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Functional parcellation of the hippocampus based on its layer-specific connectivity with default mode and dorsal attention networks

Deshpande, G and Zhao, X and Robinson, J (2022) Functional parcellation of the hippocampus based on its layer-specific connectivity with default mode and dorsal attention networks. In: NeuroImage, 254 .

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Official URL: https://doi.org/10.1016/j.neuroimage.2022.119078


Recent neuroimaging evidence suggests that there might be an anterior-posterior functional differentiation of the hippocampus along the long-axis. The HERNET (hippocampal encoding/retrieval and network) model proposed an encoding/retrieval dichotomy with the anterior hippocampus more connected to the dorsal attention network (DAN) during memory encoding, and the posterior portions more connected to the default mode network (DMN) during retrieval. Evidence both for and against the HERNET model has been reported. In this study, we test the validity of the HERNET model non-invasively in humans by computing functional connectivity (FC) in layer-specific cortico-hippocampal microcircuits. This was achieved by acquiring sub-millimeter functional magnetic resonance imaging (fMRI) data during encoding/retrieval tasks at 7T. Specifically, FC between infra-granular output layers of DAN with hippocampus during encoding and FC between supra-granular input layers of DMN with hippocampus during retrieval were computed to test the predictions of the HERNET model. Our results support some predictions of the HERNET model including anterior-posterior gradient along the long axis of the hippocampus. While preferential relationships between the entire hippocampus and DAN/DMN during encoding/retrieval, respectively, were observed as predicted, anterior-posterior specificity in these network relationships could not be confirmed. The strength and clarity of evidence for/against the HERNET model were superior with layer-specific data compared to conventional volume data. © 2022

Item Type: Journal Article
Publication: NeuroImage
Publisher: Academic Press Inc.
Additional Information: The copyright for this article belongs to the the authors.
Keywords: article; controlled study; default mode network; dorsal attention network; functional connectivity; functional magnetic resonance imaging; hippocampus; human; information retrieval; prediction; validity
Department/Centre: Autonomous Societies / Centres > Centre for Brain Research
Date Deposited: 10 May 2022 16:17
Last Modified: 11 May 2022 11:06
URI: https://eprints.iisc.ac.in/id/eprint/71733

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