Zheng Yang, Zheng Bofang, Qiang Wei, Peng Yu, Xu Guanghua, Wang Gang, Li Lili, Shin Henry
Institute of Engineering and Medicine Interdisciplinary Studies and the State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China.
Institute of Engineering and Medicine Interdisciplinary Studies and the State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China.
Neuroimage. 2025 Jan;305:120999. doi: 10.1016/j.neuroimage.2024.120999. Epub 2025 Jan 1.
The monosynaptic cortico-motoneuronal connections suggest the possibility of individual motor units (MUs) receiving independent commands from motor cortex. However, previous studies that used corticomuscular coherence (CMC) between electroencephalogram (EEG) signals and electromyogram (EMG) signals have not directly explored the corticospinal functionality at the single motoneuron level. The objective of this study is to find out whether synchronous activities exist between the motor cortex and individual MUs. Corticomuscular coherence was calculated between the EEG signals and the MU firing event trains which were extracted using the EMG decomposition technique. The results showed that some but not all MUs indeed had significant coherent activities with the contralateral motor cortex, which we named the cortico-motoneuronal coherence (CMnC). In contrast to the CMC only occurring in β and γ bands, CMnC occurred across the four common EEG frequency bands (θ, α, β and γ). Further, we identified individual MUs that showed significant interactions with the motor cortex. These coherent MUs (CohMU) could still be found even when the EMG signals were not coupled with the cortical activities. Compared with conventional CMC, our preliminary results indicated that the CMnC could potentially help to investigate the complex coupling between cortical and muscular activities due to its ability to separate different correlated components. This study proves that corticomuscular coherence exists at a single MU level, which provides a new perspective for the research on corticomuscular coupling. Further study on the CMnC could help deepen our understanding of the neural control of movement.
单突触皮质 - 运动神经元连接提示了单个运动单位（MU）从运动皮层接收独立指令的可能性。然而，以往利用脑电图（EEG）信号与肌电图（EMG）信号之间的皮质 - 肌肉相干性（CMC）进行的研究，并未直接在单个运动神经元水平上探究皮质脊髓功能。本研究的目的是查明运动皮层与单个运动单位之间是否存在同步活动。在EEG信号与使用EMG分解技术提取的运动单位放电事件序列之间计算皮质 - 肌肉相干性。结果表明，部分而非全部运动单位确实与对侧运动皮层存在显著的相干活动，我们将其命名为皮质 - 运动神经元相干性（CMnC）。与仅在β和γ频段出现的CMC不同，CMnC在四个常见的EEG频段（θ、α、β和γ）均有出现。此外，我们识别出了与运动皮层表现出显著相互作用的单个运动单位。即使EMG信号未与皮层活动耦合，仍能发现这些相干运动单位（CohMU）。与传统的CMC相比，我们的初步结果表明，CMnC由于能够分离不同的相关成分，可能有助于研究皮质和肌肉活动之间的复杂耦合。本研究证明了皮质 - 肌肉相干性存在于单个运动单位水平，为皮质 - 肌肉耦合研究提供了新的视角。对CMnC的进一步研究有助于深化我们对运动神经控制的理解。
