title: Behavioral and Electrophysiological Alterations for Reinforcement Learning in Manic and Euthymic Patients with Bipolar Disorder.
abstract: OBJECTIVE
  Bipolar disorder is characterized by behavioral changes such as risk-taking and increasing goal-directed activities, which may result from altered reward processing. Patients with bipolar disorder show impaired reward learning in situations that require the integration of reinforced feedback over time. In this study, we examined the behavioral and electrophysiological characteristics of reward learning in manic and euthymic patients with bipolar disorder using a probabilistic reward task.
  
  
  METHODS
  Twenty-four manic and 20 euthymic patients with bipolar I disorder and 24 healthy control subjects performed the probabilistic reward task. We assessed response bias (RB) as a preference for the stimulus paired with the more frequent reward and feedback-related negativity (FRN) to correct identification of the rich stimulus.
  
  
  RESULTS
  Both manic and euthymic patients showed significantly lower RB scores in the early learning stage (block 1) in comparison with the late learning stage (block 2 or block 3) of the task, as well as significantly lower RB scores in the early stage compared to healthy subjects. Relatively more negative FRN amplitude is elicited by no presentation of an expected reward, compared to that elicited by presentation of expected feedback. The FRN became significantly more negative from the early (block 1) to the later stages (blocks 2 and 3) in both manic and euthymic patients, but not in healthy subjects. Changes in RB scores and FRN amplitudes between blocks 2 and 3 and block 1 correlated positively in healthy controls, but correlated negatively in manic and euthymic patients. The severity of manic symptoms correlated positively with reward learning scores and negatively with the FRN.
  
  
  CONCLUSIONS
  These findings suggest that patients with bipolar disorder during euthymic or manic states have behavioral and electrophysiological alterations in reward learning compared to healthy subjects. This dysfunctional reward processing may be related to the abnormal decision-making or altered goal-directed activities frequently seen in patients with bipolar disorder.
authors.affiliation: Department of Psychiatry, National Center for Mental Health, Seoul, South Korea.
authors.forename: Vin
authors.initials: V
authors.lastname: Ryu
authors.affiliation: Department of Psychiatry, Seoul Bukbu Hospital, Seoul, South Korea.
authors.forename: Ra Yeon
authors.initials: RY
authors.lastname: Ha
authors.affiliation: Institute of Behavioral Science in Medicine, College of Medicine, Yonsei University, Seoul, South Korea.
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Neuropsychiatry, College of Medicine, Seoul National University, Seoul, South Korea.
authors.forename: Kyooseob
authors.initials: K
authors.lastname: Ha
authors.affiliation: Institute of Behavioral Science in Medicine, College of Medicine, Yonsei University, Seoul, South Korea.|Department of Psychiatry, College of Medicine, Yonsei University, Seoul, South Korea.
authors.forename: Hyun-Sang
authors.initials: HS
authors.lastname: Cho
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D015982:Bias; D001676:Biofeedback, Psychology; D001714:Bipolar Disorder / Q000145:classification / Q000503:physiopathology* / Q000534:rehabilitation* / Q000628:therapy; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011336:Probability; D011569:Psychiatric Status Rating Scales; D012054:Reinforcement, Psychology
keywords: Bipolar disorder; Feedback-related negativity; Probabilistic learning; Response bias; Reward