Imaging temporal discounting in smokers and nonsmokers

描述(由申请人提供)：拟议研究的总体目标是确定与长期接触滥用药物有关的冲动决策的神经基础。这些信息对于理解习惯性吸毒的形成和戒除具有潜在的重要意义。此外，它可能对执行控制的动机系统和神经认知机制之间的相互作用提供重要的见解，这些机制是药物滥用、ADHD和病态赌博等疾病的核心。在这一应用中，冲动的决策将使用时间贴现范式进行评估，在该范式中，我们将衡量对立即或很快获得的小额奖励的偏好，以及对稍后获得的较大奖励的偏好。因此，这项研究的具体目的是利用功能磁共振成像(FMRI)技术识别吸烟者和非吸烟者大脑激活模式的差异，这些差异对应于在时间折扣任务中的行为差异。这项研究将使用与事件相关的设计来比较选择任务中的激活模式，这些任务旨在将与时间折扣相关的加工与大小和相对奖励即时性等奖励维度的加工分开。我们假设，在时间折扣过程中，当一种奖励方案立即可用，另一种被推迟时，吸烟者将在腹侧纹状体表现出更高的激活水平(特别是。做出这些选择的非吸烟者中，内侧OFC、内侧OFC、内侧前额叶皮质、后扣带皮质的比例更高(“区域”：McClure等人，2004年；2007年)。相比之下，非吸烟者在腹外侧额叶皮质、背外侧前额叶皮质、右侧前额叶皮质和顶叶后皮质(“区”)的激活水平高于吸烟者。在时间折扣期间，当两种奖励选择都被推迟时，我们预测不吸烟的人也会比吸烟者在这些区域表现出更高的激活水平。PI已经参与了一项受资助的研究，旨在研究临时折扣与吸烟之间的行为机制。这项拟议的研究将使她能够向使用功能磁共振技术探索神经区域和这些区域之间的相互关系迈出第一步。潜在的健康影响：这项研究将确定当个人评估替代方案的主观价值时涉及的大脑区域，这些替代方案的奖励大小和延迟到可用时不同。它还将确定当个人表达对替代方案的偏好时涉及的领域，以及吸烟者和不吸烟者在这些偏好背后的激活模式方面的任何差异。了解哪些结构参与了这种决策及其连通性，可能会为因慢性药物使用、事故或中风而表现出冲动决策的人提供个性化的治疗目标。

DESCRIPTION (provided by applicant): The overall aim of the proposed research is to identify the neural substrates of impulsive decision making associated with chronic exposure to drugs of abuse. Such information is potentially important for understanding the development and cessation of habitual drug use. Furthermore, it may provide important insights into the interaction of motivational systems and neurocognitive mechanisms of executive control, which are central to a number of disorders such as drug abuse, ADHD and pathological gambling. In this application, impulsive decision making will be assessed using a temporal discounting paradigm in which we measure preference for small rewards available either immediately or soon versus larger rewards available much later. Accordingly, the specific aim of the research proposed here is to identify differences in brain activation patterns in smokers and nonsmokers corresponding to the behavioral differences on a temporal discounting task using functional magnetic resonance imaging (fMRI) techniques. The study will use an event-related design to compare activation patterns during choice tasks designed to separate processing associate with temporal discounting from processing of reward dimensions like size and relative reward immediacy. We hypothesize that, during temporal discounting, when one reward alternative is available immediately and the other delayed, smokers will exhibit higher levels of activation in ventral striatum (esp. nucleus accumbens), medial OFC, medial prefrontal cortex, posterior cingulate cortex than nonsmokers making these choices (" areas": McClure et al., 2004; 2007). In contrast, nonsmokers will exhibit higher levels of activation in ventrolateral and dorsolateral prefrontal cortex, right lateral OFC and posterior parietal cortex (" areas") than smokers. During temporal discounting when both reward alternatives are delayed, we predict that nonsmokers will also exhibit higher levels of activation in the areas compared to smokers. The PI is already engaged in funded research examining the behavioral mechanisms linking temporal discounting and cigarette smoking. The proposed research would permit her to take the first step towards exploring the neural regions and inter-relationships between these regions using fMRI techniques. Potential health impact: This research will identify areas of the brain that are involved when individuals evaluate the subjective value of alternatives differing in their reward size and the delay until their availability. It will also identify areas that are involved when individuals express a preference between the alternatives, and any differences between smokers and nonsmokers in activation patterns underlying these preferences. Understanding which structures are involved in such decision making and their connectivity, may suggest individualized treatment targets for people exhibiting impulsive decision-making due to chronic drug use, accident or stroke.