Galizio M, Allen A R
Department of Psychology, University of North Carolina, Wilmington 28403.
J Exp Anal Behav. 1991 Sep;56(2):193-203. doi: 10.1901/jeab.1991.56-193.
Rats were trained on concurrent schedules in which pressing one lever postponed shock and pressing the other lever produced periods of signaled timeout from avoidance on variable-ratio schedules. These procedures generated high rates of timeout-reinforced responding and provided a baseline for studying the effects of drugs on behavior maintained by different types of negative reinforcement (shock postponement vs. timeout). Morphine (2.5 to 10.0 mg/kg) reduced behavior maintained by timeout at doses that increased or had no effect on avoidance responding. In contrast, d-amphetamine (0.125 to 2.0 mg/kg) produced large increases in timeout responding at doses that had minimal effect on avoidance in rats trained on variable-interval and variable-ratio schedules. Thus, the event-dependent effects of morphine, observed in previous studies in which timeout responding was maintained at low rates by interval schedules, were replicated with high timeout rates maintained by variable-ratio schedules. The effects of d-amphetamine could also be described as "event dependent" because timeout responding was stimulated more than avoidance regardless of the maintenance schedule or baseline rate.
大鼠接受了并发程序训练，其中按压一个杠杆可推迟电击，按压另一个杠杆则在可变比率程序下产生有信号提示的回避超时时段。这些程序产生了高比率的超时强化反应，并为研究药物对由不同类型负强化（电击推迟与超时）维持的行为的影响提供了基线。吗啡（2.5至10.0毫克/千克）在增加或对回避反应无影响的剂量下，减少了由超时维持的行为。相比之下，在接受可变间隔和可变比率程序训练的大鼠中，右旋苯丙胺（0.125至2.0毫克/千克）在对回避影响最小的剂量下，使超时反应大幅增加。因此，在先前研究中观察到的吗啡的事件依赖性效应（其中超时反应通过间隔程序以低比率维持），在可变比率程序维持的高超时比率下得到了重复。右旋苯丙胺的效应也可描述为“事件依赖性”，因为无论维持程序或基线比率如何，超时反应都比回避反应受到更多刺激。
