Short-term retrograde amnesia in rats.

Abstract

Retroactive effects of electroconvulsive shock (ECS) were studied in 477 male hooded rats which received ECS 0.5-60.0 sec. after single passive avoidance training trials. As in previous studies, impairment in retention was inversely related to duration of ECS-delay interval. However, unlike earlier studies, impairment was observed only at relatively short (0.5-10.0 sec.) ECS-delays. Impairment is attributed to brief RA and not to aversive effects of ECS which were shown to develop only after repeated ECS treatments. The results are discussed in terms of both the consolidation hypothesis and alternative "conflict" and "competing-response" hypotheses of ECS effects.

Attenuation of response deficits by electroconvulsive shock

“…Retrograde amnesia frequently occurs when multiple ECS are employed or when a single ECS is used which closely follows a learning task (McGaugh, 1966). The present experiments do not appear to be explained by a retrograde amnesia hypothesis because, typically, a single ECS administered 1 day after learning does not produce retrograde amnesia in rats (Chorover & Schiller, 1965;Duncan, 1949). As shown in Experiment 5, there is no evidence that memory disruption accounts for the present results.…”

Extinction of the effect of one ECS

“…This interpretation has also been suggested by Hudspeth & Gerbrandt (1965) explain the present results which support an interference hypothesis since an active avoidance procedure was utilized. Chorover & Schiller (1965) have presented data which they interpret to indicate that the consolidated process is complete within 10 sec. If they are correct, then this study is not relevant to the consolidation hypothesis.…”

Memory consolidation: Probit analysis of retrograde-amnesia data

“…after the onset of foot-shock, because of the evidence that 0.5 sec. establishes avoidance (Chorover & SChiller, 1965). The conventional practice is to measure trial-to-ECS intervals from the termination of foot-shock, on the assumption that memory consolidation starts only then.…”