Reward activity in satiated overweight women is decreased during unbiased viewing but increased when imagining taste: an event-related fMRI study

Abstract

Objective: The aim of this functional magnetic resonance imaging (fMRI) study was to investigate reward-related brain activity in satiated overweight and healthy-weight participants in response to high-calorie palatable food pictures, when viewing the pictures without prior instructions (called unbiased viewing) versus imagining the taste of the shown pictures (called taste imagination). We predicted that neural activation in brain reward regions would be greater in overweight participants than in healthy-weight ones and that this difference between groups would be strongest during unbiased viewing. Method: Neural activation was measured using fMRI in 14 overweight (mean body mass index (BMI): 29.8 kg m À2 ) and 15 healthy-weight (mean BMI: 21.1 kg m À2 ) participants who were satiated, in response to palatable and unpalatable highcalorie and low-calorie food pictures, presented in an event-related design during two conditions: unbiased viewing (no prior instructions) versus taste imagination. Results: A group  condition interaction was found in 14 brain regions involved in food reward processing during the presentation of high-calorie palatable food stimuli. During the taste imagination condition, neural activation in these regions was greater in the overweight participants than in the healthy-weight ones. Contrary to our expectations, the opposite pattern was observed during unbiased viewing: activation in reward regions in the overweight participants was reduced compared with the healthy-weight ones. In all brain reward regions except for the left amygdala, the group  condition interaction was specific to high-calorie palatable food stimuli. Conclusion: Greater reward activity in the overweight participants compared with the control group when imagining taste may represent an increased reward response induced by high-calorie palatable food. During unbiased viewing, reduced reward activation in the overweight participants compared with those with a healthy weight may reflect avoidance of high-calorie palatable food stimuli. Taken together, this pattern of activation may reflect ambivalence in the overweight group between desire for (in the taste imagination condition) and avoidance of (in the unbiased viewing condition) high-calorie palatable food stimuli.

Pavlovian Craving and Overeating: A Conditioned Incentive Model

“…Cue elicited food craving is important for understanding overeating as it correlates with food intake (see, e.g., [5,10]). Further, these food cravings primarily concern palatable energy dense foods [11] and cue induced increases in the desire to eat or food craving have been observed to occur even when sated [12,13].…”

Brain-Based Etiology of Weight Regulation

“…Overweight/obese individuals consistently show significantly greater response in the striatum, insula, medial OFC, and amygdala (9)(10)(11)(12)(13)(14)(15)(16). Similarly, during cue-elicited anticipation of receipt of palatable food, obese individuals also show greater response in gustatory and somatosensory brain regions (postcentral gyrus, rolandic operculum, AI/FO) and regions associated with visual processing and attention (visual and anterior cingulate cortices), the encoding of stimulus salience (precuneus (13,17,18)).…”

The potential role of and deficits in frontal cortical brain areas implicated in executive control of food intake

“…On the other hand, Hollman et al 3 showed a greater cortical activation in the cognitive-restrained subjects, related to predisposition to control food intake, especially the hedonic effects of it. 3 Rather puzzling are the observations by Frankort et al, 4 introducing diverting effects to pictures of foods that are high or low calorie and have a range in palatability. The observations described in the first two papers partly confirm previous observations, [5][6][7][8][9][10][11] that in addition have shown that effects may depend on the severity of obesity, age and sex, leading to the hypothesis that low GM volumes and high WM volumes increase the risk for obesity.…”

“…The authors interpret this pattern of results as suggesting roles for both BMI and attention in the reward processing of high-calorie palatable food stimuli, and that the reduced activation in the overweight in the unbiased viewing condition may reflect avoidance toward the high-calorie foods. 4 Taken together, these papers suggest that activity in frontal brain regions, following a meal, may be associated with the ability to inhibit post-prandial food-related behaviors and intake. This inhibition is crucial to control energy intake.…”

“…The data are interpreted to support the view that an active reappraisal of an unhealthy food recruits brain valuation systems in combination with prefrontal control areas associated with response inhibition, and that individuals with high levels of cognitive restraint show an automatic predisposition to regulate hedonic aspects of feeding. 3 Finally, Frankort et al 4 report data from a study examining how attention affects reward-related brain activity in satiated overweight and normal weight in response to high-calorie palatable food pictures. They compared patterns of neural activity in response to the pictures when subjects were either not given any instructions or when they were asked to imagine the taste of the food item.…”