Sean O'Connell
BME PhD Defense Presentation
Date: 2025-07-11
Time: 12:00 PM-2:00 PM
Location / Meeting Link: HSRB II Room N600; https://emory.zoom.us/my/seanoco
Committee Members:
Chethan Pandarinath, PhD (Co-advisor); Sam Sober, PhD (Co-advisor); Gordon Berman, PhD; Young-Hui Chang, PhD; Chris Rodgers, PhD; Matthew Tresch, PhD
Title: Methods for Analysis of High-Resolution Muscle Recordings During Dynamic Movement and Generation of Realistic Motor Unit Datasets for Ground Truth
Abstract:
A key focus of motor neuroscience is to understand how the descending neural drive influences muscle fibers during force production. To this end, recent advances in intramuscular multielectrode arrays have enabled high-quality multichannel recordings of many motor unit action potentials (MUAPs) for the first time. However, identifying individual MUAPs from multichannel recordings is a significant challenge for existing spike sorting methods, which are typically optimized for action potentials from neurons in the brain. To overcome this challenge, we developed the Enhanced Motor Unit sorter (EMUsort), an extension to Kilosort4 that achieves high-performance MUAP spike sorting with additional usability features. We applied EMUsort to EMG data we recorded from the rat forelimb during locomotion using high-resolution Myomatrix EMG arrays. Unlike previous methods, EMUsort addresses unique challenges encountered with MUAP data, including: 1) long time delays across electrodes due to propagation along fibers, 2) more complex waveform shapes compared to brain recordings, and 3) overlap of MUAPs due to cumulative recruitment. The effects of our changes were quantitatively evaluated against realistic simulated datasets that we created to closely replicate the data we collected. EMUsort outperforms Kilosort4 and MUedit, increasing sorting accuracy by up to 20% during periods with high motor unit overlap. In sum, EMUsort provides a significant improvement to MUAP spike sorter accuracy, especially during regions of high MUAP overlap, in an easy-to-use software package.