Xiang J, Kakigi R, Hoshiyama M, Kaneoke Y, Naka D, Takeshima Y, Koyama S
Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
Electroencephalogr Clin Neurophysiol. 1997 Sep;104(5):393-401. doi: 10.1016/s0168-5597(97)00058-0.
The somatosensory evoked magnetic fields (SEFs) and evoked potentials (SEPs) following passive toe movement were studied in 10 normal subjects. Five main components were identified in SEFs recorded around the vertex around the foot area of the primary sensory cortex (SI). The first and second components, 1M and 2M, were identified at approximately 35 and 46 ms. Equivalent current dipoles (ECDs) of both 1M and 2M were estimated around SI in the hemisphere contralateral to the movement toe, and were probably generated in area 3a or area 2, which mainly receive inputs ascending through muscle and joint afferents. The large inter-individual difference of 1M and 2M in terms of ECD orientation was probably due to a large anatomical variance of the foot area of SI. The third and fourth components, 3M and 4M, were identified at approximately 62 ms and 87 ms, respectively. They appeared to be a single large long-duration component with two peaks. Since the 3M and 4M components were significantly larger than the 1M and 2M components in amplitude and their ECD location was significantly superior to that of 1M and 2M, we suspected that they were generated in different sites from those of 1M and 2M, probably area 3b or area 4. Four components, 1E, 2E, 3E and 4E, were identified in SEPs, which appeared to correspond to 1M, 2M, 3M and 4M, respectively. The variation observed in the scalp distribution of the primary component, 1E, could be accounted for by the variation of the orientation of ECD of the 1M component. There was a large difference in the waveform of the long-latency component (longer than 100 ms) between SEFs and SEPs. The 5E of SEPs was a large amplitude component, but the 5M of SEFs was small or absent. We speculate that this long-latency component was generated by multiple generators.
对10名正常受试者进行了被动足趾运动后的体感诱发电场（SEFs）和诱发电位（SEPs）研究。在初级感觉皮层（SI）足部区域周围的头顶记录的SEFs中识别出五个主要成分。第一和第二个成分，即1M和2M，分别在约35毫秒和46毫秒时被识别出来。1M和2M的等效电流偶极子（ECDs）在运动足趾对侧半球的SI周围被估计，可能产生于3a区或2区，这两个区域主要接收通过肌肉和关节传入纤维上行的输入。1M和2M在ECD方向上的个体差异较大，可能是由于SI足部区域的解剖结构差异较大。第三和第四个成分，即3M和4M，分别在约62毫秒和87毫秒时被识别出来。它们似乎是一个具有两个峰值的单一大型长时程成分。由于3M和4M成分的振幅明显大于1M和2M成分，且其ECD位置明显高于1M和2M，我们怀疑它们是在与1M和2M不同的部位产生的，可能是3b区或4区。在SEPs中识别出四个成分，即1E、2E、3E和4E，它们似乎分别对应于1M、2M、3M和4M。在主要成分1E的头皮分布中观察到的变化可以由1M成分的ECD方向变化来解释。SEFs和SEPs的长潜伏期成分（长于100毫秒）的波形存在很大差异。SEPs的5E是一个大振幅成分，但SEFs的5M很小或不存在。我们推测这个长潜伏期成分是由多个发生器产生的。
