Acquisition of speech and language depends on vocal imitation of adult tutors, such as parents. Songbirds provide the best experimental system for studying the neurobiology of vocal learning because they acquire their songs by listening to adult tutors and then learn to produce them through a sensorimotor process that is highly similar to speech learning. The cortical region HVC (proper name) is essential for song learning and song production, and it is proposed to function analogously to the human premotor cortex. Despite more than four decades of research, the fundamental cellular composition of HVC remains poorly understood. Previous studies have revealed that multiple classes and sub-classes of projection neurons exist in HVC, suggesting that the control of song production is much more complex than originally thought, although the limitations of current electrophysiological and morphological techniques have been a major challenge to comprehensive cell-type identification. To address this, the present proposal will perform the first high-throughput classification of HVC cell types using single-cell RNA sequencing (scRNA-seq). The study will then examine how the genomic profile of HVC is shaped by tutor experience to identify transcriptomic changes that may relate to vocal learning. The experimental results may potentially transform frameworks for understanding the mechanistic functioning of HVC and the generation of motor song production (i.e., complex, learned behavior) and also elucidate some of the ways in which the brain is shaped by the sensory environment to facilitate the acquisition of vocalizations. This work ultimately aims to improve our understanding of the neural mechanisms underlying speech production and motor behavior at a previously-unattainable level of cellular resolution. The research strategy described in this proposal will provide the applicant, Dr. Devin Merullo, with novel training in high- throughput bioinformatic techniques and precisely-targeted circuit and cellular manipulations. This proposal is a unique collaborative opportunity between the sponsor, Dr. Todd Roberts, and co-sponsor, Dr. Genevieve Konopka, at the University of Texas Southwestern Medical Center. The efforts outlined in this proposal will thus prepare Dr. Merullo for an independent research career and lead to the application of novel methodologies in songbirds, thereby enabling research questions to be addressed in a way that has been largely unavailable until now.
Songbirds currently offer the best experimental system for studying the neurobiology of vocal learning due to the behavioral and neural similarities of song learning with human speech acquisition. This proposal will employ single-cell RNA sequencing to characterize and identify all cell types in a brain region critical for vocal learning and vocal production in zebra finches, and then examine the ways in which auditory experience shapes these cell-specific transcriptomic profiles. The studies proposed here have the potential to provide insights into conserved molecular pathways relevant to brain development, plasticity, and speech and language disorders.
