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Author: 蕭翔友
Thesis Title: 利用128通道低溫超導腦磁儀研究大腦聲音的認知行為
Advisor: 楊鴻昌
Yang, Hong-Chang
洪姮娥
Horng, Herng-Er
Degree: 碩士
Master
Department: 光電工程研究所
Graduate Institute of Electro-Optical Engineering
Thesis Publication Year: 2009
Academic Year: 97
Language: 中文
Number of pages: 46
Keywords (in Chinese): 腦磁儀,聲音認知
Thesis Type: Academic thesis/ dissertation
Reference times: Clicks: 163Downloads: 0
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  • 人腦接受到聲音刺激,造成神經元活化,因神經元的活化繼而產生電流,使用128通道腦磁儀量測其產生的磁場,再藉由磁場訊號反推出電流密度分佈區域,即可得知大腦接受刺激時,神經元活化的區域。此法因不用外加磁場,也沒有輻射的危險,用於醫學研究探討,是十分安全的儀器。
    實驗主要使用一段長度300 ms、 500 Hz、73分貝的單調音讓受測者的單耳接受聲音刺激,在SQUID感測元件所量測到的人腦磁場訊號中,可以發現當聲音開始以後的100 ms附近會產生峰值,稱為N100m on-response,在聲音結束的100 ms 附近也會產生峰值,稱為N100m off-response。而128通道腦磁儀可以在毫秒的時間等級接收到磁場訊號,故擁有較佳時間的解析度。即是,腦部接收刺激訊號後,可以在毫秒的時間等級,觀察在人腦內部神經元活化的傳遞行為。
    在分析上面使用一套軟體CURRY,由獨立成份分析法(independent component analysis)挑出雜訊,找出主要成份:N100m on-response、N100m off-response磁場訊號,計算電流偶極子(current dipole)的方向、位置、大小;並且反推出神經元活化區域 (source localization)。
    在給予聲音刺激觀察大腦的神經傳遞行為上,能初步的得知N100m on-response以及N100m off-response二處的神經元活化區座落在聽覺皮質層上。而且經由計算出的電流偶極子也在大腦的聽覺皮質層上,細部上,可觀察出N100m on-response的電流偶極子位置會在聽覺皮質層的外層,而N100m off-response的電流偶極子則位在聽覺皮質層較深層的位置。
    聲音震動傳送到內耳,再透過部分的腦幹(耳蝸核和下丘)沿著聽覺神經移動傳達到丘腦,再傳遞到大腦聽覺皮質層。研究中顯示給予左耳聲音刺激時,右腦部份的磁場訊號會最先到鋒值,左腦延遲的時間大致都在10 ms左右;然而給予右耳聲音刺激時左、右腦的延遲時間,則因人而異,主要原因應為左、右腦的不對稱性所導致。
    腦磁儀這種非侵入式的量測儀器,不僅能幫助我們研究在給予刺激以後,大腦的反應行為,未來希望也能應用在醫學的檢驗測量上面。

    第一章 緒論……………………………………………………1 1-1 研究動機 ……………………………………1 1-2 腦磁訊號 ……………………………………3 第二章 實驗及分析方法………………………………………8 2-1 SQUID腦磁儀………………………………….8 2-2 定位與訊號量測………………………………12 2-3 聲音刺激時分析法……………………………20 第三章 結果與討論……………………………………………21 3-1 聲音刺激的左、右腦延遲現象分析…………21 3-2 聲音刺激在N100m on and off-response神經活化區 及電流偶極子位置比較…………………… 30 第四章 結論……………………………………………………40 參考文獻…………………………………………………………42 附件………………………………………………………………45 致謝………………………………………………………………46

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