Functional role of mirror neuron system on human movement

本研究通过以下实验探讨了镜像神经元系统在人体运动中的功能作用。(1)为了探讨基于初级运动皮层镜像神经元系统（MNS）的镜像盒（MB）疗法的效果，我们研究了直接（无镜像）和间接（有镜像）观察健康受试者自我运动对经颅磁刺激（TMS）诱发的运动诱发电位（MEP）变化的影响。mep来自第一背骨间肌（FDI）和桡侧腕屈肌（FCR）。观察自我运动时的体感诱发电位（SEPs）。在有和没有镜子的情况下，自我运动的观察结果都增加了MEP振幅。在有镜子和没有镜子的自我运动观察中，SEPs的增加与MEPs相似。我们得出的结论是，尽管MN系统可以通过观察自我运动来激活，其方式与观察另一个人的运动类似，但对皮质脊髓兴奋性没有可检测到的影响，这是通过镜子观察到的运动所特有的。(2)研究了不同音量朗读任务对右、左撇子手运动皮层兴奋性的影响。将tms分别应用于两个手部运动皮层，并记录所有受试者的两个FDI肌肉的mep。结果发现，在正常对话中，无论被试的惯用手是什么，在音量朗读任务中，手运动皮层的双侧促进都是存在的。与阅读任务相比，下颚肌的弱激活不影响双脑半球手部运动皮层的兴奋性。这意味着在阅读任务中，口腔运动皮层的激活和下颌肌肉传入事件的激活几乎不参与手运动皮层的兴奋性。此外，观察另一个人阅读任务的视频片段也诱导了双侧手运动皮层的易化。与右手运动皮层相比，左手运动皮层的兴奋性增加在大声阅读任务中得到了证实，正如之前报道的那样。研究结果表明，阅读诱导的双侧手运动皮层易化可能是由MNS激活引起的。此外，我们还讨论了在日常生活对话中经常观察到的双手手势与手势的关系。(3) 3球级联视频片段观察对经颅磁刺激诱发MEP评价的带状运动皮层兴奋性的影响。从FDI和对手政策（OP）肌肉中记录meps。实验条件为：1)运动想象与视频片段观察（真实），2)运动想象与视频片段观察（无球玩3个球级联）（假），3)自我运动想象与3个球级联。在实际条件下，FDI和OP对MEPs的提升都最大。增强程度依次是在自我状态下，然后是假状态下。这些结果表明，视频剪辑观察如此复杂和困难的动作有助于形成运动意象而不是自我运动意象。有趣的是，假动作对运动意象没有太大影响。这一结果与前人的研究结果相吻合。少

In this study, functional role of mirror neuron system on human movement was investigated in the following experiments.(1) To explore the effect of mirror box (MB) therapy based on the mirror neuron system (MNS) of the primary motor cortex, we examined if direct (without a mirror) and indirect (with a mirror) observation of self-movement in healthy subjects induced changes in motor evoked potential (MEP) evoked by transcranial magnetic stimulation (TMS). MEPs were elicited from the first dorsal interosseous (FDI) and the flexor carpi radialis (FCR) muscles. Somatosensory evoked potentials (SEPs) during self-movement observation were also recorded. Both observations of self-movement with and without a mirror increased MEP amplitude. The SEPs increased similar to the MEPs during both observations of self-movement with and without a mirror. We conclude that although the MN system can be activated by observing self-movement in a manner similar to that achieved by observing movement of anot … More her person, there were no detectable effect on corticospinal excitability that were specific to movements observed with a mirror.(2) We investigated the effect of reading tasks at different vocal volumes on the excitability of hand motor cortex assessed by TMS-induced MEP in both right- and left-handed subjects. TMSs were applied to both hand motor cortices, respectively, and MEPs were recorded from both FDI muscles in all subjects. As a result, we found the bilateral facilitation of the hand motor cortices during the reading task at vocal volume in the normal conversations irrespective of subject's dominant hand. Weak activation of the jaw muscle comparable with the reading task did not affect the excitability of hand motor cortices of the bilateral hemispheres. This means that the activation of the oral motor cortex and the activation of the jaw muscle afferents hardly contribute to the excitability of hand motor cortex during the reading task. Furthermore, observation for video clip of another person's reading task also induced the bilateral facilitation of hand motor cortices. Increased excitability of left hand motor cortex compared to that of right motor cortex was confirmed during the reading loud task in the right-handed subjects only, as previously reported. Findings suggest the reading-induced bilateral facilitation of hand motor cortices which may be caused by the activation of MNS. Further, we discussed the relation to bimanual band gesture often observed in conversations in daily life.(3) Effect of video clip observation in which a person plays 3 balls cascade on the excitability of band motor cortex assessed by TMS-induced MEP. MEPswere recorded from FDI and opponens pollicis (OP) muscle. Experimental conditions were, 1) motor imagery with video clip observation (real), 2) motor imagery with video clip observation in which a person plays 3 balls cascade without balls (fake) and 3) self motor imagery for 3 balls cascade. The most enhancements of MEPs in both FDI and OP were found in real condition. Degrees of enhancement were ordered in self and then fake condition. These results suggest that the video clip observation of such a complex and difficult action help to make motor imagery rather than self motor imagery for that. Interestingly, fake action does not have much effect to make motor imagery. This result well corresponds to the previous studies which show the properties of MNS. Less