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Department of Biology, University of Southern California, Los Angeles, California 90089-2520, USA
Address for correspondence: Sarah W. Bottjer, Department of Biology, HNB 218, 3641 Watt Way, University of Southern California, Los Angeles, California 90089-2520, USA. Voice: 213-740-9183; fax: 213-740-5687. bottjer{at}usc.edu;  http://www-rcf.usc.edu/~bottjer/ Ann. N.Y. Acad. Sci. 1016: 395-415 (2004).
A hallmark of sensitive periods of development is an enhanced capacity for learning, such that experience exerts a profound effect on the brain resulting in the establishment of behaviors and underlying neural circuitry that can last a lifetime. Songbirds, like humans, have a sensitive period for vocal learning: they acquire the sounds used for vocal communication during a restricted period of development. In principle, any organism that undertakes vocal learning is faced with the same challenge: to form some representation of target vocal sounds based on auditory experience, and then to translate that auditory target into a motor program that reproduces the sound. Both birds and humans achieve this translation by using auditory (and other) feedback resulting from incipient vocalizations ("babbling" in humans, "subsong" in birds) to adjust motor commands until vocal output produces a good copy of the target sounds. Similarities between vocal learning in birds and humans suggest that many aspects of the learning process have evolved to meet demands imposed by vocal communication. Thus songbirds provide a valuable animal model in which to study the physiological basis of learned vocal communication and the nature of sensitive periods in general. In this article, I describe aspects of both behavioral and neural frameworks that currently inform our thinking about mechanisms underlying vocal learning and behavior in songbirds, and highlight ideas that may need re-examination.
Key Words: zebra finch • song system • sensorimotor integration • NMDA receptor • silent synapses • postsynaptic potentials • axon pruning • topography • corollary discharge This article has been cited by other articles:
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