title: A study of the effects of lorazepam and dextromethorphan on the response to cortical 1 Hz repetitive transcranial magnetic stimulation.
abstract: We studied the effects of lorazepam and dextromethorphan on the responses to 1 Hz repetitive transcranial magnetic stimulation applied to the left human motor cortex. Lorazepam, dextromethorphan or placebo was administered to 45 normal controls in a double-blind fashion 2.5 h before the repetitive transcranial magnetic stimulation procedure. Motor cortical excitability was measured with single transcranial magnetic stimulation pulses before and after 15 min of 1 Hz repetitive transcranial magnetic stimulation applied at supra-threshold intensity. 1 Hz repetitive transcranial magnetic stimulation resulted in a decrease in motor cortical excitability in the placebo group but not in the groups taking lorazepam or dextromethorphan. These results suggest that cortical responses to 1 Hz repetitive transcranial magnetic stimulation are dependent on activity at both gamma-aminobutyric acid and N-methyl-D-asparate receptor systems.
authors.affiliation: Alfred Psychiatry Research Centre, The Alfred and Monash University Department of Psychological Medicine, Commercial Road Melbourne, Victoria 3004, Australia. paul.fitzgerald@med.monash.edu.au
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fitzgerald
authors.forename: Jessica
authors.initials: J
authors.lastname: Benitez
authors.forename: Tom
authors.initials: T
authors.lastname: Oxley
authors.forename: Jeff Z
authors.initials: JZ
authors.lastname: Daskalakis
authors.forename: Anthony R
authors.initials: AR
authors.lastname: de Castella
authors.forename: Jayashri
authors.initials: J
authors.lastname: Kulkarni
mesh_terms: D000328:Adult; D003915:Dextromethorphan / Q000008:administration & dosage*; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000187:drug effects*; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage*; D005260:Female; D018757:GABA Modulators / Q000008:administration & dosage*; D006801:Humans; D008140:Lorazepam / Q000008:administration & dosage*; D008297:Male; D009044:Motor Cortex / Q000187:drug effects / Q000502:physiology; D018079:Receptors, GABA / Q000502:physiology; D050781:Transcranial Magnetic Stimulation
chemical_list: D018691:Excitatory Amino Acid Antagonists; D018757:GABA Modulators; D018079:Receptors, GABA; D003915:Dextromethorphan; D008140:Lorazepam