Fitzgerald Paul B, Benitez Jessica, Oxley Tom, Daskalakis Jeff Z, de Castella Anthony R, Kulkarni Jayashri
Alfred Psychiatry Research Centre, The Alfred and Monash University Department of Psychological Medicine, Commercial Road Melbourne, Victoria 3004, Australia.
Neuroreport. 2005 Sep 8;16(13):1525-8. doi: 10.1097/01.wnr.0000177005.14108.f1.
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.
