Reinforcer efficacy: measures and neural mechanisms

强化物功效：措施和神经机制

基本信息

批准号：
7178538
负责人：
SUZANNE H MITCHELL
金额：
$ 17.56万
依托单位：
OREGON HEALTH & SCIENCE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-02-01 至 2010-01-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Studies of delay discounting in humans have revealed that drug users have an exaggerated preference for small, immediate over large, delayed rewards, even when the immediate reward is substantially smaller than the delayed reward. These studies have been interpreted to mean that drug users are more impulsive than nonusers and, possibly, that drug use has altered the processes by which individuals evaluate the benefits and costs associated with rewards. These processes are believed to determine the efficacy of drug and nondrug reinforcers to control behavior. However there are costs other than delay which can cause the value of a reinforcer to be discounted. Two such costs are uncertainty and effort. Five studies are proposed to evaluate the impact of all three costs on reinforcer efficacy (delay to the receipt of a reward, uncertainty about the receipt of the reward, and the effort required to obtain the reward) using a discounting procedure that was developed by the Principal Investigator and her colleague for use with rats. The basic hypotheses are that 1) the rats that discount delayed rewards more will also discount uncertain and effortful rewards more and 2) that discounting for the three different types of cost will be similarly effected by a series of behavioral and pharmacological manipulations. Experiment 1 determines whether rats discount large, expensive rewards to similar degrees regardless of the cost type by assessing the correlation between delay discounting, uncertainty discounting and effort discounting in the same animals, and examines the impact of chronic injections of nicotine on discounting. Experiment 2 examines how the magnitude of reward affects delay, uncertainty and effort discounting. Experiment 3 determines whether preference switches from the small, cheaper reward to the large, expensive reward when a fixed cost is added to both alternatives. Experiment 4 examines whether exposure to high-reinforcer-cost conditions leads to decreases in delay, uncertainty and effort discounting. Experiment 5 investigates the role of dopamine in modulating delay, uncertainty and effort discounting. These studies will provide information about the variables taken into account when the brain evaluates reinforcer efficacy and procedures that can be used to alter reinforcer efficacy, both of which will have implications for drug abuse treatment. Further, the data collected in these studies will provide a basis for future studies, which will examine whether differences in how individuals evaluate the value of reinforcers are causally related to the initiation, progression and cessation of drug use and abuse.

描述（由申请人提供）：人类延迟打折的研究表明，即使立即的奖励大大比延迟的奖励小得多，吸毒者对小而立即的较小，延迟的奖励的偏好也夸大了。这些研究被解释为意味着吸毒者比非用户更具冲动性，而且可能的吸毒者可能改变了个人评估与奖励相关的收益和成本的过程。人们认为这些过程可以确定药物和非果辅助者控制行为的功效。但是，除延迟以外，还有其他成本会导致钢筋的价值被打折。这样的两个成本是不确定性和努力。提出了五项研究，以评估所有三个成本对增强功效的影响（延迟收到奖励，收到奖励的不确定性以及获得奖励所需的努力），使用主要研究人员及其同事与大鼠一起使用的折扣程序。基本假设是1）折扣延迟奖励的大鼠还将更折扣不确定和努力的奖励，而2）2）对三种不同类型的成本的折扣将受到一系列行为和药理操纵的影响。实验1确定大鼠是否通过评估延迟折现，不确定性折扣和同一动物的努力折现之间的相关性，并检查尼古丁对折扣的慢性注射对折扣的影响，而不管成本类型是否折扣到类似程度。实验2研究了奖励的幅度如何影响延迟，不确定性和努力折现。实验3确定，当将固定成本添加到两个替代方案中时，偏好是否从小的，便宜的奖励转换为昂贵的奖励。实验4研究了暴露于高增强成本的条件是否导致延迟，不确定性和努力折现的减少。实验5研究了多巴胺在调节延迟，不确定性和努力折现中的作用。这些研究将提供有关大脑评估增强功效和可用于改变增强疗效的程序时考虑的变量的信息，这两者都对药物滥用治疗有影响。此外，这些研究中收集的数据将为未来的研究提供基础，该研究将研究个人评估增强剂价值的差异是否与吸毒和滥用药物的起始，进步和停止有因果关系。