Kastner S, Demmer I, Ziemann U
Department of Psychiatry, University of Göttingen, Germany.
Exp Brain Res. 1998 Jan;118(1):19-26. doi: 10.1007/s002210050251.
Transient visual field defects (VFDs) and phosphenes were induced in normal volunteers by means of transcranial magnetic stimulation (TMS) using a circular magnetic coil of 12.5 cm diameter placed with its lower rim 2-4 cm above the inion in the midline. Subjects had to detect small, bright dots presented randomly for 14 ms in one of 60 locations on a computer screen resulting in a plot of the central 9 degrees of the visual field. In 8 of 17 subjects, transient VFDs were inducible at peak magnetic field strenghts of 1.1-1.4 T. In the central 1-3 degrees, detection of targets was impaired in both the upper and lower visual field, whereas at 4-9 degrees large parts of only the lower visual field were affected with a sharp cut-off along the horizontal meridian. Targets at 1 degree in the lower field were affected with lower TMS intensities than corresponding locations in the upper or peripheral locations in the lower field. Detection of central targets was affected at more caudal stimulation sites than detection of peripheral targets. Phosphenes were elicitable in 14 of 17 subjects at clearly lower field strengths of 0.6-1.0 T. Many subjects perceived chromatophosphenes. From a discussion of the literature on patients with VFDs and the known topography of the human visual system, it is concluded that the transient VFDs at 1-3 degrees are probably due to stimulation of both striate cortex (V1) and extrastriate areas (V2/V3), while VFDs in the lower visual field at eccentricities 4-9 degrees are due to stimulation of V2/V3 but not V1.
通过经颅磁刺激（TMS）在正常志愿者中诱发短暂性视野缺损（VFDs）和光幻视。使用直径为12.5 cm的圆形磁线圈，将其下缘置于中线枕外隆凸上方2 - 4 cm处。受试者必须检测在计算机屏幕上60个位置之一随机呈现14毫秒的小亮点，从而绘制出中央9度视野图。在17名受试者中的8名中，在1.1 - 1.4 T的峰值磁场强度下可诱发短暂性VFDs。在中央1 - 3度，上半视野和下半视野中目标的检测均受到损害，而在4 - 9度时，仅下半视野的大部分区域受到影响，沿水平子午线有明显的界限。下半视野中1度处的目标比上半视野或下半视野周边相应位置的目标受到更低TMS强度的影响。中央目标的检测在比周边目标更靠尾侧的刺激部位受到影响。在17名受试者中的14名中，在明显更低的0.6 - 1.0 T磁场强度下可诱发光幻视。许多受试者感知到了彩色光幻视。通过对有关VFDs患者的文献以及人类视觉系统已知地形图的讨论，可以得出结论，1 - 3度的短暂性VFDs可能是由于纹状皮层（V1）和纹外区域（V2/V3）均受到刺激，而偏心率为4 - 9度的下半视野中的VFDs是由于V2/V3受到刺激而非V1。
