Faculty Bibliography

Rats were trained in a semi-automated Y maze to find food at the end of the lighted arm. Those treated with 10 mu g lysine vasopressin, 90 min before training learned the response to a 9 10 correct choice criterion significantly faster than saline treated animals. There was no difference in rate of forgetting between the treatment groups, as evidenced by a retention test, 3 weeks after training. There was no direct effect of vasopressin on retrieval, since animals treated before the retention test performed at the same level as non treated animals. Finally, vasopressin impaired reversal from light to dark. In a second experiment, the acquisition facilitation seen in Exp. I was replicated, but there was no effect of the treatment on animals trained to dark SD. However, the impairment seen in Exp. I when vasopressin treated animals, trained to light, were reversed to dark, was replicated in this experiment in animals trained to dark and reversed to light. Previous demonstrations of vasopressin facilitation of learning and memory have, with few exceptions, relied on shock avoidance tasks. The present experiments demonstrate a reliable facilitation of appetitive learning by vasopressin. The fact that vasopressin impairs reversal may be due to an increased tendency to perseverate.

Rats tested 25 days after training in a complex maze showed significant forgetting. Stimulation of the mesencephalic reticular formation immediately prior to retention testing facilitated performance in that stimulated rats made fewer errors (but did not run faster) than non-stimulated controls. Rats exposed to a contextual cue as a reminder before testing ran faster and made fewer errors than controls. Results are discussed in terms of forgetting being due to retrieval failure, and the reticular stimulation facilitating retrieval of information concerning the spatial configuration of the maze

Etiracetam, a nonanaleptic drug related to the nootropic substance piracetam, was found to facilitate memory retrieval in rats in several experimental situations, when injected 30 min prior to retention testing. The drug was active when memory deficits were induced by electroconvulsive shock, undertraining, or by a long training-to-test interval. The behavioral paradigms included a one-trial inhibitory avoidance task and a complex multitrial, spatially discriminated approach task. The clinical interest of drugs which facilitate retrieval processes is also discussed

Rats were trained on a continuously reinforced bar-press response for water reward. Seven days later they were retested for retention, with or without pretest injection of the nootropic drug, piracetam. Drug-treated animals had significantly shorter response latencies than saline-treated animals. The results are interpreted as a facilitation of retrieval processes after forgetting. The experiment was extended under extinction conditions and it was found that after three sessions there was a tendency to facilitate extinction when response latency is used as the extinction index. The clinical interest of a drug which facilitates the retrieval aspect of the memory process without impairing extinction is discussed

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 with ECS-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 an adaptive response