title: Detecting and discriminating novel objects: The impact of perirhinal cortex disconnection on hippocampal activity patterns.
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. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc.
authors.affiliation: School of Psychology, Cardiff University, 70 Park Place, Cardiff, Wales, CF10 3AT, United Kingdom. KinnavaneL@cardiff.ac.uk.
authors.forename: Lisa
authors.initials: L
authors.lastname: Kinnavane
authors.affiliation: School of Psychology, Cardiff University, 70 Park Place, Cardiff, Wales, CF10 3AT, United Kingdom.
authors.forename: Eman
authors.initials: E
authors.lastname: Amin
authors.affiliation: School of Psychology, Cardiff University, 70 Park Place, Cardiff, Wales, CF10 3AT, United Kingdom.
authors.forename: Cristian M
authors.initials: CM
authors.lastname: Olarte-Sánchez
authors.affiliation: School of Psychology, Cardiff University, 70 Park Place, Cardiff, Wales, CF10 3AT, United Kingdom.
authors.forename: John P
authors.initials: JP
authors.lastname: Aggleton
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002452:Cell Count; D004192:Discrimination, Psychological / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology; D006624:Hippocampus / Q000033:anatomy & histology / Q000502:physiology*; D018782:Maze Learning / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology*; D016761:Oncogene Proteins v-fos / Q000378:metabolism; D000071039:Perirhinal Cortex / Q000293:injuries / Q000502:physiology*; D051381:Rats; D021641:Recognition, Psychology / Q000502:physiology*
chemical_list: D016761:Oncogene Proteins v-fos
keywords: entorhinal cortex; hippocampus; nucleus reuniens; prefrontal cortex; recognition memory