Identification of a motor-to-auditory pathway important for vocal learning

• Published in: Nature neuroscience Vol. 20; no. 7; pp. 978 - 986
• Main Authors: Roberts, Todd F, Hisey, Erin, Tanaka, Masashi, Kearney, Matthew G, Chattree, Gaurav, Yang, Cindy F, Shah, Nirao M, Mooney, Richard
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.07.2017; Nature Publishing Group
• Subjects: 14; 631/378/2629/2631; 631/378/3920; Ablation; Adults; Aging - physiology; Animal behavior; Animal Genetics and Genomics; Animals; Animals, Genetically Modified; Auditory cortex; Auditory Cortex - physiology; Auditory Pathways - physiology; Auditory system; Behavioral Sciences; Biological Techniques; Biomedicine; Brain; Cell Count; Cortex (auditory); Deafness - physiopathology; Degradation; Event-related potentials; Finches; Learning; Learning - physiology; Male; Motor task performance; Neural circuitry; Neural Pathways - physiology; Neuroanatomical Tract-Tracing Techniques; Neurobiology; Neurons; Neurons - physiology; Neurosciences; Physiological aspects; Song; Telencephalon - physiology; Temporal cortex; Temporal variations; Testing; Vocalization behavior; Vocalization, Animal - physiology
• ISSN: 1097-6256; 1546-1726
• DOI: 10.1038/nn.4563

Although vocal learning is widely speculated to depend on motor to auditory (i.e., forward) pathways, the neurons that convey forward signals important to vocal learning remain unknown. Here the authors identify neurons that transmit signals from songbird motor to auditory regions and demonstrate their role in vocal learning. Learning to vocalize depends on the ability to adaptively modify the temporal and spectral features of vocal elements. Neurons that convey motor-related signals to the auditory system are theorized to facilitate vocal learning, but the identity and function of such neurons remain unknown. Here we identify a previously unknown neuron type in the songbird brain that transmits vocal motor signals to the auditory cortex. Genetically ablating these neurons in juveniles disrupted their ability to imitate features of an adult tutor's song. Ablating these neurons in adults had little effect on previously learned songs but interfered with their ability to adaptively modify the duration of vocal elements and largely prevented the degradation of songs' temporal features that is normally caused by deafening. These findings identify a motor to auditory circuit essential to vocal imitation and to the adaptive modification of vocal timing.