Fig. 1.

Schematic of the song system and other specialized areas of the songbird brain. HVC (formerly the high vocal center, now represented using simply the abbreviation) is a sensorimotor site that projects into two important pathways. First is the song motor pathway (SMP; purple), which is important in the performance of song behavior. Second is the anterior forebrain pathway (AFP; green), which is important for song learning. Each of those pathways converges onto the vocal motor nucleus RA (the robust nucleus of the arcopallium). Secondary auditory areas caudal mesopallium (CM; white) and caudomedial portion of the nidopallium (NCM; white) are not considered part of the canonical song system, but they also play important roles in song learning and perception. Area X, Area X of the medial striatum; DLM, dorsolateral medial nucleus of the thalamus; LMAN, lateral portion of the magnocellular nucleus of the anterior nidopallium; NIf, nucleus interfacialis; NXIIts, tracheosyringeal portion of the 12th cranial nerve; L1–L3, subregions of Field L, the primary auditory thalamorecipient region of the nidopallium.