Motor thresholds in humans: a transcranial magnetic stimulation study comparing different pulse waveforms, current directions and stimulator types
Motor thresholds in humans: a transcranial magnetic stimulation study comparing different pulse waveforms, current directions and stimulator types
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DOI：
10.1016/s1388-2457(00)00513-7
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发表时间：
2001-02-01
影响因子：
4.7
通讯作者：
Topka, H
中科院分区：
文献类型：
--
作者：
Kammer, T;Beck, S;Topka, H
目的：为了评价不同的磁刺激器设备的刺激效果的脉冲波形和电流方向在motor cortex.Methods：在8名正常人，我们测定了运动阈值的经颅磁刺激在一个小的手肌肉。我们使用了3种常见刺激器（Dantec Magpro、Magstim 200和Magstim Rapid）的焦点8字形线圈，并系统地改变了电流方向（后前与前后，垂直于中央沟）以及脉冲波形（单相与双相）。线圈的位置保持不变，与立体定向positioning device.Results：运动阈值变化一致，不断变化的刺激参数，尽管大量的个体间变异性。通过将这些值相对于不同刺激器中的电容器的能量的平方根进行归一化，我们发现了阈值变化的均匀模式。标准化Magstim阈值始终高于标准化Dantec阈值1.3倍。对于两种刺激器类型，如果电流以后-前方向而不是前-后方向通过运动皮层，则单相脉冲更有效。相反，双相脉冲较弱的第一次向上中风在后-前方向。我们计算的平均因子转化为另一种配置的强度值的一个特定的配置，通过规范化的不同的阈值，每个人的受试者，他的最低阈值value.Conclusions：我们的转换因子使我们能够比较刺激强度的研究，使用不同的设备和脉冲形式。作为波形和电流方向的函数的刺激的有效性遵循与外周神经制备中相同的模式（J Physiol（Lond）513（1998）571）。(C)2001爱思唯尔科学爱尔兰有限公司保留所有权利。
Objectives: To evaluate the stimulation effectiveness of different magnetic stimulator devices with respect to pulse waveform and current direction in the motor cortex.Methods: In 8 normal subjects we determined motor thresholds of transcranial magnetic stimulation in a small hand muscle. We used focal figure-of-eight coils of 3 common stimulators (Dantec Magpro, Magstim 200 and Magstim Rapid) and systematically varied current direction (postero-anterior versus antero-posterior, perpendicular to the central sulcus) as well as pulse waveform (monophasic versus biphasic). The coil position was kept constant with a stereotactic positioning device.Results: Motor thresholds varied consistently with changing stimulus parameters, despite substantial interindividual variability. By normalizing the values with respect to the square root of the energy of the capacitors in the different stimulators, we found a homogeneous pattern of threshold variations. The normalized Magstim threshold values were consistently higher than the normalized Dantec thresholds by a factor of 1.3. For both stimulator types the monophasic pulse was more effective if the current passed the motor cortex in a postero-anterior direction rather than antero-posterior. In contrast, the biphasic pulse was weaker with the first upstroke in the postero-anterior direction. We calculated mean factors for transforming the intensity values of a particular configuration into that of another configuration by normalizing the different threshold values of each individual subject to his lowest threshold value.Conclusions: Our transformation factors allow us to compare stimulation intensities from studies using different devices and pulse forms. The effectiveness of stimulation as a function of waveform and current direction follows the same pattern as in a peripheral nerve preparation (J Physiol (Lond) 513 (1998) 571). (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.