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Auditory and Vestibular Systems

開催日 2014/9/13
時間 11:00 - 12:00
会場 Poster / Exhibition(Event Hall B)

Representation of fricative consonants in the auditory cortex of rats

  • P3-133
  • 西田 陽子 / Yoko Nishida:1,2 小川 剛 / Go Ogawa:2 工藤 雅治 / Masaharu Kudoh:2 
  • 1:東京家政大・看護 / Department of Nursing, Faculty of Nursing,Tokyo Kasei University 2:帝京大・医・生理 / Department of Physiology, Teikyo University School of Medicine, Tokyo, Japan 

Rat pups emit harmonic type and noise type calls in a low frequency range. Noise type calls consist of broad band noises. Flavoprotein autofluorescence imaging (excitation: 450-490 nm, emission: 500-550 nm) shows that synthetic pup noise calls evoke marked responses in the posterior part of the primary auditory cortex (AI) and posterior auditory field (PAF). Synthetic noise calls evoked enhanced fluorescence responses in PAF of mother rats than nulliparous control rats. Fricative consonants of humans also consist of band noises. Fricative consonants /s/ and /sh/ were synthesized as band noises with center frequency of 6.3 kHz and 4.6 kHz (bandwidth: 1.0 kHz), respectively. Rats can learn to discriminate between these fricative consonants. Synthetic fricative consonants evoked prominent fluorescence responses in AI. In the present study, representation of band noises in the rat auditory cortex was investigated using flavoprotein fluorescence imaging. Band noises with high center frequency elicited fluorescence responses in anterior part and those with low center frequency in posterior part of AI, corresponding with tonotopic organization of rat AI. Broad band noises elicited wider response area than narrow band noises. Sites of peak fluorescence response could be distinct for fricative consonants, while response areas were mostly overlapped. In rats trained to discriminate between consonants in three-day test sessions, fricative consonants evoked marked fluorescence responses in distinct areas in the dorsal auditory field (DAF) and anterior auditory field (AAF), in addition to AI. These findings suggest that spatial representation of band noises in AI, DAF and AAF play a critical role in discrimination learning of fricative consonants.

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