Modugno Nicola, Currà Antonio, Conte Antonella, Inghilleri Maurizio, Fofi Luisa, Agostino Rocco, Manfredi Mario, Berardelli Alfredo
Istituto Neurologico Mediterraneo Neuromed IRCCS, Via Atinense 18, 86077 Pozzilli (IS), Italy.
Clin Neurophysiol. 2003 Dec;114(12):2416-22. doi: 10.1016/s1388-2457(03)00262-1.
Repetitive transcranial magnetic stimulation (rTMS) modulates cortical excitability. These effects outlast the rTMS train, and range from inhibition to facilitation according to the variables used for rTMS. Several studies have demonstrated short and long-term effects on motor evoked potential (MEP) size, whereas the effects on intracortical inhibition (ICI) and facilitation (ICF) are still unclear. We investigated short- (1-15 min), intermediate- (16-30 min), and long-term (6 h) effects on intracortical excitability.
Fourteen healthy subjects were stimulated with rTMS trains of 900 pulses (1 Hz, 90% resting motor threshold (rMTh)), delivered over the primary motor cortex and the occipital area. MTh, MEP size, silent period, intracortical inhibition at short (ICI) and long inter-stimulus intervals, and ICF were tested before and after rTMS.
ICI was reduced 16-30 min after 1 Hz rTMS trains over the primary motor area, whereas the other response variables remained unchanged. The ICI reduction at 16-30 min was reproducible on different days in the same subjects; it was absent at 6 h and after stimulation of the occipital area.
Subthreshold 1 Hz rTMS decreases ICI by reducing the excitability of intracortical inhibitory interneurones or by altering the electrical properties of the facilitatory chain of neurons responsible for the I waves.
重复经颅磁刺激（rTMS）可调节皮质兴奋性。这些效应在rTMS刺激序列结束后仍持续存在，并且根据用于rTMS的变量，其效应范围从抑制到易化。多项研究已证明其对运动诱发电位（MEP）大小有短期和长期影响，而对皮质内抑制（ICI）和易化（ICF）的影响仍不清楚。我们研究了其对皮质内兴奋性的短期（1 - 15分钟）、中期（16 - 30分钟）和长期（6小时）影响。
对14名健康受试者在初级运动皮质和枕叶区域施加900个脉冲的rTMS刺激序列（1赫兹，90%静息运动阈值（rMTh））。在rTMS前后测试运动阈值、MEP大小、静息期、短（ICI）和长刺激间隔时的皮质内抑制以及ICF。
在初级运动区进行1赫兹rTMS刺激序列后16 - 30分钟，ICI降低，而其他反应变量保持不变。在同一受试者的不同日期，16 - 30分钟时的ICI降低是可重复的；在6小时时以及枕叶区域刺激后未出现这种降低。
阈下1赫兹rTMS通过降低皮质内抑制性中间神经元的兴奋性或改变负责I波的神经元易化链的电特性来降低ICI。
