臺灣博碩士論文加值系統

研究是利用128通道全腦式腦磁圖儀來探討人類大腦聽覺皮質反應，在本文中我們著重討論在不同頻率的聲音刺激下，聽覺誘發的開端反應on-N1m與終端反應off-N1m的時間以及空間演化特性。總共有6位自願性的受測者參加這個試驗，我們將受測者利用左耳及右耳聆聽250, 500, 1000, 2000 (Hz)的單調音時所產生的聽覺誘發磁場記錄下來。
我們成功的利用腦磁圖儀擷取到受測者左腦和右腦的聽覺誘發磁場，發現耳朵接收到不同頻率的聲音刺激後，左右腦都會產生清楚的on-N1m訊號。不同於on-N1m，大腦在接收到左耳的聲音刺激結束後，由對側腦誘發的off-N1m的機率比同側腦誘發的還要顯著許多，但是右耳接受到聲音刺激後，對側腦跟同側腦誘發off-N1m的機率卻沒有顯著差異。
計算出左腦和右腦聽覺誘發磁場在每一個時刻的mean global field power (MGFP)，再利用MGFP隨著時間變化的波形來判斷反應的持續時間以及反應最顯著的時刻，接著再統計出所有受測者聽覺誘發磁場on-N1m與off-N1m等效電流偶極(equivalent current dipole, ECD)模型反應最大的時刻。
利用單一等效電流偶極模型可以良好的模擬左腦和右腦的聽覺誘發磁場，藉以推算出可能產生on-N1m與off-N1m反應的神經細胞所在區域。分析MGFP在on-N1m與off-N1m反應的峰值時刻前後5 ms所對應的等效電流偶極最大值，發現兩者的位置都在大腦顳上回附近，但是off-N1m的活化區域較on-N1m分布在更為深層之處，顯示on-N1m與off-N1m可能是由不同的神經細胞群所產生。
進一步我們分析等效電流偶極的位置隨時間的變化，藉以探討神經網路可能的傳導路徑，發現右腦產生的on-N1m與off-N1m對應的等效電流偶極隨著時間都會從大腦中間到大腦側邊的方向前進，而兩者的動態變化路線都會因為聲音的特性頻率不同而有所改變，顯示除了on-N1m以外，off-N1m也有其獨特的頻率拓撲。

致謝 1
摘要 2
目錄 4
1. 緒論 6
1.1 腦磁圖研究 6
1.2 大腦的聽覺誘發磁場：開端反應 8
1.3 大腦的聽覺誘發磁場：終端反應 10
2. 研究動機與實驗方法 11
2.1 研究動機 11
2.2 腦磁圖儀系統 12
2.3 受測者 13
2.4 聲音刺激 15
2.5 受測者頭部座標的標定 16
2.6 聲音刺激誘發腦磁訊號(Auditory Evoked Field, AEF)量測 21
2.7 數據分析 22
3. 結果與討論 28
4. 結論 41
參考文獻 42
附錄1 愛丁堡慣用手量表 44

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