ISPUB.COM The Internet Journal of Neurology Volume 20 Number 1 DOI: 10.5580/IJN.52988 1 of 11 Effect of Low Level Laser Therapy on Brain Activity Assessed by QEEG and QEEGt in Normal Subjects C Machado, Y Machado, M Chinchilla, S Shanks, H Foyaca-Sibat Citation C Machado, Y Machado, M Chinchilla, S Shanks, H Foyaca-Sibat. Effect of Low Level Laser Therapy on Brain Activity Assessed by QEEG and QEEGt in Normal Subjects. The Internet Journal of Neurology. 2018 Volume 20 Number 1. DOI: 10.5580/IJN.52988 Abstract Objectives: The use low-level laser therapy (LLLT) is steadily increasing in diverse areas of medicine including wound healing, relief from pain and inflammation, and treating neurodegenerative diseases. LLLT also appears to be beneficial for treating traumatic brain injury, depression, and cognitive disorders. The objective of this pilot study was to assess the effects of LLLT on brain activity in healthy volunteers. Materials and Methods: Healthy male (n=5) and female (n=5) subjects, 22 to 28 years old were enrolled. A 20-minute electroencephalogram (EEG) was obtained before and after exposure to LLLT. EEGs were recorded using 19 monopolar derivations of the International 10-20 System with linked earlobes as reference. Using a hand-held probe, the entire skull of each subject was exposed to red 635 nm laser light for 10 minutes. EEG data were assessed using quantitative EEG (QEEG) and tomographic quantitative EEG (QEEGT) methods. Results: Comparing EEG records before and after the application of LLLT revealed significant activation in several areas of the brain. Brain maps for alpha and gamma absolute powers demonstrated clear increments in nine subjects. A decrement in alpha and gamma absolute powers after LLLT stimulation only occurred in one subject. There were no reported adverse events. Conclusion: Exposing the brain to 635 nm laser light for 10 minutes resulted in significant activation of several areas of the brain. Further research should be done with a larger sample to create a larger body of normative data for comparing the effects of LLLT for treating various neurological diseases. Conflict of Interest Statement: Mr. Shanks is an employee of the company which manufactures the low-level laser device used in this study. The remaining authors have stated explicitly that there are no conflicts of interest in connection with this article. INTRODUCTION In 1967, the Hungarian Endre Mester first proposed the use of low-power laser to increase hair growth and stimulate wound healing in mice1,2 and shortly afterwards, he began using lasers to treat patients with non-healing skin ulcers.3 Since that time, the use low-level laser therapy (LLLT), also known as nonthermal laser and photobiomodulation, its use has steadily increased in diverse areas of medicine such as wound healing, relief from pain and inflammation and treating neurodegenerative diseases.4,5 Experimental transcranial photobiomodulation using LLLT has been reported to stimulate, preserve and regenerate cells and tissues in mice. The mechanism of action involves photon absorption in the mitochondria (cytochrome-C oxidase) and ion channels in cells leading to activation of signaling pathways, up-regulation of transcription factors, and increased expression of protective genes (possibly mediated by light absorption by opsins).6 Mice have shown an improvement improved memory and learning using LLLT.7 Secondary effects of photon absorption include increases in ATP, a brief burst of reactive oxygen species, an increase in nitric oxide, and modulation of calcium levels. Tertiary effects include activation of a wide range of transcription factors leading to improved cell survival, increased proliferation and migration, and new protein synthesis.7-9 Xuan and colleagues have reported on the use of LLLT to treat stroke and traumatic brain injury in experimental