Parallel Interdigitated Distributed Networks within the Individual Estimated by Intrinsic Functional Connectivity

Summary

Certain organizational features of brain networks present in the individual are lost when central tendencies are examined in the group. Here we investigated the detailed network organization of four individuals each scanned 24 times using MRI. We discovered that the distributed network known as the default network is comprised of two separate networks possessing adjacent regions in eight or more cortical zones. A distinction between the networks is that one is coupled to the hippocampal formation while the other is not. Further exploration revealed that these two networks were juxtaposed with additional networks that themselves fractionate group-defined networks. The collective networks display a repeating spatial progression in multiple cortical zones, suggesting that they are embedded within a broad macroscale gradient. Regions contributing to the newly defined networks are spatially variable across individuals and adjacent to distinct networks, raising issues for network estimation in group-averaged data and applied endeavors, including targeted neuromodulation.

Highlights

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  Within-individual characterization of brain networks reveals new spatial details

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  Group-defined networks fractionate into distinct parallel networks in individuals

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  Parallel networks possess closely juxtaposed regions in numerous cortical zones

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  Networks share a conserved motif that may be organized along a macroscale gradient

Abstract

Braga and Buckner examine the detailed organization of brain networks within individual people. They discovered that multiple closely juxtaposed cortical regions form parallel distributed networks. Separate large-scale networks may emerge from a common organizing principle.