THE CAUSAL ROLE OF THETA OSCILLATIONS IN THE FRONTOPARIETAL NETWORK ON COGNITIVE FLEXIBILITY

Cognitive flexibility is crucial for efficient goal-directed behavior, especially in rapidly changing environments. While recent studies have consistently shown enhanced theta power and synchronization in the frontoparietal network during flexible task-switching, direct evidence establishing a causal link between theta-rhythm brain oscillation and cognitive flexibility remains limited. In this study, we applied transcranial alternating current stimulation (tACS) to the frontoparietal network at a theta frequency (6 Hz) with a phase difference of either 0° (inphase) or 180° (antiphase) to explore its impact on task-switching performance. The results showed no significant tACS modulation effects on switch costs or neural oscillatory synchronization in the frontoparietal network. However, a consistent negative correlation was observed between frontoparietal theta power in the early time window of cue-target interval and task switching performance, implying the close relationship between proactive control in task switching and frontoparietal theta activities.