Memory for spatial location: Functional dissociation of entorhinal cortex and hippocampus

Abstract

To test whether there is a functional dissociation between the hippocampus and entorhinal cortex, rats were trained on a variable spatial-location matching-to-sample (working memory) task with various delays. After training, rats with entorhinal cortex, entorhinal-cortex-plus-hippocampus/subiculum, hippocampus, control, or cortical control lesions were tested for performance within the task. Results indicated that in the variable spatial-location condition relative to the control and cortical controls, all lesioned groups showed a profound impairment in performance of the task across all delays. They were subsequently tested for acquisition of a constant spatial location task. In the constant spatial-location condition, the entorhinal cortex and entorhinal-cortex-plus-hippocampus/subiculum lesioned groups did not learn the task, whereas the hippocampal lesioned group did. It is suggested that there is a functional dissociation between the hippocampus and the entorhinal cortex. It is proposed that the hippocampus encodes new spatial information within a working-memory system, whereas the entorhinal cortex represents spatial information within a reference-memory system as part of a spatial cognitive map. © 1994, Psychonomic Society, Inc.. All rights reserved.