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da Silva Costa AA, Moraes R, den Otter R, Gennaro F, Bakker L, Rocha Dos Santos PC, Hortobágyi T. Corticomuscular and intermuscular coherence as a function of age and walking balance difficulty. Neurobiol Aging 2024; 141:85-101. [PMID: 38850592 DOI: 10.1016/j.neurobiolaging.2024.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 04/12/2024] [Accepted: 05/08/2024] [Indexed: 06/10/2024]
Abstract
We determined beta-band intermuscular (IMC) and corticomuscular coherence (CMC) as a function of age and walking balance difficulty. Younger (n=14, 23y) and older individuals (n=19, 71y) walked 13 m overground, on a 6-cm-wide ribbon overground, and on a 6-cm-wide (5-cm-high) beam. Walking distance as a proxy for walking balance and speed were computed. CMC was estimated between electroencephalographic signal at Cz electrode and surface electromyographic signals of seven leg muscles, while IMC was calculated in four pairs of leg muscles, during stance and swing gait phases. With increasing difficulty, walking balance decreased in old individuals and speed decreased gradually independent of age. Beam walking increased IMC, while age increased IMC in proximal muscle pairs, and decreased IMC in distal muscle pairs. Age and difficulty increased CMC independent of gait phases. Concluding, CMC and IMC increased with walking balance difficulty and age, except for distal muscle pairs, which had lower IMC with age. These findings suggest an age-related increase in corticospinal involvement in the neural control of walking balance. DATA AVAILABILITY: The datasets used in this study are available from the corresponding author upon reasonable request.
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Affiliation(s)
- Andréia Abud da Silva Costa
- Ribeirão Preto Medical School, Graduate Program in Rehabilitation and Functional Performance, University of São Paulo, Brazil; Biomechanics and Motor Control Lab, School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, Brazil; Department of Human Movement Sciences, University of Groningen Medical Center, Groningen, the Netherlands.
| | - Renato Moraes
- Ribeirão Preto Medical School, Graduate Program in Rehabilitation and Functional Performance, University of São Paulo, Brazil; Biomechanics and Motor Control Lab, School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, Brazil
| | - Rob den Otter
- Department of Human Movement Sciences, University of Groningen Medical Center, Groningen, the Netherlands
| | - Federico Gennaro
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Lisanne Bakker
- Department of Human Movement Sciences, University of Groningen Medical Center, Groningen, the Netherlands
| | - Paulo Cezar Rocha Dos Santos
- Department of Computer Science & Applied Mathematics, Weizmann Institute of Science, Israel; The Center of Advanced Technologies in Rehabilitation, Sheba Medical Center, Israel; IDOR/Pioneer Science Initiative, Rio de Janeiro, RJ, Brazil
| | - Tibor Hortobágyi
- Department of Human Movement Sciences, University of Groningen Medical Center, Groningen, the Netherlands; Department of Kinesiology, Hungarian University of Sports Science, Budapest 1123, Hungary; Department of Sport Biology, Institute of Sport Sciences and Physical Education, University of Pécs, Pécs, Hungary
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Borzelli D, Vieira TMM, Botter A, Gazzoni M, Lacquaniti F, d'Avella A. Synaptic inputs to motor neurons underlying muscle coactivation for functionally different tasks have different spectral characteristics. J Neurophysiol 2024; 131:1126-1142. [PMID: 38629162 DOI: 10.1152/jn.00199.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 04/11/2024] [Accepted: 04/11/2024] [Indexed: 06/01/2024] Open
Abstract
The central nervous system (CNS) may produce the same endpoint trajectory or torque profile with different muscle activation patterns. What differentiates these patterns is the presence of cocontraction, which does not contribute to effective torque generation but allows to modulate joints' mechanical stiffness. Although it has been suggested that the generation of force and the modulation of stiffness rely on separate pathways, a characterization of the differences between the synaptic inputs to motor neurons (MNs) underlying these tasks is still missing. In this study, participants coactivated the same pair of upper-limb muscles, i.e., the biceps brachii and the triceps brachii, to perform two functionally different tasks: limb stiffness modulation or endpoint force generation. Spike trains of MNs were identified through decomposition of high-density electromyograms (EMGs) collected from the two muscles. Cross-correlogram showed a higher synchronization between MNs recruited to modulate stiffness, whereas cross-muscle coherence analysis revealed peaks in the β-band, which is commonly ascribed to a cortical origin. These peaks did not appear during the coactivation for force generation, thus suggesting separate cortical inputs for stiffness modulation. Moreover, a within-muscle coherence analysis identified two subsets of MNs that were selectively recruited to generate force or regulate stiffness. This study is the first to highlight different characteristics, and probable different neural origins, of the synaptic inputs driving a pair of muscles under different functional conditions. We suggest that stiffness modulation is driven by cortical inputs that project to a separate set of MNs, supporting the existence of a separate pathway underlying the control of stiffness.NEW & NOTEWORTHY The characterization of the pathways underlying force generation or stiffness modulation are still unknown. In this study, we demonstrated that the common input to motor neurons of antagonist muscles shows a high-frequency component when muscles are coactivated to modulate stiffness but not to generate force. Our results provide novel insights on the neural strategies for the recruitment of multiple muscles by identifying specific spectral characteristics of the synaptic inputs underlying functionally different tasks.
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Affiliation(s)
- Daniele Borzelli
- Department of Biomedical, Dental, Morphological and Functional Imaging Sciences, University of Messina, Messina, Italy
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Taian M M Vieira
- Laboratory for Engineering of the Neuromuscular System, Department of Electronics and Telecommunications, Politecnico di Torino, Turin, Italy
- PoliToBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Alberto Botter
- Laboratory for Engineering of the Neuromuscular System, Department of Electronics and Telecommunications, Politecnico di Torino, Turin, Italy
- PoliToBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Marco Gazzoni
- Laboratory for Engineering of the Neuromuscular System, Department of Electronics and Telecommunications, Politecnico di Torino, Turin, Italy
- PoliToBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Francesco Lacquaniti
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
- Department of Systems Medicine and Center of Space BioMedicine, University of Rome Tor Vergata, Rome, Italy
| | - Andrea d'Avella
- Department of Biomedical, Dental, Morphological and Functional Imaging Sciences, University of Messina, Messina, Italy
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
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Guo Y, Jones EJ, Škarabot J, Inns TB, Phillips BE, Atherton PJ, Piasecki M. Common synaptic inputs and persistent inward currents of vastus lateralis motor units are reduced in older male adults. GeroScience 2024; 46:3249-3261. [PMID: 38238546 PMCID: PMC11009172 DOI: 10.1007/s11357-024-01063-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 01/02/2024] [Indexed: 04/13/2024] Open
Abstract
Although muscle atrophy may partially account for age-related strength decline, it is further influenced by alterations of neural input to muscle. Persistent inward currents (PIC) and the level of common synaptic inputs to motoneurons influence neuromuscular function. However, these have not yet been described in the aged human quadriceps. High-density surface electromyography (HDsEMG) signals were collected from the vastus lateralis of 15 young (mean ± SD, 23 ± 5 y) and 15 older (67 ± 9 y) men during submaximal sustained and 20-s ramped contractions. HDsEMG signals were decomposed to identify individual motor unit discharges, from which PIC amplitude and intramuscular coherence were estimated. Older participants produced significantly lower knee extensor torque (p < 0.001) and poorer force tracking ability (p < 0.001) than young. Older participants also had lower PIC amplitude (p = 0.001) and coherence estimates in the alpha frequency band (p < 0.001) during ramp contractions when compared to young. Persistent inward currents and common synaptic inputs are lower in the vastus lateralis of older males when compared to young. These data highlight altered neural input to the clinically and functionally important quadriceps, further underpinning age-related loss of function which may occur independently of the loss of muscle mass.
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Affiliation(s)
- Yuxiao Guo
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK
| | - Eleanor J Jones
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK
| | - Jakob Škarabot
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Thomas B Inns
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK
| | - Bethan E Phillips
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK
| | - Philip J Atherton
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK
| | - Mathew Piasecki
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK.
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Woods S, McKiel A, Herda T, Klentrou P, Holmes M, Gabriel D, Falk B. Motor unit firing rates during slow and fast contractions in boys and men. Eur J Appl Physiol 2024:10.1007/s00421-024-05500-8. [PMID: 38762834 DOI: 10.1007/s00421-024-05500-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Accepted: 05/03/2024] [Indexed: 05/20/2024]
Abstract
BACKGROUND Motor unit (MU) activation during maximal contractions is lower in children compared with adults. Among adults, discrete MU activation differs, depending on the rate of contraction. We investigated the effect of contraction rate on discrete MU activation in boys and men. METHODS Following a habituation session, 14 boys and 20 men completed two experimental sessions for knee extension and wrist flexion, in random order. Maximal voluntary isometric torque (MVIC) was determined before completing trapezoidal isometric contractions (70%MVIC) at low (10%MVIC/s) and high (35%MVIC/s) contraction rates. Surface electromyography was captured from the vastus lateralis (VL) and flexor carpi radialis (FCR) and decomposed into individual MU action potential (MUAP) trains. RESULTS In both groups and muscles, the initial MU firing rate (MUFR) was greater (p < 0.05) at high compared with low contraction rates. The increase in initial MUFR at the fast contraction in the VL was greater in men than boys (p < 0.05). Mean MUFR was significantly lower during fast contractions only in the FCR (p < 0.05). In both groups and muscles, the rate of decay of MUFR with increasing MUAP amplitude was less steep (p < 0.05) during fast compared with slow contractions. CONCLUSION In both groups and muscles, initial MUFRs, as well as MUFRs of large MUs were higher during fast compared with slow contractions. However, in the VL, the increase in initial MUFR was greater in men compared with boys. This suggests that in large muscles, men may rely more on increasing MUFR to generate torque at faster rates compared with boys.
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Affiliation(s)
- Stacey Woods
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada
| | - Andrew McKiel
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada
| | - Trent Herda
- School of Education and Human Sciences, University of Kansas, Lawrence, KS, USA
| | - Panagiota Klentrou
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Michael Holmes
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - David Gabriel
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada
| | - Bareket Falk
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada.
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada.
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Santos PCRD, Heimler B, Koren O, Flash T, Plotnik M. Dopamine improves defective cortical and muscular connectivity during bilateral control of gait in Parkinson's disease. Commun Biol 2024; 7:495. [PMID: 38658666 PMCID: PMC11043351 DOI: 10.1038/s42003-024-06195-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 04/15/2024] [Indexed: 04/26/2024] Open
Abstract
Parkinson's Disease (PD)-typical declines in gait coordination are possibly explained by weakness in bilateral cortical and muscular connectivity. Here, we seek to determine whether this weakness and consequent decline in gait coordination is affected by dopamine levels. To this end, we compare cortico-cortical, cortico-muscular, and intermuscular connectivity and gait outcomes between body sides in people with PD under ON and OFF medication states, and in older adults. In our study, participants walked back and forth along a 12 m corridor. Gait events (heel strikes and toe-offs) and electrical cortical and muscular activities were measured and used to compute cortico-cortical, cortico-muscular, and intermuscular connectivity (i.e., coherences in the alpha, beta, and gamma bands), as well as features characterizing gait performance (e.g., the step-timing coordination, length, and speed). We observe that people with PD, mainly during the OFF medication, walk with reduced step-timing coordination. Additionally, our results suggest that dopamine intake in PD increases the overall cortico-muscular connectivity during the stance and swing phases of gait. We thus conclude that dopamine corrects defective feedback caused by impaired sensory-information processing and sensory-motor integration, thus increasing cortico-muscular coherences in the alpha bands and improving gait.
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Affiliation(s)
- Paulo Cezar Rocha Dos Santos
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel.
- Center of Advanced Technologies in Rehabilitation, Sheba Medical Center, Ramat Gan, Israel.
- IDOR/Pioneer Science Initiative, Rio de Janeiro, Brazil.
| | - Benedetta Heimler
- Center of Advanced Technologies in Rehabilitation, Sheba Medical Center, Ramat Gan, Israel
| | - Or Koren
- Center of Advanced Technologies in Rehabilitation, Sheba Medical Center, Ramat Gan, Israel
| | - Tamar Flash
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel
| | - Meir Plotnik
- Center of Advanced Technologies in Rehabilitation, Sheba Medical Center, Ramat Gan, Israel.
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
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Kutluyarov RV, Zakoyan AG, Voronkov GS, Grakhova EP, Butt MA. Neuromorphic Photonics Circuits: Contemporary Review. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:3139. [PMID: 38133036 PMCID: PMC10745993 DOI: 10.3390/nano13243139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/08/2023] [Accepted: 12/10/2023] [Indexed: 12/23/2023]
Abstract
Neuromorphic photonics is a cutting-edge fusion of neuroscience-inspired computing and photonics technology to overcome the constraints of conventional computing architectures. Its significance lies in the potential to transform information processing by mimicking the parallelism and efficiency of the human brain. Using optics and photonics principles, neuromorphic devices can execute intricate computations swiftly and with impressive energy efficiency. This innovation holds promise for advancing artificial intelligence and machine learning while addressing the limitations of traditional silicon-based computing. Neuromorphic photonics could herald a new era of computing that is more potent and draws inspiration from cognitive processes, leading to advancements in robotics, pattern recognition, and advanced data processing. This paper reviews the recent developments in neuromorphic photonic integrated circuits, applications, and current challenges.
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Affiliation(s)
- Ruslan V. Kutluyarov
- School of Photonics Engineering and Research Advances (SPhERA), Ufa University of Science and Technology, 32, Z. Validi St., 450076 Ufa, Russia
| | - Aida G. Zakoyan
- School of Photonics Engineering and Research Advances (SPhERA), Ufa University of Science and Technology, 32, Z. Validi St., 450076 Ufa, Russia
| | - Grigory S. Voronkov
- School of Photonics Engineering and Research Advances (SPhERA), Ufa University of Science and Technology, 32, Z. Validi St., 450076 Ufa, Russia
| | - Elizaveta P. Grakhova
- School of Photonics Engineering and Research Advances (SPhERA), Ufa University of Science and Technology, 32, Z. Validi St., 450076 Ufa, Russia
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Farina D, Enoka RM. Evolution of surface electromyography: From muscle electrophysiology towards neural recording and interfacing. J Electromyogr Kinesiol 2023; 71:102796. [PMID: 37343466 DOI: 10.1016/j.jelekin.2023.102796] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/23/2023] Open
Abstract
Surface electromyography (EMG) comprises a recording of electrical activity from the body surface generated by muscle fibres during muscle contractions. Its characteristics depend on the fibre membrane potentials and the neural activation signal sent from the motor neurons to the muscles. EMG has been classically used as the primary investigation tool in kinesiology studies in a variety of applications. More recently, surface EMG techniques have evolved from single-channel methods to high-density systems with hundreds of electrodes. High-density EMG recordings can be deconvolved to estimate the discharge times of spinal motor neurons innervating the recorded muscles, with algorithms that have been developed and validated in the last two decades. Within limits and with some variability across muscles, these techniques provide a non-invasive method to study relatively large populations of motor neurons in humans. Surface EMG is thus evolving from a peripheral measure of muscle electrical activity towards a neural recording and neural interfacing signal. These advances in technology have had a major impact on our fundamental understanding of the neural control of movement and have exposed new perspectives in neurotechnologies. Here we provide an overview and perspective of modern EMG technology, as derived from past achievements, and its impact in neurophysiology and neural engineering.
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Affiliation(s)
- Dario Farina
- Department of Bioengineering, Imperial College London, United Kingdom.
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado Boulder, CO, United States
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Del Vecchio A, Marconi Germer C, Kinfe TM, Nuccio S, Hug F, Eskofier B, Farina D, Enoka RM. The Forces Generated by Agonist Muscles during Isometric Contractions Arise from Motor Unit Synergies. J Neurosci 2023; 43:2860-2873. [PMID: 36922028 PMCID: PMC10124954 DOI: 10.1523/jneurosci.1265-22.2023] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 02/03/2023] [Accepted: 02/12/2023] [Indexed: 03/17/2023] Open
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.SIGNIFICANCE STATEMENT It has been suggested that the nervous system controls synergistic muscles by projecting common synaptic inputs to the engaged motor neurons. In our study, we reduced the dimensionality of the output produced by pools of synergistic motor neurons innervating the hand and thigh muscles during isometric contractions. We found two neural modules, each representing a different common input, that were each specific for one of the muscles. In the vastii muscles, we found a continuous distribution of motor unit modes spanning the two synergistic muscles. Some of the motor units from the homonymous vastii muscle were controlled by the dominant neural module of the other synergistic muscle. In contrast, we found two distinct neural modules for the hand muscles.
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Affiliation(s)
- Alessandro Del Vecchio
- Department Artificial Intelligence in Biomedical Engineering, Friedrich-Alexander University, 91052 Erlangen, Germany
| | - Carina Marconi Germer
- Department of Bioengineering, Federal University of Pernambuco, CEP 50670-901 Recife, Brazil
| | - Thomas M Kinfe
- Division of Functional Neurosurgery and Stereotaxy, Friedrich-Alexander University, 91052 Erlangen, Germany
| | - Stefano Nuccio
- Department Human Movement Science, University of Rome Foro Italico, 00185 Rome, Italy
| | - François Hug
- Le Laboratoire Motricité Humaine Expertise Sport Santé, Université Côte d'Azur, 06103 Nice, France
| | - Bjoern Eskofier
- Department Artificial Intelligence in Biomedical Engineering, Friedrich-Alexander University, 91052 Erlangen, Germany
| | - Dario Farina
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado CO 80309
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Use of Surface Electromyography to Estimate End-Point Force in Redundant Systems: Comparison between Linear Approaches. Bioengineering (Basel) 2023; 10:bioengineering10020234. [PMID: 36829728 PMCID: PMC9952324 DOI: 10.3390/bioengineering10020234] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 02/12/2023] Open
Abstract
Estimation of the force exerted by muscles from their electromyographic (EMG) activity may be useful to control robotic devices. Approximating end-point forces as a linear combination of the activities of multiple muscles acting on a limb may lead to an inaccurate estimation because of the dependency between the EMG signals, i.e., multi-collinearity. This study compared the EMG-to-force mapping estimation performed with standard multiple linear regression and with three other algorithms designed to reduce different sources of the detrimental effects of multi-collinearity: Ridge Regression, which performs an L2 regularization through a penalty term; linear regression with constraints from foreknown anatomical boundaries, derived from a musculoskeletal model; linear regression of a reduced number of muscular degrees of freedom through the identification of muscle synergies. Two datasets, both collected during the exertion of submaximal isometric forces along multiple directions with the upper limb, were exploited. One included data collected across five sessions and the other during the simultaneous exertion of force and generation of different levels of co-contraction. The accuracy and consistency of the EMG-to-force mappings were assessed to determine the strengths and drawbacks of each algorithm. When applied to multiple sessions, Ridge Regression achieved higher accuracy (R2 = 0.70) but estimations based on muscle synergies were more consistent (differences between the pulling vectors of mappings extracted from different sessions: 67%). In contrast, the implementation of anatomical constraints was the best solution, both in terms of consistency (R2 = 0.64) and accuracy (74%), in the case of different co-contraction conditions. These results may be used for the selection of the mapping between EMG and force to be implemented in myoelectrically controlled robotic devices.
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O’Keeffe R, Rathod V, Shirazi SY, Mehrdad S, Edwards A, Rao S, Atashzar SF. Linear versus Nonlinear Muscle Networks: A Case Study to Decode Hidden Synergistic Patterns During Dynamic Lower-limb Tasks. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.15.524160. [PMID: 36711641 PMCID: PMC9882131 DOI: 10.1101/2023.01.15.524160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This paper, for the first time, compares the behaviors of nonlinear versus linear muscle networks in decoding hidden peripheral synergistic neural patterns during dynamic functional tasks. In this paper, we report a case study during which one healthy subject conducts a series of four lower limb repetitive tasks. Specifically, the paper focuses on tasks that involve the right knee joint, including walking, sit-tostand, stepping, and drop-jump. Twelve muscles were recorded using the Delsys Trigno system. The linear muscle network was generated using coherence analysis, and the nonlinear network was generated using Spearman's correlation. The results show that the degree, clustering coefficient, and global efficiency of the muscle network have the highest value among tasks in the linear domain for the walking task, while a low linear synergistic network behavior for the sit-to-stand is observed. On the other hand, the results show that the nonlinear functional muscle network decodes high connectivity (degree) and clustering coefficient and efficiency for the sit-tostand when compared with other tasks. We have also developed a two-dimensional functional connectivity plane composed of linear and nonlinear features and shown that it can span the lower-limb dynamic task space. The results of this paper for the first time highlight the importance of observing both linear and nonlinear connectivity patterns, especially for complex dynamic tasks. It should also be noted that through a simultaneous EEG recording (using BrainVision System), we have shown that, indeed, cortical activity may indirectly explain highly-connected nonlinear muscle network for the sit-to-stand task, highlighting the importance of nonlinear muscle network as a neurophysiological window of observation beyond the periphery.
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Maillet J, Avrillon S, Nordez A, Rossi J, Hug F. Handedness is associated with less common input to spinal motor neurons innervating different hand muscles. J Neurophysiol 2022; 128:778-789. [PMID: 36001792 DOI: 10.1152/jn.00237.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Whether the neural control of manual behaviours differs between the dominant and non-dominant hand is poorly understood. This study aimed to determine whether the level of common synaptic input to motor neurons innervating the same or different muscles differs between the dominant and the non-dominant hand. Seventeen participants performed two motor tasks with distinct mechanical requirements: an isometric pinch and an isometric rotation of a pinched dial. Each task was performed at 30% of maximum effort and was repeated with the dominant and non-dominant hand. Motor units were identified from two intrinsic (flexor digitorum interosseous and thenar) and one extrinsic muscle (flexor digitorum superficialis) from high-density surface electromyography recordings. Two complementary approaches were used to estimate common synaptic inputs. First, we calculated the coherence between groups of motor neurons from the same and from different muscles. Then, we estimated the common input for all pairs of motor neurons by correlating the low-frequency oscillations of their discharge rate. Both analyses led to the same conclusion, indicating less common synaptic input between motor neurons innervating different muscles in the dominant hand than in the non-dominant hand, which was only observed during the isometric rotation task. No between-side differences in common input were observed between motor neurons of the same muscle. This lower level of common input could confer higher flexibility in the recruitment of motor units, and therefore, in mechanical outputs. Whether this difference between the dominant and non-dominant arm is the cause or the consequence of handedness remains to be determined.
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Affiliation(s)
- Jean Maillet
- Nantes Université, Movement - Interactions - Performance, MIP, UR 4334, Nantes, France
| | - Simon Avrillon
- Neuromechanics and Rehabilitation Technology Group, Department of Bioengineering, Faculty of Engineering, Imperial College London, United Kingdom
| | - Antoine Nordez
- Nantes Université, Movement - Interactions - Performance, MIP, UR 4334, Nantes, France.,Institut Universitaire de France (IUF), Paris, France
| | - Jeremy Rossi
- grid.6279.aJean Monnet University, Saint Etienne, France
| | - François Hug
- Institut Universitaire de France (IUF), Paris, France.,LAMHESS, Université Côte d'Azur, Nice, France.,The University of Queensland, School of Biomedical Sciences, Brisbane, Queensland, Australia
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12
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Hu X, Song A, Wang J, Zeng H, Wei W. Finger Movement Recognition via High-Density Electromyography of Intrinsic and Extrinsic Hand Muscles. Sci Data 2022; 9:373. [PMID: 35768439 PMCID: PMC9243097 DOI: 10.1038/s41597-022-01484-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 06/15/2022] [Indexed: 11/09/2022] Open
Abstract
Surface electromyography (sEMG) is commonly used to observe the motor neuronal activity within muscle fibers. However, decoding dexterous body movements from sEMG signals is still quite challenging. In this paper, we present a high-density sEMG (HD-sEMG) signal database that comprises simultaneously recorded sEMG signals of intrinsic and extrinsic hand muscles. Specifically, twenty able-bodied participants performed 12 finger movements under two paces and three arm postures. HD-sEMG signals were recorded with a 64-channel high-density grid placed on the back of hand and an 8-channel armband around the forearm. Also, a data-glove was used to record the finger joint angles. Synchronisation and reproducibility of the data collection from the HD-sEMG and glove sensors were ensured. The collected data samples were further employed for automated recognition of dexterous finger movements. The introduced dataset offers a new perspective to study the synergy between the intrinsic and extrinsic hand muscles during dynamic finger movements. As this dataset was collected from multiple participants, it also provides a resource for exploring generalized models for finger movement decoding.
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Affiliation(s)
- Xuhui Hu
- State Key Laboratory of Bioelectronics, Nanjing, China.,Jiangsu Key Laboratory of Remote Measurement and Control, Nanjing, China.,School of Instrument Science and Engineering, Southeast University, Nanjing, China
| | - Aiguo Song
- State Key Laboratory of Bioelectronics, Nanjing, China. .,Jiangsu Key Laboratory of Remote Measurement and Control, Nanjing, China. .,School of Instrument Science and Engineering, Southeast University, Nanjing, China.
| | - Jianzhi Wang
- State Key Laboratory of Bioelectronics, Nanjing, China.,Jiangsu Key Laboratory of Remote Measurement and Control, Nanjing, China.,School of Instrument Science and Engineering, Southeast University, Nanjing, China
| | - Hong Zeng
- State Key Laboratory of Bioelectronics, Nanjing, China.,Jiangsu Key Laboratory of Remote Measurement and Control, Nanjing, China.,School of Instrument Science and Engineering, Southeast University, Nanjing, China
| | - Wentao Wei
- School of Design Arts and Media, Nanjing University of Science and Technology, Nanjing, China
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13
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Exercise Effects on Motor Skill Consolidation and Intermuscular Coherence Depend on Practice Schedule. Brain Sci 2022; 12:brainsci12040436. [PMID: 35447968 PMCID: PMC9030594 DOI: 10.3390/brainsci12040436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 11/16/2022] Open
Abstract
Cardiorespiratory or aerobic exercise immediately after practice of an upper-extremity motor skill task can facilitate skill consolidation, as demonstrated by enhanced performances at 24 h and 7-day retention tests. The purpose of this study was to examine the effect of acute cardiorespiratory exercise on motor skill consolidation when skill practice involved low and high levels of contextual interference introduced through repetitive and interleaved practice schedules, respectively. Forty-eight young healthy adults were allocated to one of four groups who performed either repetitive or interleaved practice of a pinch grip motor sequence task, followed by either a period of seated rest or a bout of high-intensity interval cycling. At pre- and post-practice and 24 h and 7-day retention tests, we assessed motor skill performance and β-band (15–35 Hz) intermuscular coherence using surface electromyography (EMG) collected from the abductor pollicis brevis and first dorsal interosseous. At the 7-day retention test, off-line consolidation was enhanced in the cardiorespiratory exercise relative to the rest group, but only among individuals who performed interleaved motor skill practice (p = 0.02). Similarly, at the 7-day retention test, β-band intermuscular coherence increased to a greater extent in the exercise group than in the rest group for those who performed interleaved practice (p = 0.02). Under the present experimental conditions, cardiorespiratory exercise preferentially supported motor skill consolidation and change in intermuscular coherence when motor skill practice involved higher rather than lower levels of contextual interference.
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14
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Rossato J, Tucker KJ, Avrillon S, Lacourpaille L, Holobar A, Hug F. Less common synaptic input between muscles from the same group allows for more flexible coordination strategies during a fatiguing task. J Neurophysiol 2022; 127:421-433. [PMID: 35020505 DOI: 10.1152/jn.00453.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study aimed to determine whether neural drive is redistributed between muscles during a fatiguing isometric contraction, and if so, whether the initial level of common synaptic input between these muscles constrains this redistribution. We studied two muscle groups: triceps surae (14 participants) and quadriceps (15 participants). Participants performed a series of submaximal isometric contractions and a torque-matched contraction maintained until task failure. We used high-density surface electromyography to identify the behavior of 1874 motor units from the soleus, gastrocnemius medialis (GM), gastrocnemius lateralis(GL), rectus femoris, vastus lateralis (VL), and vastus medialis(VM). We assessed the level of common drive between muscles in absence of fatigue using a coherence analysis. We also assessed the redistribution of neural drive between muscles during the fatiguing contraction through the correlation between their cumulative spike trains (index of neural drive). The level of common drive between VL and VM was significantly higher than that observed for the other muscle pairs, including GL-GM. The level of common drive increased during the fatiguing contraction, but the differences between muscle pairs persisted. We also observed a strong positive correlation of neural drive between VL and VM during the fatiguing contraction (r=0.82). This was not observed for the other muscle pairs, including GL-GM, which exhibited differential changes in neural drive. These results suggest that less common synaptic input between muscles allows for more flexible coordination strategies during a fatiguing task, i.e., differential changes in neural drive across muscles. The role of this flexibility on performance remains to be elucidated.
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Affiliation(s)
- Julien Rossato
- Nantes Université, Laboratory "Movement, Interactions, Performance" (EA 4334), Nantes, France
| | - Kylie J Tucker
- The University of Queensland, School of Biomedical Sciences, Brisbane, Queensland, Australia
| | - Simon Avrillon
- Legs + Walking AbilityLab, Shirley Ryan AbilityLab, Chicago, IL, United States.,Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, United States
| | - Lilian Lacourpaille
- Nantes Université, Laboratory "Movement, Interactions, Performance" (EA 4334), Nantes, France
| | - Ales Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Slovenia
| | - François Hug
- Nantes Université, Laboratory "Movement, Interactions, Performance" (EA 4334), Nantes, France.,Institut Universitaire de France (IUF), Paris, France.,Université Côte d'Azur, LAMHESS, Nice, France
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15
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Schmidt A, Feldotto B, Gumpert T, Seidel D, Albu-Schäffer A, Stratmann P. Adapting Highly-Dynamic Compliant Movements to Changing Environments: A Benchmark Comparison of Reflex- vs. CPG-Based Control Strategies. Front Neurorobot 2021; 15:762431. [PMID: 34955801 PMCID: PMC8709475 DOI: 10.3389/fnbot.2021.762431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 11/18/2021] [Indexed: 12/02/2022] Open
Abstract
To control highly-dynamic compliant motions such as running or hopping, vertebrates rely on reflexes and Central Pattern Generators (CPGs) as core strategies. However, decoding how much each strategy contributes to the control and how they are adjusted under different conditions is still a major challenge. To help solve this question, the present paper provides a comprehensive comparison of reflexes, CPGs and a commonly used combination of the two applied to a biomimetic robot. It leverages recent findings indicating that in mammals both control principles act within a low-dimensional control submanifold. This substantially reduces the search space of parameters and enables the quantifiable comparison of the different control strategies. The chosen metrics are motion stability and energy efficiency, both key aspects for the evolution of the central nervous system. We find that neither for stability nor energy efficiency it is favorable to apply the state-of-the-art approach of a continuously feedback-adapted CPG. In both aspects, a pure reflex is more effective, but the pure CPG allows easy signal alteration when needed. Additionally, the hardware experiments clearly show that the shape of a control signal has a strong influence on energy efficiency, while previous research usually only focused on frequency alignment. Both findings suggest that currently used methods to combine the advantages of reflexes and CPGs can be improved. In future research, possible combinations of the control strategies should be reconsidered, specifically including the modulation of the control signal's shape. For this endeavor, the presented setup provides a valuable benchmark framework to enable the quantitative comparison of different bioinspired control principles.
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Affiliation(s)
- Annika Schmidt
- Sensor Based Robotic Systems and Intelligent Assistance Systems, Department of Informatics, Technical University of Munich, Garching, Germany.,German Aerospace Center (DLR), Institute of Robotics and Mechatronics, Weßling, Germany
| | - Benedikt Feldotto
- Robotics, Artificial Intelligence and Real-Time Systems, Department of Informatics, Technical University of Munich, Garching, Germany
| | - Thomas Gumpert
- German Aerospace Center (DLR), Institute of Robotics and Mechatronics, Weßling, Germany
| | - Daniel Seidel
- German Aerospace Center (DLR), Institute of Robotics and Mechatronics, Weßling, Germany
| | - Alin Albu-Schäffer
- Sensor Based Robotic Systems and Intelligent Assistance Systems, Department of Informatics, Technical University of Munich, Garching, Germany.,German Aerospace Center (DLR), Institute of Robotics and Mechatronics, Weßling, Germany
| | - Philipp Stratmann
- Sensor Based Robotic Systems and Intelligent Assistance Systems, Department of Informatics, Technical University of Munich, Garching, Germany.,German Aerospace Center (DLR), Institute of Robotics and Mechatronics, Weßling, Germany
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16
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Cho Y, Park S, Lee J, Yu KJ. Emerging Materials and Technologies with Applications in Flexible Neural Implants: A Comprehensive Review of Current Issues with Neural Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2005786. [PMID: 34050691 DOI: 10.1002/adma.202005786] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/29/2020] [Indexed: 05/27/2023]
Abstract
Neuroscience is an essential field of investigation that reveals the identity of human beings, with a comprehensive understanding of advanced mental activities, through the study of neurobiological structures and functions. Fully understanding the neurotransmission system that allows for connectivity among neuronal circuits has paved the way for the development of treatments for neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, and depression. The field of flexible implants has attracted increasing interest mainly to overcome the mechanical mismatch between rigid electrode materials and soft neural tissues, enabling precise measurements of neural signals from conformal contact. Here, the current issues of flexible neural implants (chronic device failure, non-bioresorbable electronics, low-density electrode arrays, among others are summarized) by presenting material candidates and designs to address each challenge. Furthermore, the latest investigations associated with the aforementioned issues are also introduced, including suggestions for ideal neural implants. In terms of the future direction of these advances, designing flexible devices would provide new opportunities for the study of brain-machine interfaces or brain-computer interfaces as part of locomotion through brain signals, and for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Younguk Cho
- School of Electrical Engineering, Yonsei University, Seoul, 03722, Korea
| | - Sanghoon Park
- School of Electrical Engineering, Yonsei University, Seoul, 03722, Korea
| | - Juyoung Lee
- School of Electrical Engineering, Yonsei University, Seoul, 03722, Korea
| | - Ki Jun Yu
- School of Electrical Engineering, YU-KIST Institute, Yonsei University, Seoul, 03722, Korea
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17
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Tanzarella S, Muceli S, Santello M, Farina D. Synergistic Organization of Neural Inputs from Spinal Motor Neurons to Extrinsic and Intrinsic Hand Muscles. J Neurosci 2021; 41:6878-6891. [PMID: 34210782 PMCID: PMC8360692 DOI: 10.1523/jneurosci.0419-21.2021] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 06/02/2021] [Accepted: 06/03/2021] [Indexed: 11/21/2022] Open
Abstract
Our current understanding of synergistic muscle control is based on the analysis of muscle activities. Modules (synergies) in muscle coordination are extracted from electromyographic (EMG) signal envelopes. Each envelope indirectly reflects the neural drive received by a muscle; therefore, it carries information on the overall activity of the innervating motor neurons. However, it is not known whether the output of spinal motor neurons, whose number is orders of magnitude greater than the muscles they innervate, is organized in a low-dimensional fashion when performing complex tasks. Here, we hypothesized that motor neuron activities exhibit a synergistic organization in complex tasks and therefore that the common input to motor neurons results in a large dimensionality reduction in motor neuron outputs. To test this hypothesis, we factorized the output spike trains of motor neurons innervating 14 intrinsic and extrinsic hand muscles and analyzed the dimensionality of control when healthy individuals exerted isometric forces using seven grip types. We identified four motor neuron synergies, accounting for >70% of the variance of the activity of 54.1 ± 12.9 motor neurons, and we identified four functionally similar muscle synergies. However, motor neuron synergies better discriminated individual finger forces than muscle synergies and were more consistent with the expected role of muscles actuating each finger. Moreover, in a few cases, motor neurons innervating the same muscle were active in separate synergies. Our findings suggest a highly divergent net neural inputs to spinal motor neurons from spinal and supraspinal structures, contributing to the dimensionality reduction captured by muscle synergies.SIGNIFICANCE STATEMENT We addressed whether the output of spinal motor neurons innervating multiple hand muscles could be accounted for by a modular organization, i.e., synergies, previously described to account for the coordination of multiple muscles. We found that motor neuron synergies presented similar dimensionality (implying a >10-fold reduction in dimensionality) and structure as muscle synergies. Nonetheless, the synergistic behavior of subsets of motor neurons within a muscle was also observed. These results advance our understanding of how neuromuscular control arises from mapping descending inputs to muscle activation signals. We provide, for the first time, insights into the organization of neural inputs to spinal motor neurons which, to date, has been inferred through analysis of muscle synergies.
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Affiliation(s)
- Simone Tanzarella
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Silvia Muceli
- Division of Signal Processing and Biomedical Engineering, Department of Electrical Engineering, Chalmers University of Technology, Gothenburg 412 96, Sweden
| | - Marco Santello
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287-9709
| | - Dario Farina
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
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18
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Germer CM, Farina D, Elias LA, Nuccio S, Hug F, Del Vecchio A. Surface EMG cross talk quantified at the motor unit population level for muscles of the hand, thigh, and calf. J Appl Physiol (1985) 2021; 131:808-820. [PMID: 34236246 DOI: 10.1152/japplphysiol.01041.2020] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cross talk is an important source of error in interpreting surface electromyography (EMG) signals. Here, we aimed at characterizing cross talk for three groups of synergistic muscles by the identification of individual motor unit action potentials. Moreover, we explored whether spatial filtering (single and double differential) of the EMG signals influences the level of cross talk. Three experiments were conducted. Participants (total 25) performed isometric contractions at 10% of the maximal voluntary contraction (MVC) with digit muscles and knee extensors and at 30% MVC with plantar flexors. High-density surface EMG signals were recorded and decomposed into motor unit spike trains. For each muscle, we quantified the cross talk induced to neighboring muscles and the level of contamination by the nearby muscle activity. We also estimated the influence of cross talk on the EMG power spectrum and intermuscular correlation. Most motor units (80%) generated significant cross-talk signals to neighboring muscle EMG in monopolar recording mode, but this proportion decreased with spatial filtering (50% and 42% for single and double differential, respectively). Cross talk induced overestimations of intermuscular correlation and has a small effect on the EMG power spectrum, which indicates that cross talk is not reduced with high-pass temporal filtering. Conversely, spatial filtering reduced the cross-talk magnitude and the overestimations of intermuscular correlation, confirming to be an effective and simple technique to reduce cross talk. This paper presents a new method for the identification and quantification of cross talk at the motor unit level and clarifies the influence of cross talk on EMG interpretation for muscles with different anatomy.NEW & NOTEWORTHY We proposed a new method for the identification and quantification of cross talk at the motor unit level. We show that surface EMG cross talk can lead to physiological misinterpretations of EMG signals such as overestimations in the muscle activity and intermuscular correlation. Cross talk had little influence on the EMG power spectrum, which indicates that conventional temporal filtering cannot minimize cross talk. Spatial filter (single and double differential) effectively reduces but not abolish cross talk.
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Affiliation(s)
- Carina M Germer
- Neural Engineering Research Laboratory, Center for Biomedical Engineering, University of Campinas, Campinas, Brazil.,Department of Bioengineering, Federal University of Pernambuco, Recife, Brazil
| | - Dario Farina
- Department of Bioengineering, Faculty of Engineering, Imperial College London, London, United Kingdom
| | - Leonardo A Elias
- Neural Engineering Research Laboratory, Center for Biomedical Engineering, University of Campinas, Campinas, Brazil.,Department of Electronics and Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, Brazil
| | - Stefano Nuccio
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico," Rome, Italy
| | - François Hug
- Laboratory "Movement, Interactions, Performance," Nantes University, Nantes, France.,Institut Universitaire de France, Paris, France.,School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Alessandro Del Vecchio
- Department of Artificial Intelligence in Biomedical Engineering, Faculty of Engineering, Friedrich-Alexander University, Erlangen-Nuremberg, Germany
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19
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Ibáñez J, Del Vecchio A, Rothwell JC, Baker SN, Farina D. Only the Fastest Corticospinal Fibers Contribute to β Corticomuscular Coherence. J Neurosci 2021; 41:4867-4879. [PMID: 33893222 PMCID: PMC8260170 DOI: 10.1523/jneurosci.2908-20.2021] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/04/2021] [Accepted: 03/15/2021] [Indexed: 01/09/2023] Open
Abstract
Human corticospinal transmission is commonly studied using brain stimulation. However, this approach is biased to activity in the fastest conducting axons. It is unclear whether conclusions obtained in this context are representative of volitional activity in mild-to-moderate contractions. An alternative to overcome this limitation may be to study the corticospinal transmission of endogenously generated brain activity. Here, we investigate in humans (N = 19; of either sex), the transmission speeds of cortical β rhythms (∼20 Hz) traveling to arm (first dorsal interosseous) and leg (tibialis anterior; TA) muscles during tonic mild contractions. For this purpose, we propose two improvements for the estimation of corticomuscular β transmission delays. First, we show that the cumulant density (cross-covariance) is more accurate than the commonly-used directed coherence to estimate transmission delays in bidirectional systems transmitting band-limited signals. Second, we show that when spiking motor unit activity is used instead of interference electromyography, corticomuscular transmission delay estimates are unaffected by the shapes of the motor unit action potentials (MUAPs). Applying these improvements, we show that descending corticomuscular β transmission is only 1-2 ms slower than expected from the fastest corticospinal pathways. In the last part of our work, we show results from simulations using estimated distributions of the conduction velocities for descending axons projecting to lower motoneurons (from macaque histologic measurements) to suggest two scenarios that can explain fast corticomuscular transmission: either only the fastest corticospinal axons selectively transmit β activity, or else the entire pool does. The implications of these two scenarios for our understanding of corticomuscular interactions are discussed.SIGNIFICANCE STATEMENT We present and validate an improved methodology to measure the delay in the transmission of cortical β activity to tonically-active muscles. The estimated corticomuscular β transmission delays obtained with this approach are remarkably similar to those expected from transmission in the fastest corticospinal axons. A simulation of β transmission along a pool of corticospinal axons using an estimated distribution of fiber diameters suggests two possible mechanisms by which fast corticomuscular transmission is achieved: either a very small fraction of the fastest descending axons transmits β activity to the muscles or, alternatively, the entire population does and natural cancellation of slow channels occurs because of the distribution of axon diameters in the corticospinal tract.
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Affiliation(s)
- J Ibáñez
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
- Department of Clinical and Movement Disorders, Institute of Neurology, University College London, London WC1N 3BG, United Kingdom
| | - A Del Vecchio
- Department Artificial Intelligence in Biomedical Engineering, Friedrich-Alexander University, Erlangen-Nürnberg, Erlangen 91052, Germany
| | - J C Rothwell
- Department of Clinical and Movement Disorders, Institute of Neurology, University College London, London WC1N 3BG, United Kingdom
| | - S N Baker
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - D Farina
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
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20
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Laine CM, Cohn BA, Valero-Cuevas FJ. Temporal control of muscle synergies is linked with alpha-band neural drive. J Physiol 2021; 599:3385-3402. [PMID: 33963545 DOI: 10.1113/jp281232] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 04/21/2021] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS It is theorized that the nervous system controls groups of muscles together as functional units, or 'synergies', resulting in correlated electromyographic (EMG) signals among muscles. However, such correlation does not necessarily imply group-level neural control. Oscillatory synchronization (coherence) among EMG signals implies neural coupling, but it is not clear how this relates to control of muscle synergies. EMG was recorded from seven arm muscles of 10 adult participants rotating an upper limb ergometer, and EMG-EMG coherence, EMG amplitude correlations and their relationship with each other were characterized. A novel method to derive multi-muscle synergies from EMG-EMG coherence is presented and these are compared with classically defined synergies. Coherent alpha-band (8-16 Hz) drive was strongest among muscles whose gross activity levels are well correlated within a given task. The cross-muscle distribution and temporal modulation of coherent alpha-band drive suggests a possible role in the neural coordination/monitoring of synergies. ABSTRACT During movement, groups of muscles may be controlled together by the nervous system as an adaptable functional entity, or 'synergy'. The rules governing when (or if) this occurs during voluntary behaviour in humans are not well understood, at least in part because synergies are usually defined by correlated patterns of muscle activity without regard for the underlying structure of their neural control. In this study, we investigated the extent to which comodulation of muscle output (i.e. correlation of electromyographic (EMG) amplitudes) implies that muscles share intermuscular neural input (assessed via EMG-EMG coherence analysis). We first examined this relationship among pairs of upper limb muscles engaged in an arm cycling task. We then applied a novel multidimensional EMG-EMG coherence analysis allowing synergies to be characterized on the basis of shared neural drive. We found that alpha-band coherence (8-16 Hz) is related to the degree to which overall muscle activity levels correlate over time. The extension of this coherence analysis to describe the cross-muscle distribution and temporal modulation of alpha-band drive revealed a close match to the temporal and structural features of traditionally defined muscle synergies. Interestingly, the coherence-derived neural drive was inversely associated with, and preceded, changes in EMG amplitudes by ∼200 ms. Our novel characterization of how alpha-band neural drive is dynamically distributed among muscles is a fundamental step forward in understanding the neural origins and correlates of muscle synergies.
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Affiliation(s)
- Christopher M Laine
- Chan Division of Occupational Science and Occupational Therapy, University of Southern California, Los Angeles, CA, USA
| | - Brian A Cohn
- Department of Computer Science, University of Southern California, Los Angeles, CA, USA
| | - Francisco J Valero-Cuevas
- Department of Computer Science, University of Southern California, Los Angeles, CA, USA.,Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA.,Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA
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21
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Wen Y, Avrillon S, Hernandez-Pavon JC, Kim SJ, Hug F, Pons JL. A convolutional neural network to identify motor units from high-density surface electromyography signals in real time. J Neural Eng 2021; 18. [PMID: 33721852 DOI: 10.1088/1741-2552/abeead] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 03/15/2021] [Indexed: 11/11/2022]
Abstract
OBJECTIVES This paper aims to investigate the feasibility and the validity of applying deep convolutional neural networks (CNN) to identify motor unit (MU) spike trains and estimate the neural drive to muscles from high-density electromyography (HD-EMG) signals in real time. Two distinct deep CNNs are compared with the convolution kernel compensation (CKC) algorithm using simulated and experimentally recorded signals. The effects of window size and step size of the input HD-EMG signals are also investigated. APPROACH The MU spike trains were first identified with the CKC algorithm. The HD-EMG signals and spike trains were used to train the deep CNN. Then, the deep CNN decomposed the HD-EMG signals into MU discharge times in real time. Two CNN approaches are compared with the CKC: 1) multiple single-output deep CNN (SO-DCNN) with one MU decomposed per network, and 2) one multiple-output deep CNN (MO-DCNN) to decompose all MUs (up to 23) with one network. MAIN RESULTS The MO-DCNN outperformed the SO-DCNN in terms of training time (3.2 to 21.4 s/epoch vs. 6.5 to 47.8 s/epoch, respectively) and prediction time (0.04 vs. 0.27 s/sample, respectively). The optimal window size and step size for MO-DCNN were 120 and 20 data points, respectively. It results in sensitivity of 98% and 85% with simulated and experimentally recorded HD-EMG signals, respectively. There is a high cross-correlation coefficient between the neural drive estimated with CKC and that estimated with MO-DCNN (range of r-value across conditions: 0.88-0.95). SIGNIFICANCE We demonstrate the feasibility and the validity of using deep CNN to accurately identify MU activity from HD-EMG with a latency lower than 80 ms, which falls within the lower bound of the human electromechanical delay. This method opens many opportunities for using the neural drive to interface humans with assistive devices.
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Affiliation(s)
- Yue Wen
- Legs and Walking Lab, Shirley Ryan AbilityLab, 355 East Erie Street, Chicago, Illinois, 60611-2654, UNITED STATES
| | - Simon Avrillon
- Shirley Ryan AbilityLab, 355 E Erie St, Chicago, Illinois, 60601, UNITED STATES
| | - Julio Cesar Hernandez-Pavon
- Department of Physical Medicine and Rehabilitation, Northwestern University Feinberg School of Medicine, 251 E Huron St, Chicago, Illinois, 60611, UNITED STATES
| | - Sangjoon Jonathan Kim
- Shirley Ryan AbilityLab, 355 E Erie St, Chicago, Illinois, 60611-2654, UNITED STATES
| | - Francois Hug
- Laboratoire 'Motricite, Interactions, Performance', Universite de Nantes, JE 2438 UFRSTAPS,, 25 bis Guy Mollet BP 72206, Nantes, F-44000 France, Nantes, 72206, FRANCE
| | - Jose Luis Pons
- Bioengineering Group, Spanish Research Council, Serrano 117, Arganda del Rey (Madrid), 28006, SPAIN
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22
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Enoka RM, Farina D. Force Steadiness: From Motor Units to Voluntary Actions. Physiology (Bethesda) 2021; 36:114-130. [DOI: 10.1152/physiol.00027.2020] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Voluntary actions are controlled by the synaptic inputs that are shared by pools of spinal motor neurons. The slow common oscillations in the discharge times of motor units due to these synaptic inputs are strongly correlated with the fluctuations in force during submaximal isometric contractions (force steadiness) and moderately associated with performance scores on some tests of motor function. However, there are key gaps in knowledge that limit the interpretation of differences in force steadiness.
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Affiliation(s)
- Roger M. Enoka
- Department of Integrative Physiology, University of Colorado Boulder, Colorado
| | - Dario Farina
- Department of Bioengineering, Faculty of Engineering, Imperial College London, London, United Kingdom
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23
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Hug F, Del Vecchio A, Avrillon S, Farina D, Tucker K. Muscles from the same muscle group do not necessarily share common drive: evidence from the human triceps surae. J Appl Physiol (1985) 2021; 130:342-354. [DOI: 10.1152/japplphysiol.00635.2020] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In this study, we demonstrated that the three muscles composing the human triceps surae share minimal common drive during isometric contractions. Our results suggest that reducing the number of effectively controlled degrees of freedom may not always be the strategy used by the central nervous system to control movements. Independent control of some, but not all, synergist muscles may allow for more flexible control to comply with secondary goals (e.g., joint stabilization).
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Affiliation(s)
- François Hug
- Laboratory “Movement, Interactions, Performance” (EA 4334), Nantes University, Nantes, France
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
- Institut Universitaire de France (IUF), Paris, France
| | - Alessandro Del Vecchio
- Neuromechanics and Rehabilitation Technology Group, Department of Bioengineering, Faculty of Engineering, Imperial College London, London, United Kingdom
- Department of Artificial Intelligence in Biomedical Engineering, Friedrich-Alexander University, Erlangen-Nürnberg, Erlangen,Germany
| | - Simon Avrillon
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
- Legs + Walking AbilityLab, Shirley Ryan AbilityLab, Chicago, Illinois
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois
| | - Dario Farina
- Neuromechanics and Rehabilitation Technology Group, Department of Bioengineering, Faculty of Engineering, Imperial College London, London, United Kingdom
| | - Kylie Tucker
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
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24
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Turpin NA, Uriac S, Dalleau G. How to improve the muscle synergy analysis methodology? Eur J Appl Physiol 2021; 121:1009-1025. [PMID: 33496848 DOI: 10.1007/s00421-021-04604-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 01/10/2021] [Indexed: 01/02/2023]
Abstract
Muscle synergy analysis is increasingly used in domains such as neurosciences, robotics, rehabilitation or sport sciences to analyze and better understand motor coordination. The analysis uses dimensionality reduction techniques to identify regularities in spatial, temporal or spatio-temporal patterns of multiple muscle activation. Recent studies have pointed out variability in outcomes associated with the different methodological options available and there was a need to clarify several aspects of the analysis methodology. While synergy analysis appears to be a robust technique, it remain a statistical tool and is, therefore, sensitive to the amount and quality of input data (EMGs). In particular, attention should be paid to EMG amplitude normalization, baseline noise removal or EMG filtering which may diminish or increase the signal-to-noise ratio of the EMG signal and could have major effects on synergy estimates. In order to robustly identify synergies, experiments should be performed so that the groups of muscles that would potentially form a synergy are activated with a sufficient level of activity, ensuring that the synergy subspace is fully explored. The concurrent use of various synergy formulations-spatial, temporal and spatio-temporal synergies- should be encouraged. The number of synergies represents either the dimension of the spatial structure or the number of independent temporal patterns, and we observed that these two aspects are often mixed in the analysis. To select a number, criteria based on noise estimates, reliability of analysis results, or functional outcomes of the synergies provide interesting substitutes to criteria solely based on variance thresholds.
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Affiliation(s)
- Nicolas A Turpin
- IRISSE (EA 4075), UFR SHE-STAPS Department, University of La Réunion, 117 Rue du Général Ailleret, 97430, Le Tampon, France.
| | - Stéphane Uriac
- IRISSE (EA 4075), UFR SHE-STAPS Department, University of La Réunion, 117 Rue du Général Ailleret, 97430, Le Tampon, France
| | - Georges Dalleau
- IRISSE (EA 4075), UFR SHE-STAPS Department, University of La Réunion, 117 Rue du Général Ailleret, 97430, Le Tampon, France
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25
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Suzuki R, Kanehisa H, Washino S, Watanabe H, Shinohara M, Yoshitake Y. Reconstruction of net force fluctuations from surface EMGs of multiple muscles in steady isometric plantarflexion. Exp Brain Res 2021; 239:601-612. [PMID: 33388812 DOI: 10.1007/s00221-020-05987-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/13/2020] [Indexed: 12/22/2022]
Abstract
The purposes of this study were to clarify if force fluctuations during steady multi-muscle contractions have a temporal correlation with a low-frequency component of rectified surface EMG (rEMG) in the involved muscles and collection of that component across muscles allows for the reconstruction of force fluctuations across a wide range of contraction intensities. Healthy young men (n = 15) exerted steady isometric plantarflexion force at 5-60% of maximal force. Surface EMG was recorded from the medial and lateral gastrocnemii, soleus, peroneus longus, abductor hallucis, and tibialis anterior muscles. The cross-correlation function (CCF) between plantarflexion force fluctuations and low-pass filtered rEMG in each muscle was calculated for 8 s. To reconstruct force fluctuations from rEMGs, the product of rEMG and an identified constant factor were summed across muscles with time-lag compensation for electro-mechanical delay. A distinct peak of the CCF was found between plantarflexion force fluctuations and rEMG in most cases except for the tibialis anterior. The CCF peak was greatest in the medial gastrocnemius and soleus. Reconstructed force from rEMGs was temporally correlated with measured force fluctuations across contraction intensities (average CCF peak: r = 0.65). The results indicate that individual surface rEMG has a low-frequency component that is temporally correlated with net force fluctuations during steady multi-muscle contractions and contributes to the reconstruction of force fluctuations across a wide range of contraction intensities. It suggests a potential applicability of individual surface EMGs for identifying the contributing muscles to controlling or disturbing isometric steady force in multi-muscle contractions.
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Affiliation(s)
- Ryosei Suzuki
- Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 3860018, Japan
| | - Hiroaki Kanehisa
- School of Sports and Health Sciences, Ritsumeikan University, 1-1-1 Nozihigashi, Kusatsu, Shiga, 5258577, Japan
| | - Sohei Washino
- Human Augmentation Research Center, National Institute of Advanced Industrial Science and Technology, 6-2-3 Kashiwanoha, Kashiwa, Chiba, 2770882, Japan
| | - Hironori Watanabe
- Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama, 3508585, Japan
| | - Minoru Shinohara
- School of Biological Sciences, Georgia Institute of Technology, 555 14th St NW, Atlanta, GA, 30332, USA
| | - Yasuhide Yoshitake
- Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 3860018, Japan. .,School of Human Movement and Nutrition Sciences, The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia.
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26
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Avrillon S, Del Vecchio A, Farina D, Pons JL, Vogel C, Umehara J, Hug F. Individual differences in the neural strategies to control the lateral and medial head of the quadriceps during a mechanically constrained task. J Appl Physiol (1985) 2021; 130:269-281. [DOI: 10.1152/japplphysiol.00653.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We observed that the distribution of the strength of neural drive between the vastus lateralis and vastus medialis during a single-joint isometric task varied across participants. Also, we observed that the proportion of neural drive that was shared within and between these muscles also varied across participants. These results provide evidence that the neural strategies to control the vastus lateralis and vastus medialis muscles widely vary across individuals, even during a mechanically constrained task.
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Affiliation(s)
- Simon Avrillon
- Legs + Walking AbilityLab, Shirley Ryan AbilityLab, Chicago, Illinois
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois
- Laboratory Movement, Interactions, Performance, Université de Nantes, Nantes, France
| | - Alessandro Del Vecchio
- Department of Artificial Intelligence in Biomedical Engineering, Friedrich-Alexander University, Erlangen-Nürnberg, Erlangen, Germany
- Neuromechanics and Rehabilitation Technology Group, Department of Bioengineering, Faculty of Engineering, Imperial College, London, United Kingdom
| | - Dario Farina
- Neuromechanics and Rehabilitation Technology Group, Department of Bioengineering, Faculty of Engineering, Imperial College, London, United Kingdom
| | - José L. Pons
- Legs + Walking AbilityLab, Shirley Ryan AbilityLab, Chicago, Illinois
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois
| | - Clément Vogel
- Laboratory Movement, Interactions, Performance, Université de Nantes, Nantes, France
| | - Jun Umehara
- Department of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - François Hug
- Laboratory Movement, Interactions, Performance, Université de Nantes, Nantes, France
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia
- Institut Universitaire de France, Paris, France
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27
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Del Vecchio A, Sylos-Labini F, Mondì V, Paolillo P, Ivanenko Y, Lacquaniti F, Farina D. Spinal motoneurons of the human newborn are highly synchronized during leg movements. SCIENCE ADVANCES 2020; 6:6/47/eabc3916. [PMID: 33219027 PMCID: PMC7679172 DOI: 10.1126/sciadv.abc3916] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 09/30/2020] [Indexed: 05/30/2023]
Abstract
Motoneurons of neonatal rodents show synchronous activity that modulates the development of the neuromuscular system. However, the characteristics of the activity of human neonatal motoneurons are largely unknown. Using a noninvasive neural interface, we identified the discharge timings of individual spinal motoneurons in human newborns. We found highly synchronized activities of motoneurons of the tibialis anterior muscle, which were associated with fast leg movements. Although neonates' motor units exhibited discharge rates similar to those of adults, their synchronization was significantly greater than in adults. Moreover, neonatal motor units showed coherent oscillations in the delta band, which is directly translated into force generation. These results suggest that motoneuron synchronization in human neonates might be an important mechanism for controlling fast limb movements, such as those of primitive reflexes. In addition to help revealing mechanisms of development, the proposed neural interface might monitor children at risk of developing motor disorders.
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Affiliation(s)
- A Del Vecchio
- Department of Bioengineering, Imperial College London, White City, W12 0BZ London, UK
- Department Artificial Intelligence in Biomedical Engineering, Friedrich-Alexander University, Erlangen-Nuernberg, 91052 Erlangen, Germany
| | - F Sylos-Labini
- Laboratory of Neuromotor Physiology, IRCCS Fondazione Santa Lucia, 00179 Rome, Italy
| | - V Mondì
- Neonatology and Neonatal Intensive Care Unit, Casilino Hospital, 00169 Rome, Italy
| | - P Paolillo
- Neonatology and Neonatal Intensive Care Unit, Casilino Hospital, 00169 Rome, Italy
| | - Y Ivanenko
- Laboratory of Neuromotor Physiology, IRCCS Fondazione Santa Lucia, 00179 Rome, Italy
| | - F Lacquaniti
- Laboratory of Neuromotor Physiology, IRCCS Fondazione Santa Lucia, 00179 Rome, Italy
- Department of Systems Medicine and Center of Space Biomedicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - D Farina
- Department of Bioengineering, Imperial College London, White City, W12 0BZ London, UK.
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28
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Watanabe T, Nojima I, Mima T, Sugiura H, Kirimoto H. Magnification of visual feedback modulates corticomuscular and intermuscular coherences differently in young and elderly adults. Neuroimage 2020; 220:117089. [DOI: 10.1016/j.neuroimage.2020.117089] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/05/2020] [Accepted: 06/21/2020] [Indexed: 10/24/2022] Open
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29
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Dos Santos PCR, Lamoth CJC, Barbieri FA, Zijdewind I, Gobbi LTB, Hortobágyi T. Age-specific modulation of intermuscular beta coherence during gait before and after experimentally induced fatigue. Sci Rep 2020; 10:15854. [PMID: 32985547 PMCID: PMC7522269 DOI: 10.1038/s41598-020-72839-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 09/07/2020] [Indexed: 12/19/2022] Open
Abstract
We examined the effects of age on intermuscular beta-band (15–35 Hz) coherence during treadmill walking before and after experimentally induced fatigue. Older (n = 12) and younger (n = 12) adults walked on a treadmill at 1.2 m/s for 3 min before and after repetitive sit-to-stand, rSTS, to induce muscle fatigability. We measured stride outcomes and coherence from 100 steps in the dominant leg for the synergistic (biceps femoris (BF)-semitendinosus, rectus femoris (RF)-vastus lateralis (VL), gastrocnemius lateralis (GL)-Soleus (SL), tibialis anterior (TA)-peroneus longus (PL)) and for the antagonistic (RF-BF and TA-GL) muscle pairs at late swing and early stance. Older vs. younger adults had 43–62% lower GL-SL, RF-VL coherence in swing and TA-PL and RF-VL coherence in stance. After rSTS, RF-BF coherence in late swing decreased by ~ 20% and TA-PL increased by 16% independent of age (p = 0.02). Also, GL-SL coherence decreased by ~ 23% and increased by ~ 23% in younger and older, respectively. Age affects the oscillatory coupling between synergistic muscle pairs, delivered presumably via corticospinal tracts, during treadmill walking. Muscle fatigability elicits age-specific changes in the common fluctuations in muscle activity, which could be interpreted as a compensation for muscle fatigability to maintain gait performance.
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Affiliation(s)
- Paulo Cezar Rocha Dos Santos
- Department of Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. .,Posture and Gait Studies Laboratory (LEPLO), Institute of Biosciences, Graduate Program in Movement Sciences, São Paulo State University (UNESP), Rio Claro, Brazil. .,Department of Human Movement Sciences, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV, Groningen, The Netherlands.
| | - Claudine J C Lamoth
- Department of Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Fabio Augusto Barbieri
- Department of Physical Education, Human Movement Research Laboratory (MOVI-LAB), Graduate Program in Movement Sciences, São Paulo State University (UNESP), Bauru, Brazil
| | - Inge Zijdewind
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Lilian Teresa Bucken Gobbi
- Posture and Gait Studies Laboratory (LEPLO), Institute of Biosciences, Graduate Program in Movement Sciences, São Paulo State University (UNESP), Rio Claro, Brazil
| | - Tibor Hortobágyi
- Department of Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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30
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Tanzarella S, Muceli S, Del Vecchio A, Casolo A, Farina D. Non-invasive analysis of motor neurons controlling the intrinsic and extrinsic muscles of the hand. J Neural Eng 2020; 17:046033. [PMID: 32674079 DOI: 10.1088/1741-2552/aba6db] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE We present a non-invasive framework for investigating efferent commands to 14 extrinsic and intrinsic hand muscles. We extend previous studies (limited to a few muscles) on common synaptic input among pools of motor neurons in a large number of muscles. APPROACH Seven subjects performed sinusoidal isometric contractions to complete seven types of grasps, with each finger and with three combinations of fingers in opposition with the thumb. High-density surface EMG (HD-sEMG) signals (384 channels in total) recorded from the 14 muscles were decomposed into the constituent motor unit action potentials. This provided a non-invasive framework for the investigation of motor neuron discharge patterns, muscle coordination and efferent commands of the hand muscles during grasping. Moreover, during grasping tasks, it was possible to identify common neural information among pools of motor neurons innervating the investigated muscles. For this purpose, principal component analysis (PCA) was applied to the smoothed discharge rates of the decoded motor units. MAIN RESULTS We found that the first principal component (PC1) of the ensemble of decoded motor neuron spike trains explained a variance of (53.0 ± 10.9) % and was positively correlated with force (R = 0.67 ± 0.10 across all subjects and tasks). By grouping the pools of motor neurons from extrinsic or intrinsic muscles, the PC1 explained a proportion of variance of (57.1 ± 11.3) % and (56.9 ± 11.8) %, respectively, and was correlated with force with R = 0.63 ± 0.13 and 0.63 ± 0.13, respectively. SIGNIFICANCE These observations demonstrate a low dimensional control of motor neurons across multiple muscles that can be exploited for extracting control signals in neural interfacing. The proposed framework was designed for hand rehabilitation perspectives, such as post-stroke rehabilitation and hand-exoskeleton control.
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Affiliation(s)
- Simone Tanzarella
- Department of Bioengineering, Imperial College London, London, United Kingdom
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31
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Tutorial: Analysis of motor unit discharge characteristics from high-density surface EMG signals. J Electromyogr Kinesiol 2020; 53:102426. [DOI: 10.1016/j.jelekin.2020.102426] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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32
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Cogliati M, Cudicio A, Toscani F, Gaffurini P, Bissolotti LM, Orizio C, Negro F. Normalized maximal rate of torque development during voluntary and stimulated static contraction in human tibialis anterior: Influence of age. Exp Gerontol 2020; 138:110999. [PMID: 32512142 DOI: 10.1016/j.exger.2020.110999] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 05/12/2020] [Accepted: 06/03/2020] [Indexed: 12/25/2022]
Abstract
The risk of falling in older adults has been related, among other factors, to the reduction of the rate of torque development (RTD) with age. It is well known that both structural/peripheral and neural factors can influence the RTD. The purpose of this study was to compare the normalized RTD in young and older participants obtained during a) rapid voluntary tension production and b) neuromuscular electrical stimulation. The tibialis anterior of 19 young subjects (10 males and 9 females; age 21-33 years old) and 19 older participants (10 males and 9 females; age 65-80 years old) was studied. The subjects performed a series of maximal isometric explosive dorsiflexions and underwent trains of supra-maximal electrical stimulations (35 Hz) on the tibialis anterior motor point. Muscle shortening was indirectly measured using a laser (surface mechanomyogram, MMG). Both torque and MMG were normalized to their maximum value. Using a 20 ms sliding window on the normalized torque signal, the normalized maximum RTD was calculated for both voluntary and stimulated contractions. Active stiffness of the muscle- tendon unit was calculated as the area of the normalized torque with respect to the normalized MMG. Normalized maximum RTD was found significantly lower in older adults during voluntary activity (young: 751.9 ± 216.3%/s and old: 513.9 ± 173.9%/s; P < .001), and higher during stimulated contractions (young: 753.1 ± 225.9%/s and old: 890.1 ± 221.3%/s; P = .009). Interestingly, active stiffness was also higher in older adults (young: 3524.6 ± 984.6‰ and old 4144.6 ± 816.6‰; P = .041) and significantly correlated to the normalized maximum RTD during stimulated contractions. This dichotomy suggests that modifications in the structural/peripheral muscle properties are not sufficient to counteract the age-related decrease in neural drive to the muscle during voluntary isometric contractions in aged participants.
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Affiliation(s)
- M Cogliati
- Centre of Research on the Neuromuscular Function and the Adapted Motor Activity, "Teresa Camplani" University of Brescia, Viale Europa, 11, 25123 Brescia, Italy
| | - A Cudicio
- Centre of Research on the Neuromuscular Function and the Adapted Motor Activity, "Teresa Camplani" University of Brescia, Viale Europa, 11, 25123 Brescia, Italy
| | - F Toscani
- Department of Clinical and Experimental Sciences, University of Brescia, Viale Europa, 11, 25123 Brescia, Italy
| | - P Gaffurini
- Rehabilitation Service, Fondazione Teresa Camplani-Casa di Cura Domus Salutis, Via Lazzaretto, 3, 25123 Brescia, Italy
| | - L M Bissolotti
- Rehabilitation Service, Fondazione Teresa Camplani-Casa di Cura Domus Salutis, Via Lazzaretto, 3, 25123 Brescia, Italy
| | - C Orizio
- Department of Clinical and Experimental Sciences, University of Brescia, Viale Europa, 11, 25123 Brescia, Italy; Centre of Research on the Neuromuscular Function and the Adapted Motor Activity, "Teresa Camplani" University of Brescia, Viale Europa, 11, 25123 Brescia, Italy.
| | - F Negro
- Department of Clinical and Experimental Sciences, University of Brescia, Viale Europa, 11, 25123 Brescia, Italy; Centre of Research on the Neuromuscular Function and the Adapted Motor Activity, "Teresa Camplani" University of Brescia, Viale Europa, 11, 25123 Brescia, Italy
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33
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Nguyen KH, Scheurich TE, Gu T, Berkowitz A. Spinal Interneurons With Dual Axon Projections to Knee-Extensor and Hip-Extensor Motor Pools. Front Neural Circuits 2020; 14:7. [PMID: 32226362 PMCID: PMC7080864 DOI: 10.3389/fncir.2020.00007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/21/2020] [Indexed: 11/13/2022] Open
Abstract
The central nervous system (CNS) may simplify control of limb movements by activating certain combinations of muscles together, i.e., muscle synergies. Little is known, however, about the spinal cord interneurons that activate muscle synergies by exciting sets of motoneurons for different muscles. The turtle spinal cord, even without brain inputs and movement-related sensory feedback, can generate the patterns of motoneuron activity underlying forward swimming, three forms of scratching, and limb withdrawal. Spinal interneurons activated during scratching are typically activated during all three forms of scratching, to different degrees, even though each form of scratching has its own knee-hip synergy. Such spinal interneurons are also typically activated rhythmically during scratching motor patterns, with hip-related timing. We proposed a hypothesis that such interneurons that are most active during rostral scratch stimulation project their axons to both knee-extensor and hip-flexor motoneurons, thus generating the rostral scratch knee-hip synergy, while those interneurons most active during pocket scratch stimulation project their axons to both knee-extensor and hip-extensor motoneurons, thus generating the pocket scratch knee-hip synergy. The activity of the entire population would then generate the appropriate synergy, depending on the location of sensory stimulation. Mathematical modeling has demonstrated that this hypothesis is feasible. Here, we provide one test of this hypothesis by injecting two fluorescent retrograde tracers into the regions of knee-extensor motoneurons (more rostrally) and hip-extensor motoneurons (more caudally). We found that there were double-labeled interneurons, which projected their axons to both locations. The dual-projecting interneurons were widely distributed rostrocaudally, dorsoventrally, and mediolaterally within the hindlimb enlargement and pre-enlargement spinal segments examined. The existence of such dual-projecting interneurons is consistent with the hypothesis that they contribute to generating the knee-hip synergy for pocket scratching. The dual-projecting interneurons, however, were only about 1% of the total interneurons projecting to each location, which suggests that they might be one of several contributors to the appropriate knee-hip synergy. Indirect projections to both motor pools and/or knee extensor-dedicated interneurons might also contribute. There is evidence for dual-projecting spinal interneurons in frogs and mice as well, suggesting that they may contribute to limb motor control in a variety of vertebrates.
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Affiliation(s)
- Khuong H Nguyen
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Thomas E Scheurich
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Tingting Gu
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Ari Berkowitz
- Department of Biology, University of Oklahoma, Norman, OK, United States.,Cellular and Behavioral Neurobiology Graduate Program, University of Oklahoma, Norman, OK, United States
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34
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Moreira LS, Elias LA, Germer CM, Palomari ET. Reliable measurement of incisal bite force for understanding the control of masticatory muscles. Arch Oral Biol 2020; 112:104683. [PMID: 32120053 DOI: 10.1016/j.archoralbio.2020.104683] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 01/12/2020] [Accepted: 02/17/2020] [Indexed: 11/16/2022]
Abstract
OBJECTIVE In the present study, we aimed at evaluating the steadiness of incisal bite force during isometric contractions of masticatory muscles. DESIGN Two separate experiments were carried out in 11 healthy young women. A first experiment was performed to test the reliability of our protocol for measurement of incisal bite force steadiness. The second experiment aimed to evaluate the steadiness of incisal bite force at four submaximal (i.e., percentage of maximum voluntary contraction, MVC) levels (5 %MVC, 10 %MVC, 15 %MVC, and 20 %MVC), along with the bilateral myoelectric activity of two masticatory muscles (temporalis and masseter). RESULTS The results from the first experiment showed that our protocol is substantially reliable (intraclass correlation coefficient, ICC > 0.80) for estimating force variability and moderate reliable (0.60 < ICC < 0.80) for estimating spectral properties of force signals. In the second experiment, we found that force standard deviation (SD) increased proportionally to the power of mean force, and coefficient of variation (CoV) was higher at low-intensity contractions and maintained at an approximately constant level for high-intensity contractions. The force-EMG relationships were linear for both muscles at the contraction intensities evaluated in the study (5 %MVC to 20 %MVC), and the median frequency did not change with contraction intensity. CONCLUSION Therefore, we presented a reliable method to estimate the incisal bite force, along with additional data on force control and myoelectric activity of jaw elevator muscles during isometric steady contractions.
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Affiliation(s)
- Luciana S Moreira
- Cellular and Structural Biology Graduate Program, Institute of Biology, University of Campinas, Campinas, SP, Brazil; EMG, Motor Control, and Experimental Electrothermotherapy Laboratory, Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas, SP, Brazil; Neural Engineering Research Laboratory, Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil.
| | - Leonardo A Elias
- Neural Engineering Research Laboratory, Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil; Center for Biomedical Engineering, University of Campinas, Campinas, SP, Brazil
| | - Carina M Germer
- Neural Engineering Research Laboratory, Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil
| | - Evanisi T Palomari
- Cellular and Structural Biology Graduate Program, Institute of Biology, University of Campinas, Campinas, SP, Brazil; EMG, Motor Control, and Experimental Electrothermotherapy Laboratory, Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas, SP, Brazil
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35
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Lacquaniti F, Sylos-Labini F, Zago M. Non-synergistic synergies of muscle activation: an apparent oxymoron. J Physiol 2019; 597:5743-5744. [PMID: 31691968 DOI: 10.1113/jp279111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Francesco Lacquaniti
- Department of Systems Medicine and Center of Space BioMedicine of the University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuromotor Physiology of the IRCCS Santa Lucia Foundation, Rome, Italy
| | | | - Myrka Zago
- Laboratory of Neuromotor Physiology of the IRCCS Santa Lucia Foundation, Rome, Italy.,Department of Civil Engineering and Computer Science Engineering and Centre of Space Biomedicine of the University of Rome Tor Vergata, Rome, Italy
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