title: Resting-state functional connectivity between fronto-parietal and default mode networks in obsessive-compulsive disorder.
abstract: BACKGROUND
  Obsessive-compulsive disorder (OCD) is characterized by an excessive focus on upsetting or disturbing thoughts, feelings, and images that are internally-generated. Internally-focused thought processes are subserved by the "default mode network" (DMN), which has been found to be hyperactive in OCD during cognitive tasks. In healthy individuals, disengagement from internally-focused thought processes may rely on interactions between DMN and a fronto-parietal network (FPN) associated with external attention and task execution. Altered connectivity between FPN and DMN may contribute to the dysfunctional behavior and brain activity found in OCD.
  
  
  METHODS
  The current study examined interactions between FPN and DMN during rest in 30 patients with OCD (17 unmedicated) and 32 control subjects (17 unmedicated). Timecourses from seven fronto-parietal seeds were correlated across the whole brain and compared between groups.
  
  
  RESULTS
  OCD patients exhibited altered connectivity between FPN seeds (primarily anterior insula) and several regions of DMN including posterior cingulate cortex, medial frontal cortex, posterior inferior parietal lobule, and parahippocampus. These differences were driven largely by a reduction of negative correlations among patients compared to controls. Patients also showed greater positive connectivity between FPN and regions outside DMN, including thalamus, lateral frontal cortex, and somatosensory/motor regions.
  
  
  CONCLUSIONS
  OCD is associated with abnormal intrinsic functional connectivity between large-scale brain networks. Alteration of interactions between FPN and DMN at rest may contribute to aspects of the OCD phenotype, such as patients' inability to disengage from internally-generated scenarios and thoughts when performing everyday tasks requiring external attention.
authors.affiliation: Department of Psychiatry, Mount Sinai School of Medicine, New York, New York, USA. emily.stern@mssm.edu
authors.forename: Emily R
authors.initials: ER
authors.lastname: Stern
authors.forename: Kate D
authors.initials: KD
authors.lastname: Fitzgerald
authors.forename: Robert C
authors.initials: RC
authors.lastname: Welsh
authors.forename: James L
authors.initials: JL
authors.lastname: Abelson
authors.forename: Stephan F
authors.initials: SF
authors.lastname: Taylor
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009434:Neural Pathways; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis / Q000503:physiopathology*; D010296:Parietal Lobe / Q000503:physiopathology*; D055815:Young Adult