The contribution of within-session averaging of drug- and vehicle-appropriate responding to the graded dose-response function in drug discrimination learning

Prior work within the taste aversion baseline of drug discrimination learning has demonstrated that the generalization function for individual rats was graded in nature. Given that within other discrimination designs such graded responding has been reported to result from an averaging of drug- and vehicle-appropriate responding at different periods within the session, the present experiment assessed the contribution of averaging to the graded responding within the aversion design. Rats trained to discriminate either naloxone (Experiment 1) or pentobarbital (Experiment 2) from distilled water were administered various doses of the training drug (or a different drug) in subsequent generalization assessments in which the within-session pattern of licking was monitored min by min over the 20-min session. Responding within the session was primarily either drug or vehicle appropriate with the specific pattern of drug- or vehicle-appropriate responding presumably dependent upon the onset and/or offset of drug action.