| Popis: |
Transcranial photobiomodulation (tPBM) of the prefrontal cortex can improve human cognition and increase electroencephalogram (EEG) alpha and beta powers, but it was unclear whether tPBM-induced heat would influence EEG oscillation powers. This study aimed to prove that tPBM-induced increases in anterior-posterior EEG powers at alpha and beta bands would be significant after removal of tPBM-associated thermal effects. We performed both sham-controlled tPBM and sham-controlled thermal stimulation (thermo_stim) experiments under the eyes-closed resting state with concurrent recordings of 64-channel EEG before, during, and after 8-min tPBM at 1064-nm wavelength and thermo_stim with temperature from 33 to 41 °C, respectively, from healthy humans (n=46 for tPBM; n=14 for thermo_stim). Sham-subtracted topographies of EEG powers at five frequency bands were averaged at the group level during and post both stimulations. Two-sample t-tests with FDR correction and effect size were calculated for comparing tPBM and thermal effects at all five frequency bands. Right-frontal tPBM induced significant increases in EEG anterior-posterior alpha and beta powers under the eyes-closed conditions, consistent with the results previously reported in the eyes-open tPBM experiments. In contrast, right-frontal thermal stimulation under the eyes-closed resting state resulted in opposite effects on EEG power patterns with respect to those by tPBM. tPBM-induced enhancement in alpha and beta oscillations occurred during the 8-min intervention after exclusion of thermal effects. The ability of tPBM to synchronize alpha and beta oscillations in the anterior-posterior regions may be linked to the enhancement of frontoparietal network and the improvement of human cognition. |
