Goldberg S R, Kelleher R T, Morse W H
Fed Proc. 1975 Aug;34(9):1771-6.
Key-press responding of squirrel monkeys produced intravenous injections of cocaine under two simple types of schedule. Under a fixed ratio schedule, every 30th response produced an injection; steady responding at high rates of over one per second were maintained during each fixed-ratio component. Under a fixed-interval schedule, the first response occurring after a fixed time of 5 min produced an injection; there was a pause at the start of each interval and then progressively increasing responding until cocaine was injected at the end of the interval. Both squirrel monkeys and rhesus monkeys also were studied under second-order schedules of drug injection. Under one type of second-order schedule, studies only in squirrel monkeys, completion of each fixed-interval component produced only a 2 sec light; completion of the 10th fixed-interval component produced the brief light and an intravenous injection of cocaine. Under a second type of second-order schedule, each fixed-ratio component completed during a fixed time interval (5 or 60 min) produced only a 2-sec light; the first fixed-ratio component completed after the interval of time elapsed produced the brief light and an intravenous (squirrel monkeys) or intramuscular (rhesus monkeys) injection of cocaine. Under both types of second-order schedules, repeated sequences of responding were maintained during each session and characteristic fixed-interval or fixed-ratio patterns of responding were controlled by the brief visual stimuli.
松鼠猴的按键反应在两种简单的程序安排下可引发静脉注射可卡因。在固定比率程序下，每第30次反应会引发一次注射；在每个固定比率阶段，都能维持每秒超过一次的高速稳定反应。在固定间隔程序下，在5分钟的固定时间后出现的第一次反应会引发一次注射；每个间隔开始时会有停顿，然后反应逐渐增加，直到在间隔结束时注射可卡因。松鼠猴和恒河猴也在药物注射的二阶程序下进行了研究。在一种二阶程序下（仅在松鼠猴中研究），每个固定间隔阶段的完成仅产生2秒的灯光；第10个固定间隔阶段的完成产生短暂灯光和一次静脉注射可卡因。在第二种二阶程序下，在固定时间间隔（5或60分钟）内完成的每个固定比率阶段仅产生2秒的灯光；在经过该时间间隔后完成的第一个固定比率阶段产生短暂灯光和一次静脉注射（松鼠猴）或肌肉注射（恒河猴）可卡因。在两种二阶程序下，每次实验期间都维持了重复的反应序列，并且短暂的视觉刺激控制着特征性的固定间隔或固定比率反应模式。
