Effects of stress on motivated behavior: Age differences and neurophysiological m

描述(由申请人提供)：压力在日常生活中很常见，似乎会改变学习和决策，包括潜在的奖励和惩罚。这一发现可能归因于压力诱导的多巴胺系统活动的增强。然而，由于大脑结构和功能的年龄相关变化，压力对年轻人和老年人的影响可能不同。这项研究的长期目标是了解压力如何影响一生中动机行为的神经机制。这项研究可以用来确定老年人管理经济决策的能力，并制定有针对性的干预措施，以满足老年人承受压力的需求。这项研究的总体目标是确定在正常衰老情况下，急性应激对学习的驱动作用机制，包括奖赏反馈和厌恶反馈。这项拟议的研究将解决这些具体目标：1)研究急性应激如何影响对积极和负面反馈的反应，2)研究急性应激如何影响涉及积极和负面激励的学习，以及3)通过从对照到应激状态的脑血流(CBF)变化来确定对急性应激做出反应的大脑区域。这项研究的中心假设是，压力会对年轻人和老年人负责反馈学习的大脑区域产生不同的影响，但会选择性地增强两个年龄段的奖励结果的显着性。为了达到这些目标，这项拟议的研究将使用功能神经成像来调查健康的年轻人和老年人对积极和消极刺激的反应的急性应激影响。冷加压任务将被用来诱导神经生理应激反应，重复测试将允许评估个体内部的应激反应。在压力处理后，参与者将在功能磁共振成像过程中完成基于反馈的概率学习任务。该任务的目标是通过使用试错法来确定选择对中的几个新刺激中的哪些更有可能产生正反馈(例如，+$1)，以及哪些更有可能导致负反馈(例如，-$1)，从而最大化收益和最小化损失。将确定神经对增强剂相关刺激的反应、预测误差和反馈。唾液皮质醇水平将被用来衡量下丘脑-垂体-肾上腺轴对压力的反应。此外，还将在压力和控制条件下测量静息状态下的脑血流量，以检查在没有认知任务的情况下，年轻人和老年人受冷加压压力调节的大脑区域。通过结合神经成像、神经内分泌和认知行为的方法，这项拟议的研究将为深入了解应激效应在衰老过程中激发认知的神经生理学机制提供实质性的见解。 与公共健康相关：这项研究的结果将帮助我们理解压力的共同经历如何改变动机和决策，以及这些压力影响如何随着年龄的变化而变化。确定压力如何影响老年人的决策动机尤为重要，因为认知功能随着年龄的增长而下降，越来越多的老年人面临着关于医疗保健、投资和人际关系的复杂决定。这项研究的结果将提供有关老年人管理经济决策能力的信息，并可能为旨在解决面临压力的老年人的特定需求的干预措施提供信息。

DESCRIPTION (provided by applicant): Stress is common in everyday life and appears to alter learning and decision making involving potential rewards and punishments. This finding that may be attributed to stress-induced enhancements of dopamine system activity. Due to age-related changes to brain structure and function, however, the impact of stress is likely to differ for younger and older adults. The long-term objective of this research is to understand how stress impacts the neural mechanisms of motivated behavior across the lifespan. This research may be used to determine older adults' ability to manage economic decisions and develop interventions targeted at addressing the needs of older adults experiencing stress. The overall aim of the proposed research is to determine the mechanisms driving effects of acute stress on learning involving rewarding and aversive feedback in normal aging. The proposed study will address these specific aims: 1) examine how acute stress affects response to positive and negative feedback, 2) examine how acute stress affects learning involving positive and negative incentives, and 3) identify the brain regions responding to acute stress via change in cerebral blood flow (CBF) from control to stress conditions. The central hypothesis of this study is that stress will exert different effects on brain regions responsible for feedback-learning in younger and older adults, but will selectively enhance the salience of rewarding outcomes in both age groups. To address these objectives, the proposed study will use functional neuroimaging to investigate acute stress effects on response to positive and negative incentives in healthy younger and older adults. The cold pressor task will be used to induce a neurophysiological stress response and repeated testing will allow for assessment of intra-individual stress responses. After the stress manipulation, participants will complete a feedback-based probabilistic learning task during functional magnetic resonance imaging. The goal of the task is to maximize gains and minimize losses by using trial and error to determine which of several novel stimuli in choice pairs are more likely to yield positive feedback (e.g., +$1) and which are more likely to result in negative feedback (e.g., -$1). Neural response to reinforcer-associated stimuli, prediction error, and feedback will be determined. Salivary cortisol levels will be used as a measure of hypothalamic-pituitary-adrenal axis reactivity to stress. In addition, cerebral blood flow will be measured at rest under stress and control conditions to examine brain regions modulated by cold pressor stress in young and old in the absence of a cognitive task. By combining neuroimaging, neuroendocrine and cognitive behavioral approaches, the proposed study will provide substantial insight into the neurophysiological mechanisms of stress effects motivated cognition in aging. PUBLIC HEALTH RELEVANCE: The findings of this study will help us to understand how the common experience of stress can alter motivation and decision making, and how these stress effects may change with age. Determining how stress affects older adults' motivation in decision making is of particular importance due to declines in cognitive function with aging and the rising number of elders faced with complex decisions about healthcare, investments, and interpersonal relationships. The results of this study will provide information about older adults' ability to manage economic decisions and may inform interventions targeted at addressing the specific needs of older adults exposed to stress.