title: Mechanisms of memory storage in a model perirhinal network.
abstract: The perirhinal cortex supports recognition and associative memory. Prior unit recording studies revealed that recognition memory involves a reduced responsiveness of perirhinal cells to familiar stimuli whereas associative memory formation is linked to increasing perirhinal responses to paired stimuli. Both effects are thought to depend on perirhinal plasticity but it is unclear how the same network could support these opposite forms of plasticity. However, a recent study showed that when neocortical inputs are repeatedly activated, depression or potentiation could develop, depending on the extent to which the stimulated neocortical activity recruited intrinsic longitudinal connections. We developed a biophysically realistic perirhinal model that reproduced these phenomena and used it to investigate perirhinal mechanisms of associative memory. These analyzes revealed that associative plasticity is critically dependent on a specific subset of neurons, termed conjunctive cells (CCs). When the model network was trained with spatially distributed but coincident neocortical inputs, CCs acquired excitatory responses to the paired inputs and conveyed them to distributed perirhinal sites via longitudinal projections. CC ablation during recall abolished expression of the associative memory. However, CC ablation during training did not prevent memory formation because new CCs emerged, revealing that competitive synaptic interactions governs the formation of CC assemblies.
authors.affiliation: Division of Biological Sciences and Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO, 65211, USA.
authors.forename: Pranit
authors.initials: P
authors.lastname: Samarth
authors.affiliation: Division of Biological Sciences and Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO, 65211, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Ball
authors.affiliation: Center for Molecular and Behavioral Neuroscience, Rutgers University-Newark, Newark, NJ, 07102, USA.
authors.forename: Gunes
authors.initials: G
authors.lastname: Unal
authors.affiliation: Center for Molecular and Behavioral Neuroscience, Rutgers University-Newark, Newark, NJ, 07102, USA.
authors.forename: Denis
authors.initials: D
authors.lastname: Paré
authors.affiliation: Division of Biological Sciences and Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO, 65211, USA. nairs@missouri.edu.
authors.forename: Satish S
authors.initials: SS
authors.lastname: Nair
mesh_terms: D000200:Action Potentials; D000818:Animals; D006801:Humans; D007395:Interneurons / Q000502:physiology; D008568:Memory / Q000502:physiology*; D008959:Models, Neurological; D016571:Neural Networks, Computer; D009473:Neuronal Plasticity; D009474:Neurons / Q000502:physiology*; D000071039:Perirhinal Cortex / Q000502:physiology*
keywords: Associative memory; Computational model; Entorhinal; Memory retrieval; Perirhinal; Synaptic plasticity