COIL PLACEMENT IN MAGNETIC BRAIN-STIMULATION RELATED TO SKULL AND BRAIN ANATOMY
COIL PLACEMENT IN MAGNETIC BRAIN-STIMULATION RELATED TO SKULL AND BRAIN ANATOMY
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DOI：
10.1016/0168-5597(91)90102-4
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发表时间：
1991-02-01
期刊：
影响因子：
--
通讯作者：
BENECKE, R
中科院分区：
文献类型：
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作者：
MEYER, BU;BRITTON, TC;BENECKE, R
系统评估了线圈位置对经颅磁脑刺激引起的肌电反应大小的影响。 通过使用颅外骨标志在颅骨表面构建单独的网格来记录刺激线圈（外径 11.6 厘米，Novametrix）的位置，然后通过分析大脑和颅骨的磁共振图像将其与底层脑沟联系起来。 平均（5 名受试者）发现，当使用从上方观察的逆时针线圈电流时，右侧第一背侧骨间肌 (FDI) 肌肉的最大反应发生在线圈位于顶点左后方 2 厘米处的中心处。 对于右侧胫骨前肌 (TA) 来说，平均而言，线圈以顶点前方 4 厘米、左侧 4 厘米的点为中心，获得了最大的响应。 在个体之间，特定肌肉反应的最佳线圈位置差异最大为 2 厘米。 这种差异可以通过每个个体的中央沟和颅外骨标志之间关系的差异来解释。 只要线圈的绕组经过运动皮层的适当区域，就可以获得响应，这提供了磁诱发响应确实源自中央前回激活的证据。 对于给定的刺激强度，皮质诱发反应的大小取决于穿过运动区域的线圈电流的方向。 对于 FDI 肌肉，当线圈电流从前向后并横向穿过中央沟通过运动条的横向部分时，获得最大的响应。 对于 TA 肌肉，线圈电流必须从前方经过运动带的最内侧部分。 使用阈值刺激强度，对特定肌肉的有效刺激仅限于几个线圈位置。 沿着中央前回移动线圈，可以识别运动带的体位顺序。 为了以更高的刺激强度选择性激活一个半球，开发了一种使用高导电镍铁合金片屏蔽一半线圈的方法。
The influence of coil position on the size of electromyographic responses evoked by transcranial magnetic brain stimulation was systematically evaluated. The position of the stimulation coil (11.6 cm outer diameter, Novametrix) was recorded by constructing individual grids on the skull surface using extracranial bony landmarks and was then related to underlying cerebral sulci by analysis of magnetic resonance images of the brain and skull. The largest responses in the right first dorsal interosseus (FDI) muscle, when using anticlockwise coil currents as viewed from above, were found, on average (5 subjects), to occur with the coil centred 2 cm behind and left of the vertex. For the right tibialis anterior (TA) muscle the largest responses were obtained, on average, with the coil centred around a point 4 cm anterior to and 4 cm left of the vertex. Between individuals, the optimal coil position for responses in a particular muscle varied up to 2 cm. This variability could be explained by the variability in the relationship between the central sulcus and the extracranial bony landmarks of each individual. Responses could be obtained whenever the windings of the coil passed over the appropriate region of the motor cortex, providing evidence that magnetically evoked responses do originate from activation of the precentral gyrus. The size of the cortically evoked responses for a given stimulus intensity depended on the direction of the coil currents passing over the motor area. For FDI muscles, the largest responses were obtained when the coil currents passed over the lateral part of the motor strip from forwards behind and transversely to the central sulcus. For TA muscles, the coil currents had to pass over the most medial part of the motor strip from forwards behind. Using threshold stimulus intensities, effective stimulation for a particular muscle was restricted to only a few coil positions. Moving the coil along the precentral gyrus, the somatotopic order of the motor strip could be identified. For selective activation of one hemisphere with higher stimulus intensities, a method of shielding half of the coil was developed using a sheet of highly conductive nickle-iron alloy.