DEVELOPMENT OF TOLERANCE TO DISRUPTIVE EFFECTS OF COCAINE ON REPEATED ACQUISITION AND PERFORMANCE OF RESPONSE SEQUENCES

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 203  (2) , 294-302
Abstract
Pigeons obtained food by making 4 responses on 3 keys in a specified sequence. Errors produced 5-s time-out periods, during which the keylights were off and responses had no effect. To establish a base line of repeated acquisition, the sequence of correct responses was changed from session to session. Cocaine (3 mg/kg) disrupted the behavior: total errors increased, the relative frequency of perseverative errors increased, the rate of within-session error reduction (learning) decreased and the total trial time (pausing) increased. During repeated drug administration (30-50 sessions), these effects disappeared, i.e., tolerance developed. Tolerance did not develop to cocaine-induced increases or decreases in time-out responding; such effects were non-disruptive in that they did not reduce the rate of food reinforcement. Cocaine (3-10 mg/kg) was also studied under a performance condition, in which the sequence of correct responses was the same from session to session. Cocaine increased performance errors and produced pausing, but tolerance developed more quickly than under the learning condition. The more rapid development of tolerance was presumably due to the stronger stimulus control of behavior under the performance condition.