We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
The Forces Generated by Agonist Muscles during Isometric Contractions Arise from Motor Unit Synergies.
- Authors
Del Vecchio, Alessandro; Marconi Germer, Carina; Kinfe, Thomas M.; Nuccio, Stefano; Hug, François; Eskofier, Bjoern; Farina, Dario; Enoka, Roger M.
- Abstract
The purpose of our study was to identify the low-dimensional latent components, defined hereafter as motor unit modes, underlying the discharge rates of the motor units in two knee extensors (vastus medialis and lateralis, eight men) and two hand muscles (first dorsal interossei and thenars, seven men and one woman) during submaximal isometric contractions. Factor analysis identified two independent motor unit modes that captured most of the covariance of the motor unit discharge rates. We found divergent distributions of the motor unit modes for the hand and vastii muscles. On average, 75% of the motor units for the thenar muscles and first dorsal interosseus were strongly correlated with the module for the muscle in which they resided. In contrast, we found a continuous distribution of motor unit modes spanning the two vastii muscle modules. The proportion of the muscle-specific motor unit modes was 60% for vastus medialis and 45% for vastus lateralis. The other motor units were either correlated with both muscle modules (shared inputs) or belonged to the module for the other muscle (15% for vastus lateralis). Moreover, coherence of the discharge rates between motor unit pools was explained by the presence of shared synaptic inputs. In simulations with 480 integrate-and-fire neurons, we demonstrate that factor analysis identifies the motor unit modes with high levels of accuracy. Our results indicate that correlated discharge rates of motor units that comprise motor unit modes arise from at least two independent sources of common input among the motor neurons innervating synergistic muscles.
- Subjects
MOTOR unit; MUSCLE contraction; VASTUS medialis; VASTUS lateralis; MOTOR neurons; CONTINUOUS distributions
- Publication
Journal of Neuroscience, 2023, Vol 43, Issue 16, p2860
- ISSN
0270-6474
- Publication type
Article
- DOI
10.1523/JNEUROSCI.1265-22.2023