Lateral Entorhinal Cortex Is Necessary for Associative But Not Nonassociative Recognition Memory

ABSTRACT: The lateral entorhinal cortex (LEC) provides one of the two major input pathways to the hippocampus and has been suggested to process the nonspatial contextual details of episodic memory. Com-bined with spatial information from the medial entorhinal cortex it is hypothesised that this contextual information is used to form an inte-grated spatially selective, context-specific response in the hippocampus that underlies episodic memory. Recently, we reported that the LEC is required for recognition of objects that have been experienced in a spe-cific context (Wilson et al. (2013) Hippocampus 23:352-366). Here, we sought to extend this work to assess the role of the LEC in recognition of all associative combinations of objects, places and contexts within an episode. Unlike controls, rats with excitotoxic lesions of the LEC showed no evidence of recognizing familiar combinations of object in place, place in context, or object in place and context. However, LEC lesioned rats showed normal recognition of objects and places inde-pendently from each other (nonassociative recognition). Together with our previous findings, these data suggest that the LEC is critical for asso-ciative recognition memory and may bind together information relating to objects, places, and contexts needed for episodic memory formation