The avian song system can be divided into three main divisions. The descending motor pathway (shown in black) includes telencephalic areas HVC and RA as well as brainstem nuclei that drive the muscles of the syrinx (nXIIts) or the respiratory system (RAm and PAm). These later two structures form part of a vocal respiratory network that also includes DM. The second division, sometimes called the ventral motor pathway, consists of projections from the diencephalon and brainstem back to HVC (shown in green). The third major division of the song system consists of the anterior pathway (shown in light red), which is made up of Area X, DLM, and LMAN. The song system receives processed auditory information from an ascending auditory pathway (shown in blue). Areas where BOS-selective responses have been recorded are outlined in red. Anatomical names: DLM, medial part of the dorsolateral thalamic nucleus; LMAN, lateral magnocellular nucleus of the anterior nidopallium; Field L is the primary auditory forebrain structure in birds; Area X, Area X of the medial striatum; NIf, nucleus interfacialis of the nidopallium; RAm, nucleus retroambigualis; PAm, nucleus paraambigualus; DM, dorsomedial nucleus of the intercollicular complex; CMM, caudal medial mesopallium; CLM, caudal lateral mesopallium; Field L, auditory forebrain areas consisting of Field L1, L2, L2a, L2b and L3; Ov/Ovm, nucleus ovoidalis; MLd, dorsal lateral nucleus of the mesencephalon; NCM, caudal medial nidopallium; LLV, ventral nucleus of the lateral lemniscus.