Delay Discounting and the Choice to Take a Drug

描述（由申请人提供）：行为与其行为者之间的延迟通常会降低行为者的主观价值，这种现象称为延迟折扣。有一个完善的定量模型，双曲线贴现函数，它描述了延迟贴现。延迟折扣研究为我们对药物滥用的理解做出了实质性的理论贡献。例如，药物滥用者比货币滥用者更快地贴现药物的价值，这表明贴现率可能取决于货币滥用者的性质。然而，比较药物和金钱折扣的实验研究了假设选择情况下每个折扣的单一幅度。在人类中，延迟性肿瘤的大小是贴现率的关键决定因素。对非人类的研究开始有助于我们理解延迟对药物选择的影响。最近，我们发现猴子对非药物成瘾者的贴现率比可卡因更高，这一结果与在药物滥用者中观察到的结果相反。这种差异可能是由于所研究的特定的免疫抑制剂的性质，或者是由于对猴子使用了真实的免疫抑制剂，而对人类使用了假设的免疫抑制剂。或者，这可能是两种干扰物的相对大小不同的结果。我们建议在给予同种异体（即，药物/非药物）的选择。目的1是建立剂量反应函数可卡因之间的选择是立即注射可卡因和食物的延迟介绍。将为不同数量和不同延迟的可用食品建立折扣功能。这种同构选择情况（即，即时药物与延迟食物）类似于药物滥用的基本折扣解释：药物滥用者被认为冲动地选择即时药物替代品，而不是更大的延迟非药物替代品。迄今为止，这种同形选择的研究很少。目的2是建立食物的大小响应函数时，选择是立即量的食物和延迟注射可卡因之间的介绍。将为不同延迟时间的不同剂量可卡因建立折扣函数。这种同质异晶选择情况很重要，因为药物滥用也可能涉及在更直接的非药物成瘾者和延迟的药物成瘾者之间进行选择，药物滥用者往往花费大量时间和精力购买药物就是一个例证。这种情况在贴现文献中几乎没有讨论过。我们对这两个目标的假设是，延迟支付的折扣将很好地描述为双曲线函数，折扣率将与延迟支付的金额成反比。这些结果将对理解药物选择的决定因素以及在治疗背景下使用延迟强化具有重要意义。

DESCRIPTION (provided by applicant): Delay between a behavior and its reinforcer usually decreases the subjective value of the reinforcer, a phenomenon termed delay discounting. There is a well-established quantitative model, the hyperbolic discounting function, which describes delay discounting. Research with delay discounting has made substantial theoretical contributions to our understanding of drug abuse. For example, drug abusers discount the value of drugs more rapidly than they do monetary reinforcers, suggesting that discounting rate may depend on the nature of the reinforcer. However, experiments comparing discounting of drugs and money have studied a single magnitude of each reinforcer in a hypothetical choice situation. In humans, magnitude of a delayed reinforcer is a crucial determinant of discounting rate. Research with non-humans is beginning to contribute to our understanding of the effects of delay on drug choice. Recently, we found that monkeys discounted non-drug reinforcers more steeply than they did cocaine, a result opposite to that observed in drug abusers. This difference may be due to the nature of the specific reinforcers studied, or to the use of real reinforcers with monkeys vs. hypothetical reinforcers with humans. Alternatively, it may be a consequence of differences in the relative magnitudes of the reinforcers. We propose to investigate the effect of reinforcer magnitude and delay on the rate of discounting of drug and non-drug reinforcers in monkeys given allomorphic (i.e., drug/non-drug) choices. Aim 1 is to establish dose-response functions for cocaine when the choice is between an immediate injection of cocaine and the delayed presentation of food. Discounting functions will be established for different amounts of food available with various delays. This allomorphic choice situation (i.e., immediate drug vs. delayed food) is analogous to the one underlying discounting interpretations of drug abuse: drug abusers are assumed to impulsively choose immediate drug reinforcers over larger, delayed non-drug reinforcers. Such allomorphic choice has received little study to date. Aim 2 is to establish magnitude-response functions for food when the choice is between the presentation of an immediate amount of food and a delayed injection of cocaine. Discounting functions will be established for different doses of cocaine available with various delays. This allomorphic choice situation is important because drug abuse also can involve choosing between more immediate non-drug reinforcers and delayed drug reinforcers, as exemplified by the fact that drug abusers often devote considerable time and effort to procuring drugs. This situation has received virtually no discussion in the discounting literature. Our hypotheses for both Aims are that the discounting of the delayed reinforcer will be well described by the hyperbolic function and that rate of discounting will vary inversely with the amount of the delayed reinforcer. The results will have important implications for understanding the determinants of drug choice and, potentially, for the use of delay to reinforcement in a therapeutic context.