Auditory feedback in learning and maintenance of vocal behaviour

Songbirds are one of the best-studied examples of vocal learners. Learning of both human speech and birdsong depends on hearing. Once learned, adult s ong in many species remains unchanging, suggesting a reduced influence of s ensory experience. Recent studies have revealed, however, that adult song i s not always stable, extending our understanding of the mechanisms involved in song maintenance, and their similarity to those active during song lear ning. Here we review some of the processes that contribute to song learning and production, with an emphasis on the role of auditory feedback. We then consider some of the possible neural substrates involved in these processe s, particularly basal ganglia circuitry. Although a thorough treatment of h uman speech is beyond the scope of this article, we point out similarities between speech and song learning, and ways in which studies of these dispar ate behaviours complement each other in developing an understanding of gene ral principles that contribute to learning and maintenance of vocal behavio ur.