Fig. 2.

Effects of MA and related compounds in rats trained to discriminate injections of MA (0.3 mg/kg) from saline under a discrete-trial avoidance/escape procedure (top) and under an FR 20 schedule of food reinforcement (bottom). A, ordinates: percentage of trials completed on the MA-associated key. B, percentage of responses on the MA-associated key. Abscissae, cumulative drug dose in milligrams per kilogram (log scale). Each point represents the mean (±S.E.M.) effect in at least six rats. V, vehicle.