COMPARING THE EFFECTS OF SELECTIVE CINGULATE CORTEX LESIONS AND CINGULUM BUNDLE LESIONS ON WATER MAZE PERFORMANCE BY RATS

The ability of Fats to learn the location of a hidden platform in a sw im maze was compared in animals with excitotoxic lesions of the anteri or or posterior (retrosplenial) cingulate cortex or radiofrequency les ions of the cingulum bundle or fimbria-fornix. Performance of this all ocentric spatial task was unaffected by the posterior cingulate cortex lesions, while anterior cingulate cortex damage produced only a mild acquisition deficit, Transection of the fornix and lesions of the cing ulum bundle produced similar patterns of impairment on initial acquisi tion, but the cingulum bundle lesions had less effect on reversal of t he task. The results from the water maze, and from a subsequent T-maze alternation task, indicate that cingulum bundle lesions can produce a spatial deficit that is similar, but milder, to that observed after f ornix transection. The results of the excitotoxic lesions suggest that previous studies examining conventional cingulate lesions may have be en influenced by damage to adjacent fibre tracts, such as the cingulum bundle.