Neuronal and Behavioral Effects of Implicit Priming in Obese Individuals

描述（由申请人提供）：肥胖是一个重要的公共卫生问题，与死亡风险增加、冠心病和2型糖尿病的风险相关。体重减轻与合并症的减少和生活质量的提高有关。然而，减肥是很困难的，而防止体重反弹则更具挑战性。因此，理解能量平衡调节的机制和确定成功减肥和维持体重的策略是重要的目标，也是NIH肥胖研究战略计划的关键组成部分。食物摄入是一个复杂的过程，涉及稳态信号（如与食欲有关的激素）和非稳态信号（如认知因素、食物的强化特性）。一个可能导致肥胖的因素是对高热量食物在认知因素方面的高度反应，如情感联系、奖励价值或食物的强化特性。这些过程中有许多涉及到习得关联，这些关联被认为是通过与外部刺激的反复配对而形成的经典条件反射，这可以影响食物偏好和摄入量。因此，提高我们对这些过程背后的神经元机制的理解，并试图修改它们，可能是促进减肥和维持体重的有用策略。因此，本研究旨在通过内隐启动研究改变食物感知对神经元反应和食物摄入行为的影响，内隐启动是指在食物图像出现之前立即呈现积极或消极的效价图像（即具有积极或消极情绪意义的图像），但不被有意识地感知。我们假设这将通过操纵与食物的情感联系来改变对食物线索的感知，这是初步数据中观察到的效果。这种方法有可能降低高热量食物的吸引力，转而支持低热量食物，从而鼓励减少高热量食物的摄入，促进减肥和维持体重。该项目的目标是确定改变食物感知对超重/肥胖个体对食物线索的大脑反应和食物摄入行为的影响。在(a)主动内隐启动干预或(b)对照干预之前和之后，将评估食物图像评级和神经元对视觉食物线索的反应。在启动条件下，高热量和低热量食物的图像将与内隐呈现（低于知觉阈值）的负效价或正效价图像配对（高热量与负效价配对；低热量与正效价配对）。在fMRI之后，全天的食物摄入量将被测量。在这项初步研究中使用神经成像将提供比单独的行为测量更敏感的测量方法，并将有助于确定干预改变行为的机制。如果该项目的目标得以实现，它不仅会产生关于食物摄入行为的神经生物学的新信息，而且还可能代表一种治疗和预防肥胖的潜在新干预手段。

DESCRIPTION (provided by applicant): Obesity is a significant public health concern associated with an increased mortality risk, and risk of coronary heart disease and type 2 diabetes. Weight loss is associated with reduced comorbid conditions and increased quality-of-life. However, weight loss can be difficult, and preventing subsequent weight regain even more challenging. As such, understanding the mechanisms underlying the regulation of energy balance and identifying strategies for successful weight-loss and maintenance are important goals, and are key components of the Strategic Plan for NIH Obesity Research. Food intake is a complex process involving homeostatic signals (e.g., appetite-related hormones) and non-homeostatic signals (e.g., cognitive factors, reinforcing properties of food). One factor that may contribute to susceptibility to obesity is a high responsivity to high-calorie foods in terms of cognitive factors such as emotional associations, reward value or reinforcing properties of food. Many of these processes involve learned associations that are thought to develop via classical conditioning through repeated pairings with external stimuli, which can influence food preferences and intake. As such, improving our understanding of the neuronal mechanisms underlying these processes and attempting to modify them may be a useful strategy to promote weight loss and maintenance. Therefore, the proposed study aims to investigate the effects of altering food perception on neuronal responses and food intake behaviors by using implicit priming, in which positively or negatively valence images (i.e., images with positive or negative emotional significance) are presented immediately prior to food images, but are not consciously perceived. We hypothesize that this will alter perception of food cues by manipulating affective associations with food items, an effect observed in preliminary data. This approach has the potential to reduce the appeal of high-calorie, in favor of low-calorie foods, which could encourage reduced intake of high-calorie foods, promoting weight loss and maintenance. The project goals are to determine the impact of changing food perceptions on both brain responses to food cues and on food intake behaviors in overweight/obese individuals. Food image ratings and neuronal responses to visual food cues will be assessed before and after either (a) an active implicit priming intervention or (b) a control intervention. In the priming condition, image of high- and low-calorie foods will be paired with implicitly presented (below perceptual threshold) images of either negative or positive valence (high-calorie paired with negative; low-calorie paired with positive). Following fMRI, food intake throughout the day will be measured. The use of neuroimaging in this pilot study will provide a more sensitive measure than behavioral measures alone and will help to identify mechanisms through which the intervention changes behavior. If the project aims are achieved, it would not only yield new information about the neurobiology of food intake behavior, but also could represent a potential novel intervention for treatment and prevention of obesity.