Birds display advanced behaviors, including vocal learning and problem-solving, yet lack a layered neocortex, a structure associated with complex behavior in mammals. To determine whether these behavioral similarities result from shared or distinct neural circuits, we used single-cell RNA sequencing to characterize the neuronal repertoire of the songbird song motor pathway. Glutamatergic vocal neurons had considerable transcriptional similarity to neocortical projection neurons; however, they displayed regulatory gene expression patterns more closely related to neurons in the ventral pallium. Moreover, while γ-aminobutyric acid–releasing neurons in this pathway appeared homologous to those in mammals and other amniotes, the most abundant avian class is largely absent in the neocortex. These data suggest that songbird vocal circuits and the mammalian neocortex have distinct developmental origins yet contain transcriptionally similar neurons.

鸟类表现出先进的行为，包括声音学习和解决问题，但缺乏分层的新皮质，这是一种与哺乳动物复杂行为相关的结构。为了确定这些行为相似性是否来自共享或不同的神经回路，我们使用单细胞 RNA 测序来表征鸣禽鸣叫运动通路的神经元库。谷氨酸能发声神经元与新皮质投射神经元具有相当大的转录相似性；然而，它们显示出与腹侧大脑皮层神经元更密切相关的调节基因表达模式。此外，虽然该途径中释放γ-氨基丁酸的神经元似乎与哺乳动物和其他羊膜动物中的神经元同源，但最丰富的鸟类类在新皮质中基本上不存在。