Theta-frequency transcranial alternating current stimulation enhances proactive control in individuals

Proactive control is defined as the capacity of an individual to selectively allocate attentional resources to task-relevant cues during the preparatory phase of a task, actively encode and sustain this information within working memory, and subsequently establish appropriate response readiness. Research demonstrates that proactive control has neuroplasticity. The dorsolateral prefrontal cortex (DLPFC) is critically implicated in the modulation of proactive control. Theta oscillations, functioning as a neural gating mechanism, facilitate the preferential allocation of attentional resources toward the processing of memory-relevant information, thereby enhancing the maintenance of such information and playing a pivotal role in memory encoding and cognitive resource distribution. The present study employed theta-frequency transcranial alternating current stimulation (tACS) targeting the DLPFC to further elucidate the neuroplasticity of proactive control. Concurrently, to investigate the relationship between fluid intelligence and proactive control, participants' fluid intelligence was assessed pre- and post-stimulation. A cohort of 58 participants was randomly assigned to receive either left DLPFC stimulation (n = 29) or right DLPFC stimulation (n = 29). The results revealed that stimulation of the left DLPFC significantly enhanced participants' proactive control capabilities. In ERP indicators, the CNV, following active stimulation, the CNV in the BX condition was significantly greater than that in the pre and sham stimulation (p ≤ 0.006). In behavioral outcomes, the accuracy rate for the BX condition was significantly higher after active stimulation compared to that in pre-stimulation and sham stimulation (p ≤ 0.017). In the lDLPFC group, fluid intelligence performance was significantly enhanced, and fluid intelligence scores after active stimulation were significantly higher compared to those during pre and sham stimulation (p ≤ 0.032). A statistically significant correlation was observed between participants' proactive control capabilities and fluid intelligence. In the rDLPFC group, no significant changes in any of the indicators were observed. These findings underscore the efficacy of neuromodulatory interventions targeting the left DLPFC in augmenting proactive control and suggest a dynamic interplay between proactive control and fluid intelligence.