Neuronal and Behavioral Effects of Implicit Priming in Obese Individuals

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 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 valenced images are presented immediately prior to food images, but are not consciously perceived.

The project goals are to determine the impact of the implicit priming intervention on both brain responses to food cues and on food intake behaviors in overweight/obese individuals. Food image ratings were assessed before and after either (a) an active implicit priming intervention or (b) a control intervention. One group of participants (n = 47; "MRI sample") completed the intervention during an fMRI scan and completed a visual food cues task both before and after the intervention (during fMRI), to assess intervention-related change in neuronal responses to food cues. In this group, food intake measures were also taken following fMRI. In a separate group of participants (n = 45; "Behavioral-only sample"), the primary outcome measure was the change in food image ratings from pre- to post-intervention; fMRI and measures of food intake were not assessed in this group.