Sources for connectivity of neural populations adjacent to songbird vocal nuclei

The first column shows the connection; arrows indicate axonal projections. The second column indicates the tracer direction studied; connections determined in both the anterograde and retrograde directions are accepted with more confidence than ones determined only in one direction. The third column lists the references where these connections were determined. The AN = >LAI & ASt indicates that AN neurons send collateral projections to LAI and ASt adjacent to RA and Area X respectively, which is similar to the collateral projections from individual LMAN neurons to RA and Area X. In the studies before 2004, the old avian brain nomenclature was used and terminology varied between studies. AN was called the LMAN shell or frontal neostriatum, DLN we consider here as a part of NCL (see main text), LAI was called dorsal archistriatum (Ad), and ASt and Area X was within a region called the lobus parolfactorius. PMN is premotor neurons of the brainstem, medulla, and possibly spinal cord. Here, we adopted a terminology that is applicable across all avian species, vocal learners and non-learners.第一列展示连接关系，箭头指示轴突投射（axonal projections）。第二列标注所研究的示踪剂方向（tracer direction）：经顺向（anterograde）与逆向（retrograde）双向确定的连接，其可信度高于仅通过单一方向确定的连接。第三列列出确定上述连接的相关参考文献。AN→LAI与ASt表示AN神经元分别向紧邻RA的LAI以及紧邻X区的ASt发出侧支投射，这与单个LMAN神经元向RA及X区发出的侧支投射模式类似。2004年之前的相关研究均采用旧版鸟类大脑命名体系，且不同研究间术语不统一，其中AN曾被称为LMAN壳区或新纹状体前部，本文将DLN视为NCL的一部分（详见正文），LAI曾被称为背侧弓状纹状体（Ad），ASt与X区则隶属于名为副嗅叶（lobus parolfactorius）的脑区。PMN为脑干、延髓甚至脊髓内的运动前神经元。本文采用了一套适用于所有鸟类（包括鸣唱学习鸟类与非鸣唱学习鸟类）的统一命名规范。