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Transcranial Near-Infrared Stimulation Enhances Cerebral Metabolism, Connectivity, and EEG Powers in Healthy Humans

Hanli Liu, Ph.D.
Transcranial photobiomodulation (tPBM) is a new non-invasive means to neuro-stimulate the human brain using near-infrared (NIR) light, which has been reported to improve cognition and memory. However, few objective measures to quantify underlying mechanism of tPBM have been reported. In recent studies, our group has demonstrated that tPBM with 1064-nm laser, when being delivered regionally on the human forehead for 8 min, can significantly enhance cerebral hemodynamic concentrations, metabolic activities, and electroencephalogram (EEG) powers at both alpha and beta rhythms across the entire scalp. Besides, we utilized a 111-channel functional near infrared spectroscopy (fNIRS) system to map cerebral hemodynamic responses over the whole head to the same tPBM. Our novel findings revealed that tPBM significantly increased topographical functional connectivity between the frontal stimulation site and the central as well as parietal regions.