Gamma tACS Reshapes Low-Dimensional Trajectories of Brain Activity in Working Memory

Functional neuroimaging research has demonstrated that the complex neural activity supporting cognitive function and behavior in the brain can be understood through the examination of low-dimensional trajectories of brain activity. Transcranial alternating current stimulation (tACS) is a highly anticipated technique for noninvasive neuromodulation. In this study, we sought to explore the potential mechanisms of tACS using neural manifold changes in low-dimensional embedding. To investigate possible mechanisms of tACS, we extracted neural manifold changes derived from electroencephalogram (EEG) data collected during working memory (WM) tasks before and after tACS and explored the relationship between these manifold changes and behavioral performance. Our findings revealed that exposure to tACS delivered at y frequency (γ-tACS) on the left dorsolateral prefrontal cortex (DLPFC) resulted in an expansion of the low-dimensional trajectories of brain activity, and this expansion was associated with adaptations that maintained behavioral stability. Therefore, applying low-dimensional analysis to EEG may provide new insights into the study of noninvasive neuromodulation mechanisms.