Department of Neuroscience, Physiology and Pharmacology, University College London (UCL), UK; Neuroscience and Behaviour Laboratory, Istituto Italiano di Tecnologia (IIT), Rome, Italy.
Department of Computer Science, University College London (UCL), UK.
Neuroimage. 2019 Sep;198:221-230. doi: 10.1016/j.neuroimage.2019.05.032. Epub 2019 May 11.
Survival in a suddenly-changing environment requires animals not only to detect salient stimuli, but also to promptly respond to them by initiating or revising ongoing motor processes. We recently discovered that the large vertex brain potentials elicited by sudden supramodal stimuli are strongly coupled with a multiphasic modulation of isometric force, a phenomenon that we named cortico-muscular resonance (CMR). Here, we extend our investigation of the CMR to the time-frequency domain. We show that (i) both somatosensory and auditory stimuli evoke a number of phase-locked and non-phase-locked modulations of EEG spectral power. Remarkably, (ii) some of these phase-locked and non-phase-locked modulations are also present in the Force spectral power. Finally, (iii) EEG and Force time-frequency responses are correlated in two distinct regions of the power spectrum. An early, low-frequency region (∼4 Hz) reflects the previously-described coupling between the phase-locked EEG vertex potential and force modulations. A late, higher-frequency region (beta-band, ∼20 Hz) reflects a second coupling between the non-phase-locked increase of power observed in both EEG and Force. In both time-frequency regions, coupling was maximal over the sensorimotor cortex contralateral to the hand exerting the force, suggesting an effect of the stimuli on the tonic corticospinal drive. Thus, stimulus-induced CMR occurs across at least two different types of cortical activities, whose functional significance in relation to the motor system should be investigated further. We propose that these different types of corticomuscular coupling are important to alter motor behaviour in response to salient environmental events.
在瞬息万变的环境中生存不仅要求动物能够察觉显著的刺激，还需要能够及时启动或修改正在进行的运动过程来对这些刺激做出反应。我们最近发现，由突发性超感觉刺激引起的大顶点脑电波与等长力的多相调制强烈耦合，我们将这种现象命名为皮质-肌肉共振（CMR）。在这里，我们将对 CMR 的研究扩展到时频域。我们表明，（i）体感和听觉刺激都会引起 EEG 频谱功率的许多锁相和非锁相调制。值得注意的是，（ii）这些锁相和非锁相调制中的一些也存在于力频谱功率中。最后，（iii）EEG 和力的时频响应在频谱功率的两个不同区域中相关。早期的低频区域（约 4 Hz）反映了之前描述的锁相 EEG 顶点电位与力调制之间的耦合。晚期的高频区域（β带，约 20 Hz）反映了在 EEG 和力中观察到的非锁相功率增加之间的第二种耦合。在这两个时频区域中，耦合在施加力的手对侧的感觉运动皮层最大，这表明刺激对紧张性皮质脊髓驱动的影响。因此，刺激诱导的 CMR 至少发生在两种不同类型的皮质活动中，其与运动系统的功能意义需要进一步研究。我们提出，这些不同类型的皮质-肌肉耦合对于改变对显著环境事件的运动行为很重要。
