Biography
Our laboratory is interested in how the nervous system mediates behavior, especially complex behaviors that must be learned. Birdsong provides a very useful model system for the study of these issues. Song is an intricate motor act that is learned in distinct phases during a bird's life, and depends on the animals auditory experience. There are critical periods for song learning, just as there are for some types of human learning. The juvenile bird uses auditory feedback to refine and correct his vocalizations, in a manner analogous to the acquisition of speech by human infants. Moreover, a discrete set of brain areas, called the song system, controls song learning and production. Finally, both the song system and the adult song behavior are sexually dimorphic, and are regulated by sex steroids. All of these features give birdsong the potential to shed light on the neural basis of learning, and on factors which control and limit learning.
At present the laboratory is focussed on a particular song circuit which behavioral studies suggest plays a special role in song learning. In juvenile birds, we have shown that the neurons in this pathway respond to a variety of sounds. Once the bird has learned its song, however, these same neurons are highly selective: they respond robustly to the sound of the bird's own song, and weakly or not at all to very similar songs of conspecific individuals or even the bird's own song played in reverse. The temporally and acoustically complex auditory response properties of these neurons suggest that they encode a neural representation of song, formed during learning. Furthermore, the development of this circuit very early during song learning and its synaptic output to the vocal motor pathway make it a likely location for the sensory learning of tutor song later used to guide motor song development. Using a variety of physiological, behavioral, pharmacological, and theoretical techniques, we are studying how the different features of song are represented in this network, how the animal's auditory experience and vocal learning shape its neuronal properties, and what the crucial function of this pathway might be.
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