McMillan D E, Hardwick W C, Li Mi
Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock 72205, USA.
J Exp Anal Behav. 2002 Jan;77(1):91-104. doi: 10.1901/jeab.2002.77-91.
Pigeons were trained to discriminate 5 mg/kg pentobarbital from saline under concurrent variable-ratio (VR) VR schedules, in which responses on the pentobarbital-biased lever were reinforced under the VR schedule with the smaller response requirements when pentobarbital was given before the session, and responses on the saline-biased key were reinforced under the VR schedule with the larger response requirements. When saline was administered before the session, the reinforcement contingencies associated with the two response keys were reversed. When responding stabilized under concurrent VR 20 VR 30, concurrent VR 10 VR 40, or concurrent VR 5 VR 50 schedules, pigeons responded almost exclusively on the key on which fewer responses were required to produce the reinforcer. When other doses of pentobarbital and other drugs were substituted for the training dose, low doses of all drugs produced responding on the saline-biased key. Higher doses of pentobarbital and chlordiazepoxide produced responding only on the pentobarbital-biased key, whereas higher doses of ethanol and phencyclidine produced responding only on this key less often. d-Amphetamine produced responding primarily on the saline-biased key. When drugs generalized to pentobarbital, the shape of the generalization curve under concurrent VR VR schedules was more often graded than quantal in shape. Thus, drug discrimination can be established under concurrent VR VR schedules, but the shapes of drug-discrimination dose-response curves under concurrent VR VR schedules more closely resemble those seen under interval schedules than those seen under fixed-ratio schedules. Graded dose-response curves under concurrent VR VR schedules may relate to probability matching and difficulty in discriminating differences in reinforcement frequency.
鸽子接受训练，在并发可变比率（VR）VR 时间表下区分 5 毫克/千克戊巴比妥和生理盐水，其中在实验前给予戊巴比妥时，对偏向戊巴比妥的杠杆的反应在具有较小反应要求的 VR 时间表下得到强化，而对偏向生理盐水的按键的反应在具有较大反应要求的 VR 时间表下得到强化。当在实验前给予生理盐水时，与两个反应按键相关的强化意外情况会反转。当在并发 VR 20 VR 30、并发 VR 10 VR 40 或并发 VR 5 VR 50 时间表下反应稳定时，鸽子几乎只在产生强化物所需反应较少的按键上做出反应。当用其他剂量的戊巴比妥和其他药物替代训练剂量时，所有药物的低剂量都会导致在偏向生理盐水的按键上做出反应。较高剂量的戊巴比妥和氯氮卓只会在偏向戊巴比妥的按键上产生反应，而较高剂量的乙醇和苯环己哌啶只会较少地在这个按键上产生反应。右旋苯丙胺主要在偏向生理盐水的按键上产生反应。当药物泛化到戊巴比妥时，并发 VR VR 时间表下的泛化曲线形状更多是渐变的而非量子化的。因此，药物辨别可以在并发 VR VR 时间表下建立，但并发 VR VR 时间表下的药物辨别剂量反应曲线形状更类似于间隔时间表下的曲线，而不是固定比率时间表下的曲线。并发 VR VR 时间表下的渐变剂量反应曲线可能与概率匹配以及辨别强化频率差异的难度有关。
