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The convergence and divergence of episodic and semantic functions across lateral parietal cortex.

Published version
Peer-reviewed

Type

Article

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Authors

Humphreys, Gina F 
Jung, JeYoung 
Lambon Ralph, Matthew A  ORCID logo  https://orcid.org/0000-0001-5907-2488

Abstract

Decades of research have highlighted the importance of lateral parietal cortex (LPC) across a myriad of cognitive domains. Yet, the underlying function of LPC remains unclear. Two domains that have emphasized LPC involvement are semantic memory and episodic memory retrieval. From each domain, sophisticated functional models have been proposed, as well as the more domain-general assumption that LPC is engaged by any form of internally directed cognition (episodic/semantic retrieval being examples). Here we used a combination of functional magnetic resonance imaging, functional connectivity, and diffusion tensor imaging white-matter connectivity to show that (i) ventral LPC (angular gyrus [AG]) was positively engaged during episodic retrieval but disengaged during semantic memory retrieval and (ii) activity negatively varied with task difficulty in the semantic task whereas episodic activation was independent of difficulty. In contrast, dorsal LPC (intraparietal sulcus) showed domain general activation that was positively correlated with task difficulty. Finally, (iii) a dorsal-ventral and anterior-posterior gradient of functional and structural connectivity was found across the AG (e.g. mid-AG connected with episodic retrieval). We propose a unifying model in which LPC as a whole might share a common underlying neurocomputation (multimodal buffering) with variations in the emergent cognitive functions across subregions arising from differences in the underlying connectivity.

Description

Keywords

angular gyrus, episodic, fMRI, parietal, semantic, Semantics, Brain Mapping, Diffusion Tensor Imaging, Parietal Lobe, Memory, Episodic, Magnetic Resonance Imaging

Journal Title

Cereb Cortex

Conference Name

Journal ISSN

1047-3211
1460-2199

Volume Title

Publisher

Oxford University Press (OUP)
Sponsorship
Medical Research Council (MR/R023883/1)
MRC (MC_UU_00030/9)