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Transcranial Photobiomodulation also known as Transcranial Low Level Light Therapy, refers to the application of light to the patient’s head for therapeutic purposes such as recovery from neurological disorder or damage.(1) Light in the red and near infrared regions of the electromagnetic spectrum are used because of their ability to penetrate the scalp, skull and brain.(2) The light is supplied by lasers or light emitting diodes (LEDs) in continuous or pulse wave mode and is applied to either the entire head or to target specific areas of the brain.(1, 3) The non-invasive nature of this treatment differentiates it from other brain stimulation techniques such as deep brain stimulation in which electrodes are inserted into the brain for treatment. Studies have been performed to assess the safety and effectiveness of transcranial light therapy in conditions such as stroke and traumatic brain injury.(4, 5) These studies have not revealed any major safety concerns with the treatment but have shown a dependence on the treatment for sustained improvement of the condition; halting treatment causes regression in patients’ progress.(5) == Proposed Mechanism of Action == While the exact mechanism of action remains unknown, studies have shown that near infrared laser light (808 nm) applied transcranially to embolized rabbits resulted in significantly higher levels of the energy containing molecule adenosine tri-phosphate (ATP) in the cerebral cortex of treated rabbits compared to the sham-treated and control rabbits.(6) Light absorbing molecules in the mitochondria of cells convert the light energy into chemical energy stored in ATP in the process of respiration. This reserve of energy is then available to power processes such as growth and repair. Interestingly, other studies have revealed a positive phototactic response of neural cells in the presence of low level laser red and near infrared light, as well as a re-elongation of cells damaged by oxidative stress.(7-9) Together, these findings are suggestive of a simultaneous repair and growth by neural cells fuelled by ATP in response to light treatment. This is consistent with the theory that mitochondrial functioning and respiration is important for neuroprotection and cognitive enhancement and may be key to preventing and alleviating several neurological disorders.(10) Furthermore, blood irradiation studies over the years has provided evidence for increased blood circulation in response to light therapy. In mice, a similar significant increase in cerebral blood flow was detected after transcranial near infrared light therapy.(11) This increase in blood flow correlated with increased concentrations of cortical nitric oxide (NO). This is further supported by the observation of increased blood flow in cerebral arteries of elderly women treated with transcranial light therapy.(12) The role of increased NO levels and blood flow must also be considered when discussing the mechanism of action for light therapy. Additional studies are warranted to decipher in greater detail the mechanism of action for light therapy in treating various neurological ailments. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Transcranial photobiomodulation」の詳細全文を読む スポンサード リンク
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