Conditioned suppression of behavior maintained by cocaine self-administration

Conditioned suppression has been demonstrated on baselines maintained by a variety of reinforcers, but never before on a drug self-administration baseline. The present study sought to determine whether conditioned suppression could be produced on a baseline maintained by cocaine. Rats were trained to self-administer cocaine by barpressing on a variable-interval schedule. A tone CS and a light CS, each paired with foot-shock, suppressed responding, thus demonstrating conditioned suppression on a drug self-administration baseline for the first time. Presenting the tone and light simultaneously significantly enhanced suppression, closely paralleling previous conditioned suppression experiments performed on a food-reinforced baseline. These results demonstrate that conditioned aversive stimuli exert similar suppressive effects on responding maintained by cocaine and responding maintained by conventional positive reinforcers.