Analysis of the mechanism of neural substrates for song and vocal control system in the forebrain nuclei (HVc.RA.X) in the song bird.

在这项对两名研究生进行的研究中，我使用了成年的雄性孟加拉雀和日本鹌鹑的雏鸟。雄性鸟类的年龄有限，学习歌唱的物种在生命的第一年就会发展出完整的歌唱曲目。对于这种类型的歌曲学习者来说，一旦歌曲在成年时被“结晶”，它就会随着时间的推移而高度刻板和稳定。传统上，人们一直认为，年龄受限的歌曲学习者不依赖听觉反馈来维持成人歌曲。在手术后20周内，我对成年男性进行了双侧耳蜗摘除手术，并每周录制一次歌曲。结果表明，手术后1周左右，SONG明显降解。耳聋后的歌曲缺陷包括音节序列的明显减少和歌唱中高基频或高频调制的刻板印象音节。低基频或低频调制的新音节出现在震耳欲聋的两周内，并随着时间的推移而增加。耳聋后10周鸣声基本稳定，与手术前鸣声模式不同。这表明，对于年龄有限的歌曲学习者来说，听觉反馈对于维持鸣叫是必要的。与其他个体隔绝的日本雏鸟发出求救信号的频率很高。定时皮下注射睾酮可诱导雏鸡鸣叫，其声学结构特征与成年雄鸡相似。在植入睾酮后第6天，雏鸡通过电刺激产生类似成年乌鸦的颤动结构的鸣叫。雏鸡脑干在电刺激下表现出两种不同发声行为的区域位于丘间内侧核(ICO)。这说明雏鸟的内侧ICO具有两种不同的功能，即产生求救信号和鸣叫。

In this study conducted with two graduate students I used adult male Bengalese finches and chicks of Japanese quails. Male birds of age-limited song learning species develop their full song repertoires in the first year of life. For this type of song learner, once song is "crystallized" in adulthood, it is highly stereotyped and stable over time. Traditionally, it has been believed that age-limited song learners do not depend upon auditory feedback for the maintenance of adult song. I surgically deafened adult males by bilateral cochlear removal and recorded song weekly for 20 weeks following the surgery. Results show that song degraded significantly within about 1 week of surgery. Song deficits after deafening included a marked decrease in syllable sequence and stereotype syllables of high fundamental frequency or high frequency modulation within song bouts. Occurrences of new syllables with low fundamental frequency or low frequency modulation within song bouts appeared within 2 weeks of deafening and increased over time. Song of next 10 weeks after deafening kept stable with different pattern from the pre-surgical song of the bird. This indicates that auditory feedback is necessary for song maintenance in Bengalese finches of age-limited song learners.Japanese quail chicks which are socially isolated form other individuals produce distress calls at a high rate. Chronical subcutaneous implantation of testosterone induced the chick crowing which has similar acoustical structural characteristics to male adult crowing. At day 6 after testosterone implantation, the chicks produced the chick crowing similar to adult crow with a trill structure by electrical stimulation. The area in brainstem of chicks that exhibit two different kinds of vocal behavior upon electrical stimulation lies in the medial intercollicular nucleus (ICo). This suggests that the medial ICo of chicks has two different functions, production of distress call and chick crowing.