Date of Award
Master of Arts in Psychology
Recently, an animal model of depression, which appeared to be sensitive to clinically effective antidepressant treatments, was described by Porsolt et al (1978b). The model was derived from the observation that rats forced to swim in inescapable warm (25°C) water for fifteen minutes become immobile after some time. Immobility was characterized by animals floating in an upright position, with only their heads above water. When retested twenty-four hours later, rats showed significantly longer lengths of immobility than naive controls. The investigators labeled this response "behavioral despair". In the present study, two experiments were performed to further investigate "behavioral despair". In experiment one, rats were exposed to escapable or inescapable warm swims of equivalent length, or no swim, and tested twenty-four hours later on duration of immobility and latency to become immobile. It was hypothesized that the inescapable group would exhibit "behavioral despair", while the escapable group would not differ from controls. Results showed that both inescapable and escapable groups were immobile significantly longer than controls, and did not differ from one another. No differences were found among groups on latency to become immobile. In a second experiment, rats were pretreated as in experiment one, and twenty-four hours later were tested on an FR 3 bar press escape task. It was hypothesized that the inescapable groups would have significantly longer latencies to escape shock than both controls and the escape group. Results showed no significant differences among groups on latency to escape shock. Results of both experiments are discussed in terms of the water escape task used, and implications for the behavioral despair model. While no firm conclusions can be drawn regarding the appropriateness of the water escape task used, it was concluded that behavioral despair does not generalize to a shock escape task. Suggestions for future research are made.
O'Neill, Katherine A., "The Effect of Forced Warm Swim on Escape Learning in Rats" (1981). Open Access Master's Theses. Paper 1655.