Anne Geller

The time relations of ECS induced amnesia

Mice were given electroconvulsive shock (ECS) after training in a passive avoidance task, and were tested for retention 1, 2, 6, and 24 h later. Performance levels on the retention test, high 1 h after training gradually deteriorated at the other testing intervals.

Impaired performance by post-trial injections of cycloheximide in a passive avoidance task

SummaryCycloheximide, injected subcutaneously after training in a passive avoidance task resulted in impaired performances on the retest given 7 days later. A gradient was observed for this effect, injections given immediately after training producing most impairment and injections given 2 h after training producing none.

Electroconvulsive shock induced amnesia and recovery

Recovery from electroconvulsive shock (ECS) induced amnesia in mice did not occur with time alone or with multiple trials in a stepthrough apparatus, although attempts were made to increase the probability of such recovery. Subjects receiving foot shock (FS) and ECS always show significantly higher latencies than unshocked controls and this difference can be increased using a threshold FS after extinction.

Impairment of delayed matching in monkeys by chlorpromazine and pentobarbital

SummaryMonkeys trained to perform in a delayed matching test under five delay conditions were given chlorpromazine hydrochloride (0.05, 0.1, 0.2 and 0.4 mg/kg) and pentobarbital sodium (1.0, 10.0 and 20.0 mg/kg) before test sessions. Both drugs decreased response rate proportionally as dose increased. Chlorpromazine initially depressed accuracy, but showed no specific effects as delay interval increased. Pentobarbital had little effect upon accuracy, although impairment on the simultaneous conditions was seen at the highest dose. It is concluded that neither drug produced specific effects upon short-term memory.

Biphasicity of the incubation curve

Two experiments were performed using a one-trial passive-avoidance task. In Experiment 1, different groups of mice were retested at different times after training. In Experiment 2, different groups were administered a footshock outside the conditioning apparatus and then were given the step-through experience at different times after the footshock. The time-response curve was found to be triphasic only in Experiment 1, while it produced a monotonie incubation curve in Experiment 2.

The Role of Consolidation in Memory

The theory of memory consolidation in its most basic form holds that there is a finite interval between the reception of a learning experience and its permanent storage. During this time the memory trace is held in a short term, impermanent system and is susceptible to disruption. Permanent or long term memory trace formation might occur through the short term system or be initiated independently. The evidence supporting a short term memory system has been obtained largely from studies using ECS in humans and experimental animals, that for a long term system from the effects, in animals, of inhibitors of RNA and protein synthesis. The purpose of this paper is to emphasize the hypothetical nature of these assumptions and to reexamine them in the light of some of the psychological variables involved.

Permanence of a long temporal gradient of retrograde amnesia induced by electroconvulsive shock

Electroconvulsive shock (ECS) was administered to mice 10 sec, 120 sec, and 3 h after training in a passive avoidance task. Subgroups were retested at 24 h, 48 h, 72 h, 1 week, and 4 weeks. A temporal gradient of retrograde amnesia was produced, with ECS still being effective even when given 3 h after training. The gradient was maintained over all retest times. No evidence of recovery could be detected.

Cycloheximide induced amnesia: Its interaction with detention

After training in a passive avoidance task, mice were detained in the safe compartment of the conditioning apparatus. This detention produced an impairment of rentention on the retest trial.Detention did not prolong the cycloheximide susceptible phase of memory formation. A summation of the amnestic effects of the two treatments occurred only at a time when both were effective alone. Cycloheximide was without effect upon the detention experience itself.

Potentiation of the amnesic effect of electroconvulsive shock by detention

Electroconvulsive shock (ECS) administered to mice 10 min after training in a one-trial passive avoidance situation decreases their step-through latencies in the retest trial given 24 h later. A similar degree of impairment is found if the animals are detained in the same compartment of the conditioning apparatus for 10 min immediately after the training trial If ECS is given at the end of the detention period, its amnesic effect on the conditioned response is greatly increased.

Biphasicity of the time-response curve and amnesic effect of electroconvulsive shock in passive avoidance conditioning

Mice were trained in a one-trial passive avoidance task and retested 2 min, 5 min, 10 min, 30 min, or 24 h later. A biphasic time-response curve was obtained with art initial increase to 5 min, a subsequent decrease, and another increase to 24 h. Other groups of Ss were administered electroconvulsive shock (ECS) 2, 5, 10, or 30 min after training and retested 24 h later. The response curve shape of the ECS-treated groups was found to correspond to that concerning the different retest times, suggesting a negative correlation between ECS amnesic effect and the strength of the conditioned response at the time of ECS administration. The inadequacy of the hypotheses, according to which ECS interferes with a gradual monotonic process, to explain ECS amnesic effect is discussed.