, Volume 10, Issue 1, pp 6-31

State-dependent learning produced by depressant and atropine-like drugs

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Summary

Rats were trained to escape from shock in a T maze. In this situation a variety of drugs were tested and compared with regard to their ability to produce state-dependent, or dissociated, learning. Three major results were obtained. First, several depressant drugs produced a state in which learning was partially dissociated from learning which occurred in the nondrug state. Pentobarbital, phenobarbital, alcohol, urethane, and meprobamate were approximately equivalent in their actions and were interchangeable. Second, atropine produced a drug state in which learning was partially dissociated from learning in the nondrug state and from learning which occurred under the depressant drugs. The effects of atropine which produced this state neither mimicked nor antagonized those effects of the depressant drugs which allowed them to dissociate learning. This result is especially important as it indicates that not all dissociation phenomena are the result of some single unidimensional process (eg., activation level changes produced by the drugs). Third, many drugs which dissociate learning in other experimental situations have weak or nonexistent dissociative effects on escape learning in the T maze. The present technique appears to be useful for directly comparing the dissociative effects of a variety of drugs.

Part of the data in this report was included in a Ph. D. thesis entitled “Control of Learned Responses by Drug States” which was submitted to the Dept. of Psychology at McGill University in 1962. This research has been supported by the National Research Council of Canada Grant APT-36, by USPHS Grants No. MH-03238-03, 3T1-GM-395, 5T1-MH-6418, and by N.I.N.D.B. Grant NB-03942.