Matthew Williams

BME PhD Proposal Presentation

Date: 2023-04-10
Time: 4:00 PM - 6:00 PM
Location / Meeting Link: O. Wayne Rollins Research Building (Emory University), Room 1052

Committee Members:
Samuel Sober, PhD (Advisor); Lena Ting, PhD; Timothy Cope, PhD; Simon Sponberg, PhD; Eiman Azim, PhD


Title: Cortical Influence on Neuromuscular Control During Skilled Movement Learning

Abstract:
To interact with the outside world, the brain must flexibly control and coordinate muscle groups to create complex movements. Studies of spiking patterns in cortex have enabled a richer understanding of how the brain plans and executes goal-directed movements. However, the connection between these cortical patterns and muscle activity has been limited by the inability to record muscle activity, called electromyography (EMG), at high spatiotemporal resolution. To address this problem and directly connect brain activity to muscle activity, we have developed electrode arrays that are capable of recording muscle fiber activity at the temporal scale of milliseconds and the spatial scale of a single motor unit. A motor unit consists of a single motor neuron in the central nervous system and all the muscle fibers it innervates. Typical devices only record motor units for a short amount of time under highly constrained experimental conditions where the animal has limited movement ability; no current devices can record single units during behavior in small animals. Recent advances in motor unit recording devices made by our group enable us to study the exact temporal pattern of multiple motor units for multiple weeks. We will use this technology to investigate how descending commands from cortex coordinate muscles to produce smooth movements and how patterns of coordination between individual neurons change throughout learning to accomplish task-specific goals. Another barrier to understanding of motor control by the central nervous system is the lack of a precise readout of muscle activity during brain manipulations and across learning. To address this problem, we will pair optogenetic perturbations in mice with a bimanual, isometric force task that can be learned in a matter of days. This allows us to elucidate the role of descending cortical control in motor learning and execution. The experiments proposed here will advance our understanding of muscle coordination by revealing how descending cortical commands influence the firing of individual motor units to enable the learning and execution of a skilled behavior.