Functional brain modules reconfigure at multiple scales across the human lifespan

TL;DR

This study investigates how functional brain modules reconfigure across different spatial scales and ages, revealing scale-specific and age-dependent changes in modular organization and flexibility.

Contribution

It introduces a multi-scale graph-theoretic analysis to uncover age-related and scale-specific reorganization of brain modules across the lifespan.

Findings

Modules become more segregated at coarse scales with age.

Default mode network regions show increased flexibility at fine scales.

Retrosplenial cortex maintains stronger within-module connections with age.

Abstract

The human brain is a complex network of interconnected brain regions organized into functional modules with distinct roles in cognition and behavior. An important question concerns the persistence and stability of these modules over the human lifespan. Here we use graph-theoretic analysis to algorithmically uncover the brain's intrinsic modular organization across multiple spatial scales ranging from small communities comprised of only a few brain regions to large communities made up of many regions. We find that at coarse scales modules become progressively more segregated, while at finer scales segregation decreases. Module composition also exhibits scale-specific and age-dependent changes. At coarse scales, the module assignments of regions normally associated with control, default mode, attention, and visual networks are highly flexible. At fine scales the most flexible regions are associated with the default mode network. Finally, we show that, with age, some regions in the default mode network, specifically retrosplenial cortex, maintain a greater proportion of functional connections to their own module, while regions associated with somatomotor and saliency/ventral attention networks distribute their links more evenly across modules.