title: Abnormal neural response to feedback on planning and guessing tasks in patients with unipolar depression.
abstract: BACKGROUND
  It has been suggested that patients with unipolar depression show abnormal responses to negative feedback in the performance of cognitive tasks. Positron emission tomography (PET) has previously identified blood flow abnormalities in depressed patients during cognitive performance. We have also used PET to identify regions where there is differential neural response to performance feedback in normal volunteers. In this study we aimed to test the hypothesis that blood flow in these regions, the medial caudate and ventromedial prefrontal cortex, would be abnormal in depressed patients.
  
  
  METHODS
  Six patients with unipolar depression and six matched controls were scanned using PET while performing cognitive tasks in the presence and absence of feedback.
  
  
  RESULTS
  Compared with controls, depressed patients failed to show significant activation in the medial caudate and ventromedial orbitofrontal cortex. Blood flow was lower and a differential response, observed in normals, under different task and feedback conditions was not seen in the patients.
  
  
  CONCLUSIONS
  The findings suggest that the behavioural response to feedback in depressed patients is associated with an abnormal neural response within the medial caudate and ventromedial orbitofrontal cortex, regions implicated in reward mechanisms. We argue that the observed abnormalities may depend on a combination of psychological factors, with both cognitive and emotive components.
authors.affiliation: Wellcome Department of Cognitive Neurology, Institute of Neurology, London.
authors.forename: R
authors.initials: R
authors.lastname: Elliott
authors.forename: B J
authors.initials: BJ
authors.lastname: Sahakian
authors.forename: A
authors.initials: A
authors.lastname: Michael
authors.forename: E S
authors.initials: ES
authors.lastname: Paykel
authors.forename: R J
authors.initials: RJ
authors.lastname: Dolan
mesh_terms: D000328:Adult; D001143:Arousal / Q000502:physiology; D001931:Brain Mapping; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000503:physiopathology; D003865:Major Depressive Disorder / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000523:psychology; D005246:Feedback / Q000502:physiology*; D005260:Female; D006801:Humans; D007721:Knowledge of Results, Psychological; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011340:Problem Solving / Q000502:physiology; D012008:Recurrence; D009435:Synaptic Transmission / Q000502:physiology*; D014055:Tomography, Emission-Computed