音楽認知におけるγ活動の意義―意識・認知との関連から― Gamma-band activity; role of music perception in the brain in relation to consciousness and cognition
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音を聴覚的に認識し, ハーモニー, 音韻, 旋律など音楽を認知することで前頭前野が活動し行動が起こる。本研究は音楽大学学生5名,音楽専門家１名, 非音楽大学生5名 (21–25歳: 男9女2) を対象とし60 ch脳波を用いて安静閉眼時, 「新世界より」「レクイエム」聴取時, イメージ時の脳活動を計測し, 音楽認知の神経基盤を明らかにすることを目的とした。Morlet waveletによる時間周波数解析を行い, 各周波数帯域の平均信号強度をroot mean squareとして求め成分比較を行った。音楽聴取時は無音安静閉眼時に比べ, δ, α, β, γ活動に有意な減少を認めた。γ活動の減少が最も大きく, 全脳部位で有意に減少した。音楽家は音楽聴取時・イメージ時ともに前頭部γ活動が減少, 非音楽家はイメージ時には前頭部γ活動が増加した。音楽家と非音楽家のγ活動の差は, 音楽という経験による意識や注意, 情動の統合や潜在記憶の差を反映する可能性がある。
Music perception involves acoustic tone activity and scene (melody, harmony) analysis, as well as its processing of musical syntax and semantics, that lead to the activation of the prefrontal cortex (and active motor) actions. The present study aimed to clarify the underlying neural networks during music perception in musicians and non-musicians. We examined spontaneous brain activities in six musicians (five musically trained students and one singer), and five non-musically trained students while listening to Dvorak's "From the new world" and Mozart's "Requiem" for 150 seconds for each piece, imaging the music for 60 seconds thereafter, using 60-ch electroencephalography (EEG). The data were analyzed and compared with those of the resting state. We adopted Morlet wavelet time-frequency analysis, and root mean square (RMS) was calculated in each frequency-band (Delta: 1–4 Hz, Theta: 4–8 Hz, Alpha: 8–13 Hz, Beta: 13–30 Hz, Gamma 30–50 Hz). During listening to the music, gamma activity was significantly decreased in all of the regions. While imaging the music, the musicians' gamma activity was significantly decreased in the entire cortical areas, whereas the non-musicians' gamma activity increased in the frontal area. A gamma activity decreased during perception of the music, especially in the prefrontal cortex in musicians; it is strongly related to the integration of recognition and emotion which reflects the processing of music in a highly integrated consciousness level. The frontal gamma activity shown here may indicate that musicians image the music in the same or similar condition as they are listening to the music that is, they do image and replay the music in the implicit memory compiled from the explicit acoustic memory while listening to the music. The differences as evidently shown in music perception between well-trained and non-trained students may reflect the differences of their education in musical experiences and expert skills obtained in their music carrier.
- Japanese Journal of Clinical Neurophysiology
Japanese Journal of Clinical Neurophysiology 41(4), 209-219, 2013
Japanese Society of Clinical Neurophysiology