No spatial learning impairment following exposure to inescapable shock

Abstract

Uncontrollable stressors produce changes both in hippocampal physiology and in cognitive performance. It has been suggested that some of the cognitive effects of uncontrollable shock may be mediated by disturbances in hippocampal processes. We evaluated the prediction that inescapable shock should produce a learning deficit in a task known to be particularly sensitive to disruption in hippocampal function-the Morris water-maze spatial-learning task. Exposure to a single session of inescapable shock of the type typically employed in learned helplessness experiments produced no apparent effect on performance regardless of whether shock was given 30 min or 6 h prior to water-maze training or whether animals were tested at retention intervals of 0, 1, 4, or 24 h following training. Similarly, no effect of inescapable shock was observed when shock treatment and water-maze training were distributed over three daily sessions. These results are inconsistent with the hypothesis that the effects of inescapable shock on cognitive performance result from disturbances in hippocampal function.