title: Orbitofrontal cortex volume and brain reward response in obesity.
abstract: OBJECTIVE
  What drives overconsumption of food is poorly understood. Alterations in brain structure and function could contribute to increased food seeking. Recently, brain orbitofrontal cortex (OFC) volume has been implicated in dysregulated eating but little is known how brain structure relates to function.
  
  
  METHODS
  We examined obese (n=18, age=28.7±8.3 years) and healthy control women (n=24, age=27.4±6.3 years) using a multimodal brain imaging approach. We applied magnetic resonance and diffusion tensor imaging to study brain gray and white matter volume as well as white matter (WM) integrity, and tested whether orbitofrontal cortex volume predicts brain reward circuitry activation in a taste reinforcement-learning paradigm that has been associated with dopamine function.
  
  
  RESULTS
  Obese individuals displayed lower gray and associated white matter volumes (P<0.05 family-wise error (FWE)- small volume corrected) compared with controls in the orbitofrontal cortex, striatum and insula. White matter integrity was reduced in obese individuals in fiber tracts including the external capsule, corona radiata, sagittal stratum, and the uncinate, inferior fronto-occipital, and inferior longitudinal fasciculi. Gray matter volume of the gyrus rectus at the medial edge of the orbitofrontal cortex predicted functional taste reward-learning response in frontal cortex, insula, basal ganglia, amygdala, hypothalamus and anterior cingulate cortex in control but not obese individuals.
  
  
  CONCLUSIONS
  This study indicates a strong association between medial orbitofrontal cortex volume and taste reinforcement-learning activation in the brain in control but not in obese women. Lower brain volumes in the orbitofrontal cortex and other brain regions associated with taste reward function as well as lower integrity of connecting pathways in obesity (OB) may support a more widespread disruption of reward pathways. The medial orbitofrontal cortex is an important structure in the termination of food intake and disturbances in this and related structures could contribute to overconsumption of food in obesity.
authors.affiliation: Department of Psychiatry, University of Colorado School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Shott
authors.affiliation: 1] Division of Endocrinology, Metabolism and Diabetes, University of Colorado School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA [2] Anschutz Health and Wellness Center, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
authors.forename: M-A
authors.initials: MA
authors.lastname: Cornier
authors.affiliation: Department of Psychology and Neuroscience, University of Colorado Boulder, Center for Neuroscience, Boulder, CO, USA.
authors.forename: V A
authors.initials: VA
authors.lastname: Mittal
authors.affiliation: Eating Disorders Center Denver, Denver, CO, USA.
authors.forename: T L
authors.initials: TL
authors.lastname: Pryor
authors.affiliation: 1] Department of Psychology and Neuroscience, University of Colorado Boulder, Center for Neuroscience, Boulder, CO, USA [2] Institute of Cognitive Neuroscience, University of Colorado Boulder, Boulder, CO, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Orr
authors.affiliation: Department of Radiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Brown
authors.affiliation: 1] Department of Psychiatry, University of Colorado School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA [2] Neuroscience Program, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA.
authors.forename: G K W
authors.initials: GK
authors.lastname: Frank
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D003120:Colorado; D004298:Dopamine / Q000378:metabolism; D005260:Female; D005502:Food; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D006963:Hyperphagia / Q000209:etiology / Q000523:psychology*; D008279:Magnetic Resonance Imaging; D009765:Obesity / Q000503:physiopathology / Q000523:psychology*; D009929:Organ Size; D010775:Photic Stimulation; D011237:Predictive Value of Tests; D012201:Reward; D011795:Surveys and Questionnaires; D013649:Taste
chemical_list: D004298:Dopamine