Sensitive periods and circuits for learned birdsong

Experience influences the development of certain behaviors and their associ ated neural circuits during a discrete period after birth. Songbirds, with their highly quantifiable vocal output and well-delineated vocal control ci rcuitry, provide an excellent context in which to examine the neural mechan isms regulating sensitive periods for learning. Recent discoveries indicate that auditory input to the vocal control circuitry in songbirds is dynamic ally modulated and show that neural circuitry previously thought to be used only in plastic juvenile song may also actively maintain stable adult song . These findings provide important clues to how sensitive periods for audit ory feedback and vocal plasticity are regulated during song development.