Marked differences were observed across strains of mice (i.e., DBA/2J, C57BL/6J, BALB/cByJ and CD-1 mice) in acquisition, performance and reversal of a place learning response in a Morris water-maze. While DBA/2J, C57BL/6J and CD-1 mice typically learned the response readily, only 20% of BALB/cByJ mice acquired the response. Commensurate with the effects of hippocampal disturbances, the performance deficits in BALB/cByJ mice were not evident when the position of the platform in the water-maze was cued. Exposure to uncontrollable foot shock did not affect the acquisition or performance of this response in the former three strains, but provoked a modest disruption of reversal performance in DBA/2J mice and markedly impaired reversal performance in BALB/cByJ mice. It seemed, however, that the response strategies adopted in these strains could be distinguished from one another. In the reversal paradigm BALB/cByJ mice initially persisted in returning to the original training quadrant rather than to the new goal quadrant. Following 2 days of training the perseveration was no longer apparent and animals seemed to adopt a random search strategy. In contrast, DBA/2J mice, which exhibited a smaller stress-induced disturbance, did not display a perseverative response style. These data suggest that inescapable shock does not disturb response-outcome associations, but may result from the induction of a perseverative response style. However, it appears that the mechanisms responsible for an interference of performance may not be uniform across strains. The mechanisms responsible for the poor performance of BALB/cByJ mice have not been determined, but the behavioral profile demonstrated is consistent with that associated with hippocampal disturbances and excessive glucocorticoid release in response to environmental stressors.

Genetics, Morris water-maze, Perseveration, Stress
Physiology and Behavior
Department of Psychology

Francis, D.D. (Darlene D.), Zaharia, M.D. (Marilee D.), Shanks, N. (Nola), & Anisman, H. (1995). Stress-induced disturbances in Morris water-maze performance: Interstrain variability. Physiology and Behavior, 58(1), 57–65. doi:10.1016/0031-9384(95)00009-8