Transcranial magnetic double stimulation:: influence of the intensity of the conditioning stimulus
Transcranial magnetic double stimulation:: influence of the intensity of the conditioning stimulus
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DOI：
10.1016/s0924-980x(97)00054-4
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发表时间：
1997-12-01
期刊：
影响因子：
--
通讯作者：
Ferbert, A
中科院分区：
文献类型：
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作者：
Schäfer, M;Biesecker, JC;Ferbert, A
系统研究了刺激参数对经颅磁双重刺激诱发复合肌电位的影响。使用Bistim接口，通过8字形磁线圈（每个圆形线圈的外径为7 cm）在左半球Cz外侧6 cm处释放两个磁刺激器。从右侧第一骨间背侧肌进行记录。在实验I中，在12.在实验II中，使用1，3和5ms的刺激间隔来研究3种固定强度的条件反射刺激的效果。运动诱发电位的幅度的最大减少被发现在条件刺激强度的65%的放松运动阈值（和在刺激间隔为1毫秒）。由于高于65%的条件刺激强度降低运动诱发电位的幅度不如在此强度下有效，因此可以排除锥体神经元的不应性作为导致所观察到的抑制的主要机制。抑制性中间神经元的激活强度低于激活锥体神经元所需的讨论作为经颅磁刺激引起的抑制作用的可能机制。(C)1997 Elsevier Science爱尔兰有限公司
The influence of stimulus parameters on compound muscle potentials evoked by transcranial magnetic double stimulation was systematically investigated. Two magnetic stimulators were discharged via a figure-of-eight-shaped magnetic coil (outer diameter of each circular coil, 7 cm) over the left hemisphere, 6 cm lateral to Cz, using a Bistim interface. Recordings were made from the right first dorsal interosseus muscle. In experiment I, in 12. healthy volunteers the intensity of the conditioning subthreshold stimulus was varied from 0 to 100% of the relaxed motor threshold at an interstimulus interval of 1 ms. In experiment Il, interstimulus intervals of 1, 3 and 5 ms were used to investigate the effect of conditioning stimuli of 3 fixed intensities. Maximal reduction of the amplitude of motor evoked potentials was found at a conditioning stimulus intensity of 65% of the relaxed motor threshold (and at an interstimulus interval of 1 ms). Because intensities of the conditioning stimulus higher than 65% reduced amplitudes of motor evoked potentials less effectively than at this intensity, refractoriness of pyramidal neurons can be ruled out as the main mechanism contributing to the observed inhibition. Activation of inhibitory interneurons by intensities lower than is necessary to activate pyramidal neurons is discussed as a possible mechanism for the inhibitory effects evoked by transcranial magnetic stimulation. (C) 1997 Elsevier Science Ireland Ltd.