Of mice and mazes: similarities between mice and rats on dry land but not water mazes.

Mice are impaired relative to rats in place and matching-to-place learning when tests are given in a swimming pool. The rat advantage may stem from a superior spatial ability or from adaptation to a niche that has prepared them for competency in the water. In the present study, mice (C57BL/6) were compared with rats (Long-Evans) in a number of dry-land spatial tasks given on a radial arm maze and in a place task given in a swimming pool. The performance of the mice matched that of the rats in all dry-land tasks, but was inferior to that of the rats in the swimming pool. The results provide further evidence for a species difference in swimming-pool performance but do not support the idea that there are necessary differences in spatial abilities between mice and rats. It is suggested that, if optimal place learning is required for neurobehavioral studies of mice, such performance is more likely to be obtained in dry-land tasks than in swimming-pool tasks. Nevertheless, the species differences warrant further study because they could provide important insights into species differences is spatial learning more generally.