Analysis of variations in brain states and impact of TES during behavioral task

Abstract

This research targeted to investigate the effects of low-gamma High Definition transcranial alternating current (HD-tACS) at the left DLPFC and primary motor cortex in healthy individuals performing continuous attention task. We selected an openly accessible dataset from openneuro.org. Dataset includes within participant implementation of High-Definition tACS (HD-tACS), stimulating two cephalic regions (frontal & motor) with biphasic stimulation waveform (30 Hz) with a total 600 stimulation trials in 30 sessions. The physiological data i.e. EOG, ECG, along with EEG and behavioral data were being recorded over the course of two 70 and 70.5 minutes’ sessions. The demographic data were acquired before and after each session together with the wellness questionnaires. The participants were given two stimulation doses separately, with 20 stimulation trials per session. The within-subject results showed significant differences between the pre- and post-stimulation data (p-value <0.05) in the F30, in each frequency band. While in M30 session, there was a significant increase in alpha and beta oscillations (p-value < .05). The gamma oscillations were not altered by low-gamma tACS at M1, whereas the theta oscillations showed a significant decrease. The phase-locking values (PLV) of frontal channels decreased in theta, alpha, beta & gamma bands, suggesting a drop in the attention of participants with the onset of stimulation. Hence, the results indicate, that lowgamma HD-tACS over left DLPFC has the potential to inhibit attention and information processing. And the low-gamma HD-tACS can improve motor function over the left primary motor cortex.