UNILATERAL LESIONS OF THE ANTEROMEDIAL CORTEX IN THE RAT IMPAIR APPROACH TO CONTRALATERAL VISUAL CUES

The effects of large unilateral lesions of the anteromedial cortex (AMC) on visually guided performance of rats in a cross maze were determined. Deficits were found in the approach to only visual cues that were located in the arm contralateral to the lesion. The deficit appeared in 3 testing conditions: when the cue was continuously visible throughout the trial; when it was visible only at the choice point; and when it was seen only at the start of the trial but not at the choice point. The failure to approach a contralateral cue was not due to a simple ipsilateral turning bias; rats with lesions could approach cues in the anterior arm as efficiently as controls. The deficit was most apparent on the initial sessions and recovery occurred for all conditions. Apparently, the AMC participates in the visual guidance of approach behavior.