title: Reward-based spatial learning in unmedicated adults with obsessive-compulsive disorder.
abstract: OBJECTIVE
  The authors assessed the functioning of mesolimbic and striatal areas involved in reward-based spatial learning in unmedicated adults with obsessive-compulsive disorder (OCD).
  
  
  METHODS
  Functional MRI blood-oxygen-level-dependent response was compared in 33 unmedicated adults with OCD and 33 healthy, age-matched comparison subjects during a reward-based learning task that required learning to use extramaze cues to navigate a virtual eight-arm radial maze to find hidden rewards. The groups were compared in their patterns of brain activation associated with reward-based spatial learning versus a control condition in which rewards were unexpected because they were allotted pseudorandomly to experimentally prevent learning.
  
  
  RESULTS
  Both groups learned to navigate the maze to find hidden rewards, but group differences in neural activity during navigation and reward processing were detected in mesolimbic and striatal areas. During navigation, the OCD group, unlike the healthy comparison group, exhibited activation in the left posterior hippocampus. Unlike healthy subjects, participants in the OCD group did not show activation in the left ventral putamen and amygdala when anticipating rewards or in the left hippocampus, amygdala, and ventral putamen when receiving unexpected rewards (control condition). Signal in these regions decreased relative to baseline during unexpected reward receipt among those in the OCD group, and the degree of activation was inversely associated with doubt/checking symptoms.
  
  
  CONCLUSIONS
  Participants in the OCD group displayed abnormal recruitment of mesolimbic and ventral striatal circuitry during reward-based spatial learning. Whereas healthy comparison subjects exhibited activation in this circuitry in response to the violation of reward expectations, unmedicated OCD participants did not and instead over-relied on the posterior hippocampus during learning. Thus, dopaminergic innervation of reward circuitry may be altered, and future study of anterior/posterior hippocampal dysfunction in OCD is warranted.
authors.affiliation: From the Division of Child and Adolescent Psychiatry in the Department of Psychiatry, the New York State Psychiatric Institute and the College of Physicians and Surgeons, Columbia University, New York; the Division of Translational Imaging, the New York State Psychiatric Institute and the Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York; the Department of Psychology, Texas A&M University, College Station, Tex.; the Institute for the Developing Mind, Children's Hospital Los Angeles, Los Angeles; and the Division of Clinical Therapeutics in the Department of Psychiatry, the New York State Psychiatric Institute and the College of Physicians and Surgeons, Columbia University, New York.
authors.forename: Rachel
authors.initials: R
authors.lastname: Marsh
authors.forename: Gregory Z
authors.initials: GZ
authors.lastname: Tau
authors.forename: Zhishun
authors.initials: Z
authors.lastname: Wang
authors.forename: Yuankai
authors.initials: Y
authors.lastname: Huo
authors.forename: Ge
authors.initials: G
authors.lastname: Liu
authors.forename: Xuejun
authors.initials: X
authors.lastname: Hao
authors.forename: Mark G
authors.initials: MG
authors.lastname: Packard
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Peterson
authors.forename: H Blair
authors.initials: HB
authors.lastname: Simpson
mesh_terms: D000328:Adult; D000679:Amygdala / Q000503:physiopathology; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D003463:Cues; D005260:Female; D059907:Functional Neuroimaging; D006624:Hippocampus / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D017072:Neostriatum / Q000503:physiopathology; D009771:Obsessive-Compulsive Disorder / Q000503:physiopathology*; D011699:Putamen / Q000503:physiopathology; D012201:Reward; D065853:Spatial Learning / Q000502:physiology*; D055815:Young Adult