CONDITIONAL ASSOCIATIVE LEARNING AND THE HIPPOCAMPAL SYSTEM

Rats with lesions of the fornix, the dorsal hippocampus, or a control operation were trained on a spatial-visual conditional associative lea rning task in which they had to learn to associate particular location s with specific visual stimuli. Animals with damage of the fornix were able to learn the task at a rate comparable to that of the control an imals, but the performance of the hippocampal rats was significantly i mpaired in comparison with that of both the control and the fornix gro ups. In a second experiment, lesions to the fornix or the dorsal hippo campus significantly impaired performance on a spatial working memory task, the eight-arm radial maze. These findings suggest that the inter action between the hippocampus and subcortical structures via the forn ix may be critical only for certain types of spatial learning and memo ry. (C) 1998 Wiley-Liss, Inc.