Introduction:

Transcranial alternating current stimulation (tACS) has emerged as a promising tool to modulate cognitive functions by entraining endogenous neural oscillations. This study investigated the behavioral and neurophysiological after-effects of theta-frequency tACS individualized to each participant’s intrinsic theta frequency (ITF).

Methods:

Twenty-two healthy participants were randomly assigned to either a real stimulation group (tACS group) or a sham group. Cognitive assessments and resting-state EEG/fMRI data were collected pre- and post-stimulation.

Results:

Participants in the real tACS group showed significant post-stimulation improvements in short-term memory, verbal fluency and category fluency scores compared to the sham group. Functional connectivity analyses revealed increased activity in the dorsal attention and frontoparietal networks only in the stimulation group, suggesting network-specific modulation

Discussion:

These effects align with the theta-gamma coupling theory and provide evidence for long-lasting neuroplastic changes following personalized tACS. This study contributes to our understanding of brain stimulation and supports the use of tACS for cognitive enhancement in healthy individuals.