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引起的多巴胺系统活性增强。然而，由于与年龄相关的大脑结构和功能的变化，压力对年轻人和老年人的影响可能有所不同。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，并制定针对老年人压力需求的干预措施。本研究的总体目的是确定急性应激对正常衰老中涉及奖励和厌恶反馈的学习影响的驱动机制。本研究将针对以下具体目标：1)研究急性应激如何影响对正反馈和负反馈的反应；2)研究急性应激如何影响涉及积极和消极激励的学习；3)通过脑血流量（CBF）从控制到压力条件的变化，确定应对急性应激的大脑区域。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组的奖励结果的显著性。为了实现这些目标，本研究将使用功能性神经影像学来研究急性应激对健康的年轻人和老年人对积极和消极激励的反应的影响。冷压任务将用于诱导神经生理应激反应，重复测试将允许评估个体内应激反应。在压力操作后，参与者将在功能磁共振成像期间完成基于反馈的概率学习任务。这项任务的目标是通过试错法来确定选择对中的几种新刺激中哪一种更有可能产生正反馈（例如，+ 1美元），哪一种更有可能产生负反馈（例如，- 1美元），从而使收益最大化，损失最小化。神经反应强化相关的刺激，预测误差，和反馈将被确定。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，将测量在压力和控制条件下休息时的脑血流量，以检查在缺乏认知任务的情况下，年轻人和老年人的冷压应激所调节的大脑区域。本研究将结合神经影像学、神经内分泌和认知行为学等研究方法，深入探讨应激对衰老过程中动机认知的神经生理机制。

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.