The Hippocampus and Memory for “What,” “Where,” and “When”

  1. Ceren Ergorul and
  2. Howard Eichenbaum1
  1. Center for Memory and Brain, Program in Neuroscience, Boston University, Boston, Massachusetts 02215, USA

Abstract

Previous studies have indicated that nonhuman animals might have a capacity for episodic-like recall reflected in memory for “what” events that happened “where” and “when”. These studies did not identify the brain structures that are critical to this capacity. Here we trained rats to remember single training episodes, each composed of a series of odors presented in different places on an open field. Additional assessments examined the individual contributions of odor and spatial cues to judgments about the order of events. The results indicated that normal rats used a combination of spatial (“where”) and olfactory (“what”) cues to distinguish “when” events occurred. Rats with lesions of the hippocampus failed in using combinations of spatial and olfactory cues, even as evidence from probe tests and initial sampling behavior indicated spared capacities for perception of spatial and odor cues, as well as some form of memory for those individual cues. These findings indicate that rats integrate “what,” “where,” and “when” information in memory for single experiences, and that the hippocampus is critical to this capacity.

Footnotes

  • Article published online ahead of print. Article and publication date are at http://www.learnmem.org/cgi/doi/10.1101/lm.73304.

    • Accepted April 14, 2004.
    • Received December 23, 2003.
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