Decis-State: Einfluss des Sättigungsgrades auf das Entscheidungsverhalten und die funktionelle Interaktion neuronaler Systeme - Eine fMRT-Studie

Abstract

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), orbitofrontal areas (OFC) and the subgenual cingulate cortex (sgACC). Here we used functional magnetic resonance imaging (fMRI) to examine the effect of food images versus images of non-food objects (e.g. furniture) on self-control and reward processing in the hungry and satiated state. Seventeen healthy adults (9 females) performed the desire-reason paradigm introduced by Diekhof & Gruber (2010, J Neurosci 30). They were scanned two times in the hungry (after 12 hours of fastening) and the satiated state. Corresponding to previous studies we found bilateral activation of Nacc and VTA at a threshold of p< 0.05 (small volume corrected) when subjects gained immediate reward from conditioned stimuli. We did not observe significant differences in behavioral performance in response to food images in the different states and when comparing rewarded food and non-food images the effect of the state on our ROIs showed only at a very low statistical threshold. However, we were able to demonstrate that non rewarded food images lead to an activation of the VTA and orbitofrontal regions as well as the sgACC when subjects were hungry. Our results indicate that in healthy lean adults there is no significant difference in reward processing of food and neutral images, if these are linked to an abstract reward (e.g. 10 points). However the different activation between states while viewing neutral (non rewarded) food images reproduce earlier studies results (e.g., Goldstone et al., 2009, EJN 30). It seems, that in healthy lean adults 12 hours of fastening and an average difference of 10mg/dl in blood sugar level only matter in a more subtle situation (i.e. when subjects reject the different images). In future studies longer fastening may enhance the difference of the effects of food images between states. A comparison between lean and obese subjects might help to find differences in reward processing. In the future these research fields may contribute to the search for new therapies for obesity.