Segregated Systems of Human Brain Networks

Abstract

The organization of the brain network enables its function. Evaluation of this organization has revealed that large-scale brain networks consist of multiple segregated subnetworks of interacting brain areas. Descriptions of resting-state network architecture have provided clues for understanding the functional significance of these segregated subnetworks, many of which correspond to distinct brain systems. The present report synthesizes accumulating evidence to reveal how maintaining segregated brain systems renders the human brain network functionally specialized, adaptable to task demands, and largely resilient following focal brain damage. The organizational properties that support system segregation are harmonious with the properties that promote integration across the network, but confer unique and important features to the brain network that are central to its function and behavior. Resting-state functional correlation networks contain large-scale communities of interacting brain regions. Several of these communities correspond to distinct functional systems of the brain. The segregation of resting-state brain systems differs across the lifespan, from infancy through old age, and in relation to cognitive ability. Nodes in different topological positions within a brain system exhibit distinct processing roles. These distinctions in node function are related to the corresponding system segregation of the brain network. Successful task performance results in temporary de-segregation of task-relevant brain systems. Neurologic and psychiatric dysfunction can be associated with differences in system segregation, depending on the locus and extent of damage. System segregation is a promising biomarker of intervention, reflecting a summary measure of the large-scale network organization of the brain.