Abstract
Many studies have identified the role of localized and distributed cognitive functionality by mapping either local task-related activity or distributed functional connectivity (FC). However, few studies have directly explored the relationship between a brain region’s localized task activity and its distributed task FC. Here we systematically evaluated the differential contributions of task-related activity and FC changes to identify a relationship between localized and distributed processes across the cortical hierarchy. We found that across multiple tasks, the magnitude of regional task-evoked activity was high in unimodal areas, but low in transmodal areas. In contrast, we found that task-state FC was significantly reduced in unimodal areas relative to transmodal areas. This revealed a strong negative relationship between localized task activity and distributed FC across cortical regions that was associated with the previously reported principal gradient of macroscale organization. Moreover, this dissociation corresponded to hierarchical cortical differences in the intrinsic timescale estimated from resting-state fMRI and region myelin content estimated from structural MRI. Together, our results contribute to a growing literature illustrating the differential contributions of a hierarchical cortical gradient representing localized and distributed cognitive processes.
Highlights
The human brain’s network organization is thought to contribute to its ability to process information, but the mechanisms linking network organization to information processing remain unclear
Given the possibility that the network dimensionality statistic could be biased by the size of each network, we devised a novel graph-theoretic measure – network pattern separation (NPS) – that accounts for network size
To assess whether frontoparietal cognitive control network (FPN)’s connectivity was truly global, we calculated whether FPN had at least one statistically significant functional connection to every other network. (Note, we define functional connection as a statistically significant correlation across all subjects.) we found that FPN had at least one statistically significant functional connection to every other network estimated at the group level
Summary
The human brain’s network organization is thought to contribute to its ability to process information, but the mechanisms linking network organization to information processing remain unclear. Neurons with mixed selectivity (i.e., complex tuning) have been shown to flexibly represent a range of stimuli and task rules[3,4]. These studies were often limited to specific brain regions (e.g., dorsolateral prefrontal cortex), rather than identifying the contribution of largescale network organization. Computational studies have provided abstract models for how various tasks might be executed[5,6], yet such abstract models leave many questions with regard to biological mechanisms It remains unclear how the human brain’s large-scale network organization might contribute to the flexible implementation of cognitive tasks
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