School of Psychology, University of New South Wales, Sydney, Australia.
Exp Clin Psychopharmacol. 2012 Jun;20(3):213-24. doi: 10.1037/a0027203. Epub 2012 Feb 27.
Individual differences in drug dependence may be mediated by several abnormalities in associative learning, including perseveration of drug-seeking following contingency change, greater control over drug-seeking by Pavlovian stimuli, or greater sensitivity to drug reinforcement establishing higher rates of drug-seeking. To evaluate these three candidate markers for nicotine dependence, Experiment 1 contrasted daily (N = 22) and nondaily smoker groups (N = 22) on a novel instrumental learning task, where one S+ was first trained as a predictor of tobacco reward before being extinguished. Experiment 2 compared daily (N = 18) and nondaily smoker groups (N = 18) on a concurrent-choice task for tobacco and chocolate reward before an extinction test in which the tobacco response was extinguished, followed by a Pavlovian-to-instrumental transfer test, wherein the impact of tobacco and chocolate cues on concurrent choice was measured (gender was balanced within each smoker group). The results showed no group difference in sensitivity to extinction of either the stimulus-drug or response-drug contingency in Experiments 1 and 2, respectively, nor did groups show a difference in Pavlovian-to-instrumental transfer of control over tobacco choice. By contrast, nicotine-dependence status was marked by a higher frequency of tobacco choice in the concurrent-choice procedure, and this choice preference was associated with subjective craving (gender did not affect any behavioral measure). These results favor the view that nicotine dependence in this sample is not determined by individual predilection for perseveration or stimulus-control over drug-seeking, but by greater sensitivity to reinforcement of instrumental drug choice. Value-based decision theories of dependence are discussed.
个体在药物依赖上的差异可能是由几种与联想学习相关的异常所介导的，包括在条件变化后仍持续觅药、巴甫洛夫刺激对觅药行为更强的控制，或对药物强化作用更敏感从而导致更高的觅药率。为了评估尼古丁依赖的这三个候选标志物，实验 1 在一项新的工具性学习任务中比较了每日吸烟者（N = 22）和非每日吸烟者（N = 22）的差异，其中 S+最初被训练为烟草奖励的预测因子，然后被消退。实验 2 在一项同时进行的烟草和巧克力奖励的选择任务中比较了每日吸烟者（N = 18）和非每日吸烟者（N = 18）的差异，然后进行消退测试，其中烟草反应被消退，接着进行一个由巴甫洛夫刺激到工具性刺激的转移测试，在这个测试中测量了烟草和巧克力线索对同时进行的选择的影响（在每个吸烟者群体中，性别是平衡的）。结果表明，在实验 1 和 2 中，两组在对刺激-药物或反应-药物条件变化的消退的敏感性上没有差异，也没有显示出在从巴甫洛夫刺激到工具性刺激的控制转移方面的差异。相比之下，尼古丁依赖状态在同时选择程序中表现为更高的烟草选择频率，这种选择偏好与主观渴望有关（性别不影响任何行为测量）。这些结果表明，在这个样本中，尼古丁依赖不是由个体对持续或对药物寻求的刺激控制的偏好决定的，而是由对工具性药物选择的强化作用的敏感性决定的。依赖的基于价值的决策理论被讨论了。
