Major dissociation between medial and lateral entorhinal input to dorsal hippocampus.

Hippocampal place cells are a model system of how the brain constructs cognitive representations and of how these representations support complex behavior, learning, and memory. There is, however, a lack of detailed knowledge about the properties of hippocampal afferents. We recorded multiple single units from the hippocampus and the medial and lateral entorhinal areas of behaving rats. Although many medial entorhinal neurons had highly specific place fields, lateral entorhinal neurons displayed weak spatial specificity. This finding demonstrates a fundamental dissociation between the information conveyed to the hippocampus by its major input streams, with spatial information represented by the medial and nonspatial information represented by the lateral entorhinal cortex.