title: Evidence for dysregulated high-frequency oscillations during sensory processing in medication-naïve, first episode schizophrenia.
abstract: BACKGROUND
  High-frequency oscillations are important for sensory processing and dysfunctions in the amplitude and synchrony of beta- and gamma-band oscillations have been demonstrated in schizophrenia (ScZ). However, the presence of aberrant high-frequency oscillations in first-episode (FE), medication-naive patients during sensory processing is unclear.
  
  
  METHODS
  Magnetoencephalographic (MEG) data were recorded from 15 never-medicated, FE-ScZ patients and 20 matched healthy controls during the perception of Mooney faces. MEG data were analysed for spectral power and single-sensor phase-locking in the beta (13-25Hz) and gamma- (25-140Hz) frequency range.
  
  
  RESULTS
  FE-ScZ patients were characterized by significantly impaired sensory processing as indicated by a reduced discrimination index (A'). Impaired behavioural performance in ScZ-patients was accompanied by decreased spectral power in the high- (60-120Hz) gamma-band range. In contrast, oscillations in the lower (25-60Hz) gamma-band were largely intact and beta-band oscillations were increased. Analysis of cross-frequency coupling showed a reduced correlation between 60 and 120Hz amplitude values and beta-band power in FE-ScZ-patients relative to controls.
  
  
  CONCLUSIONS
  Our findings show that impaired sensory processing in medication-naive, FE-schizophrenia is related to a dysregulation of neural oscillations which involves both an impairment in the generation of high gamma-band activity as well as a failure to downregulate task-irrelevant beta-band activity. Because of the interrelationship of these dysfunctions and the role of inhibitory networks in the shaping of high-frequency activity, aberrant neural oscillations in FE-schizophrenia may be linked to dysfunctions in the excitation-inhibition (E/I)-balance.
authors.affiliation: Department of Neurophysiology, Max-Planck Institute for Brain Research, Deutschordenstr, 46, Frankfurt am Main, 60528, Germany; Department of Radiology, Massachusetts General Hospital, Harvard University, Cambridge, MA 02129, USA.
authors.forename: Limin
authors.initials: L
authors.lastname: Sun
authors.forename: Nazareth
authors.initials: N
authors.lastname: Castellanos
authors.forename: Christine
authors.initials: C
authors.lastname: Grützner
authors.forename: Dagmar
authors.initials: D
authors.lastname: Koethe
authors.forename: Davide
authors.initials: D
authors.lastname: Rivolta
authors.forename: Michael
authors.initials: M
authors.lastname: Wibral
authors.forename: Laura
authors.initials: L
authors.lastname: Kranaster
authors.forename: Wolf
authors.initials: W
authors.lastname: Singer
authors.forename: Markus F
authors.initials: MF
authors.lastname: Leweke
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Uhlhaas
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D016022:Case-Control Studies; D003344:Cortical Synchronization / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010468:Perceptual Disorders / Q000209:etiology*; D010775:Photic Stimulation; D012559:Schizophrenia / Q000150:complications*; D055815:Young Adult
keywords: First-episode; High-frequency oscillations; MEG; Neural synchrony; Perceptual organization; Schizophrenia