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Published on: June 19, 2016
Neural control of muscle force: indications from a simulation model
Paola Contessa1, Carlo J De Luca
1NeuroMuscular Research Center, Boston University, Boston, Massachusetts 02215, USA. contessa@bu.edu
Journal of Neurophysiology
|December 14, 2012
Summary
This study models motoneuron firing and muscle force during isometric contractions, revealing how muscle force twitches influence motor unit behavior and force production. Findings support invariant motoneuron control during sustained contractions.
Area of Science:
- Neuroscience
- Biophysics
- Motor Control
Background:
- Voluntary isometric contractions involve complex interactions between motoneurons and muscle units.
- Understanding motor unit firing behavior and force production is crucial for motor control research.
- Existing models often simplify the dynamic interplay of muscle force twitches and motor unit recruitment.
Purpose of the Study:
- To develop and validate a computational model simulating motoneuron firing and muscle force production during voluntary isometric contractions.
- To investigate the influence of muscle force twitches on motor unit behavior and force output.
- To examine the 'common drive' and 'onion skin' properties in motor unit recruitment and firing patterns.
Main Methods:
- Developed a computational model incorporating common drive and onion skin properties.
- Simulated voluntary isometric contractions with force feedback control.
- Varied motor unit force twitches and the number of active units to model time- and force-dependent changes.
- Analyzed simulated motor unit firing rates, recruitment/derecruitment patterns, and force fluctuations.
Main Results:
- Simulations replicated key empirical findings in sustained contractions, including initial firing rate changes, ongoing motor unit recruitment/derecruitment, and increasing force fluctuations.
- The model demonstrated that muscle force generation capacity influences motor unit behavior at recruitment and derecruitment.
- An alternative mechanism for reserve motor unit capacity in generating extraordinary force was identified.
Conclusions:
- Motoneuron control appears invariant during force-varying and sustained isometric contractions.
- The model provides insights into the dynamic interplay of muscle force, motor unit behavior, and neural control.
- Highlights the importance of considering muscle force generation capacity when interpreting motor unit behavior.
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