Fig. 4.

Behavioral effects of MA, COC, and GBR 12909 in rats trained to discriminate MA under the two drug discrimination procedures and changes in extracellular levels of DA in the NAcb of drug-naive rats. Left ordinates, percentage of responding on the MA-associated key; right ordinates, percentage of basal DA levels. Each point in the dialysis data represents the average of the three samples taken at each time point (10, 20, and 30 min) after each cumulative injection; abscissae, cumulative drug dose in milligrams per kilogram.