Figure 1.

Diagram of the avian song system emphasizing its bilateral organization and the bilateral projections from the brainstem to the forebrain. The figure emphasizes two pathways crossing from one half of the brain to the other. The first is the connection from RA through the vocal respiratory network (DM and PAm) and Uva (blue). The second is the pathway from RA to DMP to the contralateral MMAN (green). Both pathways converge on the contralateral HVC. Sites of stimulation (RA, DM, and PAm), recording (Uva and RA), and lesions (Uva) have been added. Additional recording (HVC and MMAN) and lesion (MMAN) sites were used in this study but are not shown here for clarity. Also not shown are nuclei of the anterior forebrain pathway which are necessary for song learning and maintenance. NIf, Nucleus interfacialis of the nidopallium.