d-Amphetamine enhances memory performance in rats with damage to the fimbria

Rats were preoperatively trained on a 5-unit linear maze and were then subjected to fimbria lesions. The animals were then retested on the same task with one group of rats with fimbria lesions and a control group being injected daily with 0.5 mg/kg d-amphetamine sulfate prior to testing. Lesions significantly impaired postoperative performance of the task, while amphetamine facilitated performance in fimbria lesioned rats. Due to an optimal learning of the task, performance of control animals was not significantly facilitated. These results raise several important issues including the mechanisms of functional recovery after brain lesions and the role of the hippocampal formation in learning and memory.