有無聲音回饋之音樂演奏時序同步

Abstract

音樂演奏是普遍且嚴謹費力的人類行為，在世界各地的社會皆存在。過去的研究已經了解當只有來自樂器之單一音源時的音樂演奏大腦活化。然而，多個音源的時序同步對於樂團演奏是必要的，目前卻仍缺少理解。本研究以功能性磁振造影 (functional magnetic imaging, fMRI) 搭配 MR 相容的鋼琴鍵盤，比較音樂演奏時有無兩種音源的情境，兩種音源分別是來自鋼琴的聲音回饋以及節拍器的外部時間導引，本研究旨在理解音樂演奏時，涉及多個音源時序同步的大腦區域。 在本研究中，17位業餘鋼琴家在磁振造影儀器中以四種不同的聽覺情境彈奏相同的旋律，四種聲音情境分別包含：完全沒有聲音刺激 (None)、僅有鋼琴聲音回饋的單一音源 (P)、來自節拍器的外部導引之單一音源 (M)以及包含鋼琴與節拍器兩種音源 (MP)。試驗過程中的鋼琴彈奏按鍵與時間間隔會被記錄下來。若出現不準確的彈奏速度與錯誤的音高，該試驗將被排除不列入分析。 基於問卷分析的結果，不同聽覺情境之間的困難度與彈奏專注程度並無明顯差距。當僅有單一音源進行音樂演奏時，顳上迴(STG)、運動前區(PMA)、輔助運動區(SMA)以及小腦等區域被觀察到活化。相較於單一音源的音樂演奏，功能性磁振造影的比對結果顯示，進行兩個音源的音樂演奏時 (MP)，有較高的血氧濃度相依對比訊號出現在兩側的顳葉顳上迴(STG)、布羅德曼(Brodmann Area, BA) 40區、43區和右側布羅德曼38區，說明了與多個音源之音樂演奏時序同步相關的神經訊號處理模式。

Playing music is a common and demanding human behavior present in all societies around the world. Previous studies have demonstrated brain activation patterns during musical playing with one auditory source from the instrument. However, the temporal synchronization requiring multiple auditory sources coordination during musical playing is essential for musical ensemble performances but less understood. In the present study, we used functional magnetic resonance imaging (fMRI) with an MR-compatible piano keyboard to reveal brain regions involved in the temporal synchronization requiring coordination of multiple auditory sources during musical playing by comparing conditions of musical playing with and without two auditory sources which were the auditory feedback of the piano and the external timing reference from a metronome. In the present study, 17 amateur pianists were asked to play the same melody under four different auditory conditions in MRI, including playing without any auditory stimuli (None), with one auditory input of the auditory feedback from the piano (P) or of an external timing reference from a metronome (M), and with both (MP). Piano performances including which keys were pressed and the timing of them were recorded. Trials with unacceptable accuracy and inaccurate notes were excluded from analysis. Based on the questionnaire, the level of difficulty and concentration required in each condition did not vary a lot. STG, PMA, SMA, and cerebellum were involved during musical playing with one auditory source (M, P). Compared to musical playing with one auditory source, functional MRI contrasts showed blood-oxygen-level dependent (BOLD) signal increase in bilateral STG, BA 40, 43 and right BA 38 during piano playing with two sources of auditory inputs (MP), which indicates a neuronal processing pattern relating to the coordination of multiple auditory sources synchronization during music playing.