空间频率对视觉诱发磁场影响的脑磁图研究

目的 用脑磁图来研究人脑视皮质对不同空间频率黑白棋盘格翻转刺激所产生视觉诱发磁场成分之一的M100的影响，包括峰值潜伏期、振幅和源位置三方面。方法 测定9例健康志愿者对视角分别为25’、40’、50’、60’、80’、120’和240'的半视野棋盘格刺激的磁场反应。结果 格大小对M100峰值潜伏期和振幅的影响有显著统计学意义(P＜0．05)。随着格变小，M100峰值潜伏期延长、振幅减小。偶极源位于刺激野对侧的枕叶距状裂附近。结论 不同空间频率的棋盘格刺激对M100峰值潜伏期、振幅的影响均有显著意义，但对源位置无显著影响。

Magnetoencephalography Research on Effects of Spatial Frequency on Pattern Reversal Visual Evoked Magnetic Field

Objective To evaluate the effects of spatial frequency on pattern reversal visual evoked magnetic field by using magnetoencephalography. Methods Half field pattern reversal stimuli with check sizes of 25',40',50',60',80',120' and 240' of visual arch were given to 9 healthy subjects. Results The effects of the check size on M100 latency and amplitude were significant ( P <0.05).The smaller the check size was,the longer the latency was and the smaller the amplitude was.The equivalent current dipoles were located around the calcarine fissure contralateral to the stimulated visual field. Conclusion The effects of spatial frequency are significant on the latency and amplitude of M100,but not significant on the localization.