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Rats were trained in a one-trial passive avoidance task and then were submitted to electroconvulsive shock (ECS) or to sham ECS. Twenty-four hours later they were tested for retention,with the door opened either immediately or 30 sec after the beginning of the test. Rats initially forced to avoid for 30 sec continued to avoid for the entire test, but the others had the usual low step-through latencies seen withECS-treated animals. Activity measures for those animals stepping through differentiated groups having received footshock from those not having footshock and ECS. A retest 5-10 min later showed "recovery" in the amnestic animals and continued avoidance behavior for those that avoided on the first test. Results are taken as evidence that ECS effects are not on memory storage but on the capacity of the animal to organize information effectively and quickly in order to produce ah adaptive response.

Rats were given a single familiarization (FAM) session before training in a one-trial passive-avoidance task and were then submitted to hypoxia or eleotrooonvulsive shock (ECS) in an attempt to produce retrograde amnesia (RA). Another group received the same training and posttraining treatment but not prior FAM. The results indicate that under the present training conditions, prior FAM is a necessary condition for both hypoxia and ECS to produce RA. These results are considered to underline the need to modify the consolidation hypothesis. Memory for an event is not fixated in isolation, but is incorporated into already existing dynamic systems. The strength of the new memory is determined in part by the prior experience of the animal.

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