title: A transcranial magnetic stimulation study of abnormal cortical inhibition in schizophrenia.
abstract: Previous research suggests that patients with schizophrenia demonstrate deficits in a range of parameters of motor cortical and cognitive inhibition. I-wave facilitation and long-interval cortical inhibition (LICI) are two paired pulse transcranial magnetic stimulation paradigms that appear to assess aspects of cortical inhibitory function that have not previously been assessed in this patient group. Eighteen patients with schizophrenia (nine medication-free) were compared with eight control subjects. We assessed resting motor threshold (RMT) levels, LICI and I-wave facilitation. RMT levels did not differ between the three groups. There was a significant overall difference in I-wave facilitation levels. Both patient groups as compared with the control group showed increased facilitation. There were no differences between the groups in the measure of LICI. Patients with schizophrenia appear to have increased I-wave facilitation. Increased I-wave facilitation suggests deficient function of cortical inhibitory GABAergic activity. This is consistent with previous research that has found deficient cortical inhibition in patients with schizophrenia.
authors.affiliation: Alfred Psychiatry Research Centre, The Alfred and Monash University Department of Psychological Medicine, Commercial Rd, Victoria 3004, Melbourne, Australia. paul.fitzgerald@med.monash.edu.au
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fitzgerald
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Brown
authors.forename: Natasha A U
authors.initials: NA
authors.lastname: Marston
authors.forename: Tom J
authors.initials: TJ
authors.lastname: Oxley
authors.forename: Anthony
authors.initials: A
authors.lastname: de Castella
authors.forename: Zafiris Jeff
authors.initials: ZJ
authors.lastname: Daskalakis
authors.forename: Jayashri
authors.initials: J
authors.lastname: Kulkarni
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology*; D055590:Electromagnetic Phenomena / Q000295:instrumentation; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology*; D009483:Neuropsychological Tests; D012559:Schizophrenia / Q000150:complications* / Q000503:physiopathology*; D012886:Skull