Article
Neurosciences
Simone Tanzarella, Silvia Muceli, Marco Santello, Dario Farina
Summary: The study revealed a synergistic organization in motor neuron activities during complex tasks, leading to a reduction in output dimensionality. By factorizing the output of motor neurons, four motor neuron synergies and four functionally similar muscle synergies were identified. Motor neuron synergies were found to better discriminate individual finger forces compared to muscle synergies and were more consistent with the expected role of muscles in activating each finger.
JOURNAL OF NEUROSCIENCE
(2021)
Article
Clinical Neurology
Stuart Maitland, Enrique Escobedo-Cousin, Ian Schofield, Anthony O'Neill, Stuart Baker, Roger Whittaker
Summary: This study developed a new method to determine the spatial distribution of muscle fibers within human motor units using a flexible multi-channel electrode and a deconvolution method. The results demonstrated that human motor units spatially overlap and provided data on the spatial arrangement of muscle fibers.
CLINICAL NEUROPHYSIOLOGY
(2022)
Article
Orthopedics
Shuo Liang, Yu-Zhou Liu, Xiao-Qian Hu, Xin Zhao, Jie Lao
Summary: This study proposes a new approach to preserve the motor branch of the ulnar nerve by using the superficial radial nerve as a bridge. The feasibility of this technique was evaluated through cadaveric dissections. The results suggest that this modified approach can be technically viable and may preserve the ulnar nerve's recovery potential.
BMC MUSCULOSKELETAL DISORDERS
(2023)
Article
Neurosciences
Robin Rohlen, Christian Antfolk, Christer Gronlund
Summary: This study optimized and evaluated the methods for identifying and analyzing motor units (MUs) using imaging techniques. The results showed that the Haar wavelet transform (HWM) is a better method for estimating spikes compared to the band-pass filter (BPM), as it demonstrated higher agreement with simulated and experimental spikes, as well as less bias and variation.
JOURNAL OF ELECTROMYOGRAPHY AND KINESIOLOGY
(2022)
Article
Biochemistry & Molecular Biology
Yu-Lung Lin, Jennifer Nhieu, Thomas Lerdall, Liming Milbauer, Chin-Wen Wei, Dong Jun Lee, Sang-Hyun Oh, Stanley Thayer, Li-Na Wei
Summary: This study presents a novel three-dimensional bilayer hydrogel tri-culture system that allows the formation of architecturally organized motor units (MUs) in vitro. The researchers successfully co-cultured three cell types of a MU, namely motor neuron (MN), myoblast, and Schwann cell, on a bilayer hydrogel matrix. The developed model exhibited key features of MUs, including organized MU structure, myelinated nerves, aligned myotubes innervated on clustered neuromuscular junctions (NMJs), MN-driven myotube contractions, and increases in cytosolic Ca2+ upon stimulation. This model provides a valuable tool for studying neuromuscular disorders and peripheral neuropathies, as well as for physiological and pharmacological research in tissue engineering.
CELL AND BIOSCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Talita P. P. Pinto, Andrea Turolla, Marco Gazzoni, Michela Agostini, Taian M. M. Vieira
Summary: Degeneration of lower motoneurons is commonly found in stroke survivors, however, surviving motoneurons may innervate denervated muscle fibers as compensation. In this study, we used electrical stimulation and surface electromyography to examine the variations in M wave amplitudes in paretic muscles compared to non-paretic muscles after stroke. The results showed significantly greater increments in paretic muscles, indicating collateral reinnervation and enlargement of motor units. This non-invasive analysis may be useful for monitoring disease progression and clinical outcomes in stroke survivors.
APPLIED SCIENCES-BASEL
(2023)
Article
Engineering, Biomedical
Hikaru Yokoyama, Naotsugu Kaneko, Atsushi Sasaki, Akira Saito, Kimitaka Nakazawa
Summary: Objective: This study investigated the firing behavior of motor units (MUs) in the tibialis anterior (TA) muscle during slow walking using high-density surface electromyogram (HDsEMG) decomposition. Main results include gait phase-specific firing, doublet firings, and high MU synchronization during walking, which suggests flexible control of MU firing by the central nervous system during human walking.
JOURNAL OF NEURAL ENGINEERING
(2022)
Article
Physiology
Yvan Pratviel, Veronique Deschodt-Arsac, Florian Larrue, Laurent M. Arsac
Summary: Visuomotor dexterity goes beyond simple coordination, requiring a complex system involving the brain, body, and environment. Recent research suggests that a better understanding of executive control can be gained through multifractal formalisms applied to movement behavior. Eye-hand coordination arises from multiplicative cascade dynamics across temporal scales within the whole system.
FRONTIERS IN PHYSIOLOGY
(2021)
Article
Clinical Neurology
Linda Heskamp, Alexis R. Miller, Matthew G. Birkbeck, Julie Hall, Ian S. Schofield, Andrew M. Blamire, Roger G. Whittaker
Summary: This study used MRI to assess the in-vivo cross-sectional and 3D morphology of human motor units in hand, forearm, and lower leg muscles. The results showed no significant differences in the size and morphology of motor units among these muscles, and the 3D imaging revealed a more complex structure of human motor units than previously thought.
CLINICAL NEUROPHYSIOLOGY
(2022)
Review
Physiology
Edith Elgueta-Cancino, Ethan Evans, Eduardo Martinez-Valdes, Deborah Falla
Summary: This review aims to synthesize the available evidence on the effect of resistance training (RT) on motor unit firing properties. The review revealed a lack of high-quality evidence for the effect of RT on motor unit firing properties, with heterogeneity across studies affecting the conclusions that can be drawn.
FRONTIERS IN PHYSIOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Kenta Fujimura, Hitoshi Kagaya, Hiroki Tanikawa
Summary: This study investigated the usefulness of stimulating the intrinsic muscles of the hand using repetitive peripheral magnetic stimulation (rPMS) and found that rPMS can effectively stimulate the intrinsic muscles of the hand. This technique may be used as a treatment for diseases that cause immobility of the metacarpophalangeal joints.
APPLIED SCIENCES-BASEL
(2022)
Article
Physiology
Ya Zong, Zhiyuan Lu, Maoqi Chen, Lianfu Deng, Qin Xie, Ping Zhou
Summary: This study estimated the motor unit number of the second lumbrical muscle in the human hand, with findings suggesting a relatively low motor unit number which could be valuable for investigating motor units, especially during high-level muscle activation.
FRONTIERS IN PHYSIOLOGY
(2022)
Article
Physiology
Alexander I. Kostyukov, Andriy V. Gorkovenko, Yurii A. Kulyk, Oleksii V. Lehedza, Dmytro I. Shushuiev, Mariusz Zasada, Serhii S. Strafun
Summary: This study examines the non-linear effects of signal transduction in the human motor system, specifically focusing on muscle hysteresis. The results show that for two-joint movements of the forelimbs, considering force and activation synergies is sufficient, while kinematic synergy acts as a potent modulator of activation synergy.
FRONTIERS IN PHYSIOLOGY
(2022)
Article
Neurosciences
Hiroki Saito, Hikaru Yokoyama, Atsushi Sasaki, Tatsuya Kato, Kimitaka Nakazawa
Summary: This study reveals the existence of nine basic units of muscle synergies in upper limb movements, which are shared across different tasks. The central nervous system flexibly selects and modifies the contribution of these nine basic units to meet the demands of various tasks.
JOURNAL OF NEUROPHYSIOLOGY
(2022)
Article
Cell Biology
Klaus Becker, Marcio Goethel, Pedro Fonseca, Joao Paulo Vilas-Boas, Ulysses Ervilha
Summary: A common symptom in neuromuscular diseases is pain, which affects human movement. This study investigates how the brain recruits different motor units to produce torque during induced muscle pain. The results show that the strategy for maintaining force production during pain is to recruit motor units with higher recruitment threshold and action potential amplitude.
