Causal Enhancement of Cognitive Reappraisal Through Synchronized Dorsolateral and Ventrolateral Prefrontal Cortex Activity

The dorsolateral prefrontal cortex (DLPFC) and ventrolateral prefrontal cortex (VLPFC) are central to cognitive reappraisal, yet the mechanisms underlying their collaboration remain unclear. This study uses transcranial alternating current stimulation (tACS) to modulate neural synchrony between the DLPFC and VLPFC in the theta band, aiming to elucidate the effects of synchronous versus asynchronous neural interaction on reappraisal. It also examines whether these effects are unique to reappraisal or extend to other emotion regulation strategies. In Experiment 1, 43 participants underwent in-phase, antiphase, or sham tACS before performing a reappraisal task to downregulate negative emotions. The findings showed that in-phase tACS significantly enhanced reappraisal performance and reduced regulation difficulty, supporting a causal role of DLPFC-VLPFC synchrony in reappraisal. Experiment 2 combined tACS with electroencephalography to further validate these results and included distraction as a control condition. Another 43 participants engaged in both reappraisal and distraction strategies following either in-phase or sham tACS. Phase-locking values confirmed that in-phase tACS selectively enhanced theta-band oscillations between the DLPFC and VLPFC. Consistent with Experiment 1, in-phase tACS specifically improved reappraisal performance, as indicated by reduced negative emotional responses, lower regulation difficulty, and a decrease in late positive potential amplitude, with no effect on distraction. This study provides the first causal evidence that enhancing DLPFC-VLPFC synchrony improves reappraisal performance. These findings highlight the potential of neural modulation to optimize brain network connectivity, offering promising avenues for targeted interventions in emotion regulation.