Enhanced resting activity of the oral somatosensory cortex in obese subjects

Wang, Gene‐Jack; Volkow, Nora D.; Felder, Christoph; Fowler, Joanna S.; Levy, A. V.; Pappas, Naomi; Wong, Christopher; Zhu, Wei; Netusil, Noelwah

doi:10.1097/00001756-200207020-00016

Cited by 116 publications

(90 citation statements)

References 20 publications

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“…The latter observation corresponded to regions where a previous study had revealed enhanced activity in obese subject tested at baseline (non stimulation) (Wang et al 2002) (Fig.7 d,e). An enhanced activity of regions that process palatability could make obese subjects favor food over other natural reinforcers, whereas decreased activation of dopaminergic targets by the actual food consumption might lead to overconsumption as a means to compensate for weak D2R-mediated signaling (Stice et al 2008a).…”

Section: The Impact Of Dysfunction In Inhibitory Controlsupporting

confidence: 85%

Food and Drug Reward: Overlapping Circuits in Human Obesity and Addiction

Volkow

Wang

Fowler

et al. 2011

Current Topics in Behavioral Neurosciences

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326

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Both drug addiction and obesity can be defined as disorders in which the saliency value of one type of reward (drugs and food, respectively) becomes abnormally enhanced relative to, and at the expense of others. This model is consistent with the fact that both drugs and food have powerful reinforcing effects -partly mediated by dopamine increases in the limbic system-that, under certain circumstances or in vulnerable individuals, could overwhelm the brain's homeostatic control mechanisms. Such parallels have generated significant interest in understanding the shared vulnerabilities and trajectories between addiction and obesity. Now, brain imaging discoveries have started to uncover common features between these two conditions and to delineate some of the overlapping brain circuits whose dysfunctions may explain stereotypic and related behavioral deficits in human subjects. These results suggest that both obese and drug addicted individuals suffer from impairments in dopaminergic pathways that regulate neuronal systems associated not only with reward sensitivity and incentive motivation, but also with conditioning (memory/learning), impulse control (behavioral inhibition), stress reactivity and interoceptive awareness. Here, we integrate findings predominantly derived from positron emission tomography that investigate the role of dopamine in drug addiction and in obesity and propose an updated working model to help identify treatment strategies that may benefit both of these conditions.

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Section: The Impact Of Dysfunction In Inhibitory Controlsupporting

confidence: 85%

Food and Drug Reward: Overlapping Circuits in Human Obesity and Addiction

Volkow

Wang

Fowler

et al. 2011

Current Topics in Behavioral Neurosciences

342

326

View full text Add to dashboard Cite

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“…Though there is limited literature on the role of the somatosensory cortex in food intake and obesity. Imaging studies reported activation of the somatosensory cortex in normal weight subjects with exposure to visual images of low caloric foods (Killgore et al, 2003) and with satiety (Tataranni et al, 1999), and we had shown higher than normal baseline metabolism in the somatosensory cortex in obese subjects (Wang et al, 2002). Also a recent study reported that in obese individuals with leptin deficiency administration of leptin normalized their body weight and reduced brain activation in parietal cortex while viewing food-related stimuli (Baicy et al, 2007).…”

Section: Correlation Between D2r and Somatosensory Cortexsupporting

confidence: 58%

“…This led us to reconsider the possibility that the higher risk for overeating in subjects with low D2 receptor availability may also be driven by DA's regulation of DLPFC and medial prefrontal regions, which have been shown to participate in the inhibition of inappropriate behavioral response tendencies (Mesulam, 1985;Le Doux, 1987;Goldstein and Volkow, 2002). Thus we performed secondary analysis on data from subjects that had been previously recruited as part of studies to evaluate changes in D2 receptors (Wang et al, 2001) and of brain glucose metabolism in obesity (Wang et al, 2002) and data from age matched controls. Our working hypothesis was that D2 receptor availability in obese subjects would be associated with disrupted activity in prefrontal regions.…”

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confidence: 99%

Low dopamine striatal D2 receptors are associated with prefrontal metabolism in obese subjects: Possible contributing factors

et al. 2008

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Dopamine's role in inhibitory control is well recognized and its disruption may contribute to behavioral disorders of discontrol such as obesity. However, the mechanism by which impaired dopamine neurotransmission interferes with inhibitory control is poorly understood. We had previously documented a reduction in dopamine D2 receptors in morbidly obese subjects. To assess if the reductions in dopamine D2 receptors were associated with activity in prefrontal brain regions implicated in inhibitory control we assessed the relationship between dopamine D2 receptor availability in striatum with brain glucose metabolism (marker of brain function) in ten morbidly obese subjects (BMI>40 kg/m 2 ) and compared it to that in twelve non-obese controls. PET was used with [ 11 C]raclopride to assess D2 receptors and with [ 18 F] FDG to assess regional brain glucose metabolism. In obese subjects striatal D2 receptor availability was lower than controls and was positively correlated with metabolism in dorsolateral prefrontal, medial orbitofrontal, anterior cingulate gyrus and somatosensory cortices. In controls correlations with prefrontal metabolism were not significant but comparisons with those in obese subjects were not significant, which does not permit to ascribe the associations as unique to obesity. The associations between striatal D2 receptors and prefrontal metabolism in obese subjects suggest that decreases in striatal D2 receptors could contribute to overeating via their modulation of striatal prefrontal pathways, which participate in inhibitory control and salience attribution. The association between striatal D2 receptors and metabolism in somatosensory cortices (regions that process palatability) could underlie one of the mechanisms through which dopamine regulates the reinforcing properties of food. KeywordsOrbitofrontal cortex; Cingulate gyrus; Dorsolateral prefrontal; Dopamine transporters; Raclopride, PET The increase in obesity and associated metabolic diseases seen over the past decade has raised concern that if not controlled this may become the number one preventable public health threat for the 21st century (Sturm, 2002 (Berthoud, 2007). The extent to which individuals differ in their ability to inhibit these responses and control how much they eat is likely to modulate their risk for overeating in our current food rich environments (Berthoud, 2007).We had shown that in healthy individuals D2 receptor availability in the striatum modulated eating behavioral patterns (Volkow et al., 2003). Specifically the tendency to eat when exposed to negative emotions was negatively correlated with D2 receptor availability (the lower the D2 receptors the higher the likelihood that an individual would eat if emotionally stressed). In addition, in a different study, we showed that morbidly obese subjects (BMI>40) had lower than normal D2 receptor availability and these reductions were proportional to their BMI (Wang et al., 2001). These findings led us to postulate that low D2 receptor availability could put an...

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“…6 A baseline comparison of regional brain glucose metabolism between obese (Ob) and normal weight subjects revealed that even without FS, Ob subjects had significantly higher metabolism in the parietal somatosensory cortex where the lips and tongue are represented, which was interpreted to reflect increased sensitivity of the regions that process food palatability. 7 Studies in laboratory animals have also identified regional activation of the prefrontal cortex, 8 amygdala 9 and nucleus accumbens 10 upon exposure to rewarding food stimuli. Here, we evaluate the regional brain metabolic responses to a food stimulus to assess the brain response to food reinforcers.…”

Section: Introductionmentioning

confidence: 99%

Differences in response to food stimuli in a rat model of obesity: in-vivo assessment of brain glucose metabolism

et al. 2008

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Objective: Food intake is regulated by factors that modulate caloric requirements as well as food's reinforcing properties. In this study, we measured brain glucose utilization to an olfactory stimulus (bacon scent), and we examined the role of food restriction and genetic predisposition to obesity on such brain metabolic activity. Methods: Zucker obese (Ob) and lean (Le) rats were divided into four groups: (1) Ob ad-libitum fed, (2) Ob food restricted (70% of ad libitum), (3) Le ad-libitum fed and (4) Le food restricted. Rats were scanned using m-positron emission tomography and 2-[ 18 F]-fluoro-2-deoxy-D-glucose under two conditions: (1) baseline scan (no stimulation) and (2) challenge scan (food stimulation, FS). Results: FS resulted in deactivation of the right and left hippocampus. Ob rats showed greater changes with FS than Le rats (deactivation of hippocampus and activation of the medial thalamus) and Ob but not Le animals deactivated the frontal cortex and activated the superior colliculus. Access to food resulted in an opposite pattern of metabolic changes to the food stimuli in olfactory nucleus (deactivated in unrestricted and activated in restricted) and in right insular/parietal cortex (activated in unrestricted and deactivated in restricted). In addition, restricted but not unrestricted animals activated the medial thalamus. Conclusions: The greater changes in the Ob rats suggest that leptin modulates the regional brain responses to a familiar food stimulus. Similarly, the differences in the pattern of responses with food restriction suggest that FS is influenced by access to food conditions. The main changes with FS occurred in the hippocampus, a region involved in memory, the insular cortex, a region involved with interoception (perception of internal sensations), the medial thalamus (region involved in alertness) and in regions involved with sensory perception (olfactory bulb, olfactory nucleus, occipital cortex, superior colliculus and parietal cortex), which corroborates their relevance in the perception of food.

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Enhanced resting activity of the oral somatosensory cortex in obese subjects

Cited by 116 publications

References 20 publications

Food and Drug Reward: Overlapping Circuits in Human Obesity and Addiction

Food and Drug Reward: Overlapping Circuits in Human Obesity and Addiction

Low dopamine striatal D2 receptors are associated with prefrontal metabolism in obese subjects: Possible contributing factors

Differences in response to food stimuli in a rat model of obesity: in-vivo assessment of brain glucose metabolism

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