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Flexing the principal gradient of the cerebral cortex to suit changing semantic task demands.

Published version
Peer-reviewed

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Authors

Zheng, Li 
Krieger-Redwood, Katya 
Halai, Ajay 
Margulies, Daniel S 

Abstract

Understanding how thought emerges from the topographical structure of the cerebral cortex is a primary goal of cognitive neuroscience. Recent work has revealed a principal gradient of intrinsic connectivity capturing the separation of sensory-motor cortex from transmodal regions of the default mode network (DMN); this is thought to facilitate memory-guided cognition. However, studies have not explored how this dimension of connectivity changes when conceptual retrieval is controlled to suit the context. We used gradient decomposition of informational connectivity in a semantic association task to establish how the similarity in connectivity across brain regions changes during familiar and more original patterns of retrieval. Multivoxel activation patterns at opposite ends of the principal gradient were more divergent when participants retrieved stronger associations; therefore, when long-term semantic information is sufficient for ongoing cognition, regions supporting heteromodal memory are functionally separated from sensory-motor experience. In contrast, when less related concepts were linked, this dimension of connectivity was reduced in strength as semantic control regions separated from the DMN to generate more flexible and original responses. We also observed fewer dimensions within the neural response towards the apex of the principal gradient when strong associations were retrieved, reflecting less complex or varied neural coding across trials and participants. In this way, the principal gradient explains how semantic cognition is organised in the human cerebral cortex: the separation of DMN from sensory-motor systems is a hallmark of the retrieval of strong conceptual links that are culturally shared.

Description

Peer reviewed: True

Keywords

Research Article, Neuroscience, cortical gradient, semantic cognition, informational connectivity, representational space, Human

Journal Title

Elife

Conference Name

Journal ISSN

2050-084X
2050-084X

Volume Title

Publisher

eLife Sciences Publications, Ltd
Sponsorship
European Research Council (771863 - FLEXSEM)
Medical Research Council (MRC Career Development Award MR/V031481/1)
Rosetrees Trust (A1699)