Effects of Transcranial Photobiomodulation on Motor Functions in Healthy Individuals: A Randomized Controlled Trial

Abstract

Objective This study investigated the effects of transcranial photobiomodulation (tPBM) targeting the supplementary motor area (SMA) on motor performance and neural activity in healthy individuals. Methods In a randomized, double-blind, sham-controlled trial, 60 right-handed participants received active tPBM (850 nm, 60 mW/cm 2 , 36 J/cm 2 ) or sham stimulation over the SMA for four consecutive days. Motor performance was assessed using a sequential finger-tapping task for both hands. Neural activity was evaluated using quantitative electroencephalography (qEEG) at rest. Results Active tPBM significantly improved non-dominant hand motor performance compared to sham, with reductions in reaction time and total movement time, and increased accuracy (all p < 0.001 after Bonferroni correction). qEEG showed significant increases in alpha and beta power at C3 and C4 electrodes in the active group (all p < 0.001 after correction). No significant changes were observed in the sham group. Conclusion These findings suggest that short-term tPBM targeting the SMA can enhance motor performance, particularly of the non-dominant hand, and increase sensorimotor alpha and beta power in healthy young adults. Further research is needed to clarify the underlying mechanisms and potential clinical applications.