本研究目的在於使用腦電波量測腦白質疏鬆症病人及單側中風偏癱病人進行手部運動時，感覺運動區腦波律動的變化情形，並探討這類病人與正常人之間的差異。腦白質疏鬆症被認為是因為腦血液灌流不足所形成，常見於頸動脈狹窄的患者，並且合併較為顯著的認知和行為障礙，如表情淡漠及判斷力、反應能力與記憶力的下降。與腦白質病人類似的是，我們發現中風偏癱病人的感覺運動皮質Mu波 (sensorimotor Mu rhythm) 也會受到影響，且這些訊號難以使用一般的數位濾波器進行有效的萃取，故本研究採用多變數經驗模態分解法 (Multivariate empirical mode decomposition, MEMD) 進行受試者運動時的腦波萃取。 多變數經驗模態分解法能夠將不同腦波通道間，具有相同頻率性質的訊號，萃取在同一個內部模態函數 (Intrinsic mode function, IMF) 中，每一個內部模態函數具有可解析、有限帶寬、自我組成的特性，非常適合於進行隨機訊號的分析。本研究募集十位中風偏癱及十位腦白質病變患者，中風病患的受試者被要求執行每一秒、兩秒及三秒一次的自主默數穩態食指上抬運動，腦白質病變病患則是七秒一次食指上抬運動。研究成果發現，在中風病人與腦白質病變病患執行食指上抬運動時，都有運動後beta band事件相關同步律動（post-movement beta ERS）能量低下的狀況，因此可以推測運動後beta band事件相關同步律動將來或許可以作為評估病人運動功能的依據。 This study aims to analyze movement-related sensorimotor Mu rhythm when leukoaraiosis patients and semi-paralyzed stroke patients were performing self-paced finger movement task. The investigation of differences between patients and normal subjects were also performed. Leukoaraiosis is a descriptive term used to describe neuroimaging findings of diffuse hemispheric white matter abnormalities mainly characterized by loss of myelin and/or ischemic injury. Leukoaraiosis is a major risk factor and prognostic factor for stroke. Similar to leukoaraiosis, we found the sensorimotor Mu rhythm in stroke patients are also affected in performing finger movement task. Since EEG signals are weak (μv) and stochastic, the use of traditional digital filter may be unable to well extract the stochastic sensorimotor rhythms which could result in the pitfall of underestimating subject’s responses. Accordingly, a novel tool, multivariate empirical mode decomposition (MEMD), was adopted in this study to exact the sensorimotor Mu rhythm in human brain. The MEMD decomposes multi-channel EEG into sets of multi-channel intrinsic mode functions (IMF). Each set contains IMFs with similar frequency range across different channels, and each IMF is analytic, band-limited, and self-organized. The superiority of MEMD enables its capability in extracting stochastic signals. This study recruited ten stroke patients and ten leukoaraiosis patients. The stroke patients were asked to continuously perform the self-paced index finger tapping tasks, and the leukoaraiosis patients were asked to perform the movement once seven seconds. Our results demonstrated that the suppressed post-movement beta event-related desynchronizations (post-movement beta ERS) were found both in stroke and leukoaraiosis patients while performing finger movement tasks. It might be expected the measure of post-movement beta ERS could be a plausible index for evaluating patients’ motor function in future clinical applications.
