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Symposia
Auditory processing, vocal production and motor control
Chairs
In this symposium, our goal is to address questions regarding how the central nervous system integrates auditory and motor information to enable vocal communication. We propose to discuss auditory perception, sound production, motor and neural coding in songbirds and mice. Vocal production requires precise coordination between the respiratory system and the vocal organ being an extraordinary example of motor control. In songbirds, this complex task is learned through a delicate process involving auditory and proprioceptive feedback, being rarely encountered in other vertebrate species. In this symposium we will present a wide perspective of birdsong research, integrating central nervous system recordings and biomechanical models for song production. New perspectives and models for sensorimotor integration and learning will be discussed in terms of recent results concerning the processing and dynamics occurring in the song system. Discussions about molecular and genomic tools will also be included. Our goal is to discuss about sensory and motor coding integrating different perspectives, new technologies and interdisciplinary approaches, taking advantage of the common neurethological perspective that the participants provide.
Speakers
Tuning Auditory Circuits for Vocal Communication
Sarah Woolley
Columbia University
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Social communication reflects the coordinated development of sensory and motor circuits around signals that convey information. The young brain learning to communicate with hearing and voice builds auditory and vocal motor circuits that are functionally coupled to perceive and produce similar signals. I will describe progress using songbirds to understand how species identity dictates the capacities and limits of vocal learning, how early experience shapes auditory and vocal circuits, and how species and learning combine to map auditory tuning onto vocal acoustics.
Low dimensional models and electrophysiology to study neural dynamics in songbirds
Ana Amador
Dept. of Physics, University of Buenos Aires and IFIBA, CONICET, ARGENTINA
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Birdsong is a complex motor activity that emerges from the interaction between the peripheral system, the central nervous system and the environment. The similarities to human speech, both in production and learning, have positioned songbirds as unique animal models for studying the production and perception of this learned motor skill.
In this work, I will present a low dimensional dynamical system as a model of the avian neural network for song production. We developed a neural model in which the variables were the average activities of different neural populations within the nuclei of the song system. We performed electrophysiological experiments to record neural activity from one of these nuclei during song production in canaries (Serinus canaria) and found that the low dimensional model could reproduce the neural dynamics observed. Also, this model could reproduce the respiratory motor patterns used to generate song. We showed that sparse activity in one of the neural nuclei could drive a more complex activity downstream in the network. This interdisciplinary work shows how low dimensional models can be a valuable tool for studying the emergence of complex motor tasks.
Mechanisms for variability and plasticity in vocal motor performance in songbirds
Mimi Kao
Tufts University
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Complex motor skills, such as speech or playing a musical instrument, are not innately programmed, but are learned through a process of trial and error. Learning requires motor exploration and performance evaluation. How are these processes implemented in the brain and what happens in disease? Songbirds provide an experimentally tractable model to address these questions. Like humans, they learn to vocalize, first by listening to the sounds of adults during a sensitive period and then by using auditory feedback to practice and modify their vocalizations. In addition, songbirds possess a discrete cortical–basal ganglia circuit specialized for learning and producing song. Variable burst firing in the cortical outflow nucleus of this circuit, LMAN, drives song variability, and manipulations that abolish burst firing in LMAN eliminate song plasticity. Here, I will describe evidence that neurons in this circuit have access to feedback signals, gradually changing their activity in response to feedback perturbation. In addition, I will show that changing the timing and amount of LMAN bursting is sufficient to drive cumulative changes in the acoustic features, timing, and sequence of song. Subsequent inactivation of LMAN did not restore song, indicating that changes in vocal output were encoded in the motor circuit. Together, these findings highlight the importance of temporally precise burst firing in cortical–basal circuits for motor performance, plasticity, and pathology.
From Song to Synapse
Richard Mooney
Department of Neurobiology Duke University
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Vocalizations are an essential medium for social recognition and sexual signaling in mammals and birds. Whereas many types of vocalizations are innate, including courtship vocalizations of mice, songbirds learn their courtship songs in a process with many parallels to human speech learning. I will discuss recent advances from our lab highlighting the neural mechanisms that enable birdsong learning, including the formation of auditory memories of vocal models, evaluation of song performance, and basal ganglia-dependent vocal exploration and reinforcement. How the learned song is integrated with innate vocalizations will also be considered, with reference to recent studies that genetically map neural circuits for innate vocalizations in mice.