Dissociation between the effects of damage to perirhinal cortex and area TE

Perirhinal cortex and area TE are immediately adjacent to each other in the temporal lobe and reciprocally interconnected, These areas are thought to lie at the interface between visual perception and visual memory, but it ha s been unclear what their separate contributions might be. In three experim ents, monkeys with bilateral lesions of the perirhinal cortex exhibited a d ifferent pattern of impairment than monkeys with bilateral lesions of area TE. In experiment 1, lesions of the perirhinal cortex produced a multimodal deficit in recognition memory (delayed nonmatching to sample), whereas les ions of area TE impaired performance only in the visual modality. In experi ment 2, on a test of visual recognition memory (the visual paired compariso n task) lesions of the perirhinal cortex impaired performance at long delay s but spared performance at a very short delay. In contrast, lesions of are a TE impaired performance even at the short delay. In experiment 3, lesions of the perirhinal cortex and lesions of area TE produced an opposite patte rn of impairment on two visual discrimination tasks, simple object discrimi nation learning (impaired only by perirhinal lesions), and concurrent discr imination learning (impaired only by TE lesions), Taken together, the findi ngs suggest that the perirhinal cortex, like other medial temporal lobe str uctures, is important for the formation of memory, whereas area TE is impor tant for visual perceptual processing.