LATENCY OF MOTOR EVOKED-POTENTIALS TO FOCAL TRANSCRANIAL STIMULATION VARIES AS A FUNCTION OF SCALP POSITIONS STIMULATED
LATENCY OF MOTOR EVOKED-POTENTIALS TO FOCAL TRANSCRANIAL STIMULATION VARIES AS A FUNCTION OF SCALP POSITIONS STIMULATED
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DOI：
10.1016/0168-5597(91)90001-e
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发表时间：
1991-04-01
期刊：
影响因子：
--
通讯作者：
HALLETT, M
中科院分区：
文献类型：
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作者：
FUHR, P;COHEN, LG;HALLETT, M
我们记录了静息和轻度自主活动时外展拇短肌（APB）、桡侧腕屈肌（FCR）、肱二头肌和三角肌在经颅磁刺激下的运动诱发电位（MEP）。一个连接到Cadwell MES-10磁刺激器的8形线圈被放置在不同的头皮位置上，间隔1cm。每个部位至少有24个刺激。比较了电刺激和磁刺激在肌肉激活过程中获得的mep潜伏期。根据刺激的类型和位置，5组的MEP潜伏期逐渐延长。(1)肌肉收缩时的电刺激和(2)肌肉收缩时的非局灶性磁刺激获得的潜伏期最短；静息磁刺激在(3)最优位置、(4)次优位置和(5)非最优位置的刺激下产生更长的潜伏期。各组间APB平均潜伏期差异分别为1.9、2.0、1.6和2.6 msec。其他手臂肌肉也发现了类似的潜伏期差异。这一结果与假设一致，即刺激在头皮不同部位引起的不同潜伏期是由连续数量的I波产生的兴奋性突触后电位在脊髓运动神经元上的总和决定的。
We recorded motor evoked potentials (MEP) to transcranial magnetic stimulation from abductor pollicis brevis (APB), flexor carpi radialis (FCR), biceps brachii and deltoid muscles at rest and during slight voluntary activation. An 8-shaped coil connected to a Cadwell MES-10 magnetic stimulator was positioned over different scalp positions 1 cm apart. At least 24 stimuli were delivered at each location. Latencies of MEPs were compared with those obtained by electrical and magnetic stimulation during muscle activation.Progressively longer MEP latencies were obtained in 5 groups depending on the type and position of stimulation. The shortest latencies were obtained with (1) electrical stimulation during muscle contraction and (2) non-focal magnetic stimulation during muscle contraction; magnetic stimulation at rest produced longer latencies with stimulation of (3) an optimal position, (4) a suboptimal position, and (5) a non-optimal position. Mean latency differences between successive groups were 1.9, 2.0, 1.6, and 2.6 msec for APB. Similar latency differences were found for the other arm muscles. The results are compatible with the hypothesis that the different latencies evoked by stimulation at different scalp locations are determined by the summation at spinal motoneurons of excitatory postsynaptic potentials generated by successive numbers of I waves.