Intensity-dependent effects of 1 Hz rTMS on human corticospinal excitability.
OBJECTIVE
This study explored whether the effects of repetitive transcranial magnetic stimulation (rTMS) on corticospinal excitability are dependent on the stimulation intensity and examined the effect of rTMS on inhibitory function.


METHODS
Nine normal volunteers received 15min of 1Hz rTMS at 85 and 115% of the resting motor threshold (RMT). Cortical excitability was measured before and after rTMS.


RESULTS
rTMS at both intensities produced an increase in the RMT but only 115% stimulation reduced the size of motor evoked potentials (MEPs). rTMS had no effects on the cortical silent period or cortical inhibition measured with paired pulse TMS.


CONCLUSIONS
The effects of 1Hz rTMS on motor cortex excitability are partially dependent on stimulus intensity and the effects of rTMS on motor thresholds and MEP size may differ.
Fitzgerald
Paul B
PB
Department of Psychological Medicine, Dandenong Psychiatry Research Centre, Monash University, P.O. Box 956, Victoria 3175, Australia. paul.fitzgerald@med.monash.edu.au
Brown
Timothy L
TL
Daskalakis
Z Jeff
ZJ
Chen
Robert
R
Kulkarni
J
J
D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D004307:Dose-Response Relationship, Radiation; D004569:Electroencephalography; D004574:Electromagnetic Fields; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D013116:Spinal Cord / Q000502:physiology*