Introducing Structural Reliance: A New Method to Assess Structure–Function Coupling in the Brain

The relationship between the structural connectome and functional activity in the brain is highly complex, and understanding of the connection between the two is limited. Previous work has shown a marginal reliance of functional brain activity on underlying structural connections, indicating significant flexibility of neural communication. Here, we introduce a new method to quantify structure-function coupling and compare it with a standard coupling technique by evaluating the structure-function relationship across numerous fMRI task paradigms. Through this comparison, we investigate how structure-function relationships change during different cognitive demands and we evaluate how they relate to behavior. The new method introduced here, structural reliance, exhibits different structure-function correspondence patterns throughout the brain, and it generally outperforms the standard coupling measure in coupling-based behavioral measure predictions.