Detecting and discriminating novel objects: The impact of perirhinal cortex disconnection on hippocampal activity patterns

Lisa Kinnavane, Eman Amin, Cristian M Olarte Sanchez, John P Aggleton

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Abstract

Perirhinal cortex provides object-based information and novelty/familiarity information for the hippocampus. The necessity of these inputs was tested by comparing hippocampal c-fos expression in rats with or without perirhinal lesions. These rats either discriminated novel from familiar objects (Novel-Familiar) or explored pairs of novel objects (Novel-Novel). Despite impairing Novel-Familiar discriminations, the perirhinal lesions did not affect novelty detection, as measured by overall object exploration levels (Novel-Novel condition). The perirhinal lesions also largely spared a characteristic network of linked c-fos expression associated with novel stimuli (entorhinal cortex→CA3→distal CA1→proximal subiculum). The findings show: I) that perirhinal lesions preserve behavioral sensitivity to novelty, whilst still impairing the spontaneous ability to discriminate novel from familiar objects, II) that the distinctive patterns of hippocampal c-fos activity promoted by novel stimuli do not require perirhinal inputs, III) that entorhinal Fos counts (layers II and III) increase for novelty discriminations, IV) that hippocampal c-fos networks reflect proximal-distal connectivity differences, and V) that discriminating novelty creates different pathway interactions from merely detecting novelty, pointing to top-down effects that help guide object selection. This article is protected by copyright. All rights reserved.

Original languageEnglish
Pages (from-to)1393-1413
Number of pages21
JournalHippocampus
Volume26
Issue number11
Early online date22 Jul 2016
DOIs
Publication statusPublished - Nov 2016

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Keywords

  • entorhinal cortex
  • hippocampus
  • nucleus
  • reuniens
  • prefrontal cortex
  • recognition memory

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