Hippocampal and medial prefrontal cortices encode structural task representations following progressive and interleaved training schedules.

Memory generalisations may be underpinned by either encoding- or retrieval-based generalisation mechanisms and different training schedules may bias some learners to favour one of these mechanisms over the other. We used a transitive inference task to investigate whether generalisation is influenced...

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Main Authors: Sam C Berens, Chris M Bird
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2022-10-01
Series:PLoS Computational Biology
Online Access:https://doi.org/10.1371/journal.pcbi.1010566
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author Sam C Berens
Chris M Bird
author_facet Sam C Berens
Chris M Bird
author_sort Sam C Berens
collection DOAJ
description Memory generalisations may be underpinned by either encoding- or retrieval-based generalisation mechanisms and different training schedules may bias some learners to favour one of these mechanisms over the other. We used a transitive inference task to investigate whether generalisation is influenced by progressive vs randomly interleaved training, and overnight consolidation. On consecutive days, participants learnt pairwise discriminations from two transitive hierarchies before being tested during fMRI. Inference performance was consistently better following progressive training, and for pairs further apart in the transitive hierarchy. BOLD pattern similarity correlated with hierarchical distances in the left hippocampus (HIP) and medial prefrontal cortex (MPFC) following both training schedules. These results are consistent with the use of structural representations that directly encode hierarchical relationships between task features. However, such effects were only observed in the MPFC for recently learnt relationships. Furthermore, the MPFC appeared to maintain structural representations in participants who performed at chance on the inference task. We conclude that humans preferentially employ encoding-based mechanisms to store map-like relational codes that can be used for memory generalisation. These codes are expressed in the HIP and MPFC following both progressive and interleaved training but are not sufficient for accurate inference.
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spelling doaj.art-f94d806581104b89bdc71d4f92ab10102022-12-22T02:38:08ZengPublic Library of Science (PLoS)PLoS Computational Biology1553-734X1553-73582022-10-011810e101056610.1371/journal.pcbi.1010566Hippocampal and medial prefrontal cortices encode structural task representations following progressive and interleaved training schedules.Sam C BerensChris M BirdMemory generalisations may be underpinned by either encoding- or retrieval-based generalisation mechanisms and different training schedules may bias some learners to favour one of these mechanisms over the other. We used a transitive inference task to investigate whether generalisation is influenced by progressive vs randomly interleaved training, and overnight consolidation. On consecutive days, participants learnt pairwise discriminations from two transitive hierarchies before being tested during fMRI. Inference performance was consistently better following progressive training, and for pairs further apart in the transitive hierarchy. BOLD pattern similarity correlated with hierarchical distances in the left hippocampus (HIP) and medial prefrontal cortex (MPFC) following both training schedules. These results are consistent with the use of structural representations that directly encode hierarchical relationships between task features. However, such effects were only observed in the MPFC for recently learnt relationships. Furthermore, the MPFC appeared to maintain structural representations in participants who performed at chance on the inference task. We conclude that humans preferentially employ encoding-based mechanisms to store map-like relational codes that can be used for memory generalisation. These codes are expressed in the HIP and MPFC following both progressive and interleaved training but are not sufficient for accurate inference.https://doi.org/10.1371/journal.pcbi.1010566
spellingShingle Sam C Berens
Chris M Bird
Hippocampal and medial prefrontal cortices encode structural task representations following progressive and interleaved training schedules.
PLoS Computational Biology
title Hippocampal and medial prefrontal cortices encode structural task representations following progressive and interleaved training schedules.
title_full Hippocampal and medial prefrontal cortices encode structural task representations following progressive and interleaved training schedules.
title_fullStr Hippocampal and medial prefrontal cortices encode structural task representations following progressive and interleaved training schedules.
title_full_unstemmed Hippocampal and medial prefrontal cortices encode structural task representations following progressive and interleaved training schedules.
title_short Hippocampal and medial prefrontal cortices encode structural task representations following progressive and interleaved training schedules.
title_sort hippocampal and medial prefrontal cortices encode structural task representations following progressive and interleaved training schedules
url https://doi.org/10.1371/journal.pcbi.1010566
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AT chrismbird hippocampalandmedialprefrontalcorticesencodestructuraltaskrepresentationsfollowingprogressiveandinterleavedtrainingschedules