Contingent access to stimuli associated with cocaine self-administration is required for reinstatement of drug-seeking behavior

In this study, we examined the importance of contingent access to a cocaine -related stimulus in the production of cocaine seeking following extinction of lever responding for cocaine. Rats self-administered cocaine for 2 week s in daily 3-h sessions under a fixed-ratio 1 schedule. A compound stimulus (tone + light) was presented with each infusion. Following seven daily 3-h extinction sessions, rats were reintroduced to the compound stimulus alone . This stimulus was presented in three ways: (1) contingent on lever pressi ng, (2) noncontingent, and (3) both contingent and noncontingent. Following 3 more extinction days, rats were again reintroduced to the compound stimu lus, yet with contingent access to cocaine. Only the two groups with contin gent presentation increased lever responding on the Ist day, while all grou ps increased responding for cocaine on the 2nd day. The need for contingent access to drug-associated stimuli in the absence of drug to produce drug-s eeking behavior may be relevant for studies of neural substrates of relapse .