Flexible adjustment of the effective connectivity between the fronto-parietal and visual regions supports cognitive flexibility.

Evidence indicates the significance of the fronto-parietal regions and inertia sensory processing from previous trials in cognitive flexibility. However, how flexible cognitive performance is achieved by causal interactions between cortical regions, particularly those between the fronto-parietal and stimulus processing regions, remains unknown. In the current study, the effective connectivity between the fronto-parietal and visual regions was examined in the context of a cued task-switching paradigm. We found that the fronto-parietal and visual cortex were differently activated during task transition (task repeat and task switch). Importantly, dynamic causal modeling (DCM) analysis revealed that task transition could modulate the effective connectivity between the fronto-parietal and visual cortex: task repeat decreased, while task switch enhanced, the coupling between the posterior parietal cortex (PPC) and the visual cortex. Furthermore, Granger causality analysis (GCA) showed that the dominant direction of influence was from the fronto-parietal regions to the visual cortex. Finally, individual differences in the top-down influence from the PPC to the visual cortex and the corresponding neural adjustment (task switch‒task repeat) was negatively associated with the behavioral switch cost. Our findings suggest that the interaction between the fronto-parietal and stimulus processing regions, particularly the top-down influence from the PPC to the visual cortex, is of particular importance in flexible cognitive performance.