Cortical mechanisms underlying perception of timbre

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K01960
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Brain biometrics
• Research Institution: University of Yamanashi
• Principal Investigator: CHIMOTO Sohei 山梨大学, 大学院総合研究部, 助教 (80324185)
• Project Period (FY): 2016-10-21 – 2020-03-31
• Keywords: 非対称音 / 音知覚 / 高次聴覚野 / 単一細胞記録

Outline of Final Research Achievements

The sound with a quick attack followed by a slow decay is called damped sound, while the time-reversed sound is called ramped sound. Psychophysical experiments have shown that this asymmetry influence sound perception. Previously,we found the longer perception in ramped sounds caused mainly from edge cells in the primary auditory cortex (A1). However, the coding mechanism for temporally asymmetric sounds may not be accomplished at the level of A1. In the present study we recorded single unit activities from higher auditory cortices such as the secondary auditory cortex (A2) and posterior auditory fields (PAF) and examined response patterns during damped and ramped sounds. We found that most of neurons in A2 and PAF responded to ramped or/and damped sound and about 40% of the neurons showed the sensitivities to direction of the amplitude change. These neurons might play an important role in the perception of temporally asymmetric sounds.

Free Research Field

神経生理学

Academic Significance and Societal Importance of the Research Achievements

これまで多くの聴覚野研究が麻酔下で行われてきた。しかし覚醒中では麻酔下と異なり、ニューロン反応の時間応答の多様化があることが知られている。本研究ではこれまで不明であった正常に活動中の覚醒動物において時間的に非対称な音刺激に対する高次聴覚野の単一ニューロンレベルを明らかにした。また振幅包絡変化の符号化というヒトや動物が音声コミュニケーションを行なう上で、最も重要な機能が大脳一次聴覚野を経て異なる高次聴覚野の特定の細胞群において遂行されていくことを示した。本研究によって解明された高次聴覚野による音色処理機構は音刺激から認知に至る今後の大脳高次聴覚野機能研究の礎の一つとなると考える。