title: Dysfunctional brain circuitry in obsessive-compulsive disorder: source and coherence analysis of EEG rhythms.
abstract: BACKGROUND
  Morphological and functional studies suggested involvement of several cortical and subcortical circuitries in patients with obsessive-compulsive disorder (OCD). The aim of the present study was to investigate networks involved in OCD pathophysiology, using power (coupling of EEG bands, low-resolution electromagnetic tomography-LORETA) and coherence analysis in drug-naïve patients.
  
  
  METHODS
  EEG was obtained from 37 drug-naïve patients with OCD and 37 age- and sex-matched controls. Resting EEG was recorded from 29 scalp channels. Coupling (ratio and correlation) between low and high frequencies was analyzed on Fz. For each frequency band, LORETA current density distribution, intra-hemispheric and inter-hemispheric coherence analysis were computed.
  
  
  RESULTS
  OCD had increased current density for delta in the insula and for beta in frontal, parietal and limbic lobes. OCD also had decreased inter-hemispheric coherence and reduced coupling between delta and beta frequencies.
  
  
  CONCLUSIONS
  In OCD, increased frontal beta is consistent with previous evidence of frontal dysfunction. Hyperactivity of insular delta sources, together with rhythms decoupling and reduced interhemispheric alpha coherence are consistent with additional involvement of cortico-subcortical functional connections. Combined use of power and coherence analysis may provide functional measures on different levels of involvement of cortico-subcortical circuits in neuropsychiatric disorders.
authors.affiliation: Department of Neurology, Clinical Neurophysiology, Neurorehabilitation, Institute of Experimental Neurology, IRCCS University Hospital San Raffaele, Via Olgettina 60, Milan, Italy.
authors.forename: Svetla
authors.initials: S
authors.lastname: Velikova
authors.forename: Marco
authors.initials: M
authors.lastname: Locatelli
authors.forename: Chiara
authors.initials: C
authors.lastname: Insacco
authors.forename: Enrico
authors.initials: E
authors.lastname: Smeraldi
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Comi
authors.forename: Letizia
authors.initials: L
authors.lastname: Leocani
mesh_terms: D000328:Adult; D001611:Beta Rhythm; D001921:Brain / Q000503:physiopathology*; D003700:Delta Rhythm; D004569:Electroencephalography; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008032:Limbic System / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000503:physiopathology*; D009771:Obsessive-Compulsive Disorder / Q000503:physiopathology*; D011569:Psychiatric Status Rating Scales; D013702:Temporal Lobe / Q000503:physiopathology; D013788:Thalamus / Q000503:physiopathology