Title: Neurobiological responses to images of food and psycho-behavioral correlates in obese binge eaters
Description: Obesity is on the rise, and its associated comorbidities and health care costs are tremendous. A contributing factor to chronic obesity is binge eating disorder (BED), which is prevalent in 20 to 30 percent of the morbidly obese population, but the distinction between obesity versus obesity with BED is still unclear. The present dissertation project investigated forty two adult men and women, thirteen obese + BED and twenty nine obese controls for multiple psycho-behavioral constructs (rigid dietary restraint, disinhibition, anxiety, and behavioral activation/behavioral inhibition). On a different day, following a 12-hour fast, the participants consumed a fixed liquid meal, and their brain function examined while images of high energy food (e.g. pizza and cakes), low energy food (e.g. cucumber and tomato) and control items (i.e. office supplies) presented to them on a screen. Using a whole brain analysis approach, functional brain activity in response to: 1/food versus nonfood, and 2/high energy food versus low energy food revealed eight brain areas significantly different between the groups: for 'food versus nonfood', activated were seven areas functionally involved in the integration of somatosensory experience with internal state, processing of sensations, cognitions, thoughts, and emotions, integration of sensory functions and memory, visual object recognition and motion, visual - somatosensory functions and associations, integration of emotional value with a sensory stimulus, mediation of motivation and expectancy for outcomes, and the integration of diverse sensory information and visuo-spatial cognition. .

One area significantly differed between the groups in response to the comparison of 'high energy food versus low energy food'. This area is functionally involved in thought, cognition, movement, planning, and motor behaviors in response to emotions and drives Thus, in response to cues representing binge-triggers, obese + BED showed greater visual attention, emotional, motivational and reward processing, as well as motor planning of future actions and heightened somatosensory experience, compared with the obese group. Scores on the 'disinhibition' scale were significantly higher in the obese + BED group compared with the obese. Correlation between 'disinhibition' scores and brain activation results in each group showed significant differences between the groups in two brain areas: right anterior cingulate gyrus-Brodmann area #32, and the left postcentral gyrus. Scores on the Behavioral Activation Scale (reward drive) were significantly lower in the obese + BED group, but the correlations between brain activation and scores on this scale did not differ between the groups.

To sum the results altogether, the obese + BED may be marked by hyperactive visual-attentional-emotional- and cognitive processing of cues representing binge-triggers, with heightened somatosensory response. The psycho-behavioral construct of 'disinhibition' highly characterizes BED, and its neurobiological substrates may include the right anterior cingulate cortex-Brodmann area #32 and left postcentral gyrus. Reduced reward responsiveness in obese + BED may reflect weak 'liking' response to food, but this behavioral construct and its' relationship to BED are still inconclusive. Future studies may use the results of this dissertation project to further investigate frequent binge eating in the absence of compensatory behaviors in the obese population.