title: Neural correlates of social exchanges during the Prisoner's Dilemma game in depression.
abstract: BACKGROUND
  Depression is a disabling disorder that significantly impacts on the interpersonal functioning of individuals. However, little is known about the neural substrates of such difficulties. In the last few years neuroeconomics, which combines imaging with multiplayer behavioural economic paradigms, has been used to study the neural substrates of normal and abnormal interpersonal interactions.
  
  
  METHODS
  This study used functional magnetic resonance imaging to investigate neural activity in unmedicated depressed participants (n = 25) and matched healthy controls (n = 25). During scanning, participants played a behavioural economic game, the Prisoner's Dilemma. In this game, the participant and a co-player independently choose either to cooperate or not cooperate with each other.
  
  
  RESULTS
  Depressed participants reported higher levels of negative feelings (betrayal, guilt) during the game than did controls. Neural activation was compared between 'imbalanced' events [when one of the players cooperated and the other defected ('CD' and 'DC')] and 'draw' events [when both players either cooperated or defected ('CC' and 'DD')]. Participants preferentially activated the anterior insula and the dorsolateral prefrontal cortex (DLPFC), a region implicated in cognitive control and regulation of emotions. Importantly, compared to controls depressed participants showed reduced activation in the left DLPFC, with the extent of signal reduction correlating with increased self-report feelings of guilt associated with DC outcomes.
  
  
  CONCLUSIONS
  Our findings suggest that depression is associated with reduced activation of the DLPFC during social events that involve unreciprocated cooperation. This abnormality may underlie anomalies in cognitive control and top-down regulation of emotions during challenging social exchanges.
authors.affiliation: Faculty of Psychology,CIBPsi, Universidad de la República,Montevideo,Uruguay.
authors.forename: V B
authors.initials: VB
authors.lastname: Gradin
authors.affiliation: Faculty of Psychology,CIBPsi, Universidad de la República,Montevideo,Uruguay.
authors.forename: A
authors.initials: A
authors.lastname: Pérez
authors.affiliation: Medical Physics,NHS Tayside,University of Dundee,Dundee,UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Macfarlane
authors.affiliation: Medical Physics,NHS Tayside,University of Dundee,Dundee,UK.
authors.forename: I
authors.initials: I
authors.lastname: Cavin
authors.affiliation: Aberdeen Biomedical Imaging Centre,University of Aberdeen,Aberdeen,UK.
authors.forename: G
authors.initials: G
authors.lastname: Waiter
authors.affiliation: Department of Psychology,Georgia State University,Atlanta, GA,USA.
authors.forename: E B
authors.initials: EB
authors.lastname: Tone
authors.affiliation: Department of Psychology,University of St Andrews,Fife,UK.
authors.forename: B
authors.initials: B
authors.lastname: Dritschel
authors.affiliation: Faculty of Psychology,CIBPsi, Universidad de la República,Montevideo,Uruguay.
authors.forename: A
authors.initials: A
authors.lastname: Maiche
authors.affiliation: School of Medicine (Neuroscience),University of Dundee,Ninewells Hospital and Medical School,Dundee,UK.
authors.forename: J D
authors.initials: JD
authors.lastname: Steele
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003299:Cooperative Behavior; D003863:Depression / Q000503:physiopathology*; D004644:Emotions; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000503:physiopathology*; D000068956:Prisoner Dilemma; D011569:Psychiatric Status Rating Scales; D012919:Social Behavior; D006113:United Kingdom; D055815:Young Adult
keywords: Depression; Prisoner's Dilemma; fMRI; neuroeconomics