Interhemispheric fronto-parietal EEG alpha phase synchronization reflects inhibitory control during the Stroop task

The ability to inhibit irrelevant information and resist distraction is central to goal-directed behavior and constitutes a core function of human cognition. Although electroencephalographic (EEG) research has consistently implicated fronto-parietal alpha-band phase synchronization in top-down processing, a core mechanism of cognitive control, its neurodynamic contribution to inhibitory control remains underexplored. In this study, we examined whether large-scale EEG alpha-band synchronization within the fronto-parietal network reflects inhibitory control during a color-word Stroop task. Twenty-four participants completed congruent, neutral, and incongruent trials while EEG activity was recorded. Inter-site phase clustering (ISPC) was used to quantify alpha-band phase synchronization across bilateral frontocentral and parietocentral regions. Behaviorally, incongruent trials elicited significantly slower reaction times and reduced accuracy compared with congruent and neutral conditions, indicating increased conflict demands. Electrophysiological results revealed significantly enhanced alpha-band phase synchronization during incongruent trials, centered on the right frontocentral region, with stronger interhemispheric coupling between the right frontocentral and left parietocentral regions. Notably, the peak latency of this connectivity positively correlated with reaction times exclusively during incongruent trials, suggesting that the temporal dynamics of alpha synchronization are closely linked to behavioral performance during conflict processing. These findings indicate that interhemispheric fronto-parietal alpha phase synchronization reflects a neural mechanism underlying inhibitory control. Our results highlight the significance of EEG alpha-band synchronization and its temporal dynamics in coordinating large-scale brain networks supporting top-down cognitive control.