title: Reduced natural oscillatory frequency of frontal thalamocortical circuits in schizophrenia.
abstract: BACKGROUND
  Converging evidence from electrophysiological studies suggests that in individuals with schizophrenia, electroencephalographic frontal fast oscillations are reduced. It is still unclear whether this reduction reflects an intrinsic deficit of underlying cortical/thalamocortical circuits and whether this deficit is specific for frontal regions. Recent electrophysiological studies in healthy individuals have established that, when perturbed, different brain regions oscillate at a specific, intrinsically generated dominant frequency, the natural frequency.
  
  
  OBJECTIVE
  To assess the natural frequency of the posterior parietal, motor, premotor, and prefrontal cortices in patients with schizophrenia and healthy control subjects.
  
  
  METHODS
  High-density electroencephalographic recordings during transcranial magnetic stimulation of 4 cortical areas were performed. Several transcranial magnetic stimulation–evoked electroencephalographic oscillation parameters, including synchronization, amplitude, and natural frequency, were compared across the schizophrenia and healthy control groups.
  
  
  METHODS
  Wisconsin Psychiatric Institute and Clinic, University of Wisconsin–Madison.
  
  
  METHODS
  Twenty patients with schizophrenia and 20 age-matched healthy control subjects.
  
  
  METHODS
  High-density electroencephalographic measurements of transcranial magnetic stimulation–evoked activity in 4 cortical areas, scores on the Positive and Negative Syndrome Scale, and performance scores (reaction time, accuracy) on 2 computerized tasks (word memory [Penn Word Recognition Test] and facial memory [Penn Facial Memory Test]).
  
  
  RESULTS
  Patients with schizophrenia showed a slowing in the natural frequency of the frontal/prefrontal regions compared with healthy control subjects (from an average of a 2-Hz decrease for the motor area to an almost 10-Hz decrease for the prefrontal cortex). The prefrontal natural frequency of individuals with schizophrenia was slower than in any healthy comparison subject and correlated with both positive Positive and Negative Syndrome Scale scores and reaction time on the Penn Word Recognition Test.
  
  
  CONCLUSIONS
  These findings suggest that patients with schizophrenia have an intrinsic slowing in the natural frequency of frontal cortical/thalamocortical circuits, that this slowing is not present in parietal areas, and that the prefrontal natural frequency can predict some of the symptoms as well as the cognitive dysfunctions of schizophrenia.
authors.affiliation: Department of Psychiatry, University of Wisconsin-Madison, USA.
authors.forename: Fabio
authors.initials: F
authors.lastname: Ferrarelli
authors.forename: Simone
authors.initials: S
authors.lastname: Sarasso
authors.forename: Yelena
authors.initials: Y
authors.lastname: Guller
authors.forename: Brady A
authors.initials: BA
authors.lastname: Riedner
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Peterson
authors.forename: Michele
authors.initials: M
authors.lastname: Bellesi
authors.forename: Marcello
authors.initials: M
authors.lastname: Massimini
authors.forename: Bradley R
authors.initials: BR
authors.lastname: Postle
authors.forename: Giulio
authors.initials: G
authors.lastname: Tononi
mesh_terms: D000328:Adult; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D004569:Electroencephalography / Q000379:methods*; D055724:Electrophysiological Phenomena; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D006801:Humans; D008297:Male; D009415:Nerve Net / Q000503:physiopathology; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D012107:Research Design; D012559:Schizophrenia / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D013788:Thalamus / Q000503:physiopathology; D050781:Transcranial Magnetic Stimulation / Q000379:methods*