Neuronal and Behavioral Effects of Implicit Priming in Obese Individuals

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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.