Modular coupling of structure-function reveals network integration (rather than segregation) as the key mechanism for cognitive task discrimination

Understanding how structural and functional brain networks interact to support cognitive processes remains a central challenge in systems neuroscience. In this study, we investigate the dynamics of structure-function coupling (SFC) at the modular level across different cognitive tasks using multimodal neuroimaging data, including anatomical, diffusion, functional at rest and functional at different tasks. By constructing high-resolution structural and functional connectivity matrices, we assessed intra-modular (SFC-INT) and inter-modular (SFC-EXT) coupling to examine their roles in task-specific reorganization. Our results reveal that variations in SFC during cognitive tasks are primarily driven by changes in inter-modular coupling, emphasizing network integration over segregation. Specifically, tasks demanding higher cognitive flexibility, such as the gender stroop task, exhibited increased SFC-EXT, indicating enhanced integration between modules. In contrast, tasks focused on memory processing showed a tendency toward segregation, with lower SFC-EXT values. These findings highlight the significance of inter-modular integration as a flexible and dynamic mechanism underlying cognitive task discrimination. Our study advances the understanding of modular brain network dynamics, suggesting that the brains ability to integrate information across modules plays a pivotal role in cognitive flexibility and task performance.