Neural Control of Birdsong

Abstract

Abstract Birdsong is a learned behaviour that displays a remarkable level of acoustic and temporal complexity. It is controlled by a well‐defined neural circuit, known as the song system, which receives highly processed auditory information from specialized higher‐order auditory areas. Over the past decade, sophisticated new song analysis tools coupled with the ability to record from identified neurons in adult and juvenile singing birds have revealed many fundamental insights into the neural mechanisms that underlie vocal production, storage of auditory memories and sensorimotor learning. Some of these include an understanding of how sleep drives song acquisition and how circuits homologous to the mammalian basal ganglia generate the motor variability that enables sensorimotor learning. The tractable nature of this system coupled with its shared similarities with human speech make birdsong a unique model for understanding the neural bases of vocal production and learning. Key Concepts: Sophisticated new methodologies in song quantification have made it possible to provide quantitative descriptions of the entire vocal imitation process in juvenile birds. Storage of the song template likely occurs in specialized higher‐order auditory forebrain areas rather than in the song system proper. The song system is a specialized neural circuit that is necessary for song production and sensorimotor learning. Neurons that form part of the descending motor pathway produce short (approximately 5 ms) bursts of action potentials that are precisely time locked to specific time segment of the song. The portion of the song system necessary for song production is organized as a recurrent pathway with structures in the thalamus and respiratory brainstem projecting back up to the forebrain. Neural variability from the basal ganglia circuit onto RA is thought to contribute to the observed motor variability in juvenile birds and likely enables the motor exploration strategy that is critical for song learning in juveniles. Sleep plays a critical role in vocal learning by allowing offline processing of sensory and motor information.