Kujirai T, Sato M, Rothwell J C, Cohen L G
MRC Human Movement and Balance Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.
Electroencephalogr Clin Neurophysiol. 1993 Aug;89(4):227-34. doi: 10.1016/0168-5597(93)90100-4.
Somatosensory evoked potentials (SEPs) evoked by electrical stimulation of the median nerve at the wrist were conditioned by a preceding magnetic stimulus given over the contralateral central scalp using interstimulus intervals of 0-50 msec. The conditioning stimulus had no effect on the size of sub-cortical or N20 components of the response, but caused a large increase in the P25 parietal wave. Later components (P40/N65) of the SEP were reduced in size. The optimum position for producing the effect was with the magnetic stimulator held over the best point on the scalp for evoking muscle responses in the contralateral hand. The threshold for affecting the SEP was approximately the same as the threshold for evoking EMG responses in active hand muscles. We conclude that the magnetic conditioning shock changed the excitability of somatosensory cortex neurones involved in producing the P25. The subsequent decrease in the later components of the SEP may be related to the increase in somatosensory detection thresholds produced by a conditioning magnetic shock.
通过在手腕处电刺激正中神经诱发的体感诱发电位（SEPs），使用0 - 50毫秒的刺激间隔，由在对侧头皮中央施加的先前磁刺激进行条件化处理。条件刺激对反应的皮层下或N20成分的大小没有影响，但导致顶叶P25波大幅增加。SEP的后期成分（P40/N65）大小减小。产生该效应的最佳位置是将磁刺激器置于头皮上诱发对侧手部肌肉反应的最佳点上方。影响SEP的阈值与在活动手部肌肉中诱发肌电图反应的阈值大致相同。我们得出结论，磁条件刺激改变了参与产生P25的体感皮层神经元的兴奋性。SEP后期成分随后的减少可能与条件磁刺激产生的体感检测阈值增加有关。
