title: Frontal areas contribute to reduced global coordination of resting-state gamma activities in drug-naïve patients with schizophrenia.
abstract: Schizophrenia has been postulated to involve impaired neuronal cooperation in large-scale neural networks, including cortico-cortical circuitry. Alterations in gamma band oscillations have attracted a great deal of interest as they appear to represent a pathophysiological process of cortical dysfunction in schizophrenia. Gamma band oscillations reflect local cortical activities, and the synchronization of these activities among spatially distributed cortical areas has been suggested to play a central role in the formation of networks. To assess global coordination across spatially distributed brain regions, Omega complexity (OC) in multichannel EEG was proposed. Using OC, we investigated global coordination of resting-state EEG activities in both gamma (30-50 Hz) and below-gamma (1.5-30 Hz) bands in drug-naïve patients with schizophrenia and investigated the effects of neuroleptic treatment. We found that gamma band OC was significantly higher in drug-naïve patients with schizophrenia compared to control subjects and that a right frontal electrode (F3) contributed significantly to the higher OC. After neuroleptic treatment, reductions in the contribution of frontal electrodes to global OC in both bands correlated with the improvement of schizophrenia symptomatology. The present study suggests that frontal brain processes in schizophrenia were less coordinated with activity in the remaining brain. In addition, beneficial effects of neuroleptic treatment were accompanied by improvement of brain coordination predominantly due to changes in frontal regions. Our study provides new evidence of improper intrinsic brain integration in schizophrenia by investigating the resting-state gamma band activity.
authors.affiliation: Department of Psychiatry and Neurobiology, Graduate School of Medical Science, Kanazawa University, Kanazawa 920-8641, Japan. mitsuru@zc4.so-net.ne.jp
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Kikuchi
authors.forename: Takanori
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Nagasawa
authors.forename: Tetsu
authors.initials: T
authors.lastname: Hirosawa
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Minabe
authors.forename: Masafumi
authors.initials: M
authors.lastname: Yoshimura
authors.forename: Werner
authors.initials: W
authors.lastname: Strik
authors.forename: Thomas
authors.initials: T
authors.lastname: Dierks
authors.forename: Thomas
authors.initials: T
authors.lastname: Koenig
mesh_terms: D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001931:Brain Mapping; D058256:Brain Waves / Q000187:drug effects / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D005500:Follow-Up Studies; D005625:Frontal Lobe / Q000187:drug effects / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012146:Rest / Q000502:physiology*; D018967:Risperidone / Q000627:therapeutic use; D012559:Schizophrenia / Q000188:drug therapy / Q000473:pathology* / Q000503:physiopathology*; D018709:Statistics, Nonparametric; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents; D018967:Risperidone