Kakigi R, Koyama S, Hoshiyama M, Watanabe S, Shimojo M, Kitamura Y
Laboratory for Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
J Neurol Sci. 1995 Feb;128(2):195-204. doi: 10.1016/0022-510x(94)00230-l.
The "gating" effects caused by active finger movements on somatosensory evoked magnetic fields (SEFs) following stimulation of the median nerve were examined in normal subjects. The effects of the interfering stimulus were best demonstrated by subtracting the "interference" wave forms from the "control" wave forms to derive the "difference" wave form. The short-latency cortical deflections, N20m-P20m, P30m-N30m and P25m-N35m were significantly attenuated with no latency changes. In contrast, the following middle-latency deflections, the N40m-P40m and the P60m-N60m were clearly changed in terms of latency and duration by the interference. The D30m-U30m and the U60m-D60m in the "difference" wave form were derived from these interference changes. It is considered that the gating effects on all deflections took place in the hemisphere contralateral to the stimulated median nerve, because all of the equivalent current dipoles (ECDs) of the short- and the middle-latency deflections in the "control", "interference" and "difference" wave forms were located there. The gating effects on the short-latency deflections were suggested to be due to the interactions between the neurons in areas 1 and 3b, which were activated by sensory inputs from cutaneous mechanoreceptors, and the neurons in area 3a which were activated by sensory inputs from the muscle spindles. The gating effects on the middle-latency deflections may mainly be due to the excitations of neurons in area 4 caused by either continuous movement-related activities or by sensory inputs spreading from the sensory cortex.
在正常受试者中，研究了主动手指运动对正中神经刺激后体感诱发磁场（SEF）产生的“门控”效应。通过从“对照”波形中减去“干扰”波形以得到“差异”波形，能最好地显示干扰刺激的效应。短潜伏期皮层偏转，即N20m - P20m、P30m - N30m和P25m - N35m显著减弱，潜伏期无变化。相比之下，随后的中潜伏期偏转，即N40m - P40m和P60m - N60m，在潜伏期和持续时间方面因干扰而明显改变。“差异”波形中的D30m - U30m和U60m - D60m源自这些干扰变化。据认为，对所有偏转的门控效应发生在受刺激正中神经对侧的半球，因为“对照”、“干扰”和“差异”波形中短潜伏期和中潜伏期偏转的所有等效电流偶极子（ECD）都位于该半球。对短潜伏期偏转的门控效应被认为是由于1区和3b区的神经元之间的相互作用，这些神经元由皮肤机械感受器的感觉输入激活，以及3a区的神经元由肌梭的感觉输入激活。对中潜伏期偏转的门控效应可能主要是由于连续的运动相关活动或从感觉皮层扩散的感觉输入引起的4区神经元的兴奋。
