title: Decisions about the past are guided by reinstatement of specific memories in the hippocampus and perirhinal cortex.
abstract: When faced with a new challenge, we often reflect on related past experiences to guide our behavior. The ability to retrieve memories that overlap with current experience, a process known as pattern completion, is theorized as a critical function of the hippocampus. Although this view has influenced research for decades, there is little empirical support for hippocampal pattern completion to individual memory elements and its influence on behavior. We used pattern analysis of brain activity measured with functional magnetic resonance imaging to demonstrate that specific elements of past experiences are reinstated in the hippocampus, as well as perirhinal cortex (PRC), when making decisions about those experiences. Linking neural measures of specific memory reinstatement in the hippocampus and PRC to behavior with computational modeling revealed that reinstatement predicts the speed of memory-based decisions. Moreover, hippocampal activation during retrieval was selectively coupled to regions of occipito-temporal cortex that showed content-specific item reinstatement. These results provide evidence for hippocampal pattern completion and its role in the mechanisms of decision making.
authors.affiliation: Department of Psychology, The University of Texas at Austin, Austin, TX 78712, United States; Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712, United States. Electronic address: mack.michael@gmail.com.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Mack
authors.affiliation: Department of Psychology, The University of Texas at Austin, Austin, TX 78712, United States; Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712, United States; Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712, United States. Electronic address: apreston@utexas.edu.
authors.forename: Alison R
authors.initials: AR
authors.lastname: Preston
mesh_terms: D000328:Adult; D001499:Bayes Theorem; D001931:Brain Mapping; D003657:Decision Making / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D008959:Models, Neurological; D009010:Monte Carlo Method; D013702:Temporal Lobe / Q000502:physiology*; D055815:Young Adult
keywords: Computational modeling; Decision making; Hippocampus; Medial temporal lobe; Memory; Perirhinal cortex