Perkel David J
Department of Biology, Box 356515, University of Washington, Seattle, WA 98195-6515, USA.
Ann N Y Acad Sci. 2004 Jun;1016:736-48. doi: 10.1196/annals.1298.039.
The brain nuclei and pathways comprising the song system of oscine songbirds bear many similarities with circuits in other bird species and in mammals. This suggests that the song system evolved as a specialization of pre-existing circuits and may retain fundamental properties in common with those of other taxa. Here we review evidence for these similarities, including electrophysiological, morphological, and neurochemical data for identifying specific cell types. In addition, we discuss connectional data, addressing similarities in axonal projections among nuclei across taxa. We focus primarily on the anterior forebrain pathway, a circuit essential for song learning and vocal plasticity, because the evidence is strongest that this circuit is homologous to mammalian circuits. These fundamental similarities highlight the importance of comparative approaches; for example, understanding the role the anterior forebrain pathway plays in song plasticity may shed light on general principles of basal ganglia function. In addition, understanding specializations of such circuits in songbirds may illuminate specific innovations critical for vocal learning.
构成鸣禽歌声系统的脑核团和神经通路与其他鸟类及哺乳动物的神经回路有许多相似之处。这表明歌声系统是作为先前存在的神经回路的特化形式进化而来的，并且可能保留了与其他类群共有的基本特性。在此，我们回顾这些相似性的证据，包括用于识别特定细胞类型的电生理、形态学和神经化学数据。此外，我们还讨论了连接数据，阐述了不同类群间核团轴突投射的相似性。我们主要关注前脑通路，这是一个对于歌声学习和发声可塑性至关重要的神经回路，因为有最有力的证据表明该回路与哺乳动物的神经回路是同源的。这些基本相似性凸显了比较方法的重要性；例如，了解前脑通路在歌声可塑性中所起的作用可能会揭示基底神经节功能的一般原理。此外，了解鸣禽中此类神经回路的特化可能会阐明对于发声学习至关重要的特定创新。
