Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland.
Clin Neurophysiol. 2011 Jan;122(1):176-82. doi: 10.1016/j.clinph.2010.05.034. Epub 2010 Jul 13.
To measure the intra-individual distribution of the latencies of motor evoked potentials (MepL) using transcranial magnetic stimulation.
We used the triple stimulation technique (TST) to quantify the proportion of excited spinal motor neurons supplying the abductor digiti minimi muscle in response to a maximal magnetic brain stimulus (Magistris et al., 1998). By systematically manipulating the TST delay, we could quantify the contribution of slow-conducting motor tract portions to the TST amplitude.
Our method allowed the establishment of a MepL distribution for each of the 29 examined healthy subjects. MepLs of 50% of the motor tract contributing to the motor evoked potential laid between the intra-individually minimal MepL (MepL(min)) and MepL(min)+4.9 ms (range 1.6-9.2). The individual MepL distributions showed two peaks in most subjects. The first peak appeared at a MepL that was 3.0 ms longer on average (range 0.7-6.0) than MepL(min); the second peak appeared at MepL(min)+8.1 ms on average (range 3.7-13.0).
Slow-conducting parts of the motor pathway contribute notably to the motor evoked potential. Our data suggest a bimodal distribution of central conduction times, which might possibly relate to different fibre types within the pyramidal tract.
We present a non-invasive method to assess slow-conducting parts of the human central motor tract.
使用经颅磁刺激测量运动诱发电位（MepL）潜伏期的个体内分布。
我们使用三重刺激技术（TST）来量化最大磁脑刺激时兴奋供应外展小指肌的脊髓运动神经元在响应中的比例（Magistris 等人，1998 年）。通过系统地改变 TST 延迟，我们可以量化慢传导运动束部分对 TST 幅度的贡献。
我们的方法允许为 29 名接受检查的健康受试者中的每一位建立 MepL 分布。对运动诱发电位有贡献的运动束的 50%的 MepL 位于个体内最小 MepL（MepL(min)）和 MepL(min)+4.9 ms 之间（范围 1.6-9.2）。个体 MepL 分布在大多数受试者中显示出两个峰值。第一个峰值出现在比 MepL(min)长 3.0 ms（范围 0.7-6.0）的 MepL 处；第二个峰值出现在平均 MepL(min)+8.1 ms（范围 3.7-13.0）处。
运动通路的慢传导部分对运动诱发电位有重要贡献。我们的数据表明，中枢传导时间存在双峰分布，这可能与皮质脊髓束内的不同纤维类型有关。
我们提出了一种评估人类中枢运动束慢传导部分的非侵入性方法。
