Tolerance to drug stimulus control

A psychoactive drug can acquire discriminative stimulus control of behavior through differential reinforcement processes. Development of tolerance to drug stimulus control reflects a dynamic interaction of conditioning and pharmacodynamic processes. Development of tolerance requires the interplay of drug maintenance regimens appropriate to the agent under study and behavioral conditions that limit an organism's ability to learn a new discrimination. Tolerance to drug discriminative control has four important characteristics: the dose of drug required to evoke stimulus control is increased, the requirement for an increased dose is limited to the period of supplemental drug treatment, the change in potency is pharmacologically specific, and the change may require suspension of discrimination training.