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）：对人类延迟折扣的研究表明，吸毒者对小的、即时的奖励比大的、延迟的奖励有过分的偏好，即使即时奖励远小于延迟的奖励。这些研究被解释为吸毒者比非吸毒者更冲动，而且吸毒可能改变了个人评估与奖励相关的收益和成本的过程。这些过程被认为决定了药物和非药物强化剂控制行为的功效。然而，除了延迟之外，还有其他成本可能导致强化物的价值打折扣。其中两个成本是不确定性和努力。提出了五项研究来评估所有三种成本对强化效果的影响（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），使用由首席研究员和她的同事对老鼠进行了研究。基本假设是：1）更多地折扣延迟奖励的老鼠也会更多地折扣不确定和努力的奖励；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学操作的类似影响。实验1通过评估同一动物的延迟贴现、不确定性贴现和努力贴现之间的相关性，确定大鼠是否将大而昂贵的奖励贴现到类似程度，而不管成本类型如何，并检查长期注射尼古丁对贴现的影响。实验 2 检查奖励的大小如何影响延迟、不确定性和努力折扣。实验 3 确定当两种选择都添加固定成本时，偏好是否从较小的、较便宜的奖励转向较大的、昂贵的奖励。实验 4 检查暴露于高强化成本条件是否会导致延迟、不确定性和努力折扣的减少。实验 5 研究了多巴胺在调节延迟、不确定性和努力折扣中的作用。这些研究将提供有关大脑评估强化剂功效时考虑的变量以及可用于改变强化剂功效的程序的信息，这两者都将对药物滥用治疗产生影响。此外，这些研究中收集的数据将为未来的研究提供基础，这些研究将检验个体评估强化物价值的差异是否与药物使用和滥用的开始、进展和停止存在因果关系。