Flexible Coordination Patterns of Rat Forelimb Motor Units Across Locomotion Speeds Restricted; Files Only
Wang, Runming (Spring 2023)
Published
Abstract
Background: The coordination of large motor unit (MU) populations during dynamic movements, such as locomotion, remains an area of inadequate understanding. While researchers have relied on Henneman's size principle for decades to understand the coordination pattern of MUs, several counterexamples of the size principle have been documented in intricate dynamic movements, revealing a more complex pattern of MU coordination. This study represents the first investigation into the flexible coordination of large MU populations across multiple dynamic behaviors.
Methods: This study conducted a comprehensive analysis of a dataset obtained from a rat named "Godzilla" on November 16, 2022. The rats were trained to perform steady walking locomotion on an adjustable treadmill, and their kinematics were captured using a 3D motion tracking system based on DeepLabCut. Electrophysiological signals were recorded using novel intramuscular EMG arrays and were analyzed using functions within the rat-loco repository. State-space analysis was employed to visualize the coordination patterns of motor units across various speed conditions. The Kernel Density Estimation metric was used to estimate the similarity across MU responses, and the pairwise Euclidean distance between state-space trajectories was calculated to quantify significant differences between coordination patterns.
Results: The results of this analysis support the hypothesis that the adjustment in motor unit coordination is continuous rather than discrete. The state-space trajectories showed that the coordination patterns of motor units were flexible as the treadmill speed was adjusted, without significant discrete shifts. The OVL values also revealed that the similarity between the motor unit coordination patterns across speed conditions was high, indicating a flexible and continuous adjustment to changing force demands.
Conclusion: This study successfully analyzed kinematic and electrophysiological signals during treadmill locomotion tasks performed by rats, providing evidence for adaptive motor unit coordination patterns across varying speed conditions. The multi-faceted analysis approach utilized in this study emphasizes the importance of comprehensive analysis to fully understand the underlying mechanisms of motor unit coordination. Further research with additional datasets will be necessary to fully evaluate the transitions between coordination strategies.
Table of Contents
Abstract: 1
Introduction and Background: 2
Methods: 7
Animal Training: 7
Kinematics capturing: 9
EMG Array Surgical Implantation: 12
EMG recording and Spike Sorting: 13
Data Analysis: 14
Results: 18
Synchronization validation: 18
Binning and spike count analysis: 19
State-space analysis: 21
Probability density overlap calculation: 24
Euclidean distance calculation: 27
Discussion: 30
Conclusion: 34
References: 35
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File download under embargo until 19 May 2025 | 2023-04-14 13:28:56 -0400 | File download under embargo until 19 May 2025 |
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