Miller M L, Brodkorb G W, Branch M N
Department of Psychology, University of Florida, Gainesville 32611, USA.
J Exp Anal Behav. 2001 Sep;76(2):217-34. doi: 10.1901/jeab.2001.76-217.
Four pigeons responded under a fixed-interval 8-min schedule of food delivery in which the amount of food delivered at the end of each interval depended on performance during the interval (i.e., a correlated schedule). Specifically, duration of access to grain was contingent upon the number of responses made during the first 4 min of the interval. This differential outcome did not affect response rates or patterning relative to performance under a simple fixed-interval 8-min schedule. Behavior under the correlated schedule was then investigated under doses of cocaine ranging from 0.3 to 10.0 mg/kg. A bitonic dose-response function was obtained for response rates and the time with head in the food hopper, whereas dose-dependent decreases were observed in the mathematical index of curvature (Fry, Kelleher, & Cook, 1960). The dose that produced the greatest increase in the head-in-hopper time was then administered prior to each session. Following repeated administration of cocaine, disruptions in response patterning were attenuated for all 4 pigeons; tolerance was also observed to the rate-increasing effects and increased head-in-hopper time for 2 pigeons after chronic cocaine administration. Tolerance therefore developed despite the fact that the initial effect of cocaine was to increase the amount of food obtained.
四只鸽子在固定间隔8分钟的食物投递时间表下做出反应，其中每个间隔结束时投递的食物量取决于该间隔内的表现（即相关时间表）。具体而言，获取谷物的时长取决于间隔前4分钟内做出的反应次数。相对于简单的固定间隔8分钟时间表下的表现，这种差异结果并未影响反应率或行为模式。然后在0.3至10.0毫克/千克的可卡因剂量下研究相关时间表下的行为。对于反应率和头部在食槽中的时间，获得了一个双调剂量反应函数，而在曲率数学指数中观察到剂量依赖性降低（弗莱、凯莱赫和库克，1960年）。然后在每次实验前给予使头部在食槽中时间增加最多的剂量。重复给予可卡因后，所有4只鸽子的反应模式干扰都减弱了；在长期给予可卡因后，还观察到2只鸽子对增加反应率的作用以及头部在食槽中时间增加产生了耐受性。因此，尽管可卡因的初始作用是增加获得的食物量，但耐受性还是产生了。
