[The effect of lysergic acid diethylamide on memory in mice].

In experiments on mice of the BALB/c strain a study was made of the influence of lysergic acid diethylamide (LSD) on the retention and reproduction of a conditioned passive avoidance reaction (CPAR). A 0.5-3.0 mg/kg of LSD Injected intraperitoneally 10 min. before the learning procedure, worsened the CPAR retention, while a 0.2 mg/kg of LSD Improved it. The drug (0.2 mg/kg) facilitated the retrieval of the reaction, which did not manifest itself in 24 and 48 hours after learning. This effect depended on the strength of the unconditioned stimulus presented during learning as well as on the time intervals between the moments of learning and testing. Facilitated CPAR retrieval was observed only during the action of the drug and disappeared in 24 hours after its administration. The possible physiological mechanisms of LSD influence on memory processes are discussed.