How Images of Food Become Cravingly Salient in Obesity

Abstract

AbstractBackgroundObesity is characterized by neurofunctional alterations within the mesocorticolimbic reward system, a brain network that originates from the midbrain ventral tegmental area (VTA). Here we tested the hypothesis that this system might be misconfigured in obesity, reflecting a bias for food-related visual stimuli and a predisposition for craving.MethodsA group of normal weight and a group of obese patients underwent a resting-state fMRI scan and the assessment of impulsivity, food craving, appetite, and implicit bias for food and non-food pictures. The VTA was used as a seed to map, for each participant, the strength of its functional connections with the rest of the brain. We then computed the difference of such maps between the groups and performed brain-behavior correlations.ResultsObese patients showed hyper-connectivity of the VTA with part of ventral occipitotemporal cortices (vOTC) recently found to be specialized for food images; there was also a hypo-connectivity with the left inferior frontal gyrus (IFG), devoted to cognitive control. The VTA-left vOTC connectivity was positively associated with food craving and bias for high-calories food; a reversed such correlation was seen for the IFG.InterpretationThese findings reveal that, in obesity, food-related visual stimuli become cravingly salient through an imbalanced connectivity of the reward system with sensory-specific regions and the frontal cortex involved in cognitive control.