Birdsong for neurobiologists

Song is a stereotyped behavior, yet its development depends on sensory feedback and learning. Early bird fanciers recognized that young birds must have a good tutor to become a good singer. They also knew that birds could be bred for more elaborate songs, as exemplified by different breeds of canaries selected for different ways of singing. Thus, variations in song between individuals and between species contain both heritable and experiential components. The study of the experiential component has shown that the nature and timing of auditory experience play an important role in shaping the outcome of song development. The ability of a bird to modify song in adulthood has drawn special attention because it implies neural plasticity in the adult brain. The discovery of the brain areas for the control of song has brought birdsong from the purely behavioral level of analysis to the interface between behavior and neurobiology. The song control system shows al I of the developmental events that attract much current research, such as neuronal growth, death, and migration, the specificity of neuronal connections, and the waiting compartment. Furthermore, sex steroids control some of these ontogenetic events as well as the expression of song and its neural substrates in adulthood. The main aim of this article is to review current research dealing with these topics.