Behavioral and Brain Sciences

Target Article

Two functional components of the hippocampal memory system

Howard Eichenbauma1, Tim Ottoa2 and Neal J. Cohena3

a1 Center for Behavioral Neuroscience, State University of New York at Stony Brook, Stony Brook, NY 11794 Electronic mail: heichenbaum@ccmail.sunysb.edu

a2 Department of Psychology, Busch Campus, Rutgers University, New Brunswick, NJ 08903

a3 Beckman Institute and Department of Psychology, University of Illinois at Urbana-Champaign, Urbana, IL 61801

Abstract

There is considerable evidence that the hippocampal system contributes both to (1) the temporary maintenance of memories and to (2) the processing of a particular type of memory representation. The findings on amnesia suggest that these two distinguishing features of hippocampal memory processing are orthogonal. Together with anatomical and physiological data, the neuropsychological findings support a model of cortico-hippocampal interactions in which the temporal and representational properties of hippocampal memory processing are mediated separately. We propose that neocortical association areas maintain shortterm memories for specific items and events prior to hippocampal processing as well as providing the final repositories of long-term memory. The parahippocampal region supports intermediate-term storage of individual items, and the hippocampal formation itself mediates an organization of memories according to relevant relationships among items. Hippocampal-cortical interactions produce (i) strong and persistent memories for events, including their constituent elements and the relationships among them, and (ii) a capacity to express memories flexibly across a wide range of circumstances.

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