Structural Connectivity of Functionally Defined Episodic Memory Networks: A Large‐Scale Connectome–Behavior Study

Abstract Background Previous task‐based fMRI work in a large cohort of young adults identified nine large‐scale functional brain networks whose encoding‐related responsivity was robustly associated with individual differences in episodic memory. It remains unclear whether structural connectivity within these task‐fMRI‐defined networks explains inter‐individual variability in memory performance. Methods We analyzed diffusion MRI data from 1,156 young adults who completed a picture‐free‐recall task. For each participant, we reconstructed whole‐brain diffusion MRI tractography and extracted within‐network connectivity for nine independent components previously defined by task‐based fMRI. Edge‐wise multiple regression models related within‐network connectivity strength to free recall performance, controlling for age and sex. False discovery rate (FDR) correction was applied across all tested edges and networks. Results No associations between within‐network structural connectivity and memory performance survived FDR correction. Several edges showed nominal (uncorrected) associations with memory, corresponding to very small effect sizes (maximum r < 0.1). Conclusions In contrast to previous findings for functional responsivity during encoding, within‐network structural connectivity in these functionally defined episodic memory networks is only weakly related to individual differences in memory in young healthy adults.