Onishi Hideaki, Sugawara Kazuhiro, Yamashiro Koya, Sato Daisuke, Kirimoto Hikari, Tamaki Hiroyuki, Shirozu Hiroshi, Kameyama Shigeki
Institute for human movement and medical sciences, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata, 950-3198, Japan.
Department of Neurosurgery, Nishi-Niigata Chuo National Hospital, Niigata, Japan.
Eur J Neurosci. 2016 Aug;44(4):2104-13. doi: 10.1111/ejn.13317. Epub 2016 Jul 11.
Magnetoencephalography (MEG) recordings were performed to investigate the inhibitory effects of conditioning stimuli with various types of interstimulus intervals (ISIs) or intensities on somatosensory evoked magnetic fields (SEFs) using a 306-ch whole-head MEG system. Twenty-three healthy volunteers participated in this study. Electrical stimuli were applied to the right median nerve at the wrist. Six pulse trains with ISIs of 500 ms were presented in Experiment 1. A paired-pulse paradigm with three kinds of conditioning stimulus (CON) intensities, 500 ms before the test stimulus (TS), was applied in Experiment 2. Finally, three CONs 500 or 1000 ms before TS were presented in Experiment 3. Three main SEF deflections (N20m, P35m, and P60m) were observed, and the source activities of P35m and P60m significantly decreased after the 2nd pulse of a six pulse trains. These source activities also significantly decreased with increasing intensity of CON. In addition, these attenuations of source activities were affected by CON-CON or CON-TS intervals. These results indicated that the source activities were modulated by the intensity and ISIs of CONs. Furthermore, P35m after the stimulation were very sensitive to CONs; however, the attenuation of P60m after the stimulation lasted for a longer period than that of P35m. Our findings suggest that the conditioning stimulation had inhibitory effects on subsequent evoked cortical responses for more than 500 ms. Our results also provide important clues about the nature of short-latency somatosensory responses in human studies.
采用306通道全头型脑磁图（MEG）系统进行脑磁图记录，以研究不同类型的刺激间隔（ISI）或强度的条件刺激对体感诱发磁场（SEF）的抑制作用。23名健康志愿者参与了本研究。在手腕处对右侧正中神经施加电刺激。实验1中呈现了6组ISI为500毫秒的脉冲序列。实验2采用了配对脉冲范式，在测试刺激（TS）前500毫秒施加三种强度的条件刺激（CON）。最后，实验3中在TS前500或1000毫秒呈现三个CON。观察到三个主要的SEF偏转（N20m、P35m和P60m），在六脉冲序列的第二个脉冲后，P35m和P60m的源活动显著降低。这些源活动也随着CON强度的增加而显著降低。此外，源活动的这些衰减受CON - CON或CON - TS间隔的影响。这些结果表明源活动受CONs的强度和ISI调制。此外，刺激后的P35m对CONs非常敏感；然而，刺激后P60m的衰减持续时间比P35m更长。我们的研究结果表明，条件刺激对随后诱发的皮层反应具有超过500毫秒的抑制作用。我们的结果也为人类研究中短潜伏期体感反应的性质提供了重要线索。
