title: Altered temporal difference learning in bulimia nervosa.
abstract: BACKGROUND
  The neurobiology of bulimia nervosa (BN) is poorly understood. Recent animal literature suggests that binge eating is associated with altered brain dopamine (DA) reward function. In this study, we wanted to investigate DA-related brain reward learning in BN.
  
  
  METHODS
  Ill BN (n = 20, age: mean = 25.2, SD = 5.3 years) and healthy control women (CW) (n = 23, age: mean = 27.2, SD = 6.4 years) underwent functional magnetic resonance brain imaging together with application of a DA-related reward learning paradigm, the temporal difference (TD) model. That task involves association learning between conditioned visual and unconditioned taste stimuli, as well as unexpected violation of those learned associations. Study participants also completed the Sensitivity to Reward and Punishment Questionnaire.
  
  
  RESULTS
  Bulimia nervosa individuals showed reduced brain response compared with CW for unexpected receipt and omission of taste stimuli, as well as reduced brain regression response to the TD computer model generated reward values, in insula, ventral putamen, amygdala, and orbitofrontal cortex. Those results were qualitatively similar in BN individuals who were nondepressed and unmedicated. Binge/purge frequency in BN inversely predicted reduced TD model response. Bulimia nervosa individuals showed significantly higher Sensitivity to Reward and Punishment compared with CW.
  
  
  CONCLUSIONS
  This is the first study that relates reduced brain DA responses in BN to the altered learning of associations between arbitrary visual stimuli and taste rewards. This attenuated response is related to frequency of binge/purge episodes in BN. The brain DA neurotransmitter system could be an important treatment target for BN.
authors: Department of Psychiatry, University of Colorado Denver, The Children's Hospital, Aurora, Colorado; Department of Neuroscience, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado. Electronic address: Guido.Frank@ucdenver.edu.
authors: Guido K W
authors: GKW
authors: Frank
authors: Department of Psychology, University of Denver, Denver, Colorado.
authors: Jeremy R
authors: JR
authors: Reynolds
authors: Department of Psychiatry, University of Colorado Denver, The Children's Hospital, Aurora, Colorado.
authors: Megan E
authors: ME
authors: Shott
authors: Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado.
authors: Randall C
authors: RC
authors: O'Reilly
mesh_terms: D000328:Adult; D001245:Association Learning / Q000502:physiology*; D001921:Brain / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods / Q000523:psychology*; D052018:Bulimia Nervosa / Q000503:physiopathology* / Q000523:psychology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000523:psychology*; D012054:Reinforcement, Psychology; D057566:Self Report