Acquisition and retention of visual discrimination learning after ablation of perirhinal cortex in the rat

Eight Dark Agouti rats were trained in a version of concurrent discrimination learning in a computer-controlled automated apparatus that allowed the use of complex abstract patterns as stimuli. Pre-operatively, they learned a five-pair concurrent discrimination and were tested for their postoperative retention of this discrimination. Rats with ablation of the perirhinal cortex were impaired in their retention of the concurrent discriminations. However, they were totally unimpaired in postoperative acquisition of two new concurrent discrimination sets. Moreover, they were also completely unimpaired in postoperative retention of these postoperatively learned discrimination sets. The deficit therefore appears to be a specific retrograde amnesia, with no evidence for anterograde effects.