经颅重复磁刺激对人脑皮层兴奋性的影响

目的　研究经颅重复磁刺激（rTMS）对人脑运动皮层兴奋性的影响。方法　5Hz×30次或15Hz×30次rTMS，以相当于120%静止运动阈值的强度，作用于12名青壮年志愿者，并利用成对的条件-检测刺激方法检验rTMS对皮层内抑制（ICI）及皮层内易化（ICF）的影响。结果　15HzrTMS显著抑制ICI达3.4min，兴奋ICF达1.5min，而运动阈值仅被降低约30s。5HzrTMS仅显著抑制ICI30s，而对ICF及运动阈值无影响。结论　高频阈上rTMS能一过性抑制皮层内抑制环路并提高皮层内兴奋性环路的活动。

Modification of intracortical excitability after repetitive transcranial magnetic stimulation

Objective To study the effect of repetitive transcranial magnetic stimulation (rTMS) on human intracortical excitability Methods A train of 30 pulses of rTMS at a frequency of 5 or 15 Hz and at an intensity of 120% of resting motor threshold was applied to human motor cortex The change of intracortical excitability,was expressed as intracortical inhibition (ICI) and the intracortical facilitation (ICF),after rTMS was tested by a conditioning test designed paired pulse paradigm Results After 15 Hz rTMS,ICI was significantly suppressed for 3 4 minutes,ICF was enhanced for 1 5 minutes,whereas the motor threshold was decreased in the first half minute The train of 5 Hz rTMS significantly suppressed ICI in the first half minute,showing no modification of ICF and motor threshold Conclusion High frequency suprathreshold rTMS can transiently suppress the activity of the intracortical inhibitory circuit and the excitability of the excitatory circuit