Effects of separate lesions of the hippocampus and the perirhinal cortex on performance in spontaneous recognition task for object and place

Abstract

Separate lesions of the hippocampus and the perirhinal cortex in rats led to distinctly different patterns of behavioral impairments in spontaneous object and place recognition tasks, in which preference to a novel object and location respectively, was tested. In both tasks, rats were tested for two delay conditions : 15 and 25 min. The lesion of the hippocampus had no effect on preference between novel and familiar objects in the object recognition task, but it impaired discrimination between objects set in novel and familiar locations in both delay conditions in the place recognition task. In contrast, the lesion of the perirhinal cortex only impaired preference in the 25-min delay condition in the object recognition task. These results suggest that the hippocampus and the perirhinal cortex are functionally differentiated from each other in recognition memory for objects and places. (Japanese Journal of Physiological Psychology and Psychophysiology, 22 (3) : 257-266, 2004.)