1
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Harris-Warrick RM, Pecchi E, Drouillas B, Brocard F, Bos R. Effect of size on expression of bistability in mouse spinal motoneurons. J Neurophysiol 2024; 131:577-588. [PMID: 38380829 DOI: 10.1152/jn.00320.2023] [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: 08/24/2023] [Revised: 02/05/2024] [Accepted: 02/20/2024] [Indexed: 02/22/2024] Open
Abstract
Bistability in spinal motoneurons supports tonic spike activity in the absence of excitatory drive. Earlier work in adult preparations suggested that smaller motoneurons innervating slow antigravity muscle fibers are more likely to generate bistability for postural maintenance. However, whether large motoneurons innervating fast-fatigable muscle fibers display bistability is still controversial. To address this, we examined the relationship between soma size and bistability in lumbar (L4-L5) ventrolateral α-motoneurons of choline acetyltransferase (ChAT)-green fluorescent protein (GFP) and Hb9-GFP mice during the first 4 wk of life. We found that as neuron size increases, the prevalence of bistability rises. Smaller α-motoneurons lack bistability, whereas larger fast α-motoneurons [matrix metalloproteinase-9 (MMP-9)+/Hb9+] with a soma area ≥ 400 µm2 exhibit significantly higher bistability. Ionic currents associated with bistability, including the persistent Nav1.6 current, the thermosensitive Trpm5 Ca2+-activated Na+ current, and the slowly inactivating Kv1.2 current, also scale with cell size. Serotonin evokes full bistability in large motoneurons with partial bistable properties but not in small motoneurons. Our study provides important insights into the neural mechanisms underlying bistability and how motoneuron size correlates with bistability in mice.NEW & NOTEWORTHY Bistability is not a common feature of all mouse spinal motoneurons. It is absent in small, slow motoneurons but present in most large, fast motoneurons. This difference results from differential expression of ionic currents that enable bistability, which are highly expressed in large motoneurons but small or absent in small motoneurons. These results support a possible role for fast motoneurons in maintenance of tonic posture in addition to their known roles in fast movements.
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Affiliation(s)
- Ronald M Harris-Warrick
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States
| | - Emilie Pecchi
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
| | - Benoît Drouillas
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
| | - Frédéric Brocard
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
| | - Rémi Bos
- Aix Marseille Univ, CNRS, Institut de Neurosciences de la Timone (INT), UMR 7289, Marseille, France
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2
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Chung B, Zia M, Thomas KA, Michaels JA, Jacob A, Pack A, Williams MJ, Nagapudi K, Teng LH, Arrambide E, Ouellette L, Oey N, Gibbs R, Anschutz P, Lu J, Wu Y, Kashefi M, Oya T, Kersten R, Mosberger AC, O'Connell S, Wang R, Marques H, Mendes AR, Lenschow C, Kondakath G, Kim JJ, Olson W, Quinn KN, Perkins P, Gatto G, Thanawalla A, Coltman S, Kim T, Smith T, Binder-Markey B, Zaback M, Thompson CK, Giszter S, Person A, Goulding M, Azim E, Thakor N, O'Connor D, Trimmer B, Lima SQ, Carey MR, Pandarinath C, Costa RM, Pruszynski JA, Bakir M, Sober SJ. Myomatrix arrays for high-definition muscle recording. eLife 2023; 12:RP88551. [PMID: 38113081 PMCID: PMC10730117 DOI: 10.7554/elife.88551] [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] [Indexed: 12/21/2023] Open
Abstract
Neurons coordinate their activity to produce an astonishing variety of motor behaviors. Our present understanding of motor control has grown rapidly thanks to new methods for recording and analyzing populations of many individual neurons over time. In contrast, current methods for recording the nervous system's actual motor output - the activation of muscle fibers by motor neurons - typically cannot detect the individual electrical events produced by muscle fibers during natural behaviors and scale poorly across species and muscle groups. Here we present a novel class of electrode devices ('Myomatrix arrays') that record muscle activity at unprecedented resolution across muscles and behaviors. High-density, flexible electrode arrays allow for stable recordings from the muscle fibers activated by a single motor neuron, called a 'motor unit,' during natural behaviors in many species, including mice, rats, primates, songbirds, frogs, and insects. This technology therefore allows the nervous system's motor output to be monitored in unprecedented detail during complex behaviors across species and muscle morphologies. We anticipate that this technology will allow rapid advances in understanding the neural control of behavior and identifying pathologies of the motor system.
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Affiliation(s)
- Bryce Chung
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Muneeb Zia
- School of Electrical and Computer Engineering, Georgia Institute of TechnologyAtlantaUnited States
| | - Kyle A Thomas
- Graduate Program in Biomedical Engineering at Emory University and Georgia TechAtlantaUnited States
| | | | - Amanda Jacob
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Andrea Pack
- Neuroscience Graduate Program, Emory UniversityAtlantaUnited States
| | - Matthew J Williams
- Graduate Program in Biomedical Engineering at Emory University and Georgia TechAtlantaUnited States
| | | | - Lay Heng Teng
- Department of Biology, Emory UniversityAtlantaUnited States
| | | | | | - Nicole Oey
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Rhuna Gibbs
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Philip Anschutz
- Graduate Program in BioEngineering, Georgia TechAtlantaUnited States
| | - Jiaao Lu
- Graduate Program in Electrical and Computer Engineering, Georgia TechAtlantaUnited States
| | - Yu Wu
- School of Electrical and Computer Engineering, Georgia Institute of TechnologyAtlantaUnited States
| | - Mehrdad Kashefi
- Department of Physiology and Pharmacology, Western UniversityLondonCanada
| | - Tomomichi Oya
- Department of Physiology and Pharmacology, Western UniversityLondonCanada
| | - Rhonda Kersten
- Department of Physiology and Pharmacology, Western UniversityLondonCanada
| | - Alice C Mosberger
- Zuckerman Mind Brain Behavior Institute at Columbia UniversityNew YorkUnited States
| | - Sean O'Connell
- Graduate Program in Biomedical Engineering at Emory University and Georgia TechAtlantaUnited States
| | - Runming Wang
- Department of Biomedical Engineering at Emory University and Georgia TechAtlantaUnited States
| | - Hugo Marques
- Champalimaud Neuroscience Programme, Champalimaud FoundationLisbonPortugal
| | - Ana Rita Mendes
- Champalimaud Neuroscience Programme, Champalimaud FoundationLisbonPortugal
| | - Constanze Lenschow
- Champalimaud Neuroscience Programme, Champalimaud FoundationLisbonPortugal
| | | | - Jeong Jun Kim
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of MedicineBaltimoreUnited States
| | - William Olson
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of MedicineBaltimoreUnited States
| | - Kiara N Quinn
- Departments of Biomedical Engineering and Neurology, Johns Hopkins School of MedicineBaltimoreUnited States
| | - Pierce Perkins
- Departments of Biomedical Engineering and Neurology, Johns Hopkins School of MedicineBaltimoreUnited States
| | - Graziana Gatto
- Salk Institute for Biological StudiesLa JollaUnited States
| | | | - Susan Coltman
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Taegyo Kim
- Department of Neurobiology & Anatomy, Drexel University, College of MedicinePhiladelphiaUnited States
| | - Trevor Smith
- Department of Neurobiology & Anatomy, Drexel University, College of MedicinePhiladelphiaUnited States
| | - Ben Binder-Markey
- Department of Physical Therapy and Rehabilitation Sciences, Drexel University College of Nursing and Health ProfessionsPhiladelphiaUnited States
| | - Martin Zaback
- Department of Health and Rehabilitation Sciences, Temple UniversityPhiladelphiaUnited States
| | - Christopher K Thompson
- Department of Health and Rehabilitation Sciences, Temple UniversityPhiladelphiaUnited States
| | - Simon Giszter
- Department of Neurobiology & Anatomy, Drexel University, College of MedicinePhiladelphiaUnited States
| | - Abigail Person
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
- Allen InstituteSeattleUnited States
| | | | - Eiman Azim
- Salk Institute for Biological StudiesLa JollaUnited States
| | - Nitish Thakor
- Departments of Biomedical Engineering and Neurology, Johns Hopkins School of MedicineBaltimoreUnited States
| | - Daniel O'Connor
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of MedicineBaltimoreUnited States
| | - Barry Trimmer
- Department of Biology, Tufts UniversityMedfordUnited States
| | - Susana Q Lima
- Champalimaud Neuroscience Programme, Champalimaud FoundationLisbonPortugal
| | - Megan R Carey
- Champalimaud Neuroscience Programme, Champalimaud FoundationLisbonPortugal
| | - Chethan Pandarinath
- Department of Biomedical Engineering at Emory University and Georgia TechAtlantaUnited States
| | - Rui M Costa
- Zuckerman Mind Brain Behavior Institute at Columbia UniversityNew YorkUnited States
| | | | - Muhannad Bakir
- School of Electrical and Computer Engineering, Georgia Institute of TechnologyAtlantaUnited States
| | - Samuel J Sober
- Department of Biology, Emory UniversityAtlantaUnited States
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3
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Caillet AH, Phillips ATM, Farina D, Modenese L. Motoneuron-driven computational muscle modelling with motor unit resolution and subject-specific musculoskeletal anatomy. PLoS Comput Biol 2023; 19:e1011606. [PMID: 38060619 PMCID: PMC10729998 DOI: 10.1371/journal.pcbi.1011606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 12/19/2023] [Accepted: 10/16/2023] [Indexed: 12/20/2023] Open
Abstract
The computational simulation of human voluntary muscle contraction is possible with EMG-driven Hill-type models of whole muscles. Despite impactful applications in numerous fields, the neuromechanical information and the physiological accuracy such models provide remain limited because of multiscale simplifications that limit comprehensive description of muscle internal dynamics during contraction. We addressed this limitation by developing a novel motoneuron-driven neuromuscular model, that describes the force-generating dynamics of a population of individual motor units, each of which was described with a Hill-type actuator and controlled by a dedicated experimentally derived motoneuronal control. In forward simulation of human voluntary muscle contraction, the model transforms a vector of motoneuron spike trains decoded from high-density EMG signals into a vector of motor unit forces that sum into the predicted whole muscle force. The motoneuronal control provides comprehensive and separate descriptions of the dynamics of motor unit recruitment and discharge and decodes the subject's intention. The neuromuscular model is subject-specific, muscle-specific, includes an advanced and physiological description of motor unit activation dynamics, and is validated against an experimental muscle force. Accurate force predictions were obtained when the vector of experimental neural controls was representative of the discharge activity of the complete motor unit pool. This was achieved with large and dense grids of EMG electrodes during medium-force contractions or with computational methods that physiologically estimate the discharge activity of the motor units that were not identified experimentally. This neuromuscular model advances the state-of-the-art of neuromuscular modelling, bringing together the fields of motor control and musculoskeletal modelling, and finding applications in neuromuscular control and human-machine interfacing research.
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Affiliation(s)
- Arnault H. Caillet
- Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Andrew T. M. Phillips
- Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom
| | - Dario Farina
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Luca Modenese
- Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
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4
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Pandeya S, Sanchez B, Nagy JA, Rutkove SB. Combining electromyographic and electrical impedance data sets through machine learning: A study in D2-mdx and wild-type mice. Muscle Nerve 2023; 68:781-788. [PMID: 37658820 DOI: 10.1002/mus.27963] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 08/10/2023] [Accepted: 08/12/2023] [Indexed: 09/05/2023]
Abstract
INTRODUCTION/AIMS Needle impedance-electromyography (iEMG) assesses the active and passive electrical properties of muscles concurrently by using a novel needle with six electrodes, two for EMG and four for electrical impedance myography (EIM). Here, we assessed an approach for combining multifrequency EMG and EIM data via machine learning (ML) to discriminate D2-mdx muscular dystrophy and wild-type (WT) mouse skeletal muscle. METHODS iEMG data were obtained from quadriceps of D2-mdx mice, a muscular dystrophy model, and WT animals. EIM data were collected with the animals under deep anesthesia and EMG data collected under light anesthesia, allowing for limited spontaneous movement. Fourier transformation was performed on the EMG data to provide power spectra that were sampled across the frequency range using three different approaches. Random forest-based, nested ML was applied to the EIM and EMG data sets separately and then together to assess healthy versus disease category classification using a nested cross-validation procedure. RESULTS Data from 20 D2-mdx and 20 WT limbs were analyzed. EIM data fared better than EMG data in differentiating healthy from disease mice with 93.1% versus 75.6% accuracy, respectively. Combining EIM and EMG data sets yielded similar performance as EIM data alone with 92.2% accuracy. DISCUSSION We have demonstrated an ML-based approach for combining EIM and EMG data obtained with an iEMG needle. While EIM-EMG in combination fared no better than EIM alone with this data set, the approach used here demonstrates a novel method of combining the two techniques to characterize the full electrical properties of skeletal muscle.
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Affiliation(s)
- Sarbesh Pandeya
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Benjamin Sanchez
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah, USA
| | - Janice A Nagy
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Seward B Rutkove
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
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5
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Chung B, Zia M, Thomas KA, Michaels JA, Jacob A, Pack A, Williams MJ, Nagapudi K, Teng LH, Arrambide E, Ouellette L, Oey N, Gibbs R, Anschutz P, Lu J, Wu Y, Kashefi M, Oya T, Kersten R, Mosberger AC, O'Connell S, Wang R, Marques H, Mendes AR, Lenschow C, Kondakath G, Kim JJ, Olson W, Quinn KN, Perkins P, Gatto G, Thanawalla A, Coltman S, Kim T, Smith T, Binder-Markey B, Zaback M, Thompson CK, Giszter S, Person A, Goulding M, Azim E, Thakor N, O'Connor D, Trimmer B, Lima SQ, Carey MR, Pandarinath C, Costa RM, Pruszynski JA, Bakir M, Sober SJ. Myomatrix arrays for high-definition muscle recording. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.21.529200. [PMID: 36865176 PMCID: PMC9980060 DOI: 10.1101/2023.02.21.529200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Neurons coordinate their activity to produce an astonishing variety of motor behaviors. Our present understanding of motor control has grown rapidly thanks to new methods for recording and analyzing populations of many individual neurons over time. In contrast, current methods for recording the nervous system's actual motor output - the activation of muscle fibers by motor neurons - typically cannot detect the individual electrical events produced by muscle fibers during natural behaviors and scale poorly across species and muscle groups. Here we present a novel class of electrode devices ("Myomatrix arrays") that record muscle activity at unprecedented resolution across muscles and behaviors. High-density, flexible electrode arrays allow for stable recordings from the muscle fibers activated by a single motor neuron, called a "motor unit", during natural behaviors in many species, including mice, rats, primates, songbirds, frogs, and insects. This technology therefore allows the nervous system's motor output to be monitored in unprecedented detail during complex behaviors across species and muscle morphologies. We anticipate that this technology will allow rapid advances in understanding the neural control of behavior and in identifying pathologies of the motor system.
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Affiliation(s)
- Bryce Chung
- Department of Biology, Emory University (Atlanta, GA, USA)
| | - Muneeb Zia
- School of Electrical and Computer Engineering, Georgia Institute of Technology (Atlanta, GA, USA)
| | - Kyle A Thomas
- Graduate Program in Biomedical Engineering at Emory University and Georgia Tech (Atlanta, GA, USA)
| | - Jonathan A Michaels
- Department of Physiology and Pharmacology, Western University (London, ON, Canada)
| | - Amanda Jacob
- Department of Biology, Emory University (Atlanta, GA, USA)
| | - Andrea Pack
- Neuroscience Graduate Program, Emory University (Atlanta, GA, USA)
| | - Matthew J Williams
- Graduate Program in Biomedical Engineering at Emory University and Georgia Tech (Atlanta, GA, USA)
| | | | - Lay Heng Teng
- Department of Biology, Emory University (Atlanta, GA, USA)
| | | | | | - Nicole Oey
- Department of Biology, Emory University (Atlanta, GA, USA)
| | - Rhuna Gibbs
- Department of Biology, Emory University (Atlanta, GA, USA)
| | - Philip Anschutz
- Graduate Program in BioEngineering, Georgia Tech (Atlanta, GA, USA)
| | - Jiaao Lu
- Graduate Program in Electrical and Computer Engineering, Georgia Tech (Atlanta, GA, USA)
| | - Yu Wu
- School of Electrical and Computer Engineering, Georgia Institute of Technology (Atlanta, GA, USA)
| | - Mehrdad Kashefi
- Department of Physiology and Pharmacology, Western University (London, ON, Canada)
| | - Tomomichi Oya
- Department of Physiology and Pharmacology, Western University (London, ON, Canada)
| | - Rhonda Kersten
- Department of Physiology and Pharmacology, Western University (London, ON, Canada)
| | - Alice C Mosberger
- Zuckerman Mind Brain Behavior Institute at Columbia University (New York, NY, USA)
| | - Sean O'Connell
- Graduate Program in Biomedical Engineering at Emory University and Georgia Tech (Atlanta, GA, USA)
| | - Runming Wang
- Department of Biomedical Engineering at Emory University and Georgia Tech (Atlanta, GA, USA)
| | - Hugo Marques
- Champalimaud Neuroscience Programme, Champalimaud Foundation (Lisbon, Portugal)
| | - Ana Rita Mendes
- Champalimaud Neuroscience Programme, Champalimaud Foundation (Lisbon, Portugal)
| | - Constanze Lenschow
- Champalimaud Neuroscience Programme, Champalimaud Foundation (Lisbon, Portugal)
- current address: Institute of Biology, Otto-von-Guericke University, (Magdeburg, Germany)
| | | | - Jeong Jun Kim
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine (Baltimore, MD, USA)
| | - William Olson
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine (Baltimore, MD, USA)
| | - Kiara N Quinn
- Departments of Biomedical Engineering and Neurology, Johns Hopkins School of Medicine (Baltimore, MD, USA)
| | - Pierce Perkins
- Departments of Biomedical Engineering and Neurology, Johns Hopkins School of Medicine (Baltimore, MD, USA)
| | - Graziana Gatto
- Salk Institute for Biological Studies (La Jolla, CA, USA)
- current address: Department of Neurology, University Hospital of Cologne (Cologne, Germany)
| | | | - Susan Coltman
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus (Aurora, CO, USA)
| | - Taegyo Kim
- Department of Neurobiology & Anatomy, Drexel University, College of Medicine (Philadelphia, PA, USA)
| | - Trevor Smith
- Department of Neurobiology & Anatomy, Drexel University, College of Medicine (Philadelphia, PA, USA)
| | - Ben Binder-Markey
- Department of Physical Therapy and Rehabilitation Sciences, Drexel University College of Nursing and Health Professions (Philadelphia, PA)
| | - Martin Zaback
- Department of Health and Rehabilitation Sciences, Temple University (Philadelphia, PA, USA)
| | - Christopher K Thompson
- Department of Health and Rehabilitation Sciences, Temple University (Philadelphia, PA, USA)
| | - Simon Giszter
- Department of Neurobiology & Anatomy, Drexel University, College of Medicine (Philadelphia, PA, USA)
| | - Abigail Person
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus (Aurora, CO, USA)
| | | | - Eiman Azim
- Salk Institute for Biological Studies (La Jolla, CA, USA)
| | - Nitish Thakor
- Departments of Biomedical Engineering and Neurology, Johns Hopkins School of Medicine (Baltimore, MD, USA)
| | - Daniel O'Connor
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine (Baltimore, MD, USA)
| | - Barry Trimmer
- Department of Biology, Tufts University (Medford, MA, USA)
| | - Susana Q Lima
- Champalimaud Neuroscience Programme, Champalimaud Foundation (Lisbon, Portugal)
| | - Megan R Carey
- Champalimaud Neuroscience Programme, Champalimaud Foundation (Lisbon, Portugal)
| | - Chethan Pandarinath
- Department of Biomedical Engineering at Emory University and Georgia Tech (Atlanta, GA, USA)
| | - Rui M Costa
- Zuckerman Mind Brain Behavior Institute at Columbia University (New York, NY, USA)
- Allen Institute (Seattle, WA, USA)
| | - J Andrew Pruszynski
- Department of Physiology and Pharmacology, Western University (London, ON, Canada)
| | - Muhannad Bakir
- School of Electrical and Computer Engineering, Georgia Institute of Technology (Atlanta, GA, USA)
| | - Samuel J Sober
- Department of Biology, Emory University (Atlanta, GA, USA)
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6
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Yadav A, Matson KJE, Li L, Hua I, Petrescu J, Kang K, Alkaslasi MR, Lee DI, Hasan S, Galuta A, Dedek A, Ameri S, Parnell J, Alshardan MM, Qumqumji FA, Alhamad SM, Wang AP, Poulen G, Lonjon N, Vachiery-Lahaye F, Gaur P, Nalls MA, Qi YA, Maric D, Ward ME, Hildebrand ME, Mery PF, Bourinet E, Bauchet L, Tsai EC, Phatnani H, Le Pichon CE, Menon V, Levine AJ. A cellular taxonomy of the adult human spinal cord. Neuron 2023; 111:328-344.e7. [PMID: 36731429 PMCID: PMC10044516 DOI: 10.1016/j.neuron.2023.01.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 11/30/2022] [Accepted: 01/11/2023] [Indexed: 02/04/2023]
Abstract
The mammalian spinal cord functions as a community of cell types for sensory processing, autonomic control, and movement. While animal models have advanced our understanding of spinal cellular diversity, characterizing human biology directly is important to uncover specialized features of basic function and human pathology. Here, we present a cellular taxonomy of the adult human spinal cord using single-nucleus RNA sequencing with spatial transcriptomics and antibody validation. We identified 29 glial clusters and 35 neuronal clusters, organized principally by anatomical location. To demonstrate the relevance of this resource to human disease, we analyzed spinal motoneurons, which degenerate in amyotrophic lateral sclerosis (ALS) and other diseases. We found that compared with other spinal neurons, human motoneurons are defined by genes related to cell size, cytoskeletal structure, and ALS, suggesting a specialized molecular repertoire underlying their selective vulnerability. We include a web resource to facilitate further investigations into human spinal cord biology.
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Affiliation(s)
- Archana Yadav
- Department of Neurology, Center for Translational and Computational Neuroimmunology, Columbia University, New York, NY, USA
| | - Kaya J E Matson
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA; Johns Hopkins University Department of Biology, Baltimore, MD 21218, USA
| | - Li Li
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Isabelle Hua
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Joana Petrescu
- Department of Neurology, Center for Translational and Computational Neuroimmunology, Columbia University, New York, NY, USA; Center for Genomics of Neurodegenerative Disease, New York Genome Center, New York, NY, USA
| | - Kristy Kang
- Department of Neurology, Center for Translational and Computational Neuroimmunology, Columbia University, New York, NY, USA; Center for Genomics of Neurodegenerative Disease, New York Genome Center, New York, NY, USA
| | - Mor R Alkaslasi
- Unit on the Development of Neurodegeneration, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA; Department of Neuroscience, Brown University, Providence, RI, USA
| | - Dylan I Lee
- Department of Neurology, Center for Translational and Computational Neuroimmunology, Columbia University, New York, NY, USA
| | - Saadia Hasan
- Inherited Neurodegenerative Diseases Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Ahmad Galuta
- Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Annemarie Dedek
- Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada; Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Sara Ameri
- Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Jessica Parnell
- Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada; Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | | | | | - Saud M Alhamad
- Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Alick Pingbei Wang
- Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Gaetan Poulen
- Department of Neurosurgery, Gui de Chauliac Hospital, and Donation and Transplantation Coordination Unit, Montpellier University Medical Center, Montpellier, France
| | - Nicolas Lonjon
- Department of Neurosurgery, Gui de Chauliac Hospital, and Donation and Transplantation Coordination Unit, Montpellier University Medical Center, Montpellier, France
| | - Florence Vachiery-Lahaye
- Department of Neurosurgery, Gui de Chauliac Hospital, and Donation and Transplantation Coordination Unit, Montpellier University Medical Center, Montpellier, France
| | - Pallavi Gaur
- Department of Neurology, Center for Translational and Computational Neuroimmunology, Columbia University, New York, NY, USA
| | - Mike A Nalls
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA; Center for Alzheimer's and Related Dementias, National Institutes of Health, Bethesda, MD, USA; Data Tecnica International LLC, Glen Echo, MD, USA
| | - Yue A Qi
- Center for Alzheimer's and Related Dementias, National Institutes of Health, Bethesda, MD, USA
| | - Dragan Maric
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke; Bethesda, MD, USA
| | - Michael E Ward
- Inherited Neurodegenerative Diseases Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Michael E Hildebrand
- Inherited Neurodegenerative Diseases Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA; Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Pierre-Francois Mery
- Institute of Functional Genomics, Montpellier University, CNRS, INSERM, Montpellier, France
| | - Emmanuel Bourinet
- Institute of Functional Genomics, Montpellier University, CNRS, INSERM, Montpellier, France
| | - Luc Bauchet
- Department of Neurosurgery, Gui de Chauliac Hospital, and Donation and Transplantation Coordination Unit, Montpellier University Medical Center, Montpellier, France; Institute of Functional Genomics, Montpellier University, CNRS, INSERM, Montpellier, France
| | - Eve C Tsai
- Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Hemali Phatnani
- Department of Neurology, Center for Translational and Computational Neuroimmunology, Columbia University, New York, NY, USA; Center for Genomics of Neurodegenerative Disease, New York Genome Center, New York, NY, USA
| | - Claire E Le Pichon
- Unit on the Development of Neurodegeneration, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - Vilas Menon
- Department of Neurology, Center for Translational and Computational Neuroimmunology, Columbia University, New York, NY, USA.
| | - Ariel J Levine
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
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7
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Kirk EA, Castellani CA, Doherty TJ, Rice CL, Singh SM. Local and systemic transcriptomic responses from acute exercise induced muscle damage of the human knee extensors. Physiol Genomics 2022; 54:305-315. [PMID: 35723223 DOI: 10.1152/physiolgenomics.00146.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle is adaptable to a direct stimulus of exercise-induced muscle damage (EIMD). Local muscle gene networks and systemic circulatory factors respond to EIMD within days, mediating anti-inflammation and cellular proliferation. Here we show in humans that local EIMD of one muscle group is associated with a systemic response of gene networks that regulate muscle structure and cellular development in non-local homologous muscle not directly altered by EIMD. In the non-dominant knee-extensors of seven males, EIMD was induced through voluntary contractions against an electric motor that lengthened muscles. Neuromuscular assessments, vastus lateralis muscle biopsies and blood draws occurred at two days prior, and one and two days post the EIMD intervention. From the muscle and blood plasma samples, RNA-seq measured transcriptome changes of differential expression using bioinformatic analyses.Relative to the time of the EIMD intervention, local muscle that was mechanically damaged had 475 genes differentially expressed, as compared to 33 genes in the non-local homologous muscle. Gene and network analysis showed that activity of the local muscle was related to structural maintenance, repair, and energetic processes, whereas gene and network activity of the non-local muscle (that was not directly modified by the EIMD) were related to muscle cell development, stress response, and structural maintenance. Altered expression of two novel miRNAs related to the EIMD response supported that systemic factors were active. Together, these results indicate that the expression of genes and gene networks that control muscle contractile structure can be modified in response to non-local EIMD in humans.
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Affiliation(s)
- Eric A Kirk
- School of Kinesiology, Faculty of Health Sciences, Western University, London, Ontario, Canada.,Molecular Genetics Unit, Department of Biology, Western University, London, Ontario, Canada
| | - Christina A Castellani
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Timothy J Doherty
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Department of Physical Medicine and Rehabilitation, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, Western University, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, Western University, London, Canada
| | - Shiva M Singh
- Molecular Genetics Unit, Department of Biology, Western University, London, Ontario, Canada
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8
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Abstract
The purpose of our review was to compare the distribution of motor unit properties across human muscles of different sizes and recruitment ranges. Although motor units can be distinguished based on several different attributes, we focused on four key parameters that have a significant influence on the force produced by muscle during voluntary contractions: the number of motor units, average innervation number, the distributions of contractile characteristics, and discharge rates within motor unit pools. Despite relatively few publications on this topic, current data indicate that the most influential factor in the distribution of these motor unit properties between muscles is innervation number. Nonetheless, despite a fivefold difference in innervation number between a hand muscle (first dorsal interosseus) and a lower leg muscle (tibialis anterior), the general organization of their motor unit pools, and the range of discharge rates appear to be relatively similar. These observations provide foundational knowledge for studies on the control of movement and the changes that occur with aging and neurological disorders.
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Affiliation(s)
- Jacques Duchateau
- Laboratory of Applied Biology and Neurophysiology, ULB Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado
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9
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Bączyk M, Manuel M, Roselli F, Zytnicki D. Diversity of Mammalian Motoneurons and Motor Units. ADVANCES IN NEUROBIOLOGY 2022; 28:131-150. [PMID: 36066824 DOI: 10.1007/978-3-031-07167-6_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Although they share the common function of controlling muscle fiber contraction, spinal motoneurons display a remarkable diversity. Alpha-motoneurons are the "final common pathway", which relay all the information from spinal and supraspinal centers and allow the organism to interact with the outside world by controlling the contraction of muscle fibers in the muscles. On the other hand, gamma-motoneurons are specialized motoneurons that do not generate force and instead specifically innervate muscle fibers inside muscle spindles, which are proprioceptive organs embedded in the muscles. Beta-motoneurons are hybrid motoneurons that innervate both extrafusal and intrafusal muscle fibers. Even among alpha-motoneurons, there exists an exquisite diversity in terms of motoneuron electrical and molecular properties, physiological and structural properties of their neuromuscular junctions, and molecular and contractile properties of the innervated muscle fibers. This diversity, across species, across muscles, and across muscle fibers in a given muscle, underlie the vast repertoire of movements that one individual can perform.
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Affiliation(s)
- Marcin Bączyk
- Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland
| | - Marin Manuel
- SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Université de Paris, Paris, France.
| | - Francesco Roselli
- Department of Neurology, Ulm University, Ulm, Germany
- Institute of Anatomy and Cell Biology, Ulm University, Ulm, Germany
- German Center for Neurodegenerative Diseases (DZNE)-Ulm, Ulm, Germany
- Neurozentrum Ulm, Ulm, Germany
| | - Daniel Zytnicki
- SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Université de Paris, Paris, France
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10
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Abstract
When animals walk overground, mechanical stimuli activate various receptors located in muscles, joints, and skin. Afferents from these mechanoreceptors project to neuronal networks controlling locomotion in the spinal cord and brain. The dynamic interactions between the control systems at different levels of the neuraxis ensure that locomotion adjusts to its environment and meets task demands. In this article, we describe and discuss the essential contribution of somatosensory feedback to locomotion. We start with a discussion of how biomechanical properties of the body affect somatosensory feedback. We follow with the different types of mechanoreceptors and somatosensory afferents and their activity during locomotion. We then describe central projections to locomotor networks and the modulation of somatosensory feedback during locomotion and its mechanisms. We then discuss experimental approaches and animal models used to investigate the control of locomotion by somatosensory feedback before providing an overview of the different functional roles of somatosensory feedback for locomotion. Lastly, we briefly describe the role of somatosensory feedback in the recovery of locomotion after neurological injury. We highlight the fact that somatosensory feedback is an essential component of a highly integrated system for locomotor control. © 2021 American Physiological Society. Compr Physiol 11:1-71, 2021.
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Affiliation(s)
- Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Quebec, Canada
| | - Turgay Akay
- Department of Medical Neuroscience, Atlantic Mobility Action Project, Brain Repair Center, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Boris I Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
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11
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Orssatto LBR, Mackay K, Shield AJ, Sakugawa RL, Blazevich AJ, Trajano GS. Estimates of persistent inward currents increase with the level of voluntary drive in low-threshold motor units of plantar flexor muscles. J Neurophysiol 2021; 125:1746-1754. [PMID: 33788617 DOI: 10.1152/jn.00697.2020] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
This study tested whether estimates of persistent inward currents (PICs) in the human plantar flexors would increase with the level of voluntary drive. High-density surface electromyograms were collected from soleus and gastrocnemius medialis of 21 participants (29.2 ± 2.6 yr) during ramp-shaped isometric contractions to 10%, 20%, and 30% (torque rise and decline of 2%/s and 30-s duration) of each participant's maximal torque. Motor units identified in all the contraction intensities were included in the paired-motor unit analysis to calculate delta frequency (ΔF) and estimate the PICs. ΔF is the difference in discharge rate of the control unit at the time of recruitment and derecruitment of the test unit. Increases in PICs were observed from 10% to 20% [Δ = 0.6 pulse per second (pps); P < 0.001] and from 20% to 30% (Δ = 0.5 pps; P < 0.001) in soleus and from 10% to 20% (Δ = 1.2 pps; P < 0.001) but not from 20% to 30% (Δ = 0.09 pps; P = 0.724) in gastrocnemius medialis. Maximal discharge rate increased for soleus and gastrocnemius medialis from 10% to 20% [Δ = 1.75 pps (P < 0.001) and Δ = 2.43 pps (P < 0.001), respectively] and from 20% to 30% [Δ = 0.80 pps (P < 0.017) and Δ = 0.92 pps (P = 0.002), respectively]. The repeated-measures correlation identified associations between ΔF and increases in maximal discharge rate for soleus (r = 0.64; P < 0.001) and gastrocnemius medialis (r = 0.77; P < 0.001). An increase in voluntary drive tends to increase PIC strength, which has key implications for the control of force but also for comparisons between muscles or studies when relative force levels might be different. Increases in voluntary descending drive amplify PICs in humans and provide an important spinal mechanism for motor unit discharging, and thus force output modulation.NEW & NOTEWORTHY Animal experiments and computational models have shown that motor neurons can amplify the synaptic input they receive via persistent inward currents. Here we show in humans that this amplification varies proportionally to the magnitude of the voluntary drive to the muscle.
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Affiliation(s)
- Lucas B R Orssatto
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Queensland, Australia
| | - Karen Mackay
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Queensland, Australia
| | - Anthony J Shield
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Queensland, Australia
| | - Raphael L Sakugawa
- Biomechanics Laboratory, Department of Physical Education, Federal University of Santa Catarina, Florianopolis, Brazil
| | - Anthony J Blazevich
- Centre for Exercise and Sports Science Research (CESSR), School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Gabriel S Trajano
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Queensland, Australia
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12
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Adam I, Elemans CPH. Increasing Muscle Speed Drives Changes in the Neuromuscular Transform of Motor Commands during Postnatal Development in Songbirds. J Neurosci 2020; 40:6722-6731. [PMID: 32487696 PMCID: PMC7455216 DOI: 10.1523/jneurosci.0111-20.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 05/19/2020] [Accepted: 05/21/2020] [Indexed: 01/04/2023] Open
Abstract
Progressive changes in vocal behavior over the course of vocal imitation leaning are often attributed exclusively to developing neural circuits, but the effects of postnatal body changes remain unknown. In songbirds, the syrinx transforms song system motor commands into sound and exhibits changes during song learning. Here we test the hypothesis that the transformation from motor commands to force trajectories by syringeal muscles functionally changes over vocal development in zebra finches. Our data collected in both sexes show that, only in males, muscle speed significantly increases and that supralinear summation occurs and increases with muscle contraction speed. Furthermore, we show that previously reported submillisecond spike timing in the avian cortex can be resolved by superfast syringeal muscles and that the sensitivity to spike timing increases with speed. Because motor neuron and muscle properties are tightly linked, we make predictions on the boundaries of the yet unknown motor code that correspond well with cortical activity. Together, we show that syringeal muscles undergo essential transformations during song learning that drastically change how neural commands are translated into force profiles and thereby acoustic features. We propose that the song system motor code must compensate for these changes to achieve its acoustic targets. Our data thus support the hypothesis that the neuromuscular transformation changes over vocal development and emphasizes the need for an embodied view of song motor learning.SIGNIFICANCE STATEMENT Fine motor skill learning typically occurs in a postnatal period when the brain is learning to control a body that is changing dramatically due to growth and development. How the developing body influences motor code formation and vice versa remains largely unknown. Here we show that vocal muscles in songbirds undergo critical transformations during song learning that drastically change how neural commands are translated into force profiles and thereby acoustic features. We propose that the motor code must compensate for these changes to achieve its acoustic targets. Our data thus support the hypothesis that the neuromuscular transformation changes over vocal development and emphasizes the need for an embodied view of song motor learning.
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Affiliation(s)
- Iris Adam
- University of Southern Denmark, Department of Biology, 5230 Odense M, Denmark
| | - Coen P H Elemans
- University of Southern Denmark, Department of Biology, 5230 Odense M, Denmark
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13
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Fogarty MJ, Sieck GC. Spinal cord injury and diaphragm neuromotor control. Expert Rev Respir Med 2020; 14:453-464. [PMID: 32077350 PMCID: PMC7176525 DOI: 10.1080/17476348.2020.1732822] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 02/18/2020] [Indexed: 12/22/2022]
Abstract
Introduction: Neuromotor control of diaphragm muscle and the recovery of diaphragm activity following spinal cord injury have been narrowly focused on ventilation. By contrast, the understanding of neuromotor control for non-ventilatory expulsive/straining maneuvers (including coughing, defecation, and parturition) is relatively impoverished. This variety of behaviors are achieved via the recruitment of the diverse array of motor units that comprise the diaphragm muscle.Areas covered: The neuromotor control of ventilatory and non-ventilatory behaviors in health and in the context of spinal cord injury is explored. Particular attention is played to the neuroplasticity of phrenic motor neurons in various models of cervical spinal cord injury.Expert opinion: There is a remarkable paucity in our understanding of neuromotor control of maneuvers in spinal cord injury patients. Dysfunction of these expulsive/straining maneuvers reduces patient quality of life and contributes to severe morbidity and mortality. As spinal cord injury patient life expectancies continue to climb steadily, a nexus of spinal cord injury and age-associated comorbidities are likely to occur. While current research remains concerned only with the minutiae of ventilation, the major functional deficits of this clinical cohort will persist intractably. We posit some future research directions to avoid this scenario.
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Affiliation(s)
- Matthew J Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, 55905, USA
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, 55905, USA
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14
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Linking Motoneuron PIC Location to Motor Function in Closed-Loop Motor Unit System Including Afferent Feedback: A Computational Investigation. eNeuro 2020; 7:ENEURO.0014-20.2020. [PMID: 32269036 PMCID: PMC7218009 DOI: 10.1523/eneuro.0014-20.2020] [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: 01/13/2020] [Revised: 03/03/2020] [Accepted: 03/16/2020] [Indexed: 11/21/2022] Open
Abstract
The goal of this study is to investigate how the activation location of persistent inward current (PIC) over motoneuron dendrites is linked to motor output in the closed-loop motor unit. Here, a physiologically realistic model of a motor unit including afferent inputs from muscle spindles was comprehensively analyzed under intracellular stimulation at the soma and synaptic inputs over the dendrites during isometric contractions over a full physiological range of muscle lengths. The motor output of the motor unit model was operationally assessed by evaluating the rate of force development, the degree of force potentiation and the capability of self-sustaining force production. Simulations of the model motor unit demonstrated a tendency for a faster rate of force development, a greater degree of force potentiation, and greater capacity for self-sustaining force production under both somatic and dendritic stimulation of the motoneuron as the PIC channels were positioned farther from the soma along the path of motoneuron dendrites. Interestingly, these effects of PIC activation location on force generation significantly differed among different states of muscle length. The rate of force development and the degree of force potentiation were systematically modulated by the variation of PIC channel location for shorter-than-optimal muscles but not for optimal and longer-than-optimal muscles. Similarly, the warm-up behavior of the motor unit depended on the interplay between PIC channel location and muscle length variation. These results suggest that the location of PIC activation over motoneuron dendrites may be distinctively reflected in the motor performance during shortening muscle contractions.
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15
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Fogarty MJ, Brown AD, Sieck GC. MOTOR NEURON LOSS IN AGING AND AMYOTROPHIC LATERAL SCLEROSIS: DIFFERENT FUSE LENGTHS, SAME EXPLOSION. PHYSIOLOGICAL MINI-REVIEWS 2020; 13:1-11. [PMID: 37577056 PMCID: PMC10416778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Advanced age and amyotrophic lateral sclerosis (ALS) are both associated with a loss of motor neurons resulting in muscle fiber atrophy and muscle weakness. Aging associated muscle fiber atrophy and weakening is termed sarcopenia, but the association with motor neuron loss is not as clearly established as in ALS, probably related to the prolonged time course of aging-related changes. Although aging and ALS effects on limb muscle strength and neuromotor performance are serious, such effects on the diaphragm muscle can be life threatening. Converging evidence indicates that larger phrenic motor neurons, innervating more fatigable type IIx and/or IIb diaphragm muscle fibers (fast fatigue intermediate, FInt and fast fatigable, FF motor units) are more susceptible to degeneration with both aging and ALS compared to smaller phrenic motor neurons innervating type I and IIa diaphragm muscle fibers (slow and fast fatigue resistant motor units, respectively). The etiology of ALS and age-related loss of motor neurons appears to involve mitochondrial function and neuroinflammation, both chronic and acute exacerbation. How mitochondrial dysfunction, neuroinflammation and motor neuron size intersect is the focus of continuing investigation.
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Affiliation(s)
- Matthew J. Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55902, USA
| | - Alyssa D. Brown
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55902, USA
| | - Gary C. Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55902, USA
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16
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Fogarty MJ, Mu EWH, Lavidis NA, Noakes PG, Bellingham MC. Size-Dependent Vulnerability of Lumbar Motor Neuron Dendritic Degeneration in SOD1 G93A Mice. Anat Rec (Hoboken) 2019; 303:1455-1471. [PMID: 31509351 DOI: 10.1002/ar.24255] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 05/22/2019] [Accepted: 06/29/2019] [Indexed: 12/14/2022]
Abstract
The motor neuron (MN) soma surface area is correlated with motor unit type. Larger MNs innervate fast fatigue-intermediate (FInt) or fast-fatiguable (FF) muscle fibers in type FInt and FF motor units, respectively. Smaller MNs innervate slow-twitch fatigue-resistant (S) or fast fatigue-resistant (FR) muscle fibers in type S and FR motor units, respectively. In amyotrophic lateral sclerosis (ALS), FInt and FF motor units are more vulnerable, with denervation and MN death occurring for these units before the more resilient S and FR units. Abnormal MN dendritic arbors have been observed in ALS in humans and rodent models. We used a Golgi-Cox impregnation protocol to examine soma size-dependent changes in the dendritic morphology of lumbar MNs in SOD1G93A mice, a model of ALS, at pre-symptomatic, onset and mid-disease stages. In wildtype control mice, the relationship between MN soma surface area and dendritic length or dendritic spine number was highly linear (i.e., increased MN soma size correlated with increased dendritic length and spines). By contrast, in SOD1G93A mice, this linear relationship was lost and dendritic length reduction and spine loss were observed in larger MNs, from pre-symptomatic stages onward. These changes correlated with the neuromotor symptoms of ALS in rodent models. At presymptomatic ages, changes were restricted to the larger MNs, likely to comprise vulnerable FInt and FF motor units. Our results suggest morphological changes of MN dendrites and dendritic spines are likely to contribute ALS pathogenesis, not compensate for it. Anat Rec, 303:1455-1471, 2020. © 2019 American Association for Anatomy.
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Affiliation(s)
- Matthew J Fogarty
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Erica W H Mu
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Nickolas A Lavidis
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Peter G Noakes
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.,Queensland Brain Institute, The University of Queensland, St Lucia, Queensland, Australia
| | - Mark C Bellingham
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
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17
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Sieck GC. Physiology in Perspective: Of Mice and Men. Physiology (Bethesda) 2019; 34:3-4. [PMID: 30540230 DOI: 10.1152/physiol.00049.2018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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