Widespread reward-system activation in obese women in response to pictures of high-calorie foods.
Behavioral studies have suggested that exaggerated reactivity to food cues, especially those associated with high-calorie foods, may be a factor underlying obesity. This increased motivational potency of foods in obese individuals appears to be mediated in part by a hyperactive reward system. We used a Philips 3T magnet and fMRI to investigate activation of reward-system and associated brain structures in response to pictures of high-calorie and low-calorie foods in 12 obese compared to 12 normal-weight women. A regions of interest (ROI) analysis revealed that pictures of high-calorie foods produced significantly greater activation in the obese group compared to controls in medial and lateral orbitofrontal cortex, amygdala, nucleus accumbens/ventral striatum, medial prefrontal cortex, insula, anterior cingulate cortex, ventral pallidum, caudate, putamen, and hippocampus. For the contrast of high-calorie vs. low-calorie foods, the obese group also exhibited a larger difference than the controls did in all of the same regions of interest except for the putamen. Within-group contrasts revealed that pictures of high-calorie foods uniformly stimulated more activation than low-calorie foods did in the obese group. By contrast, in the control group, greater activation by high-calorie foods was seen only in dorsal caudate, whereas low-calorie foods were more effective than high-calorie foods in the lateral orbitofrontal cortex, medial prefrontal cortex, and anterior cingulate cortex. In summary, compared to normal-weight controls, obese women exhibited greater activation in response to pictures of high-calorie foods in a large number of regions hypothesized to mediate motivational effects of food cues.
Stoeckel
Luke E
LE
Department of Psychology, University of Alabama at Birmingham, Birmingham, AL 35294-1170, USA. stoeckel@uab.edu
Weller
Rosalyn E
RE
Cook
Edwin W
EW
Twieg
Donald B
DB
Knowlton
Robert C
RC
Cox
James E
JE
D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003463:Cues; D005260:Female; D005502:Food; D005518:Food Preferences / Q000502:physiology / Q000523:psychology; D006801:Humans; D008279:Magnetic Resonance Imaging; D009765:Obesity / Q000503:physiopathology* / Q000523:psychology; D010775:Photic Stimulation; D012201:Reward