Modular structure–function coupling reveals different network reorganization for task performance

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 introduce and systematically compare intra-modular (SFC-INT) and inter-modular (SFC-EXT) coupling as novel metrics to elucidate their distinct roles in task-specific brain network reorganization. Our results reveal that variations in SFC during cognitive tasks are primarily driven by changes in inter-modular coupling, emphasizing the role of network integration rather than segregation. Tasks with high integrative demands exhibited increased SFC-EXT, highlighting enhanced communication between modules, whereas memory-focused tasks showed reduced inter-modular coupling. Crucially, our methodological innovation of separating intra- and inter-modular coupling significantly advances the field by providing a more precise framework for discriminating cognitive tasks based on modular network dynamics. These findings position modular SFC metrics (SFC-INT and SFC-EXT) as essential tools for task-specific analysis of structural-functional interactions in the brain.