Coll Michel-Pierre, Press Clare, Hobson Hannah, Catmur Caroline, Bird Geoffrey
Department of Experimental Psychology, University of Oxford, Oxford SE5 8AF, United Kingdom,
MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, University of London, London SE5 8AF, United Kingdom.
J Neurosci. 2017 Jun 14;37(24):5936-5947. doi: 10.1523/JNEUROSCI.3393-16.2017. Epub 2017 May 30.
The alpha mu rhythm (8-13 Hz) has been considered to reflect mirror neuron activity because it is attenuated by both action observation and action execution. The putative link between mirror neuron system activity and the mu rhythm has been used to study the involvement of the mirror system in a wide range of socio-cognitive processes and clinical disorders. However, previous research has failed to convincingly demonstrate the specificity of the mu rhythm, meaning that it is unclear whether the mu rhythm reflects mirror neuron activity. It also remains unclear whether mu rhythm suppression during action observation reflects the processing of motor or tactile information. In an attempt to assess the validity of the mu rhythm as a measure of mirror neuron activity, we used crossmodal pattern classification to assess the specificity of EEG mu rhythm response to action varying in terms of action type (whole-hand or precision grip), concurrent tactile stimulation (stimulation or no stimulation), or object use (transitive or intransitive actions) in 20 human participants. The main results reveal that above-chance crossmodal classification of mu rhythm activity was obtained in the central channels for tactile stimulation and action transitivity but not for action type. Furthermore, traditional univariate analyses applied to the same data were insensitive to differences between conditions. By calling into question the relationship between mirror system activity and the mu rhythm, these results have important implications for the use and interpretation of mu rhythm activity. The central alpha mu rhythm oscillation is a widely used measure of the human mirror neuron system that has been used to make important claims concerning cognitive functioning in health and in disease. Here, we used a novel multivariate analytical approach to show that crossmodal EEG mu rhythm responses primarily index the somatosensory features of actions, suggesting that the mu rhythm is not a valid measure of mirror neuron activity. Results may lead to the revision of the conclusions of many previous studies using this measure, and to the transition toward a theory of mu rhythm function that is more consistent with current models of sensory processing in the self and in others.
α-μ节律（8-13赫兹）被认为反映了镜像神经元活动，因为它在动作观察和动作执行时都会减弱。镜像神经元系统活动与μ节律之间的假定联系已被用于研究镜像系统在广泛的社会认知过程和临床疾病中的参与情况。然而，先前的研究未能令人信服地证明μ节律的特异性，这意味着尚不清楚μ节律是否反映镜像神经元活动。同样不清楚的是，动作观察期间μ节律的抑制是否反映了运动信息或触觉信息的处理。为了评估μ节律作为镜像神经元活动指标的有效性，我们使用跨模态模式分类来评估20名人类参与者中脑电图μ节律对动作类型（全手抓握或精准抓握）、同时进行的触觉刺激（刺激或无刺激）或物体使用（及物或不及物动作）不同的动作的反应特异性。主要结果表明，在中央通道中，对于触觉刺激和动作及物性，μ节律活动的跨模态分类高于随机水平，但对于动作类型则不然。此外，应用于相同数据的传统单变量分析对不同条件之间的差异不敏感。通过质疑镜像系统活动与μ节律之间的关系，这些结果对μ节律活动的使用和解释具有重要意义。中央α-μ节律振荡是一种广泛用于测量人类镜像神经元系统的方法，已被用于对健康和疾病中的认知功能做出重要论断。在这里，我们使用一种新颖的多变量分析方法表明，跨模态脑电图μ节律反应主要索引动作的体感特征，这表明μ节律不是镜像神经元活动的有效指标。结果可能导致许多先前使用该指标的研究结论的修订，并促使向一种与当前自我和他人感觉加工模型更一致的μ节律功能理论转变。
