Central cholinergic correlates of impaired learning

Impairment of passive avoidance learning in mice by bilateral lesions in the hippocampus and by intraventricular administration of choline acetyltransferase (CAT) inhibitors was correlated with decreased levels of CAT in the hippocampus. Intraperitoneally administered scopolamine potentiated the behavioral effects of both hippocampal lesions and CAT inhibition. A behaviorally effective dose of CAT inhibitor produced no change in hippocampal levels of acetylcholine. These results indicate that the newly synthesized acetylcholine released at hippocampal synapses is essential for mice to learn at least one kind of task.