Meyer B U, Diehl R, Steinmetz H, Britton T C, Benecke R
Department of Neurology, University of Düsseldorf, F.R.G.
Electroencephalogr Clin Neurophysiol Suppl. 1991;43:121-34.
Transcranial magnetic stimulation was performed over the motor and visual cortex with the Novametrix 12-cm diameter stimulation coil. The influence of coil position on the size of electromyographic responses and on the intensity and position of phosphenes in the binocular visual field was studied. Furthermore, it was investigated whether stimulation over the visual cortex or over the frontal eye field evoked or disturbed eye movements. Coil position was recorded by constructing grids on the skull surface using extracranial bony landmarks, and was then related individually to underlying cerebral sulci by analysis of magnetic resonance images of the brain. Motor responses. Excitatory effects were maximal when the coil windings in the middle of the coil ring lay over the particular motor representation field of area 4. The response size depended on the direction of the coil currents passing over the motor cortex. For example, coil currents passing over the lateral part of the precentral gyrus from the front and transversely to the central sulcus elicited maximal responses in hand muscles. With the currents passing over the same area in the opposite direction, response amplitudes were much smaller, suggesting activation of different inputs to cortical motoneurons. Phosphenes. Fields of fixed, white and unstructured phosphens occurred in the lower half of the visual field when the coil center was placed about 7 cm anterior to the inion on the inion-nasion line. Counterclockwise or clockwise coil currents elicited phosphenes within the left or right lower quadrant of the binocular visual field, respectively, which could be attributed to an activation of the right or left primary visual cortex (area 17). The 'cortical' phosphenes moved with voluntary eye movements, but not during caloric and optokinetic nystagmus. Phosphenes resulting from an excitation of the optic nerve rather than the retina could be evoked by stimulation over frontal parts of the skull. Eye movements. The application of single magnetic field pulses over the frontal eye field or over the visual cortex did not elicit eye movements except for small vertical eye movements as part of a magnetically elicited blink.
使用直径为12厘米的Novametrix刺激线圈对运动皮层和视觉皮层进行经颅磁刺激。研究了线圈位置对肌电图反应大小以及双眼视野中光幻视的强度和位置的影响。此外，还研究了在视觉皮层或额叶眼区进行刺激是否会诱发或干扰眼球运动。通过使用颅外骨性标志在颅骨表面构建网格来记录线圈位置，然后通过分析脑部磁共振图像将其分别与下方的脑沟相关联。运动反应。当线圈环中部的线圈绕组位于4区特定的运动代表区上方时，兴奋效应最大。反应大小取决于通过运动皮层的线圈电流方向。例如，从前方向中央沟横向通过中央前回外侧部分的线圈电流在手肌肉中引起最大反应。当电流以相反方向通过同一区域时，反应幅度要小得多，这表明激活了不同的皮质运动神经元输入。光幻视。当线圈中心位于枕外隆凸 - 鼻根线上枕外隆凸前方约7厘米处时，在视野下半部分出现固定、白色且无结构的光幻视区域。逆时针或顺时针的线圈电流分别在双眼视野的左下象限或右下象限诱发光幻视，这可归因于右侧或左侧初级视觉皮层（17区）的激活。“皮质”光幻视随自主眼球运动而移动，但在冷热性眼震和视动性眼震期间不移动。通过刺激颅骨前部可诱发由视神经而非视网膜兴奋引起的光幻视。眼球运动。除了作为磁诱发眨眼一部分的小垂直眼球运动外，在额叶眼区或视觉皮层施加单个磁场脉冲不会诱发眼球运动。
