Shimojo M, Kakigi R, Hoshiyama M, Koyama S, Kitamura Y, Watanabe S
Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
Neurosci Res. 1996 Jan;24(2):175-81. doi: 10.1016/0168-0102(95)00994-9.
Somatosensory evoked magnetic fields (SEFs) following stimulation of the median nerves bilaterally ('bilateral' waveform) were examined in normal subjects to determine the interference effects of activation of sensory areas in bilateral hemispheres. SEFs following right median nerve stimulation and those following left median nerve stimulation were summated ('summated' waveform). A 'difference' waveform was induced by subtraction of the 'bilateral' waveform from 'summated' waveform. Short-latency deflections showed no consistent differences between the 'summated' and 'bilateral' waveforms, but the middle-latency deflection. N60m-P60m, in the 'bilateral' waveform was significantly (P < 0.01) smaller than that in the 'summated' waveform. The long-latency deflection, the N90m-P90m, in the 'bilateral' waveform was markedly (P < 0.001) reduced in amplitude as compared with the 'summated' waveform. The differences were clearly identified in the 'difference' waveform, in which the main deflections, U90m-D90m, were found in all subjects. Equivalent current dipoles (ECDs) of the short- and middle-latency deflections were located in the primary sensory cortex (SI) contralateral to the stimulated nerve, but ECDs of the N90m-P90m and U90m-D90m were located in bilateral second sensory cortices (SII) which are considered to receive ascending signals from bilateral sides of the body.
在正常受试者中，检查双侧正中神经刺激后体感诱发磁场（SEF）（“双侧”波形），以确定双侧半球感觉区激活的干扰效应。将右侧正中神经刺激后的SEF与左侧正中神经刺激后的SEF进行叠加（“叠加”波形）。通过从“叠加”波形中减去“双侧”波形来诱发“差值”波形。短潜伏期偏转在“叠加”波形和“双侧”波形之间未显示出一致差异，但“双侧”波形中的中潜伏期偏转N60m - P60m明显（P < 0.01）小于“叠加”波形中的该偏转。与“叠加”波形相比，“双侧”波形中的长潜伏期偏转N90m - P90m的幅度明显（P < 0.001）降低。这些差异在“差值”波形中清晰可见，所有受试者均出现主要偏转U90m - D90m。短潜伏期和中潜伏期偏转的等效电流偶极（ECD）位于受刺激神经对侧的初级感觉皮层（SI），但N90m - P90m和U90m - D90m的ECD位于双侧第二感觉皮层（SII），被认为接收来自身体双侧的上行信号。
