Single neuron correlates of learned song

Duke University, Durham NC

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Abstract

DESCRIPTION (provided by applicant): The long-term goal of this research is to analyze neural mechanisms that underlie vocal learning. The goals of this proposal are to understand both motor and auditory codes for learned vocalizations. This proposal relates to the R21 purpose by applying a new and highly innovative chronic recording method to study neural activity in a novel model species especially well suited to address the nature of auditory-vocal integration. Auditory-guided vocal learning, as occurs in humans and songbirds (but few other taxa), requires neural integration of auditory and vocal activity. One model for the neural basis for auditory-motor integration is that single neurons at the apex of the auditory-vocal motor pathway encode specific features of the vocal gesture and also respond to the resulting sound that this gesture elicits. This proposal seeks to study single neuron activity in the telencephalic nucleus HVc of the awake, behaving swamp sparrow, a songbird that produces several different vocalizations made up of categorically distinct elementary units (i.e., song notes) that are shared to varying degrees among the song types in an individual's vocal repertoire. The first Aim is to record the activity of individual identified HVc neurons in a swamp sparrow as it sings several song types, two or more of which share a note in common. The hypothesis to be tested is that HVc remotor neuron activity correlates with individual notes but not note sequences. The second Aim is to compare the activity of individual identified HVc neurons during singing and again, then the bird's various song and note types are played back to it through a speaker. The hypothesis to be tested is that for a single HVc premotor neuron the premotor activity and auditory response corresponds to the same common vocal unit (i.e., a note). This project also will provide pilot data for future experiments designed to study how premotor and auditory activity change during vocal learning, and to test the role of HVc's auditory activity in the perception of learned vocalizations. This project can help identify neural mechanisms important to audition guided vocal learning, and thus may yield insight into neural mechanisms for speech learning, perception and production.