The pattern of brain activation induced by acute administration of cocaine may provide a useful means to evaluate medication effectiveness for treating cocaine addiction.

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Changes in respiration associated with schedule-controlled behavior were determined in seated rhesus monkeys prepared with a pressure-displacement head plethysmograph for monitoring ventilation continuously during behavioral experiments. Subjects were trained to press a lever under fixed-ratio 40 and fixed-interval 300-s schedules of stimulus termination. Episodic increases in ventilation were closely associated with periods of responding under both schedules. Recurring episodes of increased ventilation occurred during fixed-ratio responding, and were separated by brief 10-s timeouts during which ventilation decreased. Under the fixed-interval schedule, both ventilation and response rate typically increased as the 300-s interval elapsed. The effects of cocaine, caffeine, and two adenosine agonists, 5'-N-ethylcarboxamidadenosine (NECA) and 2-(carboxyethylphenylamino)adenosine-5'-carboxamide (CGS 21680), on behavior and respiration were determined using a cumulative-dosing procedure. Drug-induced suppression of behavior eliminated the episodic increases in ventilation during the performance components of both schedules. Schedule-related increases in ventilation were compared to those produced by elevated levels of CO2 in inspired air. Exposure to 4% CO2 mixed in air increased ventilation in all subjects, and the combined effects of CO2 exposure and schedule-controlled responding on respiration appeared to be additive. The results suggest that behavioral activities may increase ventilation through increased metabolic demand and increased CO2 production.Key words: respiration, caffeine, cocaine, adenosine, fixed-interval schedule, fixed-ratio schedule, stimulus-termination schedule, plethysmograph, lever press, rhesus monkeyThe influence of operant conditioning on physiological systems has been studied actively within the framework of two general experimental approaches. One approach, referred to as a contingent model (Brady & Harris, 1977), has emphasized environmental and behavioral interactions that occur as a consequence of significant physiological changes (i.e., a specified physiological response is treated as an operant). Most studies have used either heart rate or blood pressure as the operant and have focused on the role of behavioral influences in the etiology of hypertension