Comparison of the degree of discriminability of various drugs using the T-maze drug discrimination paradigm.

This paper reports preclinical data that may predict the amount of state-dependent learning likely to be produced in humans by various psychoactive drugs. In a T-maze, rats were required to turn right when drugged and left when not drugged to escape from electric shock. The number of training sessions required to learn this drug versus no drug discrimination was used as an indicator of the degree of discriminability of the training drug. Using this procedure, the discriminability of more than 100 common psychoactive drugs was determined at one or more doses. Sessions to criterion usually decreased as dosage was increased. Maximum discriminability occurred at the highest usable dose in most cases, and differed considerably for drugs of various types. The results suggest that the majority of psychoactive drugs can be investigated by use of the drug discrimination technique, and that state-dependent learning effects will not accompany clinical use of most psychoactive drugs unless intoxicating doses are used.