The effect of excitotoxic lesions centered on the hippocampus or perirhinal cortex in object recognition and spatial memory tasks

Rats with bilateral ibotenic acid lesions centered on the hippocampus (HPC) or perirhinal cortex (PRC) and sham-operated controls were tested in a ser ies of object recognition and spatial memory tasks. Both HPC and PRC rats d isplayed reduced habituation in a novel environment and were impaired in an object-location task. HPC rats were severely impaired in both the referenc e and working-memory versions of the water maze and radial arm maze tasks. In contrast, although PRC rats displayed mild deficits, in the reference me mory version of the water maze and radial arm maze tasks. they were markedl y impaired in the working-memory version of both the tasks. These findings demonstrate that under certain conditions both the HPC and PRC play a role in the processing of spatial memory. Further investigation of these conditi ons will provide important new insights into the role of these structures i n memory processes.