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Dissociable profiles of generalization/discrimination in the human hippocampus during associative retrieval

Dissociable profiles of generalization/discrimination in the human hippocampus during associative... When encountering stimuli that vary slightly from previous experiences, neural signals within the CA3 and dentate gyrus (CA3DG) hippocampal subfields are thought to facilitate mnemonic discrimination, whereas CA1 may be less sensitive to minor stimulus changes, allowing for generalization across similar events. Studies have also posited a critical role for CA1 in the comparison of events to memory‐derived expectations, but the degree to which these processes are impacted by explicit retrieval demands is yet unclear. To evaluate extant accounts of hippocampal subfield function, we acquired high‐resolution fMRI data as participants performed a task in which famous names were used to cue the retrieval of previously paired images. Although both left CA3DG and CA1 showed match enhancement effects, responding more to original paired images (targets) than to never‐before‐seen images (novels), the sensitivity of these subfields to stimulus changes and task demands diverged. CA3DG showed a goal‐independent, yet highly specific, preference for previously encountered stimuli, responding equally strongly to targets and mispaired associates, while showing equally weak responses to close lures and novels. In contrast, recognition signals in CA1 were goal‐dependent (i.e., not evoked by mispaired associates), yet accommodating of subtle stimulus differences, such that close lures evoked comparable activity as targets. © 2016 Wiley Periodicals, Inc. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Hippocampus Wiley

Dissociable profiles of generalization/discrimination in the human hippocampus during associative retrieval

De Shetler, Natalie G.; Rissman, Jesse
Hippocampus , Volume 27 (2) – Feb 1, 2017
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References (39)

Publisher
Wiley
Copyright
© 2017 Wiley Periodicals, Inc.
ISSN
1050-9631
eISSN
1098-1063
DOI
10.1002/hipo.22684
pmid
27863445
Publisher site
See Article on Publisher Site

Abstract

When encountering stimuli that vary slightly from previous experiences, neural signals within the CA3 and dentate gyrus (CA3DG) hippocampal subfields are thought to facilitate mnemonic discrimination, whereas CA1 may be less sensitive to minor stimulus changes, allowing for generalization across similar events. Studies have also posited a critical role for CA1 in the comparison of events to memory‐derived expectations, but the degree to which these processes are impacted by explicit retrieval demands is yet unclear. To evaluate extant accounts of hippocampal subfield function, we acquired high‐resolution fMRI data as participants performed a task in which famous names were used to cue the retrieval of previously paired images. Although both left CA3DG and CA1 showed match enhancement effects, responding more to original paired images (targets) than to never‐before‐seen images (novels), the sensitivity of these subfields to stimulus changes and task demands diverged. CA3DG showed a goal‐independent, yet highly specific, preference for previously encountered stimuli, responding equally strongly to targets and mispaired associates, while showing equally weak responses to close lures and novels. In contrast, recognition signals in CA1 were goal‐dependent (i.e., not evoked by mispaired associates), yet accommodating of subtle stimulus differences, such that close lures evoked comparable activity as targets. © 2016 Wiley Periodicals, Inc.

Journal

Hippocampus – Wiley

Published: Feb 1, 2017

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