Enhanced inhibitory control after out-of-phase theta tACS between the lDLPFC and dACC

It is debatable whether transcranial alternating current stimulation (tACS), administered with specific phase lags across task-relevant regions, would differently manipulate cognitive control performance. This study investigated the effects of individualized theta peak frequency tACS delivered in-phase and out-of-phase between the dorsal anterior cingulate cortex (dACC) and left dorsolateral prefrontal cortex (lDLPFC) on inhibitory control performance. Participants performed a Stroop task while receiving theta tACS over individually optimized high-definition electrode montages targeting the dACC and lDLPFC. Behavioral task performance and response-locked theta-band power in the electroencephalogram (EEG) were analyzed. Our results showed significantly reduced reaction times following out-of-phase tACS, accompanied by increased pre-response theta activity. These findings demonstrate the potential of out-of-phase theta tACS to modulate top-down control, highlighting the feasibility of utilizing phase-dependent tACS for enhancing inhibitory control performance.