Neural mechanisms and social influence in delay discounting and impulsive choice

描述(由申请人提供)：本提案中描述的工作旨在加深我们对冲动背后的神经机制的理解，以及社会影响对冲动的调节。冲动是大量不适应行为的核心，从日常生活中常见的行为(如不良饮食习惯和未能充分储蓄)到与药物成瘾、ADHD和攻击性行为等临床障碍密切相关的行为。冲动的倾向在生命周期中有很大的不同，它对社会影响(如权威人物、同龄人压力和广告)的敏感性也不同。我们将在跨期决策的背景下研究冲动。跨期决策涉及在不同时间获得的两种奖励之间的选择。众所周知，人们在短期内对奖励的贴现幅度要比长期内更大。也就是说，立即可用的奖励对我们来说具有不成比例的高价值，推迟它们(例如，推迟一周)比对未来的奖励施加类似的延迟(例如，从一周到两周)使奖励贬值的程度要大得多。对这种行为的一种解释是，人类的贴现涉及两个不同的系统，一个严重贬低未来，另一个对未来的回报更敏感。在之前的工作中，我们已经发现证据表明，可区分的神经机制可能与这些系统中的每一个相关，并且它们的相对活动与人们在当前和未来的奖励之间做出的选择相关。在这项提案中，我们将进行研究，以完善我们对这些神经机制的理解，它们与跨期选择的关系，与个体冲动差异的关系，以及它们受到社会影响的调节。在我们的前两个目标下，我们试图单独操纵每个系统，努力分离每个系统对跨期选择的贡献。在第三个目标下，我们将考察社会因素对这些机制的功能的影响，以努力更好地理解社会影响对冲动行为的中介机制。了解冲动背后的神经机制，以及这些机制是如何受到社会影响的，有望提供有助于在个人和社会层面设计干预措施的见解，从而更好地减轻个人和社会冲动的代价。

DESCRIPTION (provided by applicant): The work described in this proposal seeks to further our understanding of the neural mechanisms underlying impulsivity, and their modulation by social influences. Impulsivity lies at the heart of a large number of maladaptive behaviors, ranging from ones common in every day life (e.g., bad eating habits, and failures to adequately save) to ones closely associated with clinical disorders such as drug addiction, ADHD and aggressive behavior. The propensity for impulsivity varies substantially over the life cycle, as does its susceptibility to social influences (such as authority figures, peer-pressure, and advertising). We will study impulsivity in the context of intertemporal decision making. Intertemporal decisions involve choices between two rewards available at different times. It is well recognized that people discount rewards more steeply over the near term than over longer terms. That is, rewards that are available immediately have disproportionately high value to us, and delaying them (e.g., by a week) devalues rewards substantially more than when a similar delay is imposed on future rewards (e.g., from one week to two weeks). One explanation for this behavior is that human discounting involves two separate systems, one that heavily devalues the future, and another that is more sensitive to future reward. In previous work, we have found evidence that distinguishable neural mechanisms may be associated with each of these systems, and that their relative activity correlates with the choices that people make between immediate and future rewards. In this proposal, we will conduct studies to refine our understanding of these neural mechanisms, their relationship to intertemporal choice, to individual differences in impulsivity, and their modulation by social influences. Under our first two aims, we seek to manipulate each system individually, in an effort to isolate the contributions that each makes to intertemporal choice. Under a third aim, we will examine the influence that social factors have on the functioning of these mechanisms, in an effort to better understand the mechanisms that mediate social influences on impulsive behavior. An understanding of the neural mechanisms underlying impulsivity, and how these are impacted by social influences, promises to provide insights that will be useful in designing interventions, both at the individual and social levels that better mitigate the costs of impulsivity to the individual and society.