title: Association of body mass and brain activation during gastric distention: implications for obesity.
abstract: BACKGROUND
  Gastric distention (GD), as it occurs during meal ingestion, signals a full stomach and it is one of the key mechanisms controlling food intake. Previous studies on GD showed lower activation of the amygdala for subjects with higher body mass index (BMI). Since obese subjects have dopaminergic deficits that correlate negatively with BMI and the amygdala is innervated by dopamine neurons, we hypothesized that BMI would correlate negatively with activation not just in the amygdala but also in other dopaminergic brain regions (midbrain and hypothalamus).
  
  
  RESULTS
  We used functional magnetic resonance imaging (fMRI) to evaluate brain activation during GD in 24 healthy subjects with BMI range of 20-39 kg/m(2). Using multiple regression and cross-correlation analyses based on a family-wise error corrected threshold P = 0.05, we show that during slow GD to maximum volumes of 500 ml and 700 ml subjects with increased BMI had increased activation in cerebellum and left posterior insula, and decreased activation of dopaminergic (amygdala, midbrain, hypothalamus, thalamus) and serotonergic (pons) brain regions and anterior insula, regions that were functionally interconnected with one another.
  
  
  CONCLUSIONS
  The negative correlation between BMI and BOLD responses to gastric distention in dopaminergic (midbrain, hypothalamus, amygdala, thalamus) and serotonergic (pons) brain regions is consistent with disruption of dopaminergic and serotonergic signaling in obesity. In contrast the positive correlation between BMI and BOLD responses in posterior insula and cerebellum suggests an opposing mechanism that promotes food intake in obese subjects that may underlie their ability to consume at once large food volumes despite increasing gastric distention.
authors.affiliation: National Institute on Alcoholism and Alcohol Abuse, National Institutes of Health, Bethesda, Maryland, United States of America. tomasi@bnl.gov
authors.forename: Dardo
authors.initials: D
authors.lastname: Tomasi
authors.forename: Gene-Jack
authors.initials: GJ
authors.lastname: Wang
authors.forename: Ruiliang
authors.initials: R
authors.lastname: Wang
authors.forename: Walter
authors.initials: W
authors.lastname: Backus
authors.forename: Allan
authors.initials: A
authors.lastname: Geliebter
authors.forename: Frank
authors.initials: F
authors.lastname: Telang
authors.forename: Millar C
authors.initials: MC
authors.lastname: Jayne
authors.forename: Christopher
authors.initials: C
authors.lastname: Wong
authors.forename: Joanna S
authors.initials: JS
authors.lastname: Fowler
authors.forename: Nora D
authors.initials: ND
authors.lastname: Volkow
mesh_terms: D000328:Adult; D001835:Body Weight; D001921:Brain / Q000503:physiopathology*; D002149:Energy Intake; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009765:Obesity / Q000503:physiopathology*; D013270:Stomach / Q000503:physiopathology*