Physiology and Biophysics

David Perkel Ph.D.

Adjunct Professor (with Biology/Otolaryngology)

Ph.D. Neuroscience
University of California, San Francisco, 1992

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Neural Mechanisms of Vocal Learning

Vocal learning in songbirds is an experimentally accessible model system in which to study the neural mechanisms of learning. Juvenile birds memorize song(s) from an adult tutor and then use auditory feedback from their own songs to compare with their memory of the tutor song(s). This comparison guides a process of motor learning; through practice, juvenile birds gradually learn to produce a highly stereotyped song that resembles the tutor song. Extensive research has investigated the underlying neural circuits that are involved in song learning and production. Our lab uses a variety of electrophysiological, anatomical and behavioral approaches to probe the neural mechanisms that mediate song learning and song behavior.

Two main neural circuits have been implicated in song production and learning. The motor pathway descends from forebrain nucleus HVC, which projects to nucleus RA, which then projects to brainstem motor and premotor neurons controlling muscles of the vocal organ, the syrinx, and those of respiration. This pathway is essential for production of song. A second circuit, the anterior forebrain pathway (AFP), arises from HVC as well and projects to the basal ganglia structure area X, which projects to the thalamic nucleus DLM, which projects to a forebrain nucleus LMAN, which projects back to motor pathway nucleus RA. The AFP is essential for vocal learning but not production of previously learned song. Neurons of the AFP exhibit specific responsiveness to auditory information and are therefore well placed to provide the motor pathway with auditory feedback about the quality of the bird's own song.

Our main long-term goal is to understand at the level of neurons, synapses and circuits how song is learned and produced. Our current work falls into several categories:

- Mechanisms of pattern generation in the motor pathway

- Structure and function of the anterior forebrain pathway

- Evolutionary origin of the anterior forebrain pathway in songbirds

- Mechanisms underlying seasonal control of song (in collaboration with Eliot Brenowitz)