Gonzalez F A, Goldberg S R
J Pharmacol Exp Ther. 1977 Apr;201(1):33-43.
Dose-response functions were determined for the effects of cocaine and d-amphetamine on lever-pressing responses maintained under three schedules of food presentation: 1) a simple fixed-ratio schedule, 2) a multiple fixed-ratio, fixed-interval schedule and 3) a second-order fixed-interval schedule with fixed-ratio components. These schedules generated a variety of rates and patterns of responding. The effects of the drugs on response rate depended on the control rates of responding. The highest overall rates of responding were maintained under the fixed-ratio schedule and under the fixed-ratio component of the multiple schedule. Both cocaine and d-amphetamine produced dose-related decreases in these high response rates. Lower overall rates of responding were maintained under the second-order schedule and under the fixed-interval component of the multiple schedule. Intermediate doses of cocaine or d-amphetamine (0.1-1.0 mg/kg) increased these lower rates of responding. Under the second-order schedule and the multiple schedule, local response rates during successive segments of the fixed-intervals were differentially affected by the drugs. Cocaine and d-amphetamine markedly increased low response rates that occurred during initial segments of the fixed intervals, but either had little effect on or decreased higher responses rates that occurred during later segments of the fixed intervals. Cocaine and d-amphetamine had similar qualitative and quantitative effects on responding, but d-amphetamine was longer lasting than cocaine.
测定了可卡因和右旋苯丙胺对在三种食物呈现时间表下维持的杠杆按压反应的剂量-反应函数：1）简单固定比率时间表，2）多重固定比率、固定间隔时间表，以及3）带有固定比率成分的二阶固定间隔时间表。这些时间表产生了各种反应速率和模式。药物对反应速率的影响取决于反应的对照速率。在固定比率时间表和多重时间表的固定比率成分下维持着最高的总体反应速率。可卡因和右旋苯丙胺都使这些高反应速率产生与剂量相关的下降。在二阶时间表和多重时间表的固定间隔成分下维持着较低的总体反应速率。中等剂量的可卡因或右旋苯丙胺（0.1 - 1.0毫克/千克）提高了这些较低的反应速率。在二阶时间表和多重时间表下，固定间隔连续段期间的局部反应速率受到药物的不同影响。可卡因和右旋苯丙胺显著提高了固定间隔初始段出现的低反应速率，但对固定间隔后期段出现的较高反应速率要么几乎没有影响，要么使其降低。可卡因和右旋苯丙胺对反应具有相似的定性和定量影响，但右旋苯丙胺的作用持续时间比可卡因更长。
