Gamma Transcranial Alternating Current Stimulation Enhances Working Memory Ability in Healthy People: An EEG
Binbin Gao1, Jinyan Zhang2, Jianxu Zhang2
1School of Life Science, Beijing Institute of Technology, Beijing 100081, China.
Background:
Working memory (WM) is a core cognitive function closely linked to various cognitive processes including language, decision making, and reasoning. Transcranial alternating current stimulation (tACS), a non-invasive brain stimulation technique, has been shown to modulate cognitive abilities and treat psychiatric disorders. Although gamma tACS (γ-tACS) has demonstrated positive effects on WM, its underlying neural mechanisms remain unclear.
Methods:
In this study, we employed electroencephalogram (EEG) microstate analysis to investigate the spatiotemporal dynamics of γ-tACS effects on WM performance. Healthy participants (N = 104) participated in two-back and three-back WM tasks before and after two types (sine and triangular) of γ-tACS, with sham stimulation as a control.
Results:
Our results revealed that γ-tACS improved performance in both the two-back and three-back tasks, with triangular γ-tACS showing greater accuracy improvement in the three-back task than the sham group. Furthermore, γ-tACS significantly modulated EEG microstate dynamics, specifically downregulating microstate Class C and upregulating microstate Classes D and B. These changes were positively correlated with reduced reaction times in the three-back task.
Conclusions:
Our findings establish microstate analysis as an effective approach for evaluating γ-tACS-induced changes in global brain activity and advance the understanding of how γ-tACS influences WM.
