Singing in the brain

Aside from humans, songbirds have by far the most elaborate communicative sounds of any organism. Most complex of all are their songs (e.g., Fig. 1), which are learned and culturally transmitted between generations, often enriched by invention and improvisation (1–3). The specialized subsystem in the songbird brain that sustains this behavior, first described in 1976 (4), eventually became known as the song system (SS) (Fig. 2) (5, 6). One circuit, including the nuclei HVC (high vocal center) and RA (robust nucleus of the archistriatum), is essential for producing song motor patterns throughout life; the other, the anterior forebrain circuit, is more important for song development and plasticity (7–9). Electrophysiological studies have demonstrated that these circuits contain neurons active during singing and neurons responsive to the sounds of song (10–13). Figure 1 The winter wren, Troglodytes troglodytes , has one of the most elaborate bird songs. A male has a repertoire of 5–10 song types, each up to 10 sec in duration. Song types share many phrases, patterned in different sequences, as in these three songs of male 1 (1 A–C). Male 2 (2A), a neighbor, shares some phrases, but arranges them differently (54). Figure 2 A schematic cross section of the songbird brain depicting the traditionally defined song system and associated auditory areas. A network of discrete areas is devoted to song learning and production: the “motor pathway” (in black) is required throughout life for normal song production; the anterior forebrain circuit (in blue) is more important for song learning and plasticity. The NCM is one of the interconnected telecephalic auditory areas (in red), including the thalamorecipient area field L, that project directly and indirectly to the song system. For song system abbreviations, see Brenowitz et al. (3). Methods for functional localization using activation of …