Discrimination procedures training, testing

Discriminative stimulus effect. Rhesus monkeys, trained to discriminate A-9-THC from vehicle in a two-lever drug discrimination procedure, were tested with a variety of psychoactive drugs, including cannabinoids or drugs from other classes. The results indicated that A-9-THC discrimination showed pharmacological specificity, in that none of the noncannabinoid drugs fully substituted for A-9-THC. The classical cannabinoids, A-9-THC and A-8-THC, and the novel cannabinoids, WIN and l-butyl-2-methyl-3-(l-naphthoyl)indole, produced full dose-dependent substitution for A-9-THC in all monkeys. A heptyl indole derivative failed to substitute for A-9-THC, but it also did not displace pH] CP-55,940 from its binding site . ... 

Delayed alternation is another possible training protocol for the T/Y-maze, in which animals are rewarded for choosing any goal box in trial one. They are then returned to the start box and released after an inter-trial interval. In trial two, they have to enter the arm not visited in trial one (non-match) and are rewarded. Typically, animals acquire a criterion of 80% correct responses after a short training period. When tested in the presence of A THC, there was a significant drop in performance coupled with a reduction in monoamine turnover in their prefrontal cortex (Jentsch et al. 1997). Animals treated with a similar dose (5 mg/kg) A THC, however, were not impaired in brightness discrimination (Jentsch et al. 1996) or visual discrimination of forms procedures (Mishima et al. 2001) administered in the same apparatus. 

A two-lever food-reinforced DDL procedure includes a food reward training, a drug discrimination training with a psychoactive drug, and a final test phase (Fig. 15.1). 

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