  The human brain is organized into large-scale functional modules that have
been shown to evolve in childhood and adolescence. However, it remains unknown
whether structural brain networks are similarly refined during development,
potentially allowing for improvements in executive function. In a sample of 882
participants (ages 8-22) who underwent diffusion imaging as part of the
Philadelphia Neurodevelopmental Cohort, we demonstrate that structural network
modules become more segregated with age, with weaker connections between
modules and stronger connections within modules. Evolving modular topology
facilitated network integration, driven by age-related strengthening of hub
edges that were present both within and between modules. Critically, both
modular segregation and network integration were associated with enhanced
executive performance, and mediated the improvement of executive functioning
with age. Together, results delineate a process of structural network
maturation that supports executive function in youth.
