The PI would like to investigate how learned song is represented in the brain of songbirds. Songbirds learn their songs by imitating external models. The major brain nuclei involved in vocal control have been identified. One nucleus, HVc, undergoes marked seasonal changes in anatomy which parallel seasonal changes in song behavior. Lesion studies have shown that this nucleus is essential for normal song production. Lesions to left HVc in canaries produce more severe song deficits than right side lesions, suggesting that song control is lateralized. In addition, HVc size is correlated with the side of the learned song repertoire in individual canaries. Physiological investigations have shown that HVc neurons receive auditory input and are active during song. HVc projects to another forebrain nucleus, RA, which projects to nXIIts motorneurons that innervate the vocal organ (syrinx). Stimulation and recording techniques will be used in anaesthetized birds to study the representation of the syringeal muscles in HVc, RA and nXIIts. Anatomical studies will address the topographic connections between these nuclei. Neural activity in response to auditory stimuli and accompanying song production will be studied in awake birds with chronic implants. Multielectrode arrays will enable several sites in HVc (including right and left HVc) to be recorded simultaneously, both while the bird is singing and in response to natural and artificial auditory stimuli. The results will shed light on basic aspects of brain function: What is the brain representation of a learned skill? Does it have a modular organization at the neural level that matches modular features of the learned behavior? Do the representations for different behavioral units (song syllables) overlap, and if so how? Do the motor and perceptual representations coincide? Discovering the way in which perceptual and motor components of a learned skill are represented in the brain, and their coexistence or segregation into separate hemispheres, may uncover new principles of brain function. This in turn may help reveal conditions that encourage or limit learning.
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