Related Experiment Video
Updated: Jun 7, 2026
07:52
Multiscale Investigations of Cortical Processing by Integrating Laminar Polytrodes and Optogenetics with Micro Electrocorticography in Rodents
Published on: May 23, 2025
Assessment of across-muscle coherence using multi-unit vs. single-unit recordings
Jamie A Johnston1, Gabriele Formicone, Thomas M Hamm
1Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
Experimental Brain Research
|November 4, 2010
Summary
Multi-muscle coherence analysis of electromyographic (EMG) signals can detect correlated neural inputs to motor units (MUs). This study shows mEMG coherence is useful across many experimental conditions, providing guidelines for its interpretation.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Motor Control
Background:
- Coherence analysis of electromyographic (EMG) signals is a method to identify common neural drive to motor units (MUs) in different muscles.
- Understanding the utility and limitations of multi-muscle EMG (mEMG) coherence is crucial for interpreting neural coupling between muscles.
Purpose of the Study:
- To determine the efficacy of mEMG coherence in detecting correlated MU activity.
- To establish the range of correlation strengths where mEMG coherence is a valuable measure.
- To provide guidelines for using and interpreting mEMG coherence in physiological studies.
Main Methods:
- Simulations using a validated motor-unit model (Fuglevand et al. 1992).
- Systematic variation of common input strength, number of correlated MU pairs, and MU discharge variability.
- Calculation and analysis of coherence between simulated motor-unit and mEMG signals from two muscles.
Main Results:
- mEMG coherence positively correlates with the strength and distribution of common inputs.
- The relationship between pooled and mEMG coherence is nonlinear and independent of how correlation strength is modulated.
- mEMG coherence saturates at common input strengths exceeding those typically observed in physiological experiments.
Conclusions:
- mEMG coherence is a robust and useful measure for detecting correlated neural inputs across muscles in various experimental settings.
- Simulation results offer practical guidance for the application and interpretation of mEMG coherence analysis.
- The findings support the broader application of mEMG coherence in neuroscience and motor control research.
Related Concept Videos
01:13Motor Units
The motor unit is a fundamental component of the neuromuscular system and plays a crucial role in coordinating muscle contractions. It consists of a somatic motor neuron, which connects and controls multiple skeletal muscle fibers, forming a single functional segment. The axon of the motor neuron branches out and establishes synaptic connections known as neuromuscular junctions with individual muscle fibers within the motor unit.
Motor units come in different sizes, with smaller units...
Motor units come in different sizes, with smaller units...
00:46Motor Units
A motor unit consists of two main components: a single efferent motor neuron (i.e., a neuron that carries impulses away from the central nervous system) and all of the muscle fibers it innervates. The motor neuron may innervate multiple muscle fibers, which are single cells, but only one motor neuron innervates a single muscle fiber.
01:20Motor Unit Stimulation
When the neuron of a motor unit fires an action potential, it triggers a series of events, leading to a twitch contraction in the muscle fibers. The process of excitation-contraction coupling is crucial in relaying the action potential to the muscle fibers.
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...