Response discriminability and the hippocampus.

Abstract

Approximately 1/2 of 21 rats randomly assigned to a Sidewinder maze, 21 to a T maze, and 20 to A Cap-T maze received bilateral hippocampal damage. The others received cortical damage. After recovery, S''s alternation rate (response or response and place) on its assigned maze was taken to be an index of discriminability of responses made in each maze. Ss were then trained on a black-white successive discrimination problem. Cortically damaged Ss running the Sidewinder alternated most while those running the Cap-T alternated least. The order of maze-alternation rates was reversed among hippocampally ablated Ss. In both operated groups, the maze groups which alternated the most and the least reached criterion the fastest and the slowest, respectively.