Cohen L G, Starr A
Brain. 1987 Apr;110 ( Pt 2):451-67. doi: 10.1093/brain/110.2.451.
Short latency somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded at different times simultaneously and after an order to move the ipsilateral thumb (0, 100, 200, 300, 400 and 780 ms). Brain potentials were derived from surface electrodes over the scalp at contralateral postcentral and precentral sites and muscle potentials were derived from surface electrodes over the thenar eminence. Ipsilateral thumb movement did not affect the early lemniscal P14 or the postcentral cortical N20 but was accompanied by attenuation of the cortical postcentral P27 and cortical precentral P22, N30 and P45. These results suggest that the gating induced by voluntary movement in man occurs at thalamocortical level and that the differential effect on postcentral N20 and precentral P22 may represent the activity of different generators. Gating of SEPs during voluntary movement begins approximately 80-100 ms before EMG onset, is maximal at the time the EMG is maximal, and returns to control values after the EMG is concluded. These results suggest that the gating that precedes the onset of EMG activity is related to premotor events in the cerebral cortex and not to centripetal influences. Gating of SEPs to median nerve stimulation was localized to movements of areas innervated by the median nerve, that is, the ipsilateral thumb, index or middle finger, but not to movements of ipsilateral little finger or contralateral thumb.
在不同时间同时记录了正中神经刺激诱发的短潜伏期体感诱发电位（SEPs），并在下达移动同侧拇指的指令后（0、100、200、300、400和780毫秒）进行记录。脑电位由头皮对侧中央后回和中央前回部位的表面电极导出，肌肉电位由鱼际隆起部位的表面电极导出。同侧拇指运动不影响早期的薄束核P14或中央后回皮质N20，但伴随着中央后回皮质P27以及中央前回皮质P22、N30和P45的衰减。这些结果表明，人类自愿运动诱发的闸门效应发生在丘脑皮质水平，对中央后回N20和中央前回P22的不同影响可能代表了不同发生器的活动。自愿运动期间SEPs的闸门效应在肌电图开始前约80 - 100毫秒开始，在肌电图最大时达到最大值，并在肌电图结束后恢复到对照值。这些结果表明，肌电图活动开始前的闸门效应与大脑皮质的运动前事件有关，而与向心影响无关。正中神经刺激诱发的SEPs的闸门效应局限于正中神经支配区域的运动，即同侧拇指、示指或中指的运动，而不是同侧小指或对侧拇指的运动。
