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

在这项与两名研究生一起进行的研究中，我使用了成年雄性孟加拉雀和日本鹌鹑的雏鸟。年龄有限的鸣叫声学习种类的雄鸟在出生后的第一年就会发育出完整的鸣叫声。对于这种类型的歌曲学习者来说，一旦歌曲在成年期“具体化”，它就会随着时间的推移而高度定型和稳定。传统上，人们一直认为年龄限制的歌曲学习者不依赖于听觉反馈来维持成人歌曲。我通过手术切除双侧耳蜗使成年男性失聪，并在手术后的20周内每周录制歌曲。结果显示，术后1周左右，歌声明显下降。失聪后的歌曲缺陷包括音节序列和高基频或高频调制的刻板音节显著减少。低基频或低频调制的新音节出现在失聪的两周内，并且随着时间的推移而增加。耳聋后10周鸣声保持稳定，鸣声模式与术前不同。这表明听觉反馈对于年龄有限的孟加拉雀的歌曲维持是必要的。日本鹌鹑雏鸟在社会上与其他个体隔离，它们发出求救信号的频率很高。长期皮下注射睾酮可诱导雏鸡啼鸣，雏鸡啼鸣的声学结构特征与雄鸟啼鸣相似。注射睾酮后第6天，经电刺激，雏鸟的叫声与成年乌鸦相似，具有颤音结构。在电刺激下表现出两种不同发声行为的雏鸡脑干区域位于内侧丘间核（ICo）。由此可见，雏鸡的内侧ICo具有两种不同的功能，一种是发出求救信号，另一种是鸣叫。

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.