Interfacing Motor Units in Nonhuman Primates Identifies a Principal Neural Component for Force Control Constrained by the Size Principle

Del Vecchio A, Jones RH, Schofield IS, Kinfe TM, Ibáñez J, Farina D, Baker SN (2022)

Publication Type: Journal article

Publication year: 2022

Journal

The Journal of Neuroscience Society for Neuroscience

Book Volume: 42

Pages Range: 7386-7399

Journal Issue: 39

DOI: 10.1523/JNEUROSCI.0649-22.2022

Abstract

Motor units convert the last neural code of movement into muscle forces. The classic view of motor unit control is that the CNS sends common synaptic inputs to motoneuron pools and that motoneurons respond in an orderly fashion dictated by the size principle. This view, however, is in contrast with the large number of dimensions observed in motor cortex, which may allow individual and flexible control of motor units. Evidence for flexible control of motor units may be obtained by tracking motor units longitudinally during tasks with some level of behavioral variability. Here we identified and tracked populations of motor units in the brachioradialis muscle of two macaque monkeys during 10 sessions spanning.1 month with a broad range of rate of force development (1.8-38.6 N · m · s21). We found a very stable recruitment order and discharge characteristics of the motor units over sessions and contraction trials. The small deviations from orderly recruitment were fully predicted by the motor unit recruitment intervals, so that small shifts in recruitment thresholds happened only during contractions at a high rate of force development. Moreover, we also found that one component explained more than;50% of the motor unit discharge rate variance, and that the remaining components represented a time-shifted version of the first. In conclusion, our results show that the recruitment of motoneurons is determined by the interplay of the size principle and common input and that this recruitment scheme is not violated over time or by the speed of the contractions.

Authors with CRIS profile

Alessandro Del Vecchio Juniorprofessur für Neuromuscular Physiology and Neural Interfacing Thomas Mehari Kinfe Professur für Neurochirurgie mit dem Schwerpunkt Funktionelle Stereotaktische Neurochirurgie

Involved external institutions

Newcastle University GB United Kingdom (GB) Imperial College London / The Imperial College of Science, Technology and Medicine GB United Kingdom (GB)

How to cite

APA:

Del Vecchio, A., Jones, R.H., Schofield, I.S., Kinfe, T.M., Ibáñez, J., Farina, D., & Baker, S.N. (2022). Interfacing Motor Units in Nonhuman Primates Identifies a Principal Neural Component for Force Control Constrained by the Size Principle. The Journal of Neuroscience, 42(39), 7386-7399. https://dx.doi.org/10.1523/JNEUROSCI.0649-22.2022

MLA:

Del Vecchio, Alessandro, et al. "Interfacing Motor Units in Nonhuman Primates Identifies a Principal Neural Component for Force Control Constrained by the Size Principle." The Journal of Neuroscience 42.39 (2022): 7386-7399.

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