Baylor College of Medicine, Houston, TX 77030, USA.
J Exp Anal Behav. 2009 Nov;92(3):413-22. doi: 10.1901/jeab.2009.92-413.
Under multiple schedules of reinforcement, previous research has generally observed tolerance to the rate-decreasing effects of cocaine that has been dependent on schedule-parameter size in the context of fixed-ratio (FR) schedules, but not under the context of fixed-interval (FI) schedules of reinforcement. The current experiment examined the effects of cocaine on key-pecking responses of White Carneau pigeons maintained under a three-component multiple conjunctive FI (10 s, 30 s, & 120 s) FR (5 responses) schedule of food presentation. Dose-effect curves representing the effects of presession cocaine on responding were assessed in the context of (1) acute administration of cocaine (2) chronic administration of cocaine and (3) daily administration of saline. Chronic administration of cocaine generally resulted in tolerance to the response-rate decreasing effects of cocaine, and that tolerance was generally independent of relative FI value, as measured by changes in ED50 values. Daily administration of saline decreased ED50 values to those observed when cocaine was administered acutely. The results show that adding a FR requirement to FI schedules is not sufficient to produce schedule-parameter-specific tolerance. Tolerance to cocaine was generally independent of FI-parameter under the present conjunctive schedules, indicating that a ratio requirement, per se, is not sufficient for tolerance to be dependent on FI parameter.
在多种强化时间表下，先前的研究普遍观察到可卡因对率降低的作用具有耐受性，这取决于固定比率（FR）时间表中时间表参数的大小，但在固定间隔（FI）强化时间表的背景下则没有。当前的实验研究了可卡因对维持在三个组件多重联合 FI（10s、30s 和 120s）FR（5 次反应）食物呈现时间表下的白卡奴鸽啄键反应的影响。在（1）可卡因急性给药、（2）可卡因慢性给药和（3）每日盐水给药的背景下，评估了代表可卡因给药前对反应影响的剂量-效应曲线。可卡因的慢性给药通常导致对可卡因降低反应率的作用产生耐受性，并且这种耐受性通常与相对 FI 值无关，如 ED50 值的变化所测量的那样。每日盐水给药将 ED50 值降低到急性给予可卡因时观察到的值。结果表明，向 FI 时间表中添加 FR 要求不足以产生时间表参数特异性的耐受性。在目前的联合时间表下，可卡因的耐受性通常与 FI 参数无关，这表明比率要求本身不足以使耐受性依赖于 FI 参数。
