title: Shared reduction of oscillatory natural frequencies in bipolar disorder, major depressive disorder and schizophrenia.
abstract: BACKGROUND
  Recent studies have demonstrated that cortical brain areas tend to oscillate at a specific natural frequency when directly perturbed by transcranial magnetic stimulation (TMS). Fast electroencephalographic (EEG) oscillations, which typically originate from frontal regions, have been reported to be markedly reduced in schizophrenia.
  
  
  METHODS
  Here we employed TMS/EEG to assess the natural frequency of the premotor area in a sample of 48 age-matched participants (12 each in major depression disorder (MDD)), bipolar disorder (BPD), schizophrenia (SCZ) and healthy controls. Event related spectral perturbations (ERSP) were obtained for each study participant using wavelet decomposition.
  
  
  RESULTS
  TMS resulted in a significant activation of the beta/gamma band response (21-50 Hz) to frontal cortical perturbation in healthy control subjects. By contrast, the main frequencies of frontal EEG responses to TMS were significantly reduced in patients with BPD, MDD and SCZ (11-27 Hz) relative to healthy subjects.
  
  
  CONCLUSIONS
  Patients with bipolar disorder, major depression and schizophrenia showed a significantly lower natural frequency of frontal cortico-thalamocortical circuits compared to healthy controls. These results suggest a common neurobiological mechanism of corticothalamic impairment. The most likely candidates include dysfunction of GABAergic circuits.
  
  
  CONCLUSIONS
  Further studies are needed to consider other biological markers, gene variants, and their interaction with clinical variables.
authors.affiliation: Department of Clinical Neurosciences, Scientific Institute Ospedale San Raffaele and University Vita-Salute San Raffaele, Milano, Italy. Electronic address: canali.paola@gmail.com.
authors.forename: Paola
authors.initials: P
authors.lastname: Canali
authors.affiliation: Department of Biomedical and Clinical Sciences "L. Sacco", Università degli Studi di Milano, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Sarasso
authors.affiliation: Department of Biomedical and Clinical Sciences "L. Sacco", Università degli Studi di Milano, Italy; Fondazione Europea di Ricerca Biomedica, ONLUS Milan, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Rosanova
authors.affiliation: Department of Biomedical and Clinical Sciences "L. Sacco", Università degli Studi di Milano, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Casarotto
authors.affiliation: Department of Clinical Neurosciences, Scientific Institute Ospedale San Raffaele and University Vita-Salute San Raffaele, Milano, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Sferrazza-Papa
authors.affiliation: Coma Science Group, Cyclotron Research Centre and Neurology Department, University and University Hospital of Liegi, Belgium; Center for Sleep and Consciousness and Postle Laboratory, Department of Psychology and Psychiatry, University of Wisconsin, Madison, WI, USA.
authors.forename: Olivia
authors.initials: O
authors.lastname: Gosseries
authors.affiliation: Department of Biomedical and Clinical Sciences "L. Sacco", Università degli Studi di Milano, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Fecchio
authors.affiliation: Department of Biomedical and Clinical Sciences "L. Sacco", Università degli Studi di Milano, Italy.
authors.forename: Marcello
authors.initials: M
authors.lastname: Massimini
authors.affiliation: Department of Biomedical and Clinical Sciences "L. Sacco", Università degli Studi di Milano, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Mariotti
authors.affiliation: Department of Clinical Neurosciences, Scientific Institute Ospedale San Raffaele and University Vita-Salute San Raffaele, Milano, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Cavallaro
authors.affiliation: Department of Clinical Neurosciences, Scientific Institute Ospedale San Raffaele and University Vita-Salute San Raffaele, Milano, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Smeraldi
authors.affiliation: Department of Clinical Neurosciences, Scientific Institute Ospedale San Raffaele and University Vita-Salute San Raffaele, Milano, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Colombo
authors.affiliation: Department of Clinical Neurosciences, Scientific Institute Ospedale San Raffaele and University Vita-Salute San Raffaele, Milano, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Benedetti
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000503:physiopathology*; D058256:Brain Waves / Q000502:physiology*; D016022:Case-Control Studies; D003865:Major Depressive Disorder / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology; D012559:Schizophrenia / Q000503:physiopathology*; D013788:Thalamus / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation
keywords: GABAergic circuits; Gamma oscillations; Neuropsychiatric disorders; TMS/EEG