title: High-resolution investigation of memory-specific reinstatement in the hippocampus and perirhinal cortex.
abstract: Episodic memory involves remembering the details that characterize a prior experience. Successful memory recovery has been associated with the reinstatement of brain activity patterns in a number of sensory regions across the cortex. However, how the hippocampus and surrounding medial temporal lobe (MTL) cortex contribute to this process is less clear. Models of episodic memory posit that hippocampal pattern reinstatement, also referred to as pattern completion, may mediate cortical reinstatement during retrieval. Empirical evidence of this process, however, remains elusive. Here, we use high-resolution fMRI and encoding-retrieval multi-voxel pattern similarity analyses to demonstrate for the first time that the hippocampus, particularly right hippocampal subfield CA1, shows evidence of reinstating individual episodic memories. Furthermore, reinstatement in perirhinal cortex (PrC) is also evident. Critically, we identify distinct factors that may mediate the cortical reinstatement in PrC. First, we find that encoding activation in PrC is related to later reinstatement in this region, consistent with the theory that encoding strength in the regions that process the memoranda is important for later reinstatement. Conversely, retrieval activation in right CA1 was correlated with reinstatement in PrC, consistent with models of pattern completion. This dissociation is discussed in the context of the flow of information into and out of the hippocampus during encoding and retrieval, respectively. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Psychology, New York University.
authors.forename: Alexa
authors.initials: A
authors.lastname: Tompary
authors.affiliation: Department of Psychology, University of Toronto.
authors.forename: Katherine
authors.initials: K
authors.lastname: Duncan
authors.affiliation: Department of Psychology, New York University.|Center for Neural Science, New York University.
authors.forename: Lila
authors.initials: L
authors.lastname: Davachi
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001244:Association; D001931:Brain Mapping; D056547:CA1 Region, Hippocampal / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D016015:Logistic Models; D008279:Magnetic Resonance Imaging; D008297:Male; D061212:Memory, Episodic; D009483:Neuropsychological Tests; D000071039:Perirhinal Cortex / Q000000981:diagnostic imaging / Q000502:physiology*; D055815:Young Adult
keywords: CA1; encoding-retrieval similarity; high-resolution fMRI; medial temporal lobes