Dual Control of Feeding and Singing in the Songbird Motor System

A fundamental question in neuroscience is how complex movements are learned and produced to complete specific tasks. Motor skills are acquired and maintained through sensorimotor learning, a process through which motor output is modified in response to sensory feedback[1]. Many skilled behaviors, including speech, object manipulation, and tool-use, consist of distinct phases that can be adaptively re-ordered in real-time based on sensory feedback[2]. The nervous system must selectively coordinate muscle activity to perform multiple flexibly organized behaviors. Many functionally distinct behaviors rely on the same muscles for execution, furthering the need for controlled modulation of motor output. A critical gap exists in understanding how the nervous system coordinates the same muscles to perform distinct, flexibly organized behaviors. The overall objective of this project is to reveal how flexible and sequential movement is controlled and to quantify muscle activity across different movements and behaviors. Aim 1 will identify how patterns of muscle activity drive diverse sequential behaviors. Jaw kinematics and electromyography (EMG) activity from jaw muscles will be compared during phases of singing and eating. Aim 2 will reveal the neural substrates necessary for non-vocal learning. Novel seed-eating will be compared between control and LMAN-lesioned adult male Bengalese finches. Seed ingestion and changes in beak kinematics will be measured. This project will improve our understanding of behavioral representation and learning. Specifically, we will reveal whether specific behaviors require independent motor learning circuits, or a general circuit enables flexible performance of multiple complex behaviors. Insights from this work can inform a broader framework for multifunctional motor control. By identifying the organization of neural circuitry for distinct commands and characterizing the muscle activity underlying these behaviors, we will provide fundamental knowledge to guide rehabilitation strategies for comorbid disorders. The analogous circuitry and learning processes for vocal communication of humans and songbirds lends particular significance to neuromuscular disorders affecting facial muscles. Dysphagia, for example, is often treated with speech therapy, based on the shared musculature involved in speech and eating, but malnutrition and weight loss often persist[29]. A comprehensive understanding of how muscles function across different behaviors will support improvement of therapies aimed at restoring movement abilities. Particularly, if a shared motor program exists for a given muscle or muscle ensemble, a single treatment strategy could be designed to improve both speaking and swallowing. Project Number: 1F31NS149523-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Neurological Disorders and Stroke (NINDS) | Principal Investigator: Abigail Grassler | Institution: EMORY UNIVERSITY, ATLANTA, GA | Award Amount: $50,114 | Activity Code: F31 | Study Section: Special Emphasis Panel[ZRG1 F03D-V (20)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11385213