Takemi M, Masakado Y, Liu M, Ushiba J
School of Fundamental Science and Technology, Graduate School of Science and Technology, Keio University, Kanagawa, Japan.
Department of Rehabilitation Medicine, Tokai University School of Medicine, Kanagawa, Japan.
Neuroscience. 2015 Jun 25;297:58-67. doi: 10.1016/j.neuroscience.2015.03.045. Epub 2015 Mar 31.
Amplitudes of mu and beta (7-26Hz) oscillations measured by electroencephalography over the sensorimotor areas are suppressed during motor imagery as well as during voluntary movements. This phenomenon is referred to as event-related desynchronization (ERD) and is known to reflect motor cortical excitability. The increased motor cortical excitability associated with ERD during hand motor imagery would induce a descending cortical volley to spinal motoneurons, resulting in facilitation of spinal motoneuronal excitability. Therefore, in the present study, we tested the association of ERD during motor imagery with the excitability of spinal motoneurons in 15 healthy participants. Spinal excitability was tested using the F-wave recorded from the right abductor pollicis brevis muscle. The F-wave results from antidromic activation of spinal motoneurons and is induced by peripheral nerve stimulation. Participants performed 5s of motor imagery of right thumb abduction following 7s of rest. The right median nerve was stimulated at wrist level when the ERD magnitude of the contralateral hand sensorimotor area exceeded predetermined thresholds during motor imagery. The results showed ERD magnitude during hand motor imagery was associated with an increase in F-wave persistence, but not with the response average of F-wave amplitude or F-wave latency. These findings suggest that the ERD magnitude may be a biomarker representing increases in the excitability of both cortical and spinal levels.
通过脑电图测量的感觉运动区μ波和β波（7 - 26赫兹）振荡的幅度，在运动想象以及自主运动期间都会受到抑制。这种现象被称为事件相关去同步化（ERD），已知它反映了运动皮层的兴奋性。在手部运动想象期间，与ERD相关的运动皮层兴奋性增加会诱发下行皮层冲动至脊髓运动神经元，从而导致脊髓运动神经元兴奋性增强。因此，在本研究中，我们测试了15名健康参与者在运动想象期间的ERD与脊髓运动神经元兴奋性之间的关联。使用从右侧拇短展肌记录的F波来测试脊髓兴奋性。F波是由脊髓运动神经元的逆向激活产生的，由外周神经刺激诱发。参与者在休息7秒后进行5秒的右手拇指外展运动想象。当对侧手部感觉运动区的ERD幅度在运动想象期间超过预定阈值时，在腕部水平刺激右侧正中神经。结果显示，手部运动想象期间的ERD幅度与F波持续性增加相关，但与F波振幅或F波潜伏期的反应平均值无关。这些发现表明，ERD幅度可能是代表皮层和脊髓水平兴奋性增加的生物标志物。
