Tatham T.A., Barrett J.E.
Department of Psychiatry, Uniformed Services University of the Health Sciences, Bethesda, MD 20910-8014.
Behav Pharmacol. 1993 Apr;4(2):159-166.
A history of responding maintained by a shock-avoidance procedure can alter the effect of psychomotor stimulant drugs on punished responding. This study was designed to evaluate whether another type of historical intervention could also alter the effects of cocaine on punished responding and, as a result, clarify certain variables contributing to this effect. Lever pressing of four squirrel monkeys was suppressed by a punishment procedure consisting of a fixed-interval 5-min schedule of food presentation in which every 30th response also produced a 200-ms 5-mA electric shock. Cocaine (0.03-1.0mg/kg) had no effect on or reduced punished responding. Conditions were then changed and responding was maintained for several sessions by a differential reinforcement of low rate (DRL) schedule in which food was delivered only when one response followed another by at least 25s. The punishment schedule was then reinstated and the effects of cocaine redetermined; the dose-response curve was similar to that initially obtained. The monkeys then responded on a shock-avoidance schedule in which each response postponed the next scheduled shock for 25s; shocks occurred every 5s in the absence of responding. Subsequently, the shock-avoidance schedule was replaced by the punishment schedule and the effects of cocaine were redetermined. In contrast to the initial determination of the effects of cocaine on punished responding, and the effects obtained following training on the DRL schedule, cocaine then produced response rate increases or no change in rate at several doses that formerly reduced responding. These results demonstrate that the rate-decreasing effects of cocaine on punished responding may be reversed by a history of responding on a shock-avoidance schedule and also indicate that a history of responding on a DRL schedule is not sufficient to reverse the effects of cocaine. These data suggest that a history of responding under schedules, such as the DRL, that engender responding that is typically increased by psychomotor stimulant drugs, is not sufficient to reverse the effects of these drugs on punished responding. The reversal of the effects of cocaine on punished responding resulting from a history of avoidance responding appears to be attributable to factors other than the rate-increasing effect of cocaine on responding maintained by avoidance.
由回避电击程序维持的反应历史可以改变精神运动性兴奋药物对受惩罚反应的影响。本研究旨在评估另一种类型的历史干预是否也能改变可卡因对受惩罚反应的影响，并由此阐明导致这种影响的某些变量。对四只松鼠猴的杠杆按压行为通过一种惩罚程序进行抑制，该程序包括固定间隔5分钟的食物呈现时间表，其中每第30次反应还会产生一次持续200毫秒、强度为5毫安的电击。可卡因（0.03 - 1.0毫克/千克）对受惩罚反应没有影响或使其降低。随后改变条件，通过低反应率差异强化（DRL）时间表维持反应数节，在此时间表中，只有当一次反应与另一次反应间隔至少25秒时才给予食物。然后恢复惩罚时间表并重新确定可卡因的效果；剂量 - 反应曲线与最初获得的相似。接着猴子按照回避电击时间表进行反应，每次反应将下一次预定电击推迟25秒；在无反应时每5秒出现一次电击。随后，将回避电击时间表替换为惩罚时间表并重新确定可卡因的效果。与最初确定的可卡因对受惩罚反应的影响以及在DRL时间表训练后获得的效果相反，此时可卡因在几个先前降低反应率的剂量下使反应率增加或无变化。这些结果表明，可卡因对受惩罚反应的降低反应率作用可能会被回避电击时间表的反应历史所逆转，并且还表明DRL时间表的反应历史不足以逆转可卡因的作用。这些数据表明，在诸如DRL等时间表下的反应历史，这种时间表会产生通常会被精神运动性兴奋药物增加的反应，但不足以逆转这些药物对受惩罚反应的作用。可卡因对受惩罚反应的影响因回避反应历史而逆转，这似乎归因于除可卡因对回避维持的反应的增加反应率作用之外的其他因素。
