the skull, the emission surface 22 advantageously controls, inhibits, prevents, minimizes, or reduces temperature increases at the skull that would otherwise result from air- filled gaps between the emission surface 22 and the skull. Thus, by virtue of the emission surface 22 fitting to the curvature of the portion of the subject's skull being irradiated, the temperature of the irradiated portion of the subject's skull is lower than it would otherwise be if the emission surface 22 did not fit to the curvature of the irradiated portion of the skull. For example, by fitting the emission surface 22 to the curvature of the irradiated portion of the subject's skull, the temperature of the irradiated portion of the subject's skull can be higher than the temperature of the portion of the subject's skull if it were not irradiated, but lower than the temperature of the portion of the subject's skull if it were irradiated but the emission surface 22 did not fit to the portion of the subject's skull. The existence of air gaps between the emission surface 22 and the skull can reduce the thermal conductivity between the emission surface 22 and the skull, thereby increasing the probability of heating the skull by the irradiation.

[0113] In addition, the refractive-index mismatches between such an air gap and the emission surface 22 and/or the skull can cause a portion of the light propagating toward the skull to be reflected away from the skull. In certain embodiments, the emission surface 22 is placed in contact with the skull (or the pericranium layer covering the skull) so as to advantageously substantially reduce air gaps between the emission surface 22 and the skull in the optical path of the light. In certain other embodiments in which an intervening material (e.g., a substantially optically transmissive and substantially thermally conductive gel) is in contact with the skull and with the emission surface 22, the emission surface 22 is placed in contact with the intervening material so as to advantageously avoid creating air gaps between the emission surface 22 and the intervening material or between the intervening material and the skull.

[0114] In certain embodiments, the emission surface 22 comprises one or more optical coatings, films, layers, membranes, etc. in the optical path of the transmitted light which are adapted to reduce back reflections. By reducing back reflections, the emission surface 22 increases the amount of light transmitted to the brain and reduces the need to use higher irradiances, which may otherwise create temperature increases at the skull.

Diffusion

[0115] In certain embodiments, the light source 20 comprises one or more diffusers adapted to diffuse the light prior to reaching the skull or neural tissue to advantageously homogenize the light beam prior to reaching the emission surface 22. Generally, intervening tissues of the skull are highly scattering, which can reduce the impact of non-uniform beam intensity distributions on the illumination of the subject's cerebral cortex. However, nonuniform beam intensity distributions with substantial inhomogeneities could result in some portions of the subject's skull being heated more than others (e.g., localized heating where a "hot spot" of the light beam impinges the subject's skull).

[0116] In certain embodiments, the light source 20 advantageously homogenizes the light beam to have a non-uniformity less than approximately 3 millimeters. Figures 6A and 6B schematically illustrate the diffusive effect on the light by the light source 20. An example energy density profile of the light prior to being transmitted through the light source 20, as illustrated by FIG. 6A, is peaked at a particular emission angle. After being diffused by the light source 20, as illustrated by FIG. 6B, the energy density profile of the light does not have a substantial peak at any particular emission angle, but is substantially evenly distributed among a range of emission angles. By diffusing the light, the light source 20 distributes the light energy substantially evenly over the area to be illuminated, thereby controlling, inhibiting, preventing, minimizing, or reducing "hot spots" which would otherwise create temperature increases at the skull. Thus, by virtue of the light source 20 diffusing the light, the temperature of the irradiated portion of the subject's skull is lower than it would otherwise be if the light source 20 did not diffuse the light. For example, by diffusing the light, the temperature of the irradiated portion of the subject's skull can be higher than the temperature of the portion of the subject's skull if it were not irradiated, but lower than the temperature of the portion of the subject's skull if it were irradiated but the light were not diffused by the light source 20. In addition, by diffusing the light prior to reaching the skull, the light source 20 can effectively increase the spot size of the light impinging the skull, thereby advantageously lowering the irradiance at the skull, as described in U.S. Patent No. 7,303,578, which is incorporated in its entirety by reference herein.

[0117] In certain embodiments, the light source 20 provides sufficient diffusion of the light such that the irradiance of the light is less than a maximum tolerable level of the skull, brain, or other neural tissue. For example, the maximum tolerable level of certain embodiments is a level at which the subject experiences discomfort or pain, while in certain other embodiments, the maximum level is a level at which the subject's skull or neural tissue is damaged (e.g., burned). In certain other embodiments, the light source 20 provides sufficient diffusion of the light such that the irradiance of the light equals a therapeutic value at the target neural tissue. The light source 20 can comprise example diffusers including, but are not limited to, holographic diffusers such as those available from Physical Optics Corp. of Torrance, California and Display Optics P/N S 1333 from Reflexite Corp. of Avon, Connecticut.

Feedback

[0118] FIG. 7 is a block diagram of a control circuit 100 comprising a programmable controller 130 for controlling a light source 120 according to embodiments described herein. The control circuit 100 is configured to adjust the power of the light energy generated by the light source 120 such that the light emitted from the emission surface 122 generates a predetermined surface irradiance at the skull or vertebra corresponding to a predetermined energy delivery profile, such as a predetermined subsurface irradiance, to the target area of the brain.

[0119] In certain embodiments, the programmable controller 130 comprises a logic circuit 132, a clock 134 coupled to the logic circuit 132, and an interface 136 coupled to the logic circuit 132. The clock 134 of certain embodiments provides a timing signal to the logic circuit 132 so that the logic circuit 132 can monitor and control timing intervals of the applied light. Examples of timing intervals include, but are not limited to, total treatment times, pulse width times for pulses of applied light, and time intervals between pulses of applied light. In certain embodiments, the light source 120 can be selectively turned on and off to reduce the thermal load on the skull or neural tissue and to deliver a selected irradiance to particular areas of the brain or other neural tissue.

[0120] The interface 136 of certain embodiments provides signals to the logic circuit 132 which the logic circuit 210 uses to control the applied light. The interface 136 can comprise a user interface or an interface to a sensor monitoring at least one parameter of the treatment. In certain such embodiments, the programmable controller 130 is responsive to signals from the sensor to preferably adjust the treatment parameters to optimize the measured response. The programmable controller 130 can thus provide closed-loop monitoring and adjustment of various treatment parameters to optimize the phototherapy. The signals provided by the interface 136 from a user are indicative of parameters that may include, but are not limited to, individual subject characteristics (e.g., skin type, fat percentage), selected applied irradiances, target time intervals, and irradiance /timing profiles for the applied light.

[0121] In certain embodiments, the logic circuit 132 is coupled to a light source driver 138. The light source driver 138 is coupled to a power supply 140, which in certain embodiments comprises a battery or capacitive energy storage device and in other embodiments comprises an alternating current source. The light source driver 138 is also coupled to the light source 120. The logic circuit 132 is responsive to the signal from the clock 134 and to user input from the user interface 136 to transmit a control signal to the light source driver 138. In response to the control signal from the logic circuit 132, the light source driver 138 adjusts and controls the power applied to the light source 120. Other control circuits besides the control circuit 100 of FIG. 7 are compatible with embodiments described herein. In some embodiments, the control circuit 100 can be used to provide real-time positive and/or negative feedback.

[0122] In certain embodiments, the logic circuit 132 is responsive to signals from a sensor monitoring at least one parameter of the treatment to control the applied light. For example, certain embodiments comprise a temperature sensor in thermal communication with the scalp or skull to provide information regarding the temperature of the scalp or skull to the logic circuit 132. In such embodiments, the logic circuit 132 is responsive to the information from the temperature sensor to transmit a control signal to the light source driver 138 so as to adjust the parameters of the applied light to maintain the scalp or skull temperature below a predetermined level. Other embodiments of sensors include other biomedical sensors including, but not limited to, a blood flow sensor, a blood gas (e.g., oxygenation) sensor, an ATP production sensor, or a cellular activity sensor. Such biomedical sensors can provide real-time feedback information to the logic circuit 132. For example, if ATP production or mitochondrial activity levels are below a certain threshold level, the logic circuit 132 can generate a control signal to the light source(s) 120 to adjust a treatment parameter of the applied light, such as a treatment time, wavelength, irradiance level, or other parameter. In certain such embodiments, the logic circuit 132 is responsive to signals from the sensors to preferably adjust the parameters of the applied light to optimize the measured response. The logic circuit 132 can thus provide automatic real-time closed-loop monitoring and adjustment of various parameters of the applied light to optimize the phototherapy. In other embodiments, the control circuit 100 can be configured to provide manual closed-loop feedback. The sensors can also include biochemical sensors, EEG sensors, EROS sensors, photosensors, and/or other sensors.

Light Parameters

[0123] The various parameters of the light beam emitted from the emission surface 22 are advantageously selected to provide treatment while controlling, inhibiting, preventing, minimizing, or reducing injury or discomfort to the subject due to heating of the skull or neural tissue by the light. While discussed separately, these various parameters below can be combined with one another within the disclosed values in accordance with embodiments described herein. Wavelength

[0124] The following section discusses theories and potential action mechanisms, as they presently appear to the inventors, regarding the selection of wavelengths for certain embodiments of phototherapy described herein. The scope of the claims of the present application is not to be construed to depend on the accuracy, relevance, or specifics of any of these theories or potential action mechanisms. Thus the claims of the present application are to be construed without being bound by theory or by a specific mechanism.

[0125] In certain embodiments, non-invasive delivery and heating by the electromagnetic radiation place practical limits on the ranges of electromagnetic radiation wavelengths to be used in the treatment of the patient's brain. In certain embodiments, the wavelength of electromagnetic radiation used in the treatment of the patient's brain is selected in view of one or more of the following considerations: (1) the ability to stimulate mitochondrial function in vitro; (2) the ability to penetrate tissue; (3) the absorption in the target tissue; (4) the efficacy in ischemia models in vivo; and (5) the availability of laser sources with the desired power at the desired wavelength or wavelengths. The combination of these effects offers few wavelengths to be used as a therapeutic agent in vivo. These factors can be combined in certain embodiments to create an efficiency factor for each wavelength. Wavelengths around 800 nanometers are particularly efficient. In addition, 808-nanometer light has previously been found to stimulate mitochondrial function and to work in the myocardial infarction models in rat and dog.

[0126] In certain embodiments, light in the visible to near-infrared wavelength range is used to irradiate the subject's skull or neural tissue. In certain embodiments, the light is substantially monochromatic (i.e., light having one wavelength, or light having a narrow band of wavelengths). So that the amount of light transmitted to the brain is maximized, the wavelength of the light is selected in certain embodiments to be at or near a transmission peak (or at or near an absorption minimum) for the intervening tissue. In certain such embodiments, the wavelength corresponds to a peak in the transmission spectrum of tissue at about 820 nanometers. In certain other embodiments, the light comprises one or more wavelengths between about 630 nanometers and about 1064 nanometers, between about 600 nanometers and about 980 nanometers, between about 780 nanometers and about 840 nanometers, between about 805 nanometers and about 820 nanometers, or includes wavelengths of about 785, 790, 795, 800, 805, 810, 815, 820, 825, or 830 nanometers. An intermediate wavelength in a range between approximately 730 nanometers and approximately 750 nanometers (e.g., about 739 nanometers) appears to be suitable for penetrating the skull, although other wavelengths are also suitable and may be used. In other embodiments, a plurality of wavelengths is used (e.g. applied concurrently or sequentially). In certain embodiments, the light has a wavelength distribution peaked at a peak wavelength and has a line width less than ±10 nanometers from the peak wavelength. In certain such embodiments, the light has a line width less than 4 nanometers, full width at 90% of energy. In certain embodiments, the center wavelength is (808 ± 10) nanometers with a spectral line width less than 4 nanometers, full width at 90% of energy.

[0127] In certain embodiments, the light is generated by a light source comprising one or more laser diodes, which each provide coherent light. In embodiments in which the light from the light source is coherent, the emitted light may produce "speckling" due to coherent interference of the light. This speckling comprises intensity spikes which are created by wavefront interference effects and can occur in proximity to the target tissue being treated. For example, while the average irradiance or power density may be approximately 10 mW/cm , the power density of one such intensity spike in proximity to the brain tissue to be treated may be approximately 300 mW/cm . In certain embodiments, this increased power density due to speckling can improve the efficacy of treatments using coherent light over those using incoherent light for illumination of deeper tissues. In addition, the speckling can provide the increased power density without overheating the tissue being irradiated. The light within the speckle fields or islands containing these intensity spikes is polarized, and in certain embodiments, this polarized light provides enhanced efficacy beyond that for unpolarized light of the same intensity or irradiance.

[0128] In certain embodiments, the light source 20 includes at least one continuously emitting GaAlAs laser diode having a wavelength of about 830 nanometers. In another embodiment, the light source 20 comprises a laser source having a wavelength of about 808 nanometers.

[0129] In certain embodiments, the one or more wavelengths are selected so as to work with one or more chromophores within the target tissue. Without being bound by theory or by a specific mechanism, it is believed that irradiation of chromophores increases the production of ATP in the target tissue and/or controls, inhibits, prevents, minimizes, or reduces apoptosis of the injured tissues, thereby producing beneficial effects, as described more fully below. Additional details regarding potential action mechanisms behind wavelength selection (including in vitro and in vivo studies) can be found in U.S. Patent Application Publication No. 201 1/0144723, the entire content of which is incorporated herein by reference.

[0130] Some chromophores, such as water or hemoglobin, are ubiquitous and absorb light to such a degree that little or no penetration of light energy into a tissue occurs. For example, water absorbs light above approximately 1300 nanometers. Thus energy in this range has little ability to penetrate tissue due to the water content. However, water is transparent or nearly transparent in wavelengths between 300 and 1300 nanometers. Another example is hemoglobin, which absorbs heavily in the region between 300 and 670 nanometers, but is reasonably transparent above 670 nanometers.

[0131] Based on these broad assumptions, one can define an "IR window" into the body. Within the window, there are certain wavelengths that are more or less likely to penetrate. This discussion does not include wavelength dependent scattering effects of intervening tissues.

[0132] The absorption transmittance of various tissues have been directly measured to determine the utility of various wavelengths. FIG. 8A is a graph of the transmittance of light through blood (in arbitrary units) as a function of wavelength. Blood absorbs less in the region above 700 nanometers, and is particularly transparent at wavelengths above 780 nanometers. Wavelengths below 700 nanometers are heavily absorbed, and are not likely to be useful therapeutically (except for topical indications).

[0133] FIG. 8B is a graph of the absorption of light by brain tissue. Absorption in the brain is strong for wavelengths between 620 and 980 nanometers. This range is also where the copper centers in mitochondria absorb. The brain is particularly rich in mitochondria as it is a very active tissue metabolically (the brain accounts for 20% of blood flow and oxygen consumption). As such, the absorption of light in the 620 to 980 nanometer range is expected if a photostimulative effect is to take place.

[0134] By combining FIGS. 8A and 8B, the efficiency of energy delivery as a function of wavelength can be calculated, as shown in FIG. 8C. Wavelengths between 780 and 880 nanometers are preferable (efficiency of 0.6 or greater) for targeting the brain. The peak efficiency is about 800 to 830 nanometers (efficiency of 1.0 or greater). These wavelengths are not absorbed by water or hemoglobin, and are likely to penetrate to the brain. Once these wavelengths reach the brain, they will be absorbed by the brain and converted to useful energy.

[0135] These effects have been directly demonstrated in rat tissues. The absorption of 808 nanometer light was measured through various rat tissues, as shown in FIG. 9. Soft tissues such as skin and fat absorb little light. Muscle, richer in mitochondria, absorbs more light. Even bone is fairly transparent. However, as noted above, brain tissue, as well as spinal cord tissue, absorb 808 nanometer light well.

Irradiance or Power Density

[0136] In some embodiments, the light sources 20 emit a light beam having a time- averaged irradiance, or power density, at the emission surface 22 of the light sources 20 (e.g., at the external cranial or skull surface) between about 0.005 mW/cm² to about 10 W/cm², about

2 2 2 2 2

0.01 mW/cm to about 5 W/cm , about 0.01 mW/cm to about 1 W/cm , about 1 mW/cm to about 500 mW/cm², about 500 mW/cm² to about 1 W/cm², or overlapping ranges thereof, across the cross-sectional area of the light beam. In accordance with some embodiments, the time- averaged irradiance, or power density, of the light emitted from the light sources 20 can be reduced generally by a factor of 1/e from the values that would be used if the light sources 20 were applied to a shaved scalp instead of directly to the skull. In certain embodiments, the time- averaged irradiance at the target tissue (e.g., at a depth of approximately 2 centimeters below the dura) is at least about 0.001 mW/cm² and up to about 1 W/cm² at the level of the tissue. In various embodiments, the time-averaged subsurface irradiance at the target tissue is at least about 0.001 , 0.005, 0.01 , 0.05, 0.1 , 0.5, 1 , 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, or lOOO mW/cm , or greater, depending on the desired clinical performance.

[0137] For a pulsed light beam, the time-averaged irradiance is averaged over a long time period compared to the temporal pulse widths of the pulses (e.g., averaged over a fraction of a second longer than the temporal pulse width, over 1 second, or over multiple seconds). For a continuous-wave (CW) light beam with time -varying irradiance, the time-averaged irradiance can be an average of the instantaneous irradiance averaged over a time period longer than a characteristic time period of fluctuations of the light beam. In certain embodiments, a duty cycle in a range between 1 % and 80%, between 10% and 30%, or about 20% can be used with a peak irradiance at the target tissue of 0.001 mW/cm² to about 1 W/cm², about 0.01 mW/cm² to about 500 mW/cm², about lO mW/cm² to about l OO mW/cm², or about 25 mW/cm² to about 125 mW/cm . For example, in one embodiment, a pulsed dosimetry having a 20% duty cycle and a 50 mW/ cm is used. In certain embodiments, the pulsed light beam has an energy or fluence per pulse (e.g., peak irradiance multiplied by the temporal pulse width) at the emission surface 22 of the light source 20 between about 0.001 μ.Γ/ϋπι² to about 150 J/cm², between about 0.01 μ.Γ/ϋπι² to about 5 J/cm², between about 0.1 μJ/cm² to about 1 J/cm², between about 0.01 mJ/cm² to about 100 mJ/cm², between about 100 mJ/cm² to about 1 J/cm², or overlapping ranges thereof.

[0138] The cross-sectional area of the light beam of certain embodiments (e.g., multimode beams) can be approximated using an approximation of the beam intensity distribution. For example, as described more fully below, measurements of the beam intensity distribution can be approximated by a Gaussian (1/e² measurements) or by a "top hat" distribution and a selected perimeter of the beam intensity distribution can be used to define a bound of the area of the light beam. In certain embodiments, the irradiance at the emission surface 22 is selected to provide the desired irradiances at the target tissue. The irradiance of the light beam is preferably controllably variable so that the emitted light energy can be adjusted to provide a selected irradiance at the tissue being treated. In certain embodiments, the light beam emitted from the emission surface 22 is continuous with a total radiant power in a range of about 4 Watts to about 6 Watts. In certain embodiments, the radiant power of the light beam is 5 Watts ± 20% (CW). In certain embodiments, the peak power for pulsed light is in a range of about 10 Watts to about 30 Watts (e.g., 20 Watts). In certain embodiments, the peak power for pulsed light multiplied by the duty cycle of the pulsed light yields an average radiant power in a range of about 4 Watts to about 6 Watts (e.g., 5 Watts).

[0139] In certain embodiments, the irradiance of the light beam is selected to provide a predetermined irradiance at the target tissue (e.g., at a depth of approximately 2 centimeters from the dura). The selection of the appropriate irradiance of the light beam emitted from the emission surface 22 to use to achieve a desired target tissue irradiance preferably includes consideration of scattering by intervening bone or brain tissue. Further information regarding the scattering of light by tissue is provided by U.S. Patent No. 7,303,578, which is incorporated in its entirety by reference herein, and V. Tuchin in "Tissue Optics: Light Scattering Methods and Instruments for Medical Diagnosis," SPIE Press (2000), Bellingham, WA, pp. 3-1 1 , which is incorporated in its entirety by reference herein.

[0140] Phototherapy for the treatment of neurologic conditions (e.g., ischemic stroke, Alzheimer's Disease, Parkinson's Disease, depression, or TBI) is based in part on the discovery that irradiance or power density (i.e., power per unit area or number of photons per unit area per unit time) and energy density (i.e., energy per unit area or number of photons per unit area) of the light energy applied to tissue appear to be significant factors in determining the relative efficacy of low level phototherapy. This discovery is particularly applicable with respect to treating and saving surviving but endangered neurons in a zone of danger surrounding the primary injury. Certain embodiments described herein are based at least in part on the finding that, given a selected wavelength of light energy, it is the irradiance and/or the energy density of the light delivered to tissue (as opposed to the total power or total energy delivered to the tissue) that appears to be important factors in determining the relative efficacy of phototherapy.

[0141] Without being bound by theory or by a specific mechanism, it is believed that light energy delivered within a certain range of irradiances and energy densities provides the desired biostimulative effect on the intracellular environment, such that proper function is returned to previously nonfunctioning or poorly functioning mitochondria in at-risk neurons. The biostimulative effect may include interactions with chromophores within the target tissue, which facilitate production of ATP and/or controls, inhibits, prevents, minimizes, or reduces apoptosis of the injured cells which have experienced decreased blood flow (e.g., due to the stroke or TBI). Because strokes and TBI correspond to interruptions of blood flow to portions of the brain, it is thought that any effects of increasing blood flow by phototherapy are of less importance in the efficacy of phototherapy for stroke or TBI victims. Further information regarding the role of irradiance and exposure time is described by Hans H.F.I, van Breugel and P.R. Dop Bar in "Power Density and Exposure Time of He-Ne Laser Irradiation Are More Important Than Total Energy Dose in Photo-Biomodulation of Human Fibroblasts In Vitro," Lasers in Surgery and Medicine, Volume 12, pp. 528-537 (1992), which is incorporated in its entirety by reference herein. In addition, the significance of the irradiance used in phototherapy with regard to the devices and methods used in phototherapy of brain tissue, are described more fully in U.S. Patent No. 7,303,578 and U.S. Patent Appl. Publ. Nos. 2005/0107851 Al , 2007/0179570 Al , and 2007/0179571 Al , each of which is incorporated in its entirety by reference herein. While these previous discussions of irradiance were primarily in conjunction with phototherapy of stroke, they apply as well to phototherapy of TBI, Alzheimer's Disease, Parkinson's Disease, depression, or other neurological diseases, disorders, or conditions. For example, in certain embodiments, to obtain a desired average power density at the brain for treating TBI, higher total power at the scalp or skull can be used in conjunction with a larger spot size at the scalp or skull. Thus, by increasing the spot size at the scalp or skull, a desired average power density at the brain can be achieved with lower power densities at the scalp or skull which can reduce the possibility of overheating the scalp, skull, or brain.

[0142] In certain embodiments, delivering the neuroprotective amount of light energy includes selecting a surface irradiance of the light energy at the skull corresponding to the predetermined irradiance at the target area of the brain. As described above, light propagating through tissue is scattered and absorbed by the tissue. Calculations of the irradiance to be applied to the skull so as to deliver a predetermined irradiance to the selected target area of the brain preferably take into account the attenuation of the light energy as it propagates through bone and brain tissue. Factors known to affect the attenuation of light propagating to the brain from the skull include, but are not limited to, skull thickness, subject's age and gender, and the location of the target area of the brain, particularly the depth of the area relative to the surface of the skull.

[0143] The irradiance selected to be applied to the target area of the subject's brain depends on a number of factors, including, but not limited to, the wavelength of the applied light, heating considerations, the type of CVA (ischemic or hemorrhagic), and the subject's clinical condition, including the extent of the affected brain area. The irradiance or power density of light energy to be delivered to the target area of the subject's brain may also be adjusted to be combined with any other therapeutic agent or agents, especially pharmaceutical neuroprotective agents, to achieve the desired biological effect. In such embodiments, the selected irradiance can also depend on the additional therapeutic agent or agents chosen.

Temporal Pulse width. Temporal Pulse shape. Duty Cycle, Repetition Rate, and Irradiance per Pulse

[0144] FIG. 10A schematically illustrates a generalized temporal profile of a pulsed light beam in accordance with certain embodiments described herein. The temporal profile comprises a plurality of pulses (Pi, P₂, Pi), each pulse having a temporal pulse width during which the instantaneous intensity or irradiance I(t) of the pulse is substantially non-zero. For example, for the pulsed light beam of FIG. 10A, pulse Pi has a temporal pulse width from time t=0 to time t=Ti, pulse P₂ has a temporal pulse width from time t=T₂ to time t=T₃, and pulse Pi has a temporal pulse width from time

The temporal pulse width can also be referred to as the "pulse ON time." The pulses are temporally spaced from one another by periods of time during which the intensity or irradiance of the beam is substantially zero. For example, pulse Pi is spaced in time from pulse P₂ by a time t=T₂-Ti. The time between pulses can also be referred to as the "pulse OFF time." In certain embodiments, the pulse ON times of the pulses are substantially equal to one another, while in certain other embodiments, the pulse ON times differ from one another. In certain embodiments, the pulse OFF times between the pulses are substantially equal to one another, while in certain other embodiments, the pulse OFF times between the pulses differ from one another. As used herein, the term "duty cycle" has its broadest reasonable interpretation, including but not limited to, the pulse ON time divided by the sum of the pulse ON time and the pulse OFF time. For a pulsed light beam, the duty cycle is less than one. The values of the duty cycle and the temporal pulse width fully define the repetition rate of the pulsed light beam.

[0145] Each of the pulses can have a temporal pulse shape which describes the instantaneous intensity or irradiance of the pulse I(t) as a function of time. For example, as shown in FIG. 1 OA, the temporal pulse shapes of the pulsed light beam are irregular, and are not the same among the various pulses. In certain embodiments, the temporal pulse shapes of the pulsed light beam are substantially the same among the various pulses. For example, as schematically shown in FIG. 10B, the pulses can have a square temporal pulse shape, with each pulse having a substantially constant instantaneous irradiance over the pulse ON time. In certain embodiments, the peak irradiances of the pulses differ from one another (see, e.g., FIGS. 10A and 10B), while in certain other embodiments, the peak irradiances of the pulses are substantially equal to one another (see, e.g., Figures I OC and 10D). Various other temporal pulse shapes (e.g., triangular, trapezoidal) are also compatible with certain embodiments described herein. FIG. 10C schematically illustrates a plurality of trapezoidal pulses in which each pulse has a rise time (e.g., corresponding to the time between an instantaneous irradiance of zero and a peak irradiance of the pulse) and a fall time (e.g., corresponding to the time between the peak irradiance of the pulse and an instantaneous irradiance of zero). In certain embodiments, the rise time and the fall time can be expressed relative to a specified fraction of the peak irradiance of the pulse (e.g., time to rise/fall to 50% of the peak irradiance of the pulse).

[0146] As used herein, the term "peak irradiance" of a pulse Pi has its broadest reasonable interpretation, including but not limited to, the maximum value of the instantaneous irradiance I(t) during the temporal pulse width of the pulse. In certain embodiments, the instantaneous irradiance is changing during the temporal pulse width of the pulse (see, e.g., FIGS. 10A and IOC), while in certain other embodiments, the instantaneous irradiance is substantially constant during the temporal pulse width of the pulse (see, e.g., FIGS. 10B and 10D).

[0147] As used herein, the term "pulse irradiance" I_p of a pulse Pi has its broadest reasonable interpretation, including but not limited to, the integral of the instantaneous irradiance

T_M

I(t) of the pulse Pj over the temporal pulse width of the pulse: Ι_ρ> = l(t)- dt/(T_M - 7 ). As used herein, the term "total irradiance" ITOTAL has its broadest reasonable interpretation, including but not limited to, the sum of the pulse irradiances of the pulses: I_T0TAL = · As used herein, the

term "time-averaged irradiance" IAVE has its broadest reasonable interpretation, including but not limited to, the integral of the instantaneous irradiance I(t) over a period of time T large compared

T T

to the temporal pulse widths of the pulses: I_AVE = l(t)- dt/T . The integral l(t)- dt provides

0 0

the energy of the pulsed light beam.

[0148] For example, for a plurality of square pulses with different pulse irradiances I_p and different temporal pulse widths AT_t , the time-averaged irradiance over a time T equals

I _AVE =—∑I_p · Δ7 . For another example, for a plurality of square pulses with equal pulse irradiances I_p , with equal temporal pulse widths, and equal pulse OFF times (having a duty cycle D), the time-averaged irradiance equals I_AVE = I_P - D . For example, as shown in FIG. 10D, the time-averaged irradiance (shown as a dashed line) is less than the pulse irradiance of the pulses. [0149] The pulse irradiances and the duty cycle can be selected to provide a predetermined time-averaged irradiance. In certain embodiments in which the time-averaged irradiance is equal to the irradiance of a continuous-wave (CW) light beam, the pulsed light beam and the CW light beam have the same number of photons or flux as one another. For example, a pulsed light beam with a pulse irradiance of 5 mW/cm² and a duty cycle of 20% provides the same number of photons as a CW light beam having an irradiance of 1 mW/cm². However, in contrast to a CW light beam, the parameters of the pulsed light beam can be selected to deliver the photons in a manner which achieve results which are not obtainable using CW light beams.

[0150] In certain embodiments, one or more of the temporal pulse width, temporal pulse shape, duty cycle, repetition rate, and pulse irradiance of the pulsed light beam are selected such that no portion of tissue is heated to a temperature greater than 60 degrees Celsius, greater than 55 degrees Celsius, greater than 50 degrees Celsius, or greater than 45 degrees Celsius. In certain embodiments, one or more of the temporal pulse width, temporal pulse shape, duty cycle, repetition rate, and pulse irradiance of the pulsed light beam are selected such that no portion of tissue is heated to a temperature greater than 30 degrees Celsius above its baseline temperature, greater than 20 degrees Celsius above its baseline temperature, or greater than 10 degrees Celsius above its baseline temperature. In certain embodiments, one or more of the temporal pulse width, temporal pulse shape, duty cycle, repetition rate, and pulse irradiance of the pulsed light beam are selected such that no portion of the brain is heated to a temperature greater than 5 degrees Celsius above its baseline temperature, greater than 3 degrees Celsius above its baseline temperature, or greater than 1 degree Celsius above its baseline temperature. As used herein, the term "baseline temperature" has its broadest reasonable interpretation, including but not limited to, the temperature at which the tissue would have if it were not irradiated by the light. In contrast to previous low-light level therapies, the pulsed light beam has an average radiant power in the range of about 1 Watt to about 10 Watts or in a range of about 4 Watts to about 6 Watts.

[0151] In certain embodiments, the pulse parameters are selected to achieve other effects beyond those which are achievable using CW light beams. For example, while CW irradiation of brain cells in vivo provides an efficacious treatment of stroke, the use of CW irradiation for the treatment of TBI is more difficult, owing in part to the excess blood within the region of the skull or cranium to be irradiated (e.g., due to intracranial bleeding). This excess blood may be between the light source and the target brain tissue to be irradiated, resulting in higher absorption of the light applied to the skull before it can propagate to the target brain tissue. This absorption can reduce the amount of light reaching the target tissue and can unduly heat the intervening tissue to an undesirable level.

[0152] In certain embodiments described herein, pulsed irradiation may provide a more efficacious treatment. The pulsed irradiation can provide higher peak irradiances for shorter times, thereby providing more power to propagate to the target tissue while allowing thermal relaxation of the intervening tissue and blood between pulses to avoid unduly heating the intervening tissue. The time scale for the thermal relaxation is typically in the range of a few milliseconds. For example, the thermal relaxation time constant (e.g., the time for tissue to cool from an elevated temperature to one-half the elevated temperature) of human skin is about 3-10 milliseconds, while the thermal relaxation time constant of human hair follicles is about 40- 100 milliseconds. Thus, previous applications of pulsed light to the body for hair removal have optimized temporal pulse widths of greater than 40 milliseconds with time between pulses of hundreds of milliseconds.

[0153] However, while pulsed light of this time scale advantageously reduces the heating of intervening tissue and blood, it does not provide an optimum amount of efficaciousness as compared to other time scales. In certain embodiments described herein, the subject's skull or vertebra is irradiated with pulsed light having parameters which are not optimized to reduce thermal effects, but instead are optimized to stimulate, to excite, to induce, or to otherwise support one or more intercellular or intracellular biological processes which are involved in the survival, regeneration, or restoration of performance or viability of brain cells. Thus, in certain such embodiments, the selected temporal profile can result in temperatures of the irradiated tissue which are higher than those resulting from other temporal profiles, but which are more efficacious than these other temporal profiles. In certain embodiments, the pulsing parameters are selected to utilize the kinetics of the biological processes rather than optimizing the thermal relaxation of the tissue. In certain embodiments, the pulsed light beam has a temporal profile (e.g., peak irradiance per pulse, a temporal pulse width, and a pulse duty cycle) selected to modulate membrane potentials in order to enhance, restore, or promote cell survival, cell function, or both of the irradiated brain cells following the traumatic brain injury. For example, in certain embodiments, the pulsed light has a temporal profile which supports one or more intercellular or intracellular biological processes involved in the survival or regeneration of brain cells, but does not optimize the thermal relaxation of the irradiated tissue. In certain embodiments, the brain cells survive longer after the irradiation as compared to their survival if the irradiation did not occur. For example, the light of certain embodiments can have a protective effect on the brain cells, or can cause a regeneration process in the brain cells.

[0154] In certain embodiments, the temporal profile (e.g., peak irradiance, temporal pulse width, and duty cycle) are selected to utilize the kinetics of the biological processes while maintaining the irradiated portion of the skull or vertebrae at or below a predetermined temperature. This predetermined temperature is higher than the optimized temperature which could be achieved for other temporal profiles (e.g., other values of the peak irradiance, temporal pulse width, and duty cycle) which are optimized to minimize the temperature increase of surrounding tissue due to the irradiation. For example, a temporal profile having a peak irradiance of 10 W/cm² and a duty cycle of 20% has a time-averaged irradiance of 2 W/cm². Such a pulsed light beam provides the same number of photons to the irradiated surface as does a continuous-wave (CW) light beam with an irradiance of 2 W/cm . However, because of the "dark time" between pulses, the pulsed light beam can result in a lower temperature increase than does the CW light beam. To minimize the temperature increase of the irradiated portion of the skull or vertebra, the temporal pulse width and the duty cycle can be selected to allow a significant portion of the heat generated per pulse to dissipate before the next pulse reaches the irradiated portion. In certain embodiments described herein, rather than optimizing the beam temporal parameters to minimize the temperature increase, the temporal parameters are selected to effectively correspond to or to be sufficiently close to the timing of the biomolecular processes involved in the absorption of the photons to provide an increased efficacy. Rather than having a temporal pulse width on the order of hundreds of microseconds, certain embodiments described herein utilize a temporal pulse width which does not optimize the thermal relaxation of the irradiated tissue (e.g., milliseconds, tens of milliseconds, hundreds of milliseconds). Since these pulse widths are significantly longer than the thermal relaxation time scale, the resulting temperature increases are larger than those of smaller pulse widths, but still less than that of CW light beams due to the heat dissipation the time between the pulses.

[0155] A number of studies have investigated the effects of in vitro irradiation of cells using pulsed light on various aspects of the cells. A study of the action mechanisms of incoherent pulsed radiation at a wavelength of 820 nanometers (pulse repetition frequency of 10 Hz, pulse width of 20 milliseconds, dark period between pulses of 80 milliseconds, and duty factor (pulse duration to pulse period ratio) of 20%) on in vitro cellular adhesion has found that pulsed infrared radiation at 820 nanometers increases the cell-matrix attachment. (T.I. Karu et al , "Cell Attachment to Extracellular Matrices is Modulated by Pulsed Radiation at 820 nm and Chemicals that Modify the Activity of Enzymes in the Plasma Membrane," Lasers in Surgery and Medicine, Vol. 29, pp. 274-281 (2001) which is incorporated in its entirety by reference herein.) It was hypothesized in this study that the modulation of the monovalent ion fluxes through the plasma membrane, and not the release of arachidonic acid, is involved in the cellular signaling pathways activated by irradiation at 820 nanometers. A study of light-induced changes to the membrane conductance of ventral photoreceptor cells found behavior which was dependent on the pulse parameters, indicative of two light- induced membrane processes. (J.E. Lisman et al , "Two Light-Induced Processes in the Photoreceptor Cells of Limulus Ventral Eye," J. Gen. Physiology, Vol. 58, pp. 544-561 (1971), which is incorporated in its entirety by reference herein.) Studies of laser-activated electron injection into oxidized cytochrome c oxidase observed kinetics which establish the reaction sequence of the proton pump mechanism and some of its thermodynamic properties have time constants on the order of a few milliseconds. (I. Belevich et al. , "Exploring the proton pump mechanism of cytochrome c oxidase in real time Proc. Nat'l Acad. Sci., Vol. 104, pp. 2685-2690 (2007); I. Belevich et al , "Proton- coupled electron transfer drives the proton pump of cytochrome c oxidase " Nature, Vol. 440, pp. 829-832 (2006), both of which are incorporated in its entirety by reference herein.) An in vivo study of neural activation based on pulsed infrared light proposed a photo-thermal effect from transient tissue temperature changes resulting in direct or indirect activation of transmembrane ion channels causing propagation of the action potential. (J. Wells et al , "Biophysical mechanisms responsible for pulsed low-level laser excitation of neural tissue," Proc. SPIE, Vol. 6084, pp. 60840X (2006), which is incorporated in its entirety by reference herein.)

[0156] In certain embodiments, the temporal profile of the pulsed light beam comprises a peak irradiance, a temporal pulse width, a temporal pulse shape, a duty cycle, and a pulse repetition rate or frequency. In certain embodiments in which the pulsed light beam is transmitted through a region of the skull, at least one of the peak irradiance, temporal pulse width, temporal pulse shape, duty cycle, and pulse repetition rate or frequency is selected to provide a time-averaged irradiance (averaged over a time period including a plurality of pulses)

2 2 at the emission surface 22 of the light source 20 between about 0.01 mW/cm to about 1 W/cm ,

2 2 2

between about 10 mW/cm to about 10 W/cm , between about 100 mW/cm to about 1000 mW/cm², between about 500 mW/cm² to about 1 W/cm², or between about 650 mW/cm² to about 750 mW/cm² across the cross-sectional area of the light beam. In certain such embodiments, the time-averaged irradiance at the brain cells being treated (e.g., at a depth of approximately 2 centimeters below the dura) is greater than 0.01 mW/cm².

[0157] In certain embodiments, the temporal pulse shape is generally rectangular, generally triangular, or any other shape. In certain embodiments, the pulses have a rise time (e.g., from 10% of the peak irradiance to 90% of the peak irradiance) less than 1 % of the pulse ON time, or a fall time (e.g., from 90% of the peak irradiance to 10% of the peak irradiance) less than 1% of the pulse ON time.

[0158] During the treatment, the light energy may be continuously provided, or it may be pulsed. If the light is pulsed, the pulses range, in some embodiments from at least about 10 nanoseconds long to about 50 milliseconds long, including about 10-100 ns, 100-500 ns, 500 ns-1 ms, 1 ms-5 ms, 5-10 ms, 10-15 ms, 15-20 ms, 20-30 ms, 30-40 ms, 40-50 ms, and overlapping ranges thereof. In some embodiments, pulses are administered for 1 , 1.5, 2, 2.5, 3, 3.5, 4 or 4.5 milliseconds. In some embodiments, pulses are administered for longer than 50 milliseconds (e.g., 100 ms, 250 ms, 500 ms, 1 s, or higher). Pulsed light is administered, in some embodiments at a frequency up to 100 kHz. In several embodiments, lower frequencies are used, such as, for example, frequencies ranging from 50-150 Hz. In some embodiments, pulsed light is administered at about 60, 70, 80, 90, 95, 100, 105, 1 10, 1 15, 120, 130, and 140 Hz. Frequencies less than 50 Hz and greater than 150 Hz are used in some embodiments. For example, in several embodiments, frequencies that match endogenous neural frequencies (e.g., Alpha, Beta, Delta, and/or Theta waves) are used. In some embodiments pulsed light administration is preferred because of a reduction in the amount of heat generated in the target tissue. Parameters may be chosen, in some embodiments to minimize heat. However, certain embodiments are particularly unexpected because the parameters used to generate the most robust effects are not the same as those that would minimize heat generation. As such, certain such embodiments may more specifically target and affect a biological system (e.g. the axonal transport mechanisms) as compared to those parameters used to minimize heat.

[0159] In some embodiments, pulses described herein are administered in an on off cycle (e.g., a duty cycle). In some embodiments, the duty cycle is between .01% to about 99.9% (e.g., between about .01%-.1 %, .1%-1%, 1%-10%, 10%-20%, 20%-30%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, 70%-80%, 80%-90%, 90%-99.9%, and overlapping ranges thereof). In one embodiment, the on time is 2 ms and the off time is 1-2 ms. In another embodiment, the on time is about 1 -5 ms and the off time is about 1-5 ms. In some embodiments, the on off times are variable during the course of treatment. For example, in one embodiment, the on or off times are increased (or decreased) by about 10-50% during the course of treatment.

[0160] In certain embodiments, the pulses have a temporal pulse width (e.g., pulse ON time) in a range between about 0.001 millisecond and about 150 seconds, between about 0.01 millisecond and about 10 seconds, between about 0.1 millisecond and about 1 second, between about 0.5 millisecond and about 100 milliseconds, between about 2 milliseconds and about 20 milliseconds, or between about 1 millisecond and about 10 milliseconds. In certain embodiments, the pulse width is about 0.5, 1 , 2, 4, 6, 8, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, or 300 milliseconds. In certain embodiments, the temporal pulse width is in a range between about 0.1 milliseconds and 150 seconds.

[0161] In certain embodiments, the time between pulses (e.g., pulse OFF time) is in a range between about 0.01 millisecond and about 150 seconds, between about 0.1 millisecond and about 100 milliseconds, between about 4 milliseconds and about 1 second, between about 8 milliseconds and about 500 milliseconds, between about 8 milliseconds and about 80 milliseconds, or between about 10 milliseconds and about 200 milliseconds. In certain embodiments, the time between pulses is about 4, 8, 10, 20, 50, 100, 200, 500, 700, or 1000 milliseconds.

[0162] In several embodiments, the duty cycle is synchronized with natural neuronal rhythms. Mammalian neurons generate wave patterns of neuronal firing that can be detected and measured by electroencephalography. The primary types of neuronal waves that have been detected are Alpha, Beta, Delta, and Theta waves.

[0163] Alpha waves occur in a frequency range of 8-13 Hz and are associated with states of low levels of activity or non-arousal. For example, after completing a task and taking a period of rest, alpha waves may be generated. Alpha waves are also associated with meditative states. Thus, in several embodiments synchronizing the duty cycle with alpha waves enhances the normal effects associated with generation of alpha waves, e.g., relaxation, deeper thought etc.

[0164] Beta waves occur at frequencies ranging from about 13-40 Hz are associated with higher levels of arousal and active engagement in mental activities. In several embodiments, synchronizing the duty cycle with beta waves enhances the ability of an individual performing tasks associated with beta wave generation. For example, in some embodiments, LLLT synchronized with beta waves enables longer periods of concentration, enhanced mental acuity, reduced fatigue after periods of mental activity, etc.

[0165] Delta waves occur at frequencies ranging from about 1-4 Hz, the slowest frequency of the various brain waves. Deep sleep commonly generates Delta waves. In several embodiments, LLLT synchronized with delta waves generation enhances the depth and/or perceived quality of sleep and/or deep relaxation. In some embodiments, LLLT is used as a sleep aid, such as for insomniacs, light sleepers, or those who have difficulty sleeping through the night. In some embodiments, LLLT can be used to enhance sleep sessions of those individuals having uncommon or variable work hours (e.g., work at night and sleep during the day).

[0166] Theta waves occur at frequencies ranging from about 4-7 Hz. Theta waves may be generated when a person is aware of his/her surroundings but daydreaming or otherwise not focusing on any task in particular. Is some cases, theta waves are associated with free flow of thought and generation of creative ideas. In several embodiments, LLLT synchronized with theta waves enhances an individual's creative thought process enables an individual to generate new ideas and/or thoughts. Such embodiments can be used to, among other applications, assist in overcoming mental blocks (e.g., writer's block or phobias), enhance the efficiency of brainstorming sessions, and/or assist individuals or groups in problem solving.

[0167] In some embodiments, the duty cycle is selected to reflect cellular refractory periods.

[0168] The course of the action potential in excitable cells comprises five parts: the rising phase, the peak phase, the falling phase, the undershoot phase, and finally the refractory period. During the rising phase the membrane potential depolarizes (becomes more positive, typically from a resting potential of about -70mV), due to opening of voltage-gated sodium ion channels open, which increases membrane conductance for sodium ions. Once the membrane potential reaches a depolarization threshold (about -35 to about -40mV) the opening of sodium channels will cause other sodium channels open, resulting in a feed- forward rapid depolarization. The point at which depolarization stops is called the peak phase. At this stage, the membrane potential reaches a maximum. Subsequent to this, there is a falling phase. During this stage the membrane potential hyperpolarizes (becomes more negative). During repolarization, voltage- gated sodium ion channels inactivate and voltage-gated potassium channels activate. Both the sodium ion channels closing and the potassium ion channels opening act to repolarize the cell's membrane potential back towards the resting membrane potential.

[0169] However, the potassium conductance has a lag time that leads to a short hyperpolarization, known as the undershoot phase. This period of hyperpolarization is known as the refractory period. Eventually this potassium conductance drops and the exits the refractory period and cell returns to its resting membrane potential.

[0170] There are two refractory periods in excitable cells (e.g., neurons). The absolute refractory period is the time period after a first stimulation during which a second stimulation of the cell will not trigger an action potential (or other cellular response normally associated with a stimulus). The absolute refractory period of neurons typically range from about 1 to about 3 milliseconds. Thus, in several embodiments, the duty cycle is adjusted to provide light administration to the cells (e.g., neurons) approximately every 1-3 milliseconds, or in sync with the absolute refractory period.

[0171] The relative refractory period is the time period after a first stimulation during which the probability of a second stimulation of the cell triggering an action potential (or other cellular response normally associated with a stimulus) is reduced, but an action potential may still be possible. The relative refractory period immediately follows the absolute refractory period. During the relative refractory period, a stimulus will need to be proportionally greater (to account for the hyperpolarization) in order to cause the membrane potential of the cell to reach the depolarization threshold, and initiate a new action potential. Absent an additional stimulus, the potassium conductance will return to its resting value and the membrane potential of the cell will return to equilibrium, thus ending the relative refractory period.

[0172] As the refractory period is varied depending on the cell type, greater or lesser refractory periods can be accommodated by adjusting the duty cycle. For example, in some embodiments, the duty cycle is adjusted to provide light to the cell approximately every 0.8-1.0 seconds, 1.0-1.2 seconds, 1.2-1.4 seconds, 1.4-1.6 seconds, 1.6-1.8 seconds, 1.8-2.0 seconds, 2.0- 2.2 seconds, 2.2-2.4 seconds, 2.4-2.6 seconds, 2.6-2.8 seconds, and 2.8-3.0 seconds (and overlapping ranges thereof). Synchronization of LLLT, in some embodiments, enhances the function of the exposed cells. For example, synchronizing light administration with the refractory period of a sensory neuron, in some embodiments, increases the rate of sensory transmission in the neuron, which, in some embodiments, produces heightened sensory capacity. Additionally, synchronization of LLLT with the refractory period of motor neurons, in some embodiments, aids in normalization of neuronal firing rates, thereby increasing fine motor control and/or serving as a therapy or palsies or other such uncontrolled muscle movements.

[0173] In one embodiment, the invention comprises delivering pulsed LLLT to a neuron (or group neurons) every 1-2 milliseconds. In one embodiment, the invention comprises delivering pulsed LLLT to a cell (e.g., an excitable cell such as a neuron) in synchronicity with the activation or deactivation of an ion channel (e.g., sodium, calcium or potassium channel). In some embodiments, the LLLT is administered before an action potential occurs. In several embodiments, LLLT is administered in sync with the depolarization phase of the action potential. In several embodiments, LLLT is administered in sync with the peak phase of the action potential. In several embodiments, LLLT is administered in sync with the repolarization phase of the action potential. In several embodiments, LLLT is administered in sync with the hyperpolarization phase of the action potential. In some embodiments, the LLLT is administered during the relative refractory period, while in some embodiments, the LLLT is administered during the relative refractory period. In several embodiments, LLLT is administered for a period of time that overlaps one or more phases of an action potential. In several embodiments, LLLT is administered in sync, preceding, or following a particular action potential event. For example, in some embodiments, LLLT is administered based on the opening of sodium channels, while in some embodiments, LLLT is administered based on the potassium induced hyperpolarization of the cell membrane.

[0174] In certain embodiments in which the target brain tissue to be irradiated is deeper within the brain (e.g., 4 centimeters or more below the dura), pulsing can be used to achieve the desired power densities at the target brain tissue while reducing the heat load and the corresponding temperature increases. For example, pulsing may be used to irradiate the substantia nigra of the patient's brain. In certain other embodiments, continuous wave light may also be used.

[0175] In certain embodiments, the peak irradiance per pulse, or pulse energy density, across the cross-sectional area of the light beam at the emission surface 22 of the light source 20 is in a range between about 0.01 mW/cm² to about 1 W/cm², between about 10 mW/cm² to about 10 W/cm², between about 100 mW/cm² to about 1000 mW/cm², between about 500 mW/cm² to about 1 W/cm², between about 650 mW/cm² to about 750 mW/cm², between about 20 mW/cm² to about 20 W/cm², between about 200 mW/cm² to about 2000 mW/cm², between about

2 2 2 2

1 W/cm to about 2 W/cm , between about 1300 mW/cm to about 1500 mW/cm , between

2 2 2 2 about 1 W/cm to about 1000 W/cm , between about 10 W/cm to about 100 W/cm , between about 50 W/cm² to about 100 W/cm², or between about 65 W/cm² to about 75 W/cm².

[0176] The pulse energy density, or energy density per pulse, can be calculated as the time-averaged power density divided by pulse repetition rate, or frequency. For example, the smallest pulse energy density will happen at the smallest average power density and fastest pulse repetition rate, where the pulse repetition rate is duty cycle divided by the temporal pulse width, and the largest pulse energy density will happen at the largest average power density and slowest pulse repetition rate. For example, at a time-averaged power density of 0.01 mW/cm and a frequency of 100 kHz, the pulse energy density is 0.1 nJ/cm² and at a time-averaged power density of 10 W/cm² and a frequency of 1 Hz, the pulse energy density is 10 J/cm². As another example, at a time-averaged power density of 10 mW/cm and a frequency of 10 kHz, the pulse energy density is 1 μ.Γ/ϋπι As yet another example, at a time-averaged power density of 700

2 2

mW/cm and a frequency of 100 Hz, the pulse energy density is 7 mJ/cm .

Beam Size and Beam Profile

[0177] In certain embodiments, the light beam emitted from the light source 20 has a nominal diameter in a range of about 10 millimeters to about 40 millimeters, in a range of about 20 millimeters to about 35 millimeters, or equal to about 30 millimeters. In certain embodiments, the cross-sectional area is generally circular with a radius in a range of about 1 centimeter to about 2 centimeters. In certain embodiments, the light beam emitted from the emission surface 22 has a cross-sectional area greater than about 2 cm² or in a range of about 2 cm² to about 20 cm² at the emission surface 22 of the light source 20.

[0178] As used herein, the beam diameter is defined to be the largest chord of the perimeter of the area of the skull irradiated by the light beam at an intensity of at least 1/e of the maximum intensity of the light beam. The perimeter of the light beam used to determine the diameter of the beam is defined in certain embodiments to be those points at which the intensity of the light beam is 1/e² of the maximum intensity of the light beam. The maximum-useful diameter of certain embodiments is limited by the size of the subject's head and by the heating of the subject's head by the irradiation. The minimum-useful diameter of certain embodiments is limited by heating and by the total number of treatment sites that could be practically implemented. For example, to cover the subject's skull with a beam having a small beam diameter would correspondingly use a large number of treatment sites. In certain embodiments, the time of irradiation per treatment site can be adjusted accordingly to achieve a desired exposure dose.

[0179] Specifying the total flux inside a circular aperture with a specified radius centered on the exit aperture ("encircled energy") is a method of specifying the power (irradiance) distribution over the light beam emitted from the emission surface 22. The "encircled energy" can be used to ensure that the light beam is not too concentrated, too large, or too small. In certain embodiments, the light beam emitted from the emission surface has a total radiant power, and the light beam has a total flux inside a 20-millimeter diameter cross-sectional circle centered on the light beam at the emission surface 22 which is no more than 75% of the total radiant power. In certain such embodiments, the light beam has a total flux inside a 26- millimeter diameter cross-sectional circle centered on the light beam at the emission surface 22 which is no less than 50% of the total radiant power. [0180] In certain embodiments, the beam intensity profile has a semi-Gaussian profile, while in certain other embodiments, the beam intensity profile has a "top hat" profile. In certain embodiments, the light beam is substantially without high flux regions or "hot spots" in the beam intensity profile in which the local flux, averaged over a 3 millimeter by 3 millimeter area, is more than 10% larger than the average flux. Certain embodiments of the apparatus 10 advantageously generate a light beam substantially without hot spots, thereby avoiding large temperature gradients which would otherwise cause discomfort to the subject.

Divergence

[0181] In certain embodiments, the beam divergence emitted from the emission surface 22 is significantly less than the scattering angle of light inside the body tissue being irradiated, which is typically several degrees. In certain embodiments, the light beam has a divergence angle greater than zero and less than 35 degrees.

Total Treatment Time

[0182] The total treatment time can be controlled by the programmable controller 30. The real time clock and the timers of the programmable controller 30 can be used to control the timing of a particular therapeutic regimen and to allow for scheduled treatment (such as daily, twice a day, or every other day). In certain embodiments, the treatment proceeds continuously for a period of about 10 seconds to about 2 hours, for a period of about 1 to about 20 minutes, or for a period of about 1 to 5 minutes. For example, the total treatment time in certain embodiments is about two minutes. In other embodiments, the light energy is delivered for at least one total treatment period of at least about five minutes, or for at least one total treatment period of at least ten minutes. In some embodiments, LLLT, whether continuous or pulsed, is administered for a total time (duration per treatment session at one site) of about 1 second to 10 minutes, e.g., between about 1 s to 25 s, 25 s - 50 s, 50 s - 100 s, 1 minute - 2 minutes, 2 minutes - 3 minutes, 3 minutes - 4 minutes, 4 minutes - 5 minutes, 5 minutes - 6 minutes, 6 minutes - 7 minutes, 7 minutes - 8 minutes, 8 minutes - 9 minutes, 9 minutes - 10 minutes, or greater. In some embodiments, the total time (duration per treatment session at one site) is about 40, 50, 60, 70, 60, 90 100, 1 10, 120 seconds. The minimum treatment time of certain embodiments is limited by the biological response time (which is on the order of microseconds). The maximum treatment time of certain embodiments can be limited by heating and by practical treatment times (e.g., completing treatment within about 24 hours of stroke onset). The light energy can be pulsed during the treatment period or the light energy can be continuously applied during the treatment period. If the light is pulsed, the pulses can be 2 milliseconds long and occur at a frequency of 100 Hz or at least about 10 nanoseconds long and occur at a frequency of up to about 100 kHz, although shorter or longer pulse widths and/or lower or higher frequencies can be used. For example, the light can be pulsed at a frequency of about 1 Hz to about 100 Hz, from about 100 Hz to about 1 kHz, from about 1 kHz to about 100 kHz, less than 1 Hz, or greater than 100 kHz.

[0183] In certain embodiments, the treatment may be terminated after one treatment period, while in other embodiments, the treatment may be repeated for at least two treatment periods. The time between subsequent treatment periods can be at least about five minutes, at least two in a 24-hour period, at least about 1 to 2 days, or at least about one week. In several embodiments, treatment is performed on one or more sites (e.g., 2, 3, 4, 5, 10, 15, 20, 25, 30 or more sites). The treatment can be repeated multiple times per day and/or multiple times per week. In several embodiments, multiple treatment sessions are performed at different times (e.g., different hours, different days, etc.) on the same site (or at different sites). The length of treatment time and frequency of treatment periods can depend on several factors, including the functional recovery of the subject and the results of imaging analysis of the injury (e.g., infarct), the disease or condition being treated, the use of pulsed or continuous light, the irradiance of the light, the number of light sources used, and/or the sequence or pattern of the treatment. In certain embodiments, the timing parameters can be adjusted in response to a feedback signal from a sensor or other device (e.g., biomedical sensor, magnetic resonance imaging device) monitoring the subject.

[0184] In certain embodiments, the phototherapy is combined with other types of treatments for an improved therapeutic effect. Treatment can comprise directing light through the scalp of the patient to a target area of the brain concurrently with applying an electromagnetic field to the brain. In such embodiments, the light has an efficacious power density at the target area and the electromagnetic field has an efficacious field strength. For example, the apparatus 50 can also include systems for electromagnetic treatment, e.g., as described in U.S. Patent No. 6,042,531 issued to Holcomb, which is incorporated in its entirety by reference herein. In certain embodiments, the electromagnetic field comprises a magnetic field, while in other embodiments, the electromagnetic field comprises a radio-frequency (RF) field. As another example, treatment can comprise directing an efficacious power density of light through the scalp of the patient to a target area of the brain concurrently with applying an efficacious amount of ultrasonic energy to the brain. Such a system can include systems for ultrasonic treatment, e.g., as described in U.S. Patent No. 5,054,470 issued to Fry et al., which is incorporated in its entirety by reference herein. Examples of combined treatment systems and methods are described in PCT Application No. PCT/US 1 1/37248, filed on May 19, 201 1.

[0185]

Transmission in Human Brain

[0186] Power density (PD), or irradiance, measurements have been made to determine the transmission of laser light having a wavelength of approximately 808 nanometers through successive layers of human brain tissue. Laser light having a wavelength of (808 ± 5) nanometers with a maximum output of approximately 35 Watts was applied to the surface of the cortex using a beam delivery system which approximated the beam profile after the laser light passes through the human skull. Peak power density measurements were taken through sections of human brain tissue using an Ocean Optics spectrophotometer Model USB 2000, Serial No. G1965 and beam diameter after scattering was approximated using a Sony Model DCR-IP220, Serial No. 132289.

[0187] A fresh human brain and spinal cord specimen (obtained within six hours after death) was collected and placed in physiologic Dakins solution. The pia layer, arachnoid layer, and vasculature were intact. The brain was sectioned in the midline sagittally and the section was placed in a container and measurements taken at thicknesses of 4.0 centimeters (± 0.5 centimeter), 2.5 centimeters (± 0.3 centimeter), and 1.5 centimeters (± 0.2 centimeter). The PD measurements are shown in Table 1 :

Table 1 :

Thickness PD at cortex Average PD at thickness

4.0 cm 20 mW/cm² 4.9 μ /αη²

2.5 cm 20 mW/cm² 20 μ /αη²

1.5 cm 10 mW/cm² 148 μ /αη² FIG. 1 1 is a graph of the PD versus the depth from the dura for an input PD of 10 mW/cm² with the light bars corresponding to predicted values of the PD and dark bars corresponding to an estimated minimum working PD of is 7.5 μ /οηι , as described below.

[0188] Based upon prior animal experimentation, a conservative estimation of the minimum known PD within the tissue of the brain which is able to show efficacy in stroke animal models is 7.5 μ\¥/ϋπι². This estimated minimum working PD is drawn from an experiment in which 10 mW was applied to the rat brain surface, and 7.5 μ /οηι² PD was directly measured 1.8 centimeters from the surface. This stroke model consistently produced significant efficacy, including for strokes 1.8 centimeters from the laser probe. Note that this 7.5 μ /οηι is a conservative estimate; the same irradiance or power density at the brain surface also consistently produces significant efficacy in a 3-centimeter rabbit clot shower model. Note also that the power density measurements in the human brain experiment do not factor in the effect from the CNS -filled sulci, through which the laser energy should be readily transmitted. However, even conservatively assuming 7.5 μ /οηι² as the minimum power density hurdle and ignoring expected transmission benefits from the sulci, the experiment described above confirms that approximately 10-15 mW/cm transmitted upon the cortex (as per an example dosimetry in man) will be effective to at least 3.0 centimeters from the surface of the brain.

Phototherapy Example Study

[0189] In one example study performed under contract with Neurological Testing Service, Inc. (Charleston, SC), Infrared Transcranial Laser Therapy (TLT) was tested for efficacy in an amyloid precursor peptide (APP) transgenic mouse model of Alzheimer's Disease (AD). Laser light therapy was administered three times per week at various doses for 26 weeks, starting at 3 months of age, and the results were compared to no laser (control group). Animals were examined for amyloid load, inflammatory markers, brain Αβ levels, plasma Αβ levels, CSF Αβ levels, sAPP levels, and NS behavioral changes. The number of Αβ plaques was significantly reduced in the brain with administration of laser therapy in a dose dependent fashion. Administration of laser therapy demonstrated a dose dependent reduction in amyloid load. All therapies were effective in the reduction in amyloid deposition. All laser treatments reduced the behavioral effects seen with advanced amyloid deposition. Overall, laser therapy was effective at limiting the extent of Αβ amyloid in the brain and reversing the effect of deposition of Αβ peptide and behavioral deficits in the mouse. In addition, the laser therapies were able to reduce the expression of inflammatory markers in the APP transgenic mice. Αβ peptide levels were significantly changed in the brains of the APP transgenic mice, and there was no detectable difference in plasma Αβ peptide levels. Studies showed an increase in βΑΡΡβ and a decrease in βΑΡΡβ levels consistent with inhibition of the β-secretase activity. These studies suggest that laser light therapy is a potential candidate for therapeutic treatment of AD.

[0190] As used herein, the following abbreviations have the following definitions:

Abbreviations Definition

Αβ Abeta

APP Amyloid Precursor Protein

Αβ peptide Abeta peptide

AD Alzheimer's Disease

4G8 Abeta peptide antibody

PTI PhotoThera, Inc.

NTS Neurological Testing Service, Inc.

BACE Beta secretase

IL- 1 Interleukin- 1

TNF-a Tumor necrosis factor-a

TGF-β Transforming growth factor-β

[0191] Αβ containing senile plaques are one of the neuropathological hallmarks of Alzheimer's Disease (AD) and a considerable effort has been expended in understanding the relationship of Αβ and Αβ-containing senile plaques to AD. Much of this work has focused on the biosynthesis of Αβ and factors that influence its deposition. The Αβ peptides are primarily two peptides of either 40 or 42 amino acids generated via internal proteolysis of its precursor, the amyloid precursor protein (APP). In addition to Αβ-containing senile plaques, a variety of neuronal cytoskeletal alterations are prominent features of AD neuropathology. These include phospho-tau containing neurofibrillary tangles, free-lying dystrophic neurites and those present in neuritic senile plaques, and synapse loss. Whether these abnormal features are the result of or cause of neuronal loss is still controversial. Regardless of the precise mechanism, this neuronal and synaptic loss leads to cognitive decline. Early onset autosomal dominant AD is directly linked to mutations in one of several genes: APP, presenilin 1 (PS 1), or presenilin 2 (PS2). In addition several risk factor genes, most notably the APOE4 allele, alter risk for later onset AD, and it is clear that mutations or polymorphisms in several other genes can lead to similar AD phenotypes. [0192] The Αβ peptide is derived from APP, which is cleaved by the sequential action of the β- and γ-secretases. The β-site APP cleavage enzyme (BACE) is a member of the membrane bound aspartyl proteases which results in the cleavage of APP on the extracellular side of the membrane releasing the soluble ΑΡΡ-β (βΑΡΡβ) fragment. In addition, the γ- secretase enzyme (a complex of PS- 1 and PS-2) cleaves the transmembrane domain to release the Αβ peptide and carboxyl terminus. The a-secretase enzyme is the predominant APP activity that cleaves in the middle of the Αβ peptide and prevents the generation of the Αβ peptide. Altered functions of these enzymes can lead to the enhanced production of Αβ peptide, which may contribute to AD pathogenesis. A number of studies have shown that mutations in the APP gene or in presenilins result in the increase in β-secretase cleavage and the production of both Αβ1 -40 and Αβ1-42. In addition, a depletion of cholesterol using cholesterol lowering-agents produced a decrease in Αβ peptide synthesis and sAPP-β. Therefore, understanding the mechanisms associated with altered Αβ processing and the role of β-secretase in the process will help in the design of selective inhibitors of β-secretase and eventually therapeutic treatment of AD.

Methods and Materials

[0193] The amyloid precursor protein (APP) transgenic model of mouse Αβ peptide amyloidosis was used. APP transgenic mice were administered no laser or laser therapy as outlined below 3X/week for 26 weeks starting at 3 months of age. At the end of the experiment, animals were subject to behavioral analysis, were sacrificed and the brains were divided in half and prepared as follows: ½ brain was examined for Αβ plaque burden in the brain (i.e., plaque number), and inflammatory markers and the second ½ of the brain was homogenized for brain Αβ peptide level and sAPP levels. Animals were treated daily at 1 pm and were tested on days 176-179 for the behavioral studies and the final trials were performed on the 26^th week (four hours after the treatment). Animals were sacrificed immediately after training and plasma, CSF and brain were collected for analysis.

[0194] A control APP group was used to determine the baseline of amyloid deposits (treatment was simulated with the laser disabled, no laser energy). The group started as 3 month old mice and maintained in the study for 26 weeks to reach 9 months of age. In addition, at the end of the study, the animals were subjected to behavioral (Morris water maze) analysis. NTS was not blinded to the study parameters. The laser was prepared by PTI and shipped to NTS. The animals were subjected to behavioral studies, amyloid load, Αβ peptide analysis, inflammatory markers, sAPP levels, brain and plasma for Αβ analysis. The animals in each of the groups were allowed to complete the study and all protocols were carried out after 26 weeks. Endpoints were as follows:

— Amyloid load in brain (left hemisphere)

— Inflammatory markers in brain (IL-1 , TNF-alpha, TGF-β)

— Αβ 1-40, 1-42 in brain (½ from animals/plasma from all animals)

— Plasma Αβ levels (13 and 26 weeks: 4hrs post dose).

— sAPPa and β levels from brain. Brain collection (week 26 only) for brain/plasma/CSF Αβ peptide levels.

— Gross necropsy examination

~ Behavior analysis - MWM performed during the last week of treatment, animals to be sacrificed after last administration. Test includes tracking of swimming distance and time to reach platform.

[0195] Male APP transgenic mice (NTS, Inc.) weighing approximately 35-40 grams each were given free access to food and water before and during the experiment. The animals were administered laser therapy. The laser was prepared by PTI and delivered to NTS. The APP mice (male) used in this experiment were designed by microinjection of the human APP gene (with the Swedish and London mutations) into mouse eggs under the control of the platelet- derived growth factor B (PDGF-B) chain gene promoter. The mice were generated on a C57BL/6 background and were developed by MTI. Animals were housed in the Medical University of South Carolina Animal Facility under a 12: 12 ligh dark cycle. Animals were housed in standard non-sterile rodent microisolator cage, with filtered cage top and housed 4 to a cage. Animals were fed ad libitum and maintained by brother sister mating. Transgenic animals were identified by PCR analysis. The mice generated from this construct, develop amyloid deposits starting at 6 months of age. Animals were aged for 3 months and then maintained for 26 weeks and sacrificed for amyloid quantification.

[0196] For histological examination, the animals were anesthetized with an intraperitoneal injection of sodium pentobarbital (50 mg/kg). The animals were transcardially perfused with 4°C, phosphate -buffered saline (PBS) followed by 4% paraformaldehyde. The brains were removed and placed in 4% paraformaldehyde over night. The brains were processed to paraffin and embedded. Ten serial 30-μπι thick sections through the brain were obtained. Tissue sections were deparaffmized and washed in Tris buffered saline (TBS) pH 7.4 and blocked in the appropriate serum (mouse). Sections were blocked overnight at 4°C and then subjected to primary antibody overnight at 4°C (Αβ peptide antibody, 4G8, Signet) in order to detect the amyloid deposits in the brain of the transgenic animals. Sections were washed in TBS and secondary antibody (Vector Laboratories) was added and incubated for 1 hour at room temperature. After washing the sections were incubated as instructed in the Vector ABC Elite kit (Vector Laboratories) and stained with diaminobenzoic acid (DAB). The reactions were stopped in water and cover slipped after treatment to xylene. The amyloid area in each section was determined with a computer-assisted image analysis system, consisting of a Power Macintosh computer equipped with a Quick Capture frame grabber card, Hitachi CCD camera mounted on an Olympus microscope and camera stand. NIH Image Analysis Software, v. 1.55 was used. The images were captured and the total area of amyloid was determined over the ten sections. A single operator blinded to treatment status performed all measurements. Summing the amyloid volumes of the sections and dividing by the total number of sections calculated the amyloid volume per animal.

[0197] For quantitative analysis, we used an enzyme-linked immunosorbent assay (ELISA) to measure the levels of human Αβι_ ο and Αβι_ ₂ in the brains of APP transgenic mice (IBL, 27718 for 1-40 and 2771 1 for 1-42). Αβι_ ο and Αβι_ ₂ were extracted from mouse brains as described below:

1. Weighed frozen hemi-brains.

2. Prepared Tissue Homogenization Buffer (THB-see following recipe) by adding Protease Inhibitor Cocktail (PIC, Sigma) 1 : 1000 dilution immediately before use.

3. Homogenized hemi-brains in lmL of THB + PIC per each lOOmg of tissue (e.g. 2.2mL of buffer was used to homogenize a hemi-brain weighing 220mg).

4. Homogenized brains (using polytron) and samples were aliquoted and snap frozen in liquid nitrogen.

Tissue Homogenization Buffer (THB):

(250mM sucrose, 20mM tris base, lmM EDTA, ImM EGTA)

5 mL 1 M Tris base (pH 7.4)

21.4 g sucrose

0.5 mL 0.5 M EDTA

1.0 mL 0.25 EGTA

Added dd¾0 to 250 mL.

Sterile filtered and handled aseptically.

Stored at 4°C. [0198] ELISA assays were performed as described by the manufacturer (IBL):

1) The wells for reagent blank were determined. ΙΟΟμΙ. each of "4, EIA buffer" was put into the wells.

2) Wells for test sample blank, test sample and diluted standard were determined. Then, 1 ΟΟμΙ_^ each of test sample blank, test sample and dilutions of standard were placed into the appropriate wells.

3) The precoated plate for were incubated overnight at 4°C after covering it with plate lid.

4) Each well of the precoated plate was washed vigorously with wash buffer using washing bottle (3 times). Then, each well was filled with wash buffer and place the precoated plate for 15-30 seconds. Wash buffer was removed completely from the precoated plate by snapping. This procedure was repeated more than 7 times. Then, the remaining liquid was removed from all wells completely by snapping the precoated plate onto paper towel.

5) ΙΟΟμΕ of labeled antibody solution was pipetted into the wells of test samples, diluted standard and test sample blank.

6) The precoated plate was incubated for 1 hour at 4°C after covering it with plate lid.

7) The precoated plate was washed 9 times in the same manner above (4).

8) The required quantity of "6, Chromogen" was pipetted into a disposable test tube. And then, ΙΟΟμΕ was pipetted from the test tube into the wells.

9) The precoated plate was incubated for 30 minutes at room temperature in the dark.

10) Ι ΟΟμΕ of "7, Stop solution" was pipetted into the wells. The liquid was mixed by tapping the side of precoated plate.

1 1) The plate reader was run and measurement conducted at 450nm. The measurement shall be done within 30minutes after the addition of "7, stop solution."

[0199] For quantitative analysis of Αβ peptide levels in the plasma and CSF, an enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of human Αβι_ ο and Αβι_ ₂ in the plasma and CSF of APP transgenic mice (IBL, 27718 for 1-40 and 2771 1 for 1- 42). Αβι_ ο and Αβι_ ₂ ELISAs were performed as above. Blood was collected by saphenous vein collection or cardiac puncture (terminal bleed) in lithium:heparin and plasma was prepared by centrifugation. CSF was collected an analyzed.

[0200] For sAPP assays in the hemibrain, Western blot analysis, extracts containing 20-50 μg of total protein were mixed with Tris/glycine reducing buffer, denaturing loading buffer, loaded, and electrophoresed on 8% Tris/glycine gels (Invitrogen). Gels were transferred to nitrocellulose membranes, incubated with the respective primary antibodies followed by secondary antibodies conjugated to horseradish peroxidase and processed for visualization by enhanced chemiluminescence ECL Plus (Amersham Biosciences). The 6E10 monoclonal Ab (Signet, Dedham, MA) recognizes the first 17 amino acids of the Αβ peptide. 6E10 Ab was used for Western blotting to detect soluble APPa. Rabbit 869 antibody was used to detect sAPP by Western blotting. Secondary antibodies conjugated to horseradish peroxidase were from Jackson ImmunoResearch (West Grove, PA).

[0201] For immunohistochemical analysis for cytokine evaluation in the hemibrain, tissue sections were deparaffmized and washed in Tris buffered saline (TBS) pH 7.4 and blocked in the appropriate serum (goat). Sections were blocked overnight at 4°C and then subjected to primary antibody overnight at 4°C. Sections were washed in TBS and secondary antibody was added and incubated for 1 hour at room temperature. After washing the sections were incubated as instructed in the Vector ABC Elite kit and stained with diaminobenzoic acid (DAB). The reactions were stopped in water and cover slipped after treatment to xylene.

[0202] Morris water-maze testing was used for behavioral analysis. All mice were tested once in the Morris water maze test at the end of the experiment. Mice were trained in a 1.2 m open field water maze. The pool was filled to a depth of 30 cm with water and maintained at 25°C. The escape platform (10 cm square) was placed 1 cm below the surface of the water. During the trials, the platform was removed from the pool. The cued test was carried out in the pool surrounded with white curtains to hide any extra-maze cues. All animals underwent non- spatial pretraining ( SP) for three consecutive days. These trials are to prepare the animals for the final behavioral test to determine the retention of memory to find the platform. These trials were not recorded (for training purposes only). For the training and learning studies, the curtains were removed to extra maze cues (this allowed for identification of animals with swimming impairments). On day 1 , the mice were placed on the hidden platform for 20 seconds (trial 1), for trials 2-3 animals were released in the water at a distance of 10 cm from the cued-platform or hidden platform (trial 4) and allowed to swim to the platform. On the second day of trials, the hidden platform was moved randomly between the center of the pool or the center of each quadrant. The animals were released into the pool, randomly facing the wall and were allowed 60 seconds to reach the platform (3 trials). In the third trial, animals were given three trials, two with a hidden platform and one with a cued platform. Two days following the NSP, animals were subjected to final behavioral trials (Morris water maze test). For these trials (3 per animal), the platform was placed in the center of one quadrant of the pool and the animals released facing the wall in a random fashion. The animal was allowed to find the platform or swim for 60 seconds (latency period, the time it takes to find the platform). All animals were tested within 4- 6 hours of dosing and were randomly selected for testing by an operator blinded to the test group. Animals were tested on days 176-179 for the non-spatial pretraining and the final trials were performed on day 180.

[0203] The results are expressed as the mean ± standard error of mean (SEM). The significance of differences in the amyloid and behavioral studies were analyzed using a t-test. Comparisons were made between the 9-month-old APP control group (baseline group - started at 3 months of age) and the 9-month old treated mice. Differences below 0.05 were considered significant. Percent changes in amyloid and behavior were determined by taking the summation of the data in each group and dividing by the comparison (i.e., treated/9 month control = % change). Animals that developed severe complications following administration of laser were excluded from the study.

[0204] Animals (100 mice) were subjected to administration of no laser or laser for two minutes 3X week beginning at 3 months of age and continued for 6 months. Animals were male and were randomly assigned to the different treatment groups per Table 2 and Table 3.

Table 2:

(1) Total Number of Animals

(2) These values are based on tissue transmission and scattering measurements done on mice at earlier TLT studies (Ischemic Stroke and TBI), and updated based on measurements of scalp/skull transmission and scatter on two APP mice. The measured data was used to calculate the Radiant Power at the skin ~ Table 3, needed to deliver the irradiances listed to the animals Dura.

(3) These are calculated values showing average Irradiances for Continuous TLT and Peak Irradiances for Pulsed TLT. Irradiance at the Skin = Radiant Power/ Area of beam = Radiant Power/(7i*(0.1 cm)²) = Radiant Power/0.0314 cm² Table 3:

Irradiances for Pulsed TTL.

Results

[0205] The laser was provided as a powder to NTS. Amyloid load was determined in the animals treated with laser therapy and no laser. Table 4 and FIG. 12 illustrate the results. The no laser group demonstrated a ~2% amyloid burden which is the standard level of amyloid in this particular model at ~9 months of age (previous studies). The laser therapy demonstrated a dose dependent attenuation of the amyloid load when compared to the vehicle group. At all doses except CW, the amount of amyloid actually was lower than in the 9 month control group indicating that the laser therapy not only stopped amyloid deposition, but may have even reversed the level of amyloid. This suggests that the laser therapy was capable of attenuating the amyloid in these mice. There were no deaths in this study. Animals were examined for gross abnormalities following sacrifice. No gross pathological features were detected in the animals.

Table 4: Percent decrease in amyloid in the brain

^Percent changes are compared to no laser

* *P value compared to no laser [0206] The behavioral effects (behavior and distance) of treatment with laser therapy were determined in the APP transgenic mice at the termination of the experiment. Mice were subjected to the Morris water maze task and the latency period and distance were determined. Table 5 and FIG. 13A illustrate the results. The no laser control demonstrated a latency time of 48.58 seconds, which is the standard in this particular model at ~9 months of age (previous studies). All the laser treated animals demonstrated a significant difference in latency when compared to the control. This suggests that laser therapy was capable of attenuating the latency time in these mice.

Table 5: Behavioral changes in APP transgenic mice treated with LLT.

^Percent changes are compared to no laser

* *P value compared to no laser

[0207] Table 6 and FIG. 13B illustrate the results comparing distance traveled in the water maze. The vehicle control demonstrated a distance of 75.53 in, which is the standard in this particular model at ~9 months of age (previous studies). All the animals demonstrated a significant difference in distance when compared to the control group. This suggests that laser therapy was capable of attenuating the behavioral effects in these mice.

Table 6: Behavioral changes in APP transgenic mice treated with LLT.

*Percent changes are compared to no laser

* *P value compared to no laser [0208] The effect of laser therapy was determined on the expression of inflammatory markers (IFMs) in the brain of APP transgenic mice (FIGS. 14A-14C and Table 7). Table 7 and FIGS. 14A- 14C illustrate the results of the animals terminated at 26 weeks after the start of treatment. The no laser control demonstrated specific staining for inflammatory markers (IL- 1 , TNF and TGF-β) as indicated in Table 7, which are the standard in this particular model at ~9 months of age (previous studies). Laser therapy at all the doses demonstrated a significant difference from the control animals. This suggests that laser therapy was capable of attenuating the IFMs in these mice.

Table 7: Changes in inflammatory markers in APP transgenic mice treated with LLT*.

^Percent changes are compared to no laser

[0209] The effect of laser therapy was determined on the changes in Αβ peptide in the brain of APP transgenic mice (FIGS. 15A and 15B and Tables 8 and 9). Measurement of Αβ1 -40 and Αβ1 -42 peptide (guanidine extractable) in the brain showed an increase as the APP transgenic mice aged from 3 to 9 months. Table 8 and FIG. 15A illustrate the results of the animals terminated at 26 weeks after the start of treatment. The control demonstrated the levels of Αβ1-40 in the brain as indicated in Table 8, which is the standard in this particular model at ~9 months of age (previous studies). Laser therapy at all doses demonstrated a decrease in Αβΐ- 40 when compared to the control and they were significant. This suggests that laser therapy was capable of attenuating the Αβ1 -40 increase in these mice. Table 8: Changes in Αβ peptide levels in the brain of APP transgenic mice

*Percent changes are compared to no laser

* *P value compared to no laser

[0210] Table 9 and FIG. 15B illustrate the results of the animals terminated on the 26^th week after the start of treatment for Αβ1-42 peptide levels. The control demonstrated the levels of Αβ1-42 in the brain as indicated in Table 9, which is the standard in this particular model at ~9 months of age (previous studies). Laser therapy at all doses demonstrated a significant decrease in Αβ1 -42 when compared to control. This suggests that laser therapy was capable of attenuating the Αβ1 -42 peptide levels in these mice.

Table 9: Changes in Αβ peptide levels in the brain of APP transgenic mice

*Percent changes are compared to no laser

* *P value compared to no laser

[0211] The effect of laser therapy was determined on the changes in Αβ peptide levels in the plasma of APP transgenic mice (FIGS. 16A and 16B and Tables 10 and 1 1). Measurement of total Αβ peptide in the plasma was performed on weeks 13 and 26 in the APP transgenic mice treated from 3 to 9 months. As seen in the Tables 10 and 1 1 and FIGS. 16A and 16B, the total plasma Αβ peptide levels were similar in all groups for the 90 day time period. As the study progressed and the animals were treated with laser therapy, there was a significant change in the apparent plasma total Αβ peptide profile. This suggests that laser therapy was capable of lowering the plasma Αβ peptide levels, while brain Αβ peptide levels also changed. Table 10: Changes in plasma total Αβ peptide levels in the APP transgenic mice treated with LLT. Week 13.

^Percent changes are compared to no laser

* *P value compared to no laser

Table 1 1 : Changes in plasma total Αβ peptide levels in the APP transgenic mice treated with LLT. Week 26.

*Percent changes are compared to no laser

* *P value compared to no laser

[0212] The effects of treatment with TTP-5854 laser therapy on sAPPa and CTFP levels in the brain were determined in the APP transgenic mice at the termination of the experiment. Brain tissue was subjected to extraction and Western blot analysis for sAPPa and CTFβ levels following treatment. Tables 12 and 13 illustrate the results of the animals terminated at 26 weeks after the start of treatment. The control demonstrated a given level of sAPPa and CTFβ in the brain, which is the standard in this particular model at ~9 months of age (previous studies). Laser therapy demonstrated a significant difference in both sAPPa and CTFβ levels when compared to the control. For sAPPa, laser therapy at all doses demonstrated significant differences from the control (Table 12 and FIG. 17A). For CTFp, again all doses of laser therapy demonstrated a significant difference from the control (Table 13 and FIG. 17B). This suggests that laser therapy was capable of increasing the sAPPa and decreasing CTFβ in these mice suggesting a shift from β- to a-secretase activity. Table 12: Changes in sAPP levels in the brain of APP transgenic mice

^Percent changes are compared to no laser

* *P value compared to no laser

Table 13: Changes in CTF levels in the brain of APP transgenic mice

*Percent changes are compared to no laser

* *P value compared to no laser

[0213] The treatment with laser therapy on CSF Αβ peptide levels was determined in the APP transgenic mice at the termination of the experiment (FIG. 18 and Table 14). Mice were subjected to ELISA for total Αβ peptide levels were determined because of the small amount of CSF obtained. Table 14 illustrates the results of the animals terminated at 26 weeks after the start of treatment. The control demonstrated Αβ peptide levels shown in Table 14, which is the standard in this particular model at ~9 months of age (previous studies). CW and Pulse I demonstrated no significant difference in CSF when compared to the control. However, laser therapy at Pulse II and Pulse III demonstrated significant differences from the control (Table 14 and FIG. 18). This suggests that laser therapy was capable of attenuating the Αβ peptide levels in the brain in these mice at specific doses. Table 14: Changes in Αβ peptide levels in the CSF of APP transgenic mice

*Percent changes are compared to no laser

* *P value compared to no laser

[0214] Statistical analysis was performed on the samples as described by GraphPad Prism (Version 4.00). The changes in the different parameters were significant to the 0.05 level or greater. This is due not only to the number of animals in each group, but also to the number of samples taken for each measurement from each animal (20). Therefore, there is confidence in the numbers. The numbers fall within the range of acceptable results.

[0215] Animals were examined for gross abnormalities following sacrifice. No gross pathological features were detected in most of the animals except for Group E (Pulse III). Animals showed some lesioning in the brain following treatment. Animals after a few weeks began to develop lesions on the skin. They were switched to a regime of 1 minute treat, ice, 1 minute treat without further injury.

Discussion

[0216] Transgenic mice expressing the mutant form of the human APP gene begin to deposit amyloid fibrils by 6 months of age. This process is associated with increased Αβ peptide in the deposits in the brain. Recent studies have shown that administration of laser light therapy can be protective against various neuronal injuries. In this study, LLT was tested in the APP model to determine the efficacy on amyloid load, inflammatory markers, brain Αβ levels, plasma and CSF Αβ levels, and behavioral changes. The number of Αβ plaques was significantly reduced in the brain with administration of LLT in a dose dependent fashion. Administration of LLT demonstrated variable effects and with increasing doses showing the greatest effect of reduction of amyloid deposition. [0217] NTS was not blinded to the study as outlined by PTI. Overall, laser light therapy was effective at limiting the extent of Αβ amyloid in the brain and altering the amount of deposition of Αβ peptide and behavioral deficits in the mouse.

[0218] Additional studies and examples regarding the effects of LLLT or phototherapy are included in U.S. Patent Application Publication Nos. 201 1/0144723, 201 1/0060266 and 2009/0254154, the entire contents of which are expressly incorporated herein by reference.

[0219] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application. Those skilled in the art may adapt and apply the invention in its numerous forms, as may be best suited to the requirements of a particular use. Accordingly, the specific embodiments of the present invention as set forth are not intended as being exhaustive or limiting of the invention.

[0220] Conditional language, for example, among others, "can," "could," "might," or "may," unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment.

[0221] While the inventions have been discussed in the context of certain embodiments and examples, it should be appreciated that the inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. Some embodiments have been described in connection with the accompanying drawings. However, it should be understood that the figures are not drawn to scale. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to actual dimensions and layout of the devices illustrated. Components can be added, removed, and/or rearranged. Additionally, the skilled artisan will recognize that any of the above-described methods can be carried out using any appropriate apparatus. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with various embodiments can be used in all other embodiments set forth herein. Additionally, processing steps may be added, removed, or reordered. A wide variety of designs and approaches are possible.

[0222] For purposes of this disclosure, certain aspects, advantages, and novel features of the inventions are described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

Claims

WHAT IS CLAIMED:

1. A light therapy apparatus for therapeutically treating a chronic neurodegenerative disorder, the light therapy apparatus comprising:

a substantially flat, biocompatible base sheet configured to be implanted between the subject's scalp and the subject's skull and configured to be anchored to an outer surface of the subject's skull; and

one or more light sources mechanically coupled to the base sheet.

2. The light therapy apparatus of Claim 1, wherein, during use, the one or more light sources are positioned to irradiate at least a portion of the subject's brain with light transmitted through the subject's skull.

3. The light therapy apparatus of Claim 1 , wherein the base sheet comprises a substantially flexible material.

4. The light therapy apparatus of Claim 3, wherein the substantially flexible material is mylar.

5. The light therapy apparatus of Claim 3, wherein the substantially flexible material is polytetrafluoroethy lene .

6. The light therapy apparatus of Claim 1 , wherein the base sheet comprises a substantially rigid material.

7. The light therapy apparatus of Claim 1 , wherein the one or more light sources comprise one or more light emitting diodes.

8. The light therapy apparatus of Claim 1 , wherein the one or more light sources comprise one or more vertical cavity surface-emitting laser diodes.

9. The light therapy apparatus of Claim 1, wherein at least one of the one or more light sources is configured to emit a pulsed light beam comprising a plurality of pulses having a temporal pulse width in a range between 0.1 milliseconds and 150 seconds.

10. The light therapy apparatus of Claim 9, wherein the pulsed light beam stimulates, excites, induces, or otherwise supports one or more intercellular or intracellular biological processes involved in the survival, regeneration, or restoration of performance or viability of brain cells irradiated by the pulsed light beam.

1 1. The light therapy apparatus of Claim 9, wherein the pulsed light beam has a duty cycle, wherein the temporal pulse width and the duty cycle are sufficient for the pulsed light beam to penetrate the subject's skull to modulate membrane potentials, thereby enhancing cell survival, cell function, or both, of the brain cells irradiated by the pulsed light beam.

12. The light therapy apparatus of Claim 1, further comprising a controller mechanically coupled to the base sheet and operatively coupled to the one or more light sources and a power source operatively coupled to the controller and to the one or more light sources.

13. The light therapy apparatus of Claim 12, further comprising a biomedical sensor operatively coupled to the controller and configured to provide real-time feedback information regarding the subject's brain.

14. The light therapy apparatus of Claim 13 , wherein the biomedical sensor is configured to transmit a signal to the controller that is indicative of a patient parameter.

15. The light therapy apparatus of Claim 12, wherein the controller is configured to regulate emission of light from the one or more light sources in accordance with a therapeutic treatment regimen.

16. The light therapy apparatus of Claim 12, wherein the controller is pre-programmed prior to implantation.

17. The light therapy apparatus of Claim 12, wherein the controller is programmable or re-programmable upon being implanted between the subject's scalp and the subject's skull.

18. The light therapy apparatus of Claim 12, wherein the power source is rechargeable.

19. The light therapy apparatus of Claim 12, wherein the power source is a battery.

20. The light therapy apparatus of Claim 12, wherein the power source is located external to the subject.

21. The light therapy apparatus of Claim 1 , wherein the one or more light sources are variably positionable within the base sheet.

22. The light therapy apparatus of Claim 1, wherein, upon being implanted between the subject's scalp and the subject's skull, the one or more light sources are configured to be aligned with one or more sutures of the subject's skull, such that light emitted from the one or more light sources irradiates the one or more sutures of the subject's skull.

23. The light therapy apparatus of Claim 1, wherein the light emitted by the one or more light sources has an irradiance and a wavelength configured to therapeutically treat the chronic neurodegenerative disease.

24. The light therapy apparatus of Claim 23, wherein the wavelength is between about 780 nm and 840 nm.

25. The light therapy apparatus of Claim 23, wherein the wavelength is greater than 1300 nm.

26. The light therapy apparatus of Claim 23, wherein the irradiance is less than 10 W/cm² at the outer surface of the subject's skull.

27. The light therapy apparatus of Claim 23, wherein the irradiance is between about 0.1 mW/cm² and about 1 W/cm² at a cortical surface of the subject's brain.

28. The light therapy apparatus of Claim 23, wherein the irradiance is between about 0.5 mW/cm 2 and about 10 mW/cm 2 at a cortical surface of the subject's brain.

29. The light therapy apparatus of Claim 1, wherein the chronic neurodegenerative disease is one of stroke, Parkinson's disease, Alzheimer's disease, dementia, Lewy body disease, age-related cognitive impairment, brain cancer, amyotrophic lateral sclerosis, multiple sclerosis, Friedreich's ataxia, encephalitis, hydrocephalus, Prion disorders, Huntington's disease, and Pick's disease, or combinations thereof.

30. An implantable light therapy apparatus for treating at least a portion of a subject's brain, the light therapy apparatus comprising:

a substantially flat, biocompatible base sheet;

a plurality of light sources mechanically coupled to the base sheet, wherein, upon the light therapy apparatus being implanted below an inner surface of the subject's scalp and being anchored to an outer surface of the subject's skull, the plurality of light sources are positioned to irradiate at least a portion of the subject's neural tissue with light having a wavelength between about 780 nm and about 840 nm, the light having an irradiance configured to therapeutically treat a neurological condition of the brain;

a controller mechanically coupled to the base sheet and operatively coupled to the plurality of light sources; and

a power source operatively coupled to the controller and to the plurality of light sources.

31. The light therapy apparatus of Claim 30, wherein the plurality of light sources comprises one or more light emitting diodes.

32. The light therapy apparatus of Claim 30, wherein the plurality of light sources comprises one or more vertical cavity surface-emitting laser diodes.

33. The light therapy apparatus of Claim 30, wherein the plurality of light sources comprises a plurality of woven optical fibers disposed within the biocompatible base sheet.

34. The light therapy apparatus of Claim 30, wherein the plurality of light sources comprises one or more light sources configured to emit light having a first irradiance and a first wavelength and one or more light sources configured to emit light having a second irradiance and a second wavelength, wherein the second irradiance and the second wavelength are different from the first irradiance and the first wavelength.

35. The light therapy apparatus of Claim 30, wherein the power source comprises a rechargeable battery.

36. The light therapy apparatus of Claim 30, wherein the neurological condition is a chronic neurodegenerative disease.

37. The light therapy apparatus of Claim 36, wherein the chronic neurodegenerative disease is one of stroke, Parkinson's disease, Alzheimer's disease, dementia, Lewy body disease, age-related cognitive impairment, brain cancer, amyotrophic lateral sclerosis, multiple sclerosis, Friedreich's ataxia, encephalitis, hydrocephalus, Prion disorders, Huntington's disease, Pick's disease, or combinations thereof.

38. The light therapy apparatus of Claim 30, wherein the neurological condition is a psychiatric disorder.

39. The light therapy apparatus of Claim 38, wherein the psychiatric disorder is one of a depressive disorder, an anxiety disorder, a personality disorder, a dissociative disorder, a mood disorder, a somatoform disorder, a factitious disorder, a sexual and gender identity disorder, an adjustment disorder, a behavioral disorder, an eating disorder, a psychotic disorder, or combinations thereof.

40. The light therapy apparatus of Claim 30, wherein the neurological condition is a speech or language disorder.

41. The light therapy apparatus of Claim 30, wherein the neurological condition is a sleep disorder.

42. The light therapy apparatus of Claim 30, wherein the neurological condition is a compulsive disorder.

43. The light therapy apparatus of Claim 30, wherein the neurological condition is a developmental disorder.

44. The light therapy apparatus of Claim 30, wherein the neurological condition is epilepsy.

45. The light therapy apparatus of Claim 30, wherein the neurological condition is depression.

46. The light therapy apparatus of Claim 30, wherein the neurological condition is an addictive disorder.

47. A method for treating a patient with a neurological condition, comprising:

providing an implantable light therapy apparatus, the light therapy apparatus comprising:

a substantially flat, biocompatible base sheet;

one or more light sources mechanically coupled to the base sheet;

a controller mechanically coupled to the base sheet and operatively coupled to the one or more light sources; and

a power source operatively coupled to the controller and to the one or more light sources;

implanting the light therapy apparatus below the scalp of the patient and outside the skull of the patient; and

anchoring the light therapy apparatus to an outer surface of the skull of the patient.

48. The method of Claim 47, further comprising operating the light therapy apparatus to deliver light energy having an irradiance between about 0.01 mW/cm² and about 1 W/ cm² and a wavelength of about 780 nanometers to about 840 nanometers to a target site within the brain of the patient through the skull of the patient.

49. The method of Claim 47, wherein the neurological condition is Alzheimer's disease.

50. The method of Claim 47, wherein the neurological disorder is Parkinson's disease.

51. The method of Claim 47, wherein the neurological disorder is depression.

52. The method of Claim 47, further comprising:

identifying at least one suture of the skull; and aligning at least one of the one or more light sources with the at least one suture of the skull.

53. The method of Claim 47, wherein anchoring the light therapy apparatus comprises inserting one or more bone anchors into the skull of the patient.

54. The method of Claim 47, wherein anchoring the light therapy apparatus comprises applying a bioadhesive to the skull and positioning the light therapy apparatus over the bioadhesive.