第一章
引言
　　技巧性的動作需要精確的空間與時間調控才能順利完成，像是行走時為了保持身體的平衡，兩腿交替動作的時間協調就相當重要。節律性動作的控制可以藉由外在感覺刺激的導引達到較好的表現，對於具有不正常加速步態的巴金森症病人也經常使用重複性視覺或聽覺導引來改善他們的步頻，然而在動作表現改善背後究竟有何種生理機制則並未被深入探討。

　　節律性手指動作經常被用於感覺-動作統合之研究，在過去研究中顯示聽覺導引狀況下的節律性手指動作在目標訊號與動作間似乎出現較高吻合度(synchrony)，而視覺導引狀況下之動作吻合度則較聽覺導引為差。功能性影像學研究顯示：不同感覺導引狀況下之節律性手指動作所激發的腦部活動迴路也不盡相同。然而不同感覺訊號如何影響最終動作表現則並未被明確地解析，究竟不同感覺導引所造成之動作表現差異來自感覺訊息處理迴路的不同抑或源於動作控制訊息傳遞的差異也並不瞭解。由於生理機制的不確定，使得重複性感覺導引訓練的運用性受到質疑。

　　腦電圖為傳統量測腦部活動工具，雖然由於顱骨的障蔽使得腦電圖訊號來源不容易精確地定位，但不同腦電圖電極間同調頻率的分析(coherent spectrum)仍可有效地描述大腦活動之功能性聯結；另外，在腦部活動與肌肉收縮控制間功能性聯結也發展出皮質-肌肉同調性(cortico-muscular coherence)分析。根據過去的節律動作研究，腦部活動聯結與腦部活動-肌肉收縮聯結應該會隨著不同感覺刺激而出現不同，且經由皮質-皮質同調性(cortico-cortical coherence)以及皮質-肌肉同調性能夠觀察到節律動作表現的特徵。

　　為了釐清在不同感覺刺激下大腦如何調控節律動作表現，本研究利用腦電圖-腦電圖同調性觀察大腦活動差異；運用皮質-肌肉同調性觀察大腦-脊髓間訊息傳遞是否有所不同；以變異係數分析反映節律性手指動作在不同感覺導引下之動作穩定性;最後以動作目標力矩訊號與實際動作力矩之交互相關分析比較不同感覺導引間所造成動作吻合度差異，期望能夠對於更進一步了解大腦對於不同感覺刺激與動作控制間之整合方式。

第二章
方法
　　本實驗同步量測受試者進行三種不同節律性食指動作(聽覺導引、視覺導引、自我節律)時之腦電圖、肌電圖、動作力矩等生理訊號。實驗中共選取十二名健康受試者，其中男性七人，女性五人；平均年齡為24.92±3.06歲。實驗中所使用設備如下：(1)硬體部分：腦電圖電極(Model E5GH, Grass-Telefactor, USA)、肌電圖電極(Model F-E9M-40-5, Grass-Telefactor, USA)、腦電圖、肌電圖之生理訊號放大器(Model P511, Grass-Telefactor, USA)、壓電轉換器(Model FT-10, Grass-Telefactor, USA)與力矩訊號之直流放大器(Model P122, Grass-Telefactor, USA)、類比示波器(Instek GOS-620)、節律訊號產生器(Fotek TDVY-M6)。(2)軟體部分：以Labview 7.1（National Instruments, TX, USA）為訊號收取平台、利用MatLab 6.5(The MathWorks, Inc. USA)進行訊號分析與處理，統計檢定則使用SPSS 11.0 (SPSS Inc. USA)。

　　實驗中受試者必須進行固定頻率2 Hz的右手食指外展動作，動作強度約為25%最大自主收縮力量。實驗起始姿勢為坐姿、雙臂旋前並以副木固定於桌面、雙手十指維持自然開展並放鬆。腦電圖電極黏貼於標準10-20系統之F3、C3位置，肌電圖量測電極則黏貼於右手第一背側骨間肌肌腹上。受試者之右手食指以鋼絲連接至壓電轉換器以進行動作力矩之量測。實驗中包含三種不同狀況：(1)依聲音訊號進行之手指節律動作、(2)依視覺訊號進行之手指節律動作、(3)內在自我節律之手指動作；每種實驗狀況均收取5分鐘長度之動作與生理訊號資料，並在不同受試者間以拉丁方格方式平衡施測順序。

　　訊號處理部分，腦電圖、肌電圖訊號經低通濾波後，利用Welch方式功率頻譜密度估計，分別計算腦電圖與肌電圖訊號之自譜(auto-spectrum)以及訊號間之互譜(cross-spectrum)，並計算F3腦電圖-C3腦電圖、F3腦電圖-肌電圖、C3腦電圖-肌電圖之同調性(coherence)，所得之同調性尖頻(peak coherent frequency)強度則以統計方法檢定之。對於外部動作表現的一致性評估，則利用變異係數(coefficient of variation)方式估計肌電圖線性封包(EMG linear envelope)、動作力矩、節律最大力矩時間間隔(inter-pulse interval of rhythmic peak torque)等之變異程度。使用單因子重複量數變異數分析(repeated measured one-way ANOVA)以及LSD (least significant difference)法事後多重比較進行統計檢定，比較三種不同感覺節律狀況各項參數之差異。另外對於兩種不同外在節律刺激(聽覺與視覺)情況的動作表現，則比較目標力矩訊號與實際動作力矩之交互相關(cross correlation)以及目標力矩訊號與實際動作力矩之時間延遲( time lag)，並以paired t test進行統計檢定。

第三章
結果
　　在F3腦電圖-C3腦電圖同調性部分，大部分受試者之同調性尖頻出現於8-12 Hz頻帶，單因子重複量數變異數分析結果顯示三種不同實驗狀況間之腦電圖同調性尖頻強度有所差異(p=0.032)。事後多重比較則顯示聽覺節律狀況下之F3腦電圖-C3腦電圖同調性尖頻強度顯著大於視覺節律下之F3腦電圖-C3腦電圖同調性尖頻強度(p=0.025)；但統計結果並未發現自我節律狀況之F3腦電圖-C3腦電圖同調性尖頻強度與聽覺或視覺節律狀況之腦電圖同調性尖頻強度出現顯著差異。F3腦電圖-C3腦電圖同調性分析結果並未顯示在自我節律以及外在節律狀況下之大腦皮質功能性聯結有顯著不同，然而在不同外在節律狀況下(聽覺與視覺節律)之大腦皮質功能性聯結則有顯著差異。

　　腦電圖-肌電圖同調性分析結果顯示，F3腦電圖-肌電圖同調性強度在各實驗狀況下均未達顯著水準(95%信心水準)，單因子重複量數變異數分析結果亦顯示各不同節律情形間之F3腦電圖-肌電圖同調性強度並沒有顯著差異(p>0.05)。另一方面，C3腦電圖-肌電圖同調性分析則在不同節律狀況下均於theta頻帶(2-7 Hz)出現顯著尖頻，此外重復估計單因子變異數分析顯示三種不同節律狀況間之同調性尖頻強度有顯著差異(p=0.001)；事後多重比較結果發現聽覺節律狀況與自我節律狀況之C3腦電圖-肌電圖同調性尖頻強度均大於視覺節律狀況之C3腦電圖-肌電圖同調性尖頻強度(p=0.016; p=0.003)，而聽覺節律狀況之C3腦電圖-肌電圖同調性尖頻強度與自我節律狀況之C3腦電圖-肌電圖同調性尖頻強度則沒有顯著差異(p>0.05)。腦電圖-肌電圖同調性分析結果表示在不同感覺節律狀況下大腦動作皮質與肌肉活動間的功能性聯結隨不同感覺節律而出現顯著差異。

　　變異係數分析結果發現，不論是肌電圖線性封包、動作力矩、或是節律最大力矩時間差，在三種不同節律狀況下都沒有顯著差異存在(p>0.05)，表示本實驗中受試者沒有因不同感覺節律而影響節律性手指動作之一致性。

　　聽覺節律與視覺節律狀況之目標力矩訊號與實際動作力矩之交互相關比較則發現聽覺節律狀況下之相關係數大於視覺節律狀況下之相關係數(p=0.000)。目標訊號與實際動作力矩時間延遲分析則發現聽覺節律狀況下之時間延遲為負值(-48.78±52.29毫秒)，與視覺節律狀況下之正值(41.31±72.59毫秒)達到顯著差異(p=0.011)，以上結果顯示聽覺節律狀況下之動作與節律訊號吻合度(synchrony)較視覺節律狀況來得好，並且在聽覺節律狀況下出現預期性動作的情形。

第四章
討論
　　在本實驗中發現F3腦電圖-C3腦電圖同調性尖頻出現於8-12 Hz頻帶，與之前利用腦電圖同調性研究節律性手指動作之成果相似。此一手部動作進行時之α頻帶腦電圖同調性通常出現於主要運動區、運動前區、運動輔助區等區域間，其來源可能為1)視丘中的一般節律細胞(common thalamic pacemaker)；2)運動輔助區與主要運動區間的直接聯結；處理感覺訊息的功能部位與主要運動區之間的共振活動，代表的生理意義可能為大腦中感覺-動作訊息整合之過程。另一方面，實驗中並未發現外在(聽覺、視覺)導引與自我節律狀況間F3腦電圖-C3腦電圖同調性尖頻強度之差異。除了本實驗中的動作參數與過去研究仍有些許差異以外，過去研究中也有無法辨別自我節律以及外在節律狀況下之大腦活動差異的報告。另外，本實驗發現在聽覺與視覺節律狀況下之大腦皮質功能性聯結出現顯著差異，此發現與先前功能性影像研究相呼應，顯示不同感覺導引對於動作時間控制具有特化之影響，且大腦神經迴路活動與周圍動作表現都有一致的差異表現。
　　
　　腦電圖-肌電圖同調性分析結果顯示：F3腦電圖-肌電圖同調性強度在各實驗狀況下均未達顯著水準。可能的原因為大部分(40%)動作前區直接投射至脊髓的神經元分佈於靠近內側半球部位， F3腦電圖電極所量測之活動並不包含足夠強度之訊息，以顯示動作前區直接投射至脊髓之神經活動。C3腦電圖-肌電圖同調性分析則在不同節律狀況下均於theta頻帶(2-7 Hz)出現顯著尖頻，此一節律運動所造成之C3腦電圖-肌電圖同調性頻率分佈與先前等長收縮之研究成果有明顯不同，可能由於皮質-肌肉同調性之任務特化(task-specific)性質，使得不同動作需求所產生之皮質-肌肉同調性出現頻率分佈差異；此一腦部theta頻帶活動一般認為與動作準備與動作抑制相關，可能代表大腦皮質活動對於動作節律之調控。另外，實驗中發現聽覺節律狀況與自我節律狀況之C3腦電圖-肌電圖同調性尖頻強度均大於視覺節律狀況之C3腦電圖-肌電圖同調性尖頻強度，而聽覺節律狀況之C3腦電圖-肌電圖同調性尖頻強度與自我節律狀況之C3腦電圖-肌電圖同調性尖頻強度則沒有顯著差異。腦電圖-肌電圖同調性分析結果表示在不同感覺節律狀況下大腦動作皮質與肌肉活動間的功能性聯結隨不同感覺節律而出現顯著差異。

　　在本實驗中利用變異係數分析檢定肌電圖線性封包、動作力矩、或是節律最大力矩時間差以反映節律性手指動作在不同感覺導引下之動作穩定性。結果發現，不論是肌電圖線性封包、動作力矩、或是節律最大力矩時間差，在三種不同節律狀況下都沒有顯著差異存在。可能因為實驗中每種不同感覺導引狀況均收取600次以上之動作資料，使受試者在動作過程中出現習慣適應的情形。

　　動作目標力矩訊號與實際動作力矩之交互相關比較顯示聽覺導引之動作吻合度較視覺導引狀況好，並在聽覺導引狀況下出現動作預期情形。造成動作吻合度差異之原因可能源自於視覺導引訊號需要兩側大腦半球同時活動、處理，相較於處理聽覺導引訊息的單側活動，視覺訊號處理的複雜度可能造成與內在節律活動聯結的障礙。

第五章
結論
　　本研究以皮質-皮質間同調性、皮質-肌肉間同調性、變異係數分析、動作目標力矩訊號與實際動作力矩之交互相關分析提出在聽覺、視覺導引、自我節律動作狀況下之神經活動與動作表現差異。研究結果顯示在大腦層級與大腦-脊髓層級都可發現神經網路活動的不同節律動作間的差異與在動作表現的對應變化。本實驗成果可提供將來運用重複感覺刺激進行動作訓練之學理基礎與操作參考。

　Introduction: To elucidate the physiological significance how different sensory stimuli coordinate motor performance; we examined the cortico-cortical coherence and cortico-muscular coherence, and outcome performance when subjects conducted paced finger movements in self-paced conditions or with auditory/visual cueing in the present study. Methods: Twelve healthy subjects were recruited in the experiment completed a 2 Hz right index finger paced movement (abduction) paradigm under the three cueing conditions. The EMG of first dorsal interosseous, contralateral cortical EEG (F3 and C3), and index torque during paced index abduction were recorded. Results: Significant EEGF3-EEGC3 coherence at the alpha band (8-12 Hz) was found during the three sensory paced conditions, and post-hoc analysis indicated that only EEGF3-EEGCC3 coherence between the auditory and visual cueing conditions was statistically different. Task-specific EEGC3-EMG coherence at the theta band (2-7 Hz) was noted during paced finger movement. The power of EEGC3-EMG coherence was significantly larger for the auditory condition than that for visual condition, but no statistical difference of EEGC3-EMG coherent power was found between the auditory and self-paced conditions. No marked EEGF3-EMG coherent power was noted for all paced movements. The movement consistency, in terms of coefficient of variation of torque profile, EMG linear envelope, and inter-pulse interval of rhythmic peak torque, was not different among the three experimental protocols, whereas a better sensorimotor synchronization could be achieved by means of auditory cueing. Conclusion: The present study contrasted organization of neuronal activities and task performance among the auditory, visual, and self-paced rhythmic stimuli at the cortical and corticospinal levels. The results gain a better insight into training paradigms that rely on repetitive sensory information to shape task performance effectively.

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