title: Evidence for impaired cortical inhibition in patients with unipolar major depression.
abstract: BACKGROUND
  Several lines of evidence suggest that central cortical inhibitory mechanisms, especially associated with gamma-aminobutyric acid (GABA) neurotransmission, may play a role in the pathophysiology of major depression. Transcranial magnetic stimulation is a useful tool for investigating central cortical inhibitory mechanisms associated with GABAergic neurotransmission in psychiatric and neurological disorders.
  
  
  METHODS
  By means of transcranial magnetic stimulation, different parameters of cortical excitability, including motor threshold, the cortical silent period, and intracortical inhibition/facilitation, were investigated in 20 medication-free depressed patients and 20 age- and gender-matched healthy volunteers.
  
  
  RESULTS
  Silent period and intracortical inhibition were reduced in depressed patients, consistent with a reduced GABAergic tone. Moreover, patients showed a significant hemispheric asymmetry in motor threshold.
  
  
  CONCLUSIONS
  This study provides evidence of reduced GABAergic tone and motor threshold asymmetry in patients with major depression.
authors.affiliation: Department of Psychiatry, Charité University Medicine Berlin, Berlin, Germany. malek.bajbouj@charite.de
authors.forename: Malek
authors.initials: M
authors.lastname: Bajbouj
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Lisanby
authors.forename: Undine E
authors.initials: UE
authors.lastname: Lang
authors.forename: Heidi
authors.initials: H
authors.lastname: Danker-Hopfe
authors.forename: Isabella
authors.initials: I
authors.lastname: Heuser
authors.forename: Peter
authors.initials: P
authors.lastname: Neu
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000503:physiopathology*; D004292:Dominance, Cerebral / Q000502:physiology; D004576:Electromyography; D005260:Female; D006225:Hand / Q000294:innervation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D009433:Neural Inhibition / Q000502:physiology*; D012016:Reference Values; D012684:Sensory Thresholds / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology; D050781:Transcranial Magnetic Stimulation; D005680:gamma-Aminobutyric Acid / Q000502:physiology
chemical_list: D005680:gamma-Aminobutyric Acid