Evidence for Two Independent Factors that Modify Brain Networks to Meet Task Goals

Abstract

Summary: Humans easily and flexibly complete a wide variety of tasks. To accomplish this feat, the brain appears to subtly adjust stable brain networks. Here, we investigate what regional factors underlie these modifications, asking whether networks are either altered at (1) regions activated by a given task or (2) hubs that interconnect different networks. We used fMRI “functional connectivity” (FC) to compare networks during rest and three distinct tasks requiring semantic judgments, mental rotation, and visual coherence. We found that network modifications during these tasks were independently associated with both regional activation and network hubs. Furthermore, active and hub regions were associated with distinct patterns of network modification (differing in their localization, topography of FC changes, and variability across tasks), with activated hubs exhibiting patterns consistent with task control. These findings indicate that task goals modify brain networks through two separate processes linked to local brain function and network hubs. : Gratton et al. show that, during tasks, human brain networks are subtly modified both at task-activated regions and at topologically important hubs. Classes of regions with these two properties show distinct patterns of network changes, suggesting they index dissociable factors for modifying brain networks in a task. Keywords: fMRI, brain networks, graph theory, task control