Department of Psychiatry, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Neurosci Lett. 2010 Jul 12;478(3):141-5. doi: 10.1016/j.neulet.2010.05.004. Epub 2010 May 7.
The mu rhythm is regarded as a physiological indicator of the human mirror neuron system (MNS). The dysfunctional MNS hypothesis in patients with autistic spectrum disorder (ASD) has often been tested using EEG and MEG, targeting mu rhythm suppression during action observation/execution, although with controversial results. We explored neural activity related to the MNS in patients with ASD, focusing on power increase in the beta frequency band after observation and execution of movements, known as post-movement beta rebound (PMBR). Multiple source beamformer (MSBF) and BrainVoyager QX were used for MEG source imaging and statistical group analysis, respectively. Seven patients with ASD and ten normal subjects participated in this study. During the MEG recordings, the subjects were asked to observe and later execute object-related hand actions performed by an experimenter. We found that both groups exhibited pronounced PMBR exceeding 20% when observing and executing actions with a similar topographic distribution of maximal activity. However, significantly reduced PMBR was found only during the observation condition in the patients relative to controls in cortical regions within the MNS, namely the sensorimotor area, premotor cortex and superior temporal gyrus. Reduced PMBR during the observation condition was also found in the medial prefrontal cortex. These results support the notion of a dysfunctional execution/observation matching system related to MNS impairment in patients with ASD, and the feasibility of using MEG to detect neural activity, in particular PMBR abnormalities, as an index of MNS dysfunction during performance of motor or cognitive tasks.
mu 节律被认为是人类镜像神经元系统（MNS）的生理指标。自闭症谱系障碍（ASD）患者的 MNS 功能障碍假说经常通过 EEG 和 MEG 进行测试，针对的是在观察/执行动作期间抑制 mu 节律，尽管结果存在争议。我们探索了 ASD 患者的 MNS 相关神经活动，重点关注观察和执行运动后的 beta 频带功率增加，称为运动后 beta 反弹（PMBR）。使用多源波束形成器（MSBF）和 BrainVoyager QX 分别进行 MEG 源成像和统计组分析。七名 ASD 患者和十名正常受试者参加了这项研究。在 MEG 记录期间，要求受试者观察并随后执行由实验者执行的与物体相关的手部动作。我们发现，当观察和执行具有相似最大活动拓扑分布的动作时，两组都表现出明显的 PMBR 超过 20%。然而，与对照组相比，患者在观察条件下仅在 MNS 内的皮质区域（即感觉运动区、前运动皮层和颞上回）中发现 PMBR 显著降低。在观察条件下，内侧前额叶皮层也发现了 PMBR 降低。这些结果支持了 ASD 患者的 MNS 损伤与执行/观察匹配系统功能障碍的观点，以及使用 MEG 检测神经活动，特别是 PMBR 异常，作为执行运动或认知任务期间 MNS 功能障碍的指标的可行性。
