The influence of satiety on decision-making and functional interaction of neuronal systems: A task to access self-control in obese subjects.

Obesity is one of the most pressing issues in modern medicine. Previous studies indicated that food images activate distinct brain areas such as the nucleus accumbens (Nacc), ventral tegmental Area (VTA), and the OFC. We used fMRI to examine the effect of food images vs. images of non-food objects on self-control and reward processing in the hungry and satiated state. Nineteen healthy adults (9 f) performed a desire-reason paradigm (Diekhof & Gruber 2010) and were scanned in hungry (> 12 hours) and satiated state. Corresponding to previous studies we found bilateral activation of Nacc and VTA when subjects gained immediate reward from conditioned stimuli. However, at a threshold of p < 0.001 we did not observe significant differences in activation of mesolimbic and prefrontal regions in response to food images in the different states. When lowering the statistical criterion, we could show that non rewarded food images lead to an activation of mesolimbic structures in the hungry state. The comparison between rewarded neutral images and rewarded food images showed no difference in the activation in our ROIs. In healthy lean adults there seems to be no difference in reward processing of food and neutral images, if these are linked to an inherent reward. It seems, that in healthy lean adults 12 hours of fastening do not affect reward processing. A future comparison between lean and obese subjects might help to find differences in reward processing and in this way new therapies.