title: MEG-measured visually induced gamma-band oscillations in chronic schizophrenia: Evidence for impaired generation of rhythmic activity in ventral stream regions.
abstract: Gamma-band oscillations are prominently impaired in schizophrenia, but the nature of the deficit and relationship to perceptual processes is unclear.
  
  
  
  16 patients with chronic schizophrenia (ScZ) and 16 age-matched healthy controls completed a visual paradigm while magnetoencephalographic (MEG) data was recorded. Participants had to detect randomly occurring stimulus acceleration while viewing a concentric moving grating. MEG data were analyzed for spectral power (1-100Hz) at sensor- and source-level to examine the brain regions involved in aberrant rhythmic activity, and for contribution of differences in baseline activity towards the generation of low- and high-frequency power.
  
  
  
  Our data show reduced gamma-band power at sensor level in schizophrenia patients during stimulus processing while alpha-band and baseline spectrum were intact. Differences in oscillatory activity correlated with reduced behavioral detection rates in the schizophrenia group and higher scores on the "Cognitive Factor" of the Positive and Negative Syndrome Scale. Source reconstruction revealed that extra-striate (fusiform/lingual gyrus), but not striate (cuneus), visual cortices contributed towards the reduced activity observed at sensor-level in ScZ patients. Importantly, differences in stimulus-related activity were not due to differences in baseline activity.
  
  
  
  Our findings highlight that MEG-measured high-frequency oscillations during visual processing can be robustly identified in ScZ. Our data further suggest impairments that involve dysfunctions in ventral stream processing and a failure to increase gamma-band activity in a task-context. Implications of these findings are discussed in the context of current theories of cortical-subcortical circuit dysfunctions and perceptual processing in ScZ.
authors.affiliation: Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom. Electronic address: tineke.grent@glasgow.ac.uk.
authors.forename: Tineke
authors.initials: T
authors.lastname: Grent-'t-Jong
authors.affiliation: Department of Neurophysiology, Max Planck Institute for Brain Research, Frankfurt am Main 60528, Germany; Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt am Main 60528, Germany; School of Psychology, University of East London (UEL), London, United Kingdom.
authors.forename: Davide
authors.initials: D
authors.lastname: Rivolta
authors.affiliation: Department of Neurophysiology, Max Planck Institute for Brain Research, Frankfurt am Main 60528, Germany; Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt am Main 60528, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Sauer
authors.affiliation: Department of Psychiatry and Psychotherapy - Psychosomatics, Municipal Clinic, Frankfurt am Main 65929, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Grube
authors.affiliation: Department of Neurophysiology, Max Planck Institute for Brain Research, Frankfurt am Main 60528, Germany; Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt am Main 60528, Germany; Frankfurt Institute for Advanced Studies (FIAS), Johann Wolfgang Goethe University, Frankfurt am Main, Germany.
authors.forename: Wolf
authors.initials: W
authors.lastname: Singer
authors.affiliation: MEG Unit, Brain Imaging Centre (BIC), Johann Wolfgang Goethe University, Frankfurt am Main 60529, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Wibral
authors.affiliation: Department of Neurophysiology, Max Planck Institute for Brain Research, Frankfurt am Main 60528, Germany; Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt am Main 60528, Germany; Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Uhlhaas
mesh_terms: D000328:Adult; D000513:Alpha Rhythm; D001921:Brain / Q000503:physiopathology*; D002908:Chronic Disease; D005260:Female; D065818:Gamma Rhythm; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D011930:Reaction Time; D012559:Schizophrenia / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted
keywords: E/I-balance; MEG; Oscillations; Schizophrenia; Ventral stream; Visual cortex