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Zhang J, McClean ZJ, Khaledi N, Morgan SJ, Millet GY, Aboodarda SJ. Reliability of transcranial magnetic stimulation-evoked responses on knee extensor muscles during cycling. Exp Brain Res 2024:10.1007/s00221-024-06859-y. [PMID: 38806709 DOI: 10.1007/s00221-024-06859-y] [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: 02/21/2024] [Accepted: 05/19/2024] [Indexed: 05/30/2024]
Abstract
Transcranial magnetic stimulation (TMS) measures the excitability and inhibition of corticomotor networks. Despite its task-specificity, few studies have used TMS during dynamic movements and the reliability of TMS paired pulses has not been assessed during cycling. This study aimed to evaluate the reliability of motor evoked potentials (MEP) and short- and long-interval intracortical inhibition (SICI and LICI) on vastus lateralis and rectus femoris muscle activity during a fatiguing single-leg cycling task. Nine healthy adults (2 female) performed two identical sessions of counterweighted single-leg cycling at 60% peak power output until failure. Five single pulses and ten paired pulses were delivered to the motor cortex, and two maximal femoral nerve stimulations (Mmax) were administered during two baseline cycling bouts (unfatigued) and every 5 min throughout cycling (fatigued). When comparing both baseline bouts within the same session, MEP·Mmax-1 and LICI (both ICC: >0.9) were rated excellent while SICI was rated good (ICC: 0.7-0.9). At baseline, between sessions, in the vastus lateralis, Mmax (ICC: >0.9) and MEP·Mmax-1 (ICC: 0.7) demonstrated good reliability; LICI was moderate (ICC: 0.5), and SICI was poor (ICC: 0.3). Across the fatiguing task, Mmax demonstrated excellent reliability (ICC > 0.8), MEP·Mmax-1 ranged good to excellent (ICC: 0.7-0.9), LICI was moderate to excellent (ICC: 0.5-0.9), and SICI remained poorly reliable (ICC: 0.3-0.6). These results corroborate the cruciality of retaining mode-specific testing measurements and suggest that during cycling, Mmax, MEP·Mmax-1, and LICI measures are reliable whereas SICI, although less reliable across days, can be reliable within the same session.
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Affiliation(s)
- Jenny Zhang
- Faculty of Kinesiology, University of Calgary, KNB 420, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada
| | - Zachary J McClean
- Faculty of Kinesiology, University of Calgary, KNB 420, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada
| | - Neda Khaledi
- Faculty of Kinesiology, University of Calgary, KNB 420, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada
- Faculty of Physical Education and Sport Sciences, Kharazmi University, Tehran, Iran
| | - Sophie-Jayne Morgan
- Faculty of Kinesiology, University of Calgary, KNB 420, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada
| | - Guillaume Y Millet
- Inter-university Laboratory of Human Movement Biology, Université Jean Monnet Saint-Etienne, Université Savoie Mont-Blanc, Lyon 1, Saint-Etienne, F-42023, France
| | - Saied Jalal Aboodarda
- Faculty of Kinesiology, University of Calgary, KNB 420, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada.
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Gomez-Guerrero G, Ansdell P, Howatson G, Avela J, Walker S. Contraction intensity modulates spinal excitability during transcranial magnetic stimulation-evoked silent period in rectus femoris muscle. Eur J Appl Physiol 2024; 124:1355-1366. [PMID: 38032387 PMCID: PMC11055719 DOI: 10.1007/s00421-023-05367-1] [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: 06/05/2023] [Accepted: 11/08/2023] [Indexed: 12/01/2023]
Abstract
PURPOSE Reduced spinal excitability during the transcranial magnetic stimulation (TMS) silent period (SP) has recently been shown to last longer than previously thought in the upper limbs, as assessed via spinal electrical stimulation. Further, there is reason to expect that contraction intensity affects the duration of the reduced spinal excitability. METHODS This study investigated spinal excitability at different time delays within the TMS-evoked SP in m.rectus femoris. Fifteen participants performed non-fatiguing isometric knee extensions at 25%, 50% and 75% of maximum voluntary contraction (MVC). Lumbar stimulation (LS) induced a lumbar-evoked potential (LEP) of 50% resting M-max. TMS stimulator output induced a SP lasting ~ 200 ms. In each contraction, a LEP (unconditioned) was delivered ~ 2-3 s prior to TMS, which was followed by a second LEP (conditioned) 60, 90, 120 or 150 ms into the silent period. Five contractions were performed at each contraction intensity and for each time delay in random order. RESULTS Compared to the unconditioned LEP, the conditioned LEP amplitude was reduced (- 28 ± 34%, p = 0.007) only at 60 ms during 25% of MVC. Conditioned LEP amplitudes during 50% and 75% of MVC were reduced at 60 ms (- 37 ± 47%, p = 0.009 and - 37 ± 42%, p = 0.005, respectively) and 150 ms (- 30% ± 37%, p = 0.0083 and - 37 ± 43%, p = 0.005, respectively). LEP amplitude at 90 ms during 50% of MVC also reduced (- 25 ± 35%, p = 0.013). CONCLUSION Reduced spinal excitability is extended during 50% and 75% of MVC. In future, paired TMS-LS could be a potential method to understand changes in spinal excitability during SP (at different contraction intensities) when testing various neurophysiological phenomena.
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Affiliation(s)
- Gonzalo Gomez-Guerrero
- NeuroMuscular Research Center (NMRC), Faculty of Sport and Health Sciences, University of Jyväskylä, Viveca (VIV221), 40700, Jyväskylä, Finland.
| | - Paul Ansdell
- Faculty of Health and Life Science, Northumbria University, Newcastle Upon Tyne, UK
| | - Glyn Howatson
- Faculty of Health and Life Science, Northumbria University, Newcastle Upon Tyne, UK
- Water Research Group, North West University, Potchefstroom, South Africa
| | - Janne Avela
- NeuroMuscular Research Center (NMRC), Faculty of Sport and Health Sciences, University of Jyväskylä, Viveca (VIV221), 40700, Jyväskylä, Finland
| | - Simon Walker
- NeuroMuscular Research Center (NMRC), Faculty of Sport and Health Sciences, University of Jyväskylä, Viveca (VIV221), 40700, Jyväskylä, Finland
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Woodhead A, Rainer C, Hill J, Murphy CP, North JS, Kidgell D, Tallent J. Corticospinal and spinal responses following a single session of lower limb motor skill and resistance training. Eur J Appl Physiol 2024:10.1007/s00421-024-05464-9. [PMID: 38532177 DOI: 10.1007/s00421-024-05464-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 03/01/2024] [Indexed: 03/28/2024]
Abstract
Prior studies suggest resistance exercise as a potential form of motor learning due to task-specific corticospinal responses observed in single sessions of motor skill and resistance training. While existing literature primarily focuses on upper limb muscles, revealing a task-dependent nature in eliciting corticospinal responses, our aim was to investigate such responses after a single session of lower limb motor skill and resistance training. Twelve participants engaged in a visuomotor force tracking task, self-paced knee extensions, and a control task. Corticospinal, spinal, and neuromuscular responses were measured using transcranial magnetic stimulation (TMS) and peripheral nerve stimulation (PNS). Assessments occurred at baseline, immediately post, and at 30-min intervals over two hours. Force steadiness significantly improved in the visuomotor task (P < 0.001). Significant fixed-effects emerged between conditions for corticospinal excitability, corticospinal inhibition, and spinal excitability (all P < 0.001). Lower limb motor skill training resulted in a greater corticospinal excitability compared to resistance training (mean difference [MD] = 35%, P < 0.001) and control (MD; 37%, P < 0.001). Motor skill training resulted in a lower corticospinal inhibition compared to control (MD; - 10%, P < 0.001) and resistance training (MD; - 9%, P < 0.001). Spinal excitability was lower following motor skill training compared to control (MD; - 28%, P < 0.001). No significant fixed effect of Time or Time*Condition interactions were observed. Our findings highlight task-dependent corticospinal responses in lower limb motor skill training, offering insights for neurorehabilitation program design.
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Affiliation(s)
- Alex Woodhead
- Faculty of Sport, Technology and Health Sciences, St. Mary's University, Twickenham, Middlesex, TW1 4SX, UK.
| | - Christopher Rainer
- Faculty of Sport, Technology and Health Sciences, St. Mary's University, Twickenham, Middlesex, TW1 4SX, UK
| | - Jessica Hill
- Faculty of Sport, Technology and Health Sciences, St. Mary's University, Twickenham, Middlesex, TW1 4SX, UK
| | - Colm P Murphy
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Jamie S North
- Faculty of Sport, Technology and Health Sciences, St. Mary's University, Twickenham, Middlesex, TW1 4SX, UK
| | - Dawson Kidgell
- Monash Exercise Neuroplasticity Research Unit, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Melbourne, VIC, 3199, Australia
| | - Jamie Tallent
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Wivenhoe Park, Colchester, UK
- Monash Exercise Neuroplasticity Research Unit, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Melbourne, VIC, 3199, Australia
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Kawai K, Tazoe T, Yanai T, Kazuyuki K, Nishimura Y. Transsynaptic activation of human lumbar spinal motoneurons by transvertebral magnetic stimulation. Neurosci Res 2024; 200:20-27. [PMID: 37793496 DOI: 10.1016/j.neures.2023.10.001] [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: 08/14/2023] [Revised: 09/15/2023] [Accepted: 10/01/2023] [Indexed: 10/06/2023]
Abstract
Noninvasive spinal stimulation has been increasingly used in research on motor control and neurorehabilitation. Despite advances in percutaneous electrical stimulation techniques, magnetic stimulation is not as commonly used as electrical stimulation. Therefore, it is still under discussion what neuronal elements are activated by magnetic stimulation of the human spinal cord. In this study, we demonstrated that transvertebral magnetic stimulation (TVMS) induced transsynaptic activation of spinal motoneuron pools in the lumbar cord. In healthy humans, paired-pulse TVMS was given over an intervertebral space between the L1-L2 vertebrae with an interpulse interval of 100 ms, and the stimulus-evoked electromyographic (EMG) responses were recorded in the lower limb muscles. The results show that the evoked EMG responses after the 2nd pulse were clearly suppressed compared with the widespread responses evoked after the 1st pulse in the muscles of the lower extremity, indicating that the transsynaptic activation of spinal motoneurons by the 2nd pulse was suppressed by the effects produced by the 1st pulse. The inconsistent modulation of response suppression to stimulus intensity across individuals suggests that the TVMS-evoked EMG responses are composed of the compound potentials mediated by the direct activation of motor axons and the transsynaptic activation of motoneuron pools through sensory afferents and that the recruitment order of those fibers by TVMS may be nonhomogeneous across individuals.
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Affiliation(s)
- Kazutake Kawai
- College of Sports Sciences, Nihon University, Setagaya, Tokyo 154-8513, Japan; Neural Prosthetics Project, Department of Brain and Neuroscience, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506, Japan; Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama 359-1192, Japan
| | - Toshiki Tazoe
- Neural Prosthetics Project, Department of Brain and Neuroscience, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506, Japan.
| | - Toshimasa Yanai
- Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama 359-1192, Japan
| | - Kanosue Kazuyuki
- Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama 359-1192, Japan
| | - Yukio Nishimura
- Neural Prosthetics Project, Department of Brain and Neuroscience, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506, Japan
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Gomez-Guerrero G, Avela J, Enroth M, Häkkinen E, Ansdell P, Howatson G, Walker S. Test-retest reliability of cortico-spinal measurements in the rectus femoris at different contraction levels. Front Neurosci 2023; 17:1239982. [PMID: 37849888 PMCID: PMC10577233 DOI: 10.3389/fnins.2023.1239982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 09/08/2023] [Indexed: 10/19/2023] Open
Abstract
Single-pulse Transcranial Magnetic Stimulation (TMS) and, very recently, lumbar stimulation (LS) have been used to measure cortico-spinal excitability from various interventions using maximal or submaximal contractions in the lower limbs. However, reliability studies have overlooked a wide range of contraction intensities for MEPs, and no reliability data is available for LEPs. This study investigated the reliability of motor evoked potentials and lumbar evoked potentials at different stimulation intensities and contraction levels in m.rectus femoris. Twenty-two participants performed non-fatiguing isometric knee extensions at 20 and 60% of maximum voluntary contraction (MVC). LS induced a lumbar-evoked potential (LEP) of 25 and 50% resting maximal compound action potential (M-max). TMS stimulator output was adjusted to 120, 140, and 160% of active motor threshold (aMT). In each contraction, a single MEP or LEP was delivered. Ten contractions were performed at each stimulator intensity and contraction level in random order. Moderate-to-good reliability was found when LEP was normalized to M-max/Root Mean Square in all conditions (ICC:0.74-0.85). Excellent reliability was found when MEP was normalized to Mmax for all conditions (ICC > 0.90) at 60% of MVC. Good reliability was found for the rest of the TMS conditions. Moderate-to-good reliability was found for silent period (SP) elicited by LS (ICC: 0.71-0.83). Good-to-excellent reliability was found for SP elicited by TMS (ICC > 0.82). MEPs and LEPs elicited in m.rectus femoris appear to be reliable to assess changes at different segments of the cortico-spinal tract during different contraction levels and stimulator output intensities. Furthermore, the TMS- and LS- elicited SP was a reliable tool considered to reflect inhibitory processes at spinal and cortical levels.
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Affiliation(s)
- Gonzalo Gomez-Guerrero
- Faculty of Sport and Health Sciences, NeuroMuscular Research Center, University of Jyväskylä, Jyväskylä, Finland
| | - Janne Avela
- Faculty of Sport and Health Sciences, NeuroMuscular Research Center, University of Jyväskylä, Jyväskylä, Finland
| | - Miro Enroth
- Faculty of Sport and Health Sciences, NeuroMuscular Research Center, University of Jyväskylä, Jyväskylä, Finland
| | - Ella Häkkinen
- Faculty of Sport and Health Sciences, NeuroMuscular Research Center, University of Jyväskylä, Jyväskylä, Finland
| | - Paul Ansdell
- Faculty of Health and Life Science, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Glyn Howatson
- Faculty of Health and Life Science, Northumbria University, Newcastle upon Tyne, United Kingdom
- Water Research Group, North West University, Potchefstroom, South Africa
| | - Simon Walker
- Faculty of Sport and Health Sciences, NeuroMuscular Research Center, University of Jyväskylä, Jyväskylä, Finland
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Law M, Sachdeva R, Darrow D, Krassioukov A. Cardiovascular Effects of Spinal Cord Stimulation: The Highs, the Lows, and the Don't Knows. Neuromodulation 2023:S1094-7159(23)00714-6. [PMID: 37665302 DOI: 10.1016/j.neurom.2023.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/31/2023] [Accepted: 07/31/2023] [Indexed: 09/05/2023]
Abstract
BACKGROUND AND OBJECTIVES There are many potential etiologies of impaired cardiovascular control, from chronic stress to neurodegenerative conditions or central nervous system lesions. Since 1959, spinal cord stimulation (SCS) has been reported to modulate blood pressure (BP), heart rate (HR), and HR variability (HRV), yet the specific stimulation sites and parameters to induce a targeted cardiovascular (CV) change for mitigating abnormal hemodynamics remain unclear. To investigate the ability and parameters of SCS to modulate the CV, we reviewed clinical studies using SCS with reported HR, BP, or HRV findings. MATERIALS AND METHODS A keyword-based electronic search was conducted through MEDLINE, Embase, and PubMed data bases, last searched on February 3, 2023. Inclusion criteria were studies with human participants receiving SCS with comparison with SCS turned off, with reporting of either HR, HRV, or BP findings. Non-English studies, conference abstracts, and studies not reporting standalone effects of SCS when comparing SCS with non-SCS interventions were excluded. Results were plotted for visual analysis. When available, participant-specific stimulation parameters and effects were extracted and quantitatively analyzed using ordinary least squares regression. RESULTS A total of 59 studies were included in this review; 51 studies delivered SCS invasively through implanted/percutaneous leads. Eight studies used noninvasive, transcutaneous electrodes. We found numerous reports of cervical, high thoracic, and mid-to-low thoracolumbar SCS increasing resting BP, and cervical/mid-to-low thoracolumbar SCS decreasing BP. The effect of SCS location on HR and HRV was equivocal. We were unable to analyze stimulation parameters owing to inadequate parameter reporting in many publications. CONCLUSIONS Our findings suggest CV neuromodulation, particularly BP modulation, with SCS to be a promising frontier. Further research with larger randomized controlled trials and detailed reporting of SCS parameters will be necessary for appropriate evaluation of SCS as a CV therapy.
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Affiliation(s)
- Marco Law
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada; Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Rahul Sachdeva
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada; Department of Medicine, University of British Columbia, Vancouver, BC, Canada.
| | - David Darrow
- Department of Neurosurgery, University of Minnesota, Minneapolis, MN, USA; Division of Neurosurgery, Hennepin County Medical Center, Minneapolis, MN, USA
| | - Andrei Krassioukov
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada; Department of Medicine, University of British Columbia, Vancouver, BC, Canada; G.F. Strong Rehabilitation Centre, Vancouver Coastal Health, Vancouver, BC, Canada
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Gueugneau N, Martin A, Gaveau J, Papaxanthis C. Gravity-efficient motor control is associated with contraction-dependent intracortical inhibition. iScience 2023; 26:107150. [PMID: 37534144 PMCID: PMC10391940 DOI: 10.1016/j.isci.2023.107150] [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: 09/21/2022] [Revised: 06/04/2023] [Accepted: 06/12/2023] [Indexed: 08/04/2023] Open
Abstract
In humans, moving efficiently along the gravity axis requires shifts in muscular contraction modes. Raising the arm up involves shortening contractions of arm flexors, whereas the reverse movement can rely on lengthening contractions with the help of gravity. Although this control mode is universal, the neuromuscular mechanisms that drive gravity-oriented movements remain unknown. Here, we designed neurophysiological experiments that aimed to track the modulations of cortical, spinal, and muscular outputs of arm flexors during vertical movements with specific kinematics (i.e., optimal motor commands). We report a specific drop of corticospinal excitability during lengthening versus shortening contractions, with an increase of intracortical inhibition and no change in spinal motoneuron responsiveness. We discuss these contraction-dependent modulations of the supraspinal motor output in the light of feedforward mechanisms that may support gravity-tuned motor control. Generally, these results shed a new perspective on the neural policy that optimizes movement control along the gravity axis.
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Affiliation(s)
- Nicolas Gueugneau
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, 21000 Dijon, France
| | - Alain Martin
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, 21000 Dijon, France
| | - Jérémie Gaveau
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, 21000 Dijon, France
| | - Charalambos Papaxanthis
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, 21000 Dijon, France
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8
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Jo HJ, Kizziar E, Sangari S, Chen D, Kessler A, Kim K, Anschel A, Heinemann AW, Mensh BD, Awadalla S, Lieber RL, Oudega M, Perez MA. Multisite Hebbian Plasticity Restores Function in Humans with Spinal Cord Injury. Ann Neurol 2023; 93:1198-1213. [PMID: 36843340 PMCID: PMC10268028 DOI: 10.1002/ana.26622] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 12/29/2022] [Accepted: 02/06/2023] [Indexed: 02/28/2023]
Abstract
OBJECTIVE Spinal cord injury (SCI) damages synaptic connections between corticospinal axons and motoneurons of many muscles, resulting in devastating paralysis. We hypothesized that strengthening corticospinal-motoneuronal synapses at multiple spinal cord levels through Hebbian plasticity (i.e., "neurons that fire together, wire together") promotes recovery of leg and arm function. METHODS Twenty participants with chronic SCI were randomly assigned to receive 20 sessions of Hebbian or sham stimulation targeting corticospinal-motoneuronal synapses of multiple leg muscles followed by exercise. Based on the results from this study, in a follow-up prospective study, 11 more participants received 40 sessions of Hebbian stimulation targeting corticospinal-motoneuronal synapses of multiple arm and leg muscles followed by exercise. During Hebbian stimulation sessions, 180 paired pulses elicited corticospinal action potentials by magnetic (motor cortex) and/or electrical (thoracic spine) stimulation allowing volleys to arrive at the spinal cord 1-2 milliseconds before motoneurons were activated retrogradely via bilateral electrical stimulation (brachial plexus, ulnar, femoral, and common peroneal nerves) for biceps brachii, first dorsal interosseous, quadriceps femoris, and tibialis anterior muscles as needed. RESULTS We found in our randomized study that participants receiving Hebbian stimulation improved their walking speed and corticospinal function to a greater extent than individuals receiving sham stimulation. In agreement, prospective study participants improved their grasping and walking, corticospinal function, and quality of life metrics, exhibiting greater improvements with more sessions that persisted 9-month post-therapy. INTERPRETATION Our findings suggest that multisite Hebbian stimulation, informed by the physiology of the corticospinal system, represents an effective strategy to promote functional recovery following SCI. ANN NEUROL 2023;93:1198-1213.
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Affiliation(s)
- Hang Jin Jo
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, USA
| | - Ethan Kizziar
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, USA
- Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, USA
| | - Sina Sangari
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, USA
| | - David Chen
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, USA
| | - Allison Kessler
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, USA
| | - Ki Kim
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, USA
| | - Alan Anschel
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, USA
| | - Allen W. Heinemann
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, USA
| | - Brett D. Mensh
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, USA
| | - Saria Awadalla
- Division of Epidemiology & Biostatistics, University of Illinois at Chicago, Chicago, USA
| | - Richard L. Lieber
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, USA
- Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, USA
- Edward Jr. Hines VA Hospital, Chicago, USA
| | - Martin Oudega
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, USA
- Edward Jr. Hines VA Hospital, Chicago, USA
| | - Monica A. Perez
- Shirley Ryan AbilityLab, Chicago, USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, USA
- Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, USA
- Edward Jr. Hines VA Hospital, Chicago, USA
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9
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Maffiuletti NA, Dirks ML, Stevens-Lapsley J, McNeil CJ. Electrical stimulation for investigating and improving neuromuscular function in vivo: Historical perspective and major advances. J Biomech 2023; 152:111582. [PMID: 37088030 DOI: 10.1016/j.jbiomech.2023.111582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 04/04/2023] [Indexed: 04/25/2023]
Abstract
This historical review summarizes the major advances - particularly from the last 50 years - in transcutaneous motor-level electrical stimulation, which can be used either as a tool to investigate neuromuscular function and its determinants (electrical stimulation for testing; EST) or as a therapeutic/training modality to improve neuromuscular and physical function (neuromuscular electrical stimulation; NMES). We focus on some of the most important applications of electrical stimulation in research and clinical settings, such as the investigation of acute changes, chronic adaptations and pathological alterations of neuromuscular function with EST, as well as the enhancement, preservation and restoration of muscle strength and mass with NMES treatment programs in various populations. For both EST and NMES, several major advances converge around understanding and optimizing motor unit recruitment during electrically-evoked contractions, also taking into account the influence of stimulation site (e.g., muscle belly vs nerve trunk) and type (e.g., pulse duration, frequency, and intensity). This information is equally important both in the context of mechanistic research of neuromuscular function as well as for clinicians who believe that improvements in neuromuscular function are required to provide health-related benefits to their patients.
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Affiliation(s)
| | - Marlou L Dirks
- Department of Public Health and Sports Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK; Human and Animal Physiology, Wageningen University, Wageningen, The Netherlands
| | - Jennifer Stevens-Lapsley
- Physical Therapy Program, Department of Physical Medicine and Rehabilitation, University of Colorado, Aurora, CO, USA; VA Eastern Colorado Geriatric Research, Education, and Clinical Center (GRECC), VA Eastern Colorado Health Care System, Aurora, CO, USA
| | - Chris J McNeil
- Integrated Neuromuscular Physiology Laboratory, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
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10
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Amann M, Sidhu SK, McNeil CJ, Gandevia SC. Critical considerations of the contribution of the corticomotoneuronal pathway to central fatigue. J Physiol 2022; 600:5203-5214. [PMID: 36326193 PMCID: PMC9772161 DOI: 10.1113/jp282564] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
Neural drive originating in higher brain areas reaches exercising limb muscles through the corticospinal-motoneuronal pathway, which links the motor cortex and spinal motoneurones. The properties of this pathway have frequently been observed to change during fatiguing exercise in ways that could influence the development of central fatigue (i.e. the progressive reduction in voluntary muscle activation). However, based on differences in motor cortical and motoneuronal excitability between exercise modalities (e.g. single-joint vs. locomotor exercise), there is no characteristic response that allows for a categorical conclusion about the effect of these changes on functional impairments and performance limitations. Despite the lack of uniformity in findings during fatigue, there is strong evidence for marked 'inhibition' of motoneurones as a direct result of voluntary drive. Endogenous forms of neuromodulation, such as via serotonin released from neurones, can directly affect motoneuronal output and central fatigue. Exogenous forms of neuromodulation, such as brain stimulation, may achieve a similar effect, although the evidence is weak. Non-invasive transcranial direct current stimulation can cause transient or long-lasting changes in cortical excitability; however, variable results across studies cast doubt on its claimed capacity to enhance performance. Furthermore, with these studies, it is difficult to establish a cause-and-effect relationship between brain responsiveness and exercise performance. This review briefly summarizes changes in the corticomotoneuronal pathway during various types of exercise, and considers the relevance of these changes for the development of central fatigue, as well as the potential of non-invasive brain stimulation to enhance motor cortical excitability, motoneuronal output and, ultimately, exercise performance.
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Affiliation(s)
- Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Simranjit K. Sidhu
- School of Biomedicine, The University of Adelaide, South Australia, Australia
| | - Chris J McNeil
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Simon C Gandevia
- Neuroscience Research Australia and University of New South Wales, Sydney, Australia
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11
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Amiri E, Gharakhanlou R, Rajabi H, Giboin LS, Rezasoltani Z, Azma K. Non-local muscle fatigue is mediated at spinal and supraspinal levels. Exp Brain Res 2022; 240:1887-1897. [PMID: 35460346 DOI: 10.1007/s00221-022-06364-0] [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: 11/18/2021] [Accepted: 04/02/2022] [Indexed: 11/26/2022]
Abstract
The objective was to measure the corticospinal excitability and motoneuron responsiveness of the right and left Biceps Brachii (BB), and left Abductor Digiti Minimi (ADM) muscles in response to submaximal isotonic fatiguing contractions performed by the right BB muscle. With the familiarization session, ten young moderately active male subjects came to the lab on seven occasions. Three sets of 3 min seated elbow curls at 25% of one-repetition maximum (1RM) separated by a 1-min rest performed by the right BB muscle were used as the fatiguing protocol. The motor evoked potential (MEP), cervicomedullary motor evoked potential (CMEP), and compound muscle action potential (Mmax) of the right BB muscle (baseline and after each set of the fatiguing task), the left BB and ADM muscles (baseline, post-fatigue, post-10, and post-20 min) were measured. MEP and CMEP were then normalized to Mmax for statistical analysis. The results showed that in the right BB muscle, there was a significant reduction in the MEP after performing the fatiguing task (p= 0.03), while no significant effect of time was seen in the CMEP (p= 0.07). In the left BB muscle, the MEP significantly decreased from pre-fatigue to post-fatigue (p= 0.01) and post-10 (p= 0.001), while there was a significant decline in the CMEP post-fatigue (p= 0.03). In the left ADM muscle, MEP significantly decreased post-fatigue (p= 0.03) and no changes were seen in the CMEP (p= 0.12). These results not only confirm the incidence of non-local muscle fatigue (NLMF) in response to performing submaximal isotonic fatiguing contractions but also as a new finding, imply that both spinal and supraspinal modulations account for the NLMF response.
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Affiliation(s)
- Ehsan Amiri
- Exercise Metabolism and Performance Lab (EMPL), Faculty of Sport Sciences, Razi University, Room. 73, University Avenue, Taq-E Bostan, Kermanshah, 674441497, Iran.
| | - Reza Gharakhanlou
- Department of Sports Science, Tarbiat Modares University, Tehran, 14115-111, Iran
| | - Hamid Rajabi
- Department of Sports Science, Kharazmi University, Tehran, 14911-15719, Iran
| | - Louis-Solal Giboin
- Sensorimotor Performance Lab, Human Performance Research Center, Konstanz University, 78457, Konstanz, Germany
| | | | - Kamran Azma
- Aja University of Medical Science, Tehran, 14117-18541, Iran
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12
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Vitry F, Papaiordanidou M, Martin A. Mechanisms modulating spinal excitability after nerve stimulation inducing extra torque. J Appl Physiol (1985) 2021; 131:1162-1175. [PMID: 34264132 DOI: 10.1152/japplphysiol.00005.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The study included three experiments aiming to examine the mechanisms responsible for spinal excitability modulation, as assessed by the H-reflex, following stimulation trains delivered at two different frequencies (20 and 100 Hz) inducing extra torque (ET). A first experiment (n = 15) was conducted to evaluate changes in presynaptic inhibition acting on Ia afferents induced by these electrical stimulation trains, assessed by conditioning the soleus H-reflex (tibial nerve stimulation) with stimulation of the common peroneal nerve (D1 inhibition) and of the femoral nerve (heteronymous Ia facilitation, HF). A second experiment (n = 12) permitted to investigate homosynaptic postactivation depression (HPAD) changes after the stimulation trains. A third experiment (n = 14) analyzed changes in motoneuron intrinsic properties after the stimulation trains, by electrically stimulating the descending corticospinal tract at the thoracic level, evoking thoracic motor-evoked potentials (TMEP). Main results showed that in all experiments, spinal excitability decreased after the 20-Hz train (P < 0.05), whereas this parameter significantly increased after the 100-Hz stimulation (P < 0.05). D1 and HF were not significantly modified after either stimulation. HPAD was significantly decreased only after the 20-Hz train, whereas TMEP was significantly increased only after the 100-Hz train (P < 0.05). It is concluded that the decreased spinal excitability observed after the 20-Hz train cannot be attributed to D1 presynaptic inhibition but rather to increased HPAD of the Ia afferents terminals, whereas the increase of this parameter obtained after the 100-Hz train can be assigned to changes in intrinsic motoneuron properties allowing to maintain Ia-α-motoneurons transmission efficacy.NEW & NOTEWORTHY Using different electrophysiological techniques, results show that the downregulation of spinal excitability observed after the 20-Hz train could be ascribed to homosynaptic postactivation depression of the Ia afferents terminals, whereas changes in intrinsic motoneuron properties could explain the increased spinal excitability observed after the 100-Hz train. A novel methodology for assessing soleus D1 presynaptic inhibition and heteronymous Ia facilitation, accounting for eventual modulations of test reflex amplitude throughout the session, was developed.
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Affiliation(s)
- Florian Vitry
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, F-21000, Dijon, France
| | - Maria Papaiordanidou
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, F-21000, Dijon, France
| | - Alain Martin
- INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR des Sciences du Sport, F-21000, Dijon, France
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13
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Sangari S, Kirshblum S, Guest JD, Oudega M, Perez MA. Distinct patterns of spasticity and corticospinal connectivity following complete spinal cord injury. J Physiol 2021; 599:4441-4454. [PMID: 34107068 DOI: 10.1113/jp281862] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 06/01/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Damage to corticospinal axons have implications for the development of spasticity following spinal cord injury (SCI). Here, we examined to which extent residual corticospinal connections and spasticity are present in muscles below the injury (quadriceps femoris and soleus) in humans with motor complete thoracic SCI. We found three distinct sub-groups of people: participants with spasticity and corticospinal responses in the quadriceps femoris and soleus, participants with spasticity and corticospinal responses in the quadriceps femoris only, and participants with no spasticity or corticospinal responses in either muscle. Spasticity and corticospinal responses were present in the quadriceps but never only in the soleus muscle, suggesting a proximal to distal gradient of symptoms of hyperreflexia. These results suggest that concomitant patterns of residual corticospinal connectivity and spasticity exist in humans with motor complete SCI and that a clinical exam of spasticity might be a good predictor of residual corticospinal connectivity. ABSTRACT The loss of corticospinal axons has implications for the development of spasticity following spinal cord injury (SCI). However, the extent to which residual corticospinal connections and spasticity are present across muscles below the injury remains unknown. To address this question, we tested spasticity using the Modified Ashworth Scale and transmission in the corticospinal pathway by examining motor evoked potentials elicited by transcranial magnetic stimulation over the leg motor cortex (cortical MEPs) and by direct activation of corticospinal axons by electrical stimulation over the thoracic spine (thoracic MEPs), in the quadriceps femoris and soleus muscles, in 30 individuals with motor complete thoracic SCI. Cortical MEPs were also conditioned by thoracic electrical stimulation at intervals allowing their summation or collision. We found three distinct sub-groups of participants: 47% showed spasticity in the quadriceps femoris and soleus muscle, 30% showed spasticity in the quadriceps femoris muscle only, and 23% showed no spasticity in either muscle. While cortical MEPs were present only in the quadriceps in participants with spasticity, thoracic MEPs were present in both muscles when spasticity was present. Thoracic electrical stimulation facilitated and suppressed cortical MEPs, showing that both forms of stimulation activated similar corticospinal axons. Cortical and thoracic MEPs correlated with the degree of spasticity in both muscles. These results provide the first evidence that related patterns of residual corticospinal connectivity and spasticity exist in muscles below the injury after motor complete thoracic SCI and highlight that a clinical exam of spasticity can predict residual corticospinal connectivity after severe paralysis. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Sina Sangari
- Shirley Ryan AbilityLab, Chicago, Illinois, 60611.,Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois, 60611
| | - Steven Kirshblum
- Kessler Institute for Rehabilitation, Department of Physical Medicine and Rehabilitation, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - James D Guest
- The Miami Project to Cure Paralysis, University of Miami, Miami, 33136
| | - Martin Oudega
- Shirley Ryan AbilityLab, Chicago, Illinois, 60611.,Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, Illinois, 60611.,Edward Hines Jr. VA Hospital, Hines, Illinois, 60141
| | - Monica A Perez
- Shirley Ryan AbilityLab, Chicago, Illinois, 60611.,Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois, 60611.,Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, Illinois, 60611.,Edward Hines Jr. VA Hospital, Hines, Illinois, 60141
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14
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State-of-the-art review: spinal and supraspinal responses to muscle potentiation in humans. Eur J Appl Physiol 2021; 121:1271-1282. [PMID: 33635383 DOI: 10.1007/s00421-021-04610-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 01/17/2021] [Indexed: 02/02/2023]
Abstract
Post-activation potentiation (PAP), described as a muscular phenomenon, refers to the enhancement of contractile properties following a voluntary or electrically stimulated short duration (< 10 s) high-intensity contraction. Mechanistic factors and subsequent effects on voluntary performance have been well documented. Associations between neural activation and PAP, however, are less understood and systematically have not been explored. Thus, the aim is to critically summarize the current understanding of PAP regarding the motor pathway from the corticospinal tract to spinal level factors including the H-reflex and motor unit activation. This review highlights aspects for further investigation by providing an integrative summary of the relationship between PAP and neural control. Contractile history affects neural control in subsequent contractions, (e.g. fatiguing tasks), however, by contrast acute contractile enhancement due to PAP in relation to neural responses are not well-studied. From the limited number of investigations, motor unit discharge rates are reduced subsequent to PAP and, although less consistently reported, generally H-reflexes are depressed. Additionally, corticomedullary evoked potentials are depressed and the cortical silent period is elongated. Thus, overall there is a depression of spinal and supraspinal responses following PAP. Although specific factors responsible and their pathways are unclear, this down-regulation may occur to conserve neural activation when muscle contraction is more responsive, and concurrently a strategy used to delay neuromuscular fatigue. Indeed, the co-existence of PAP and fatigue is not a novel concept, but the interactions between PAP and neural responses are not understood and likely are more than coincidental.
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15
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Škarabot J, Brownstein CG, Casolo A, Del Vecchio A, Ansdell P. The knowns and unknowns of neural adaptations to resistance training. Eur J Appl Physiol 2020; 121:675-685. [PMID: 33355714 PMCID: PMC7892509 DOI: 10.1007/s00421-020-04567-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 11/18/2020] [Indexed: 12/22/2022]
Abstract
The initial increases in force production with resistance training are thought to be primarily underpinned by neural adaptations. This notion is firmly supported by evidence displaying motor unit adaptations following resistance training; however, the precise locus of neural adaptation remains elusive. The purpose of this review is to clarify and critically discuss the literature concerning the site(s) of putative neural adaptations to short-term resistance training. The proliferation of studies employing non-invasive stimulation techniques to investigate evoked responses have yielded variable results, but generally support the notion that resistance training alters intracortical inhibition. Nevertheless, methodological inconsistencies and the limitations of techniques, e.g. limited relation to behavioural outcomes and the inability to measure volitional muscle activity, preclude firm conclusions. Much of the literature has focused on the corticospinal tract; however, preliminary research in non-human primates suggests reticulospinal tract is a potential substrate for neural adaptations to resistance training, though human data is lacking due to methodological constraints. Recent advances in technology have provided substantial evidence of adaptations within a large motor unit population following resistance training. However, their activity represents the transformation of afferent and efferent inputs, making it challenging to establish the source of adaptation. Whilst much has been learned about the nature of neural adaptations to resistance training, the puzzle remains to be solved. Additional analyses of motoneuron firing during different training regimes or coupling with other methodologies (e.g., electroencephalography) may facilitate the estimation of the site(s) of neural adaptations to resistance training in the future.
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Affiliation(s)
- Jakob Škarabot
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Callum G Brownstein
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Jean Monnet Saint-Etienne, Université Lyon, Saint-Étienne, France
| | - Andrea Casolo
- Department of Bioengineering, Imperial College London, London, UK.,Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Alessandro Del Vecchio
- Department of Artificial Intelligence and Biomedical Engineering, Faculty of Engineering, Friedrich-Alexander University, Erlangen-Nurnberg, 91052, Erlangen, Germany
| | - Paul Ansdell
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK.
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16
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Cortical and Subcortical Neural Interactions Between Trunk and Upper-limb Muscles in Humans. Neuroscience 2020; 451:126-136. [PMID: 33075460 DOI: 10.1016/j.neuroscience.2020.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Revised: 10/01/2020] [Accepted: 10/05/2020] [Indexed: 12/28/2022]
Abstract
Activities of daily living require simultaneous and coordinated activation of trunk and upper-limb segments, which involves complex interlimb interaction within the central nervous system. Although many studies have reported associations between activity of trunk and limb muscles during functional tasks, evidence on cortical and subcortical contributions to trunk-limb neural interactions is still not fully clear. Therefore, the aim of this study was to examine interactions between trunk and upper-limb muscles in the: (i) corticospinal circuits by using motor evoked potential (MEP) elicited through transcranial magnetic stimulation; and (ii) subcortical circuits by using cervicomedullary motor evoked potential (CMEP) elicited through cervicomedullary junction magnetic stimulation. Responses were evoked in the erector spinae (trunk) and flexor carpi radialis (upper-limb) muscles in twelve able-bodied individuals: (1) while participants were relaxed; (2) during trunk muscle contractions while arms were at rest; and (3) during upper-limb muscle contractions while the trunk was at rest. Our results showed that trunk muscle CMEP responses were not affected by upper-limb muscle contractions, while MEP responses were modulated. This indicates that at least the subcortical circuits may not attribute to facilitation of the trunk muscles during upper-limb contractions. On the other hand, in the upper-limb muscles, both CMEP and MEP responses were modulated during trunk contractions. These results indicate that cortical and subcortical mechanisms attributed to facilitation of upper-limb muscles during trunk contractions. In conclusion, our study demonstrated evidence that trunk-limb neural interactions may be attributed to cortical and/or subcortical mechanisms depending on the contracted muscle.
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17
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Krenn MJ, Vargas Luna JL, Mayr W, Stokic DS. Bipolar transcutaneous spinal stimulation evokes short-latency reflex responses in human lower limbs alike standard unipolar electrode configuration. J Neurophysiol 2020; 124:1072-1082. [PMID: 32845202 DOI: 10.1152/jn.00433.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Noninvasive electrical stimulation targeting the posterior lumbosacral roots has been applied recently in reflexes studies and as a neuromodulation intervention for modifying spinal cord circuitry after an injury. Here, we characterized short-latency responses evoked by four bipolar electrode configurations placed longitudinally over the spinal column at different vertebral levels from L1 to T9. They were compared with the responses evoked by the standard unipolar (aka monopolar) electrode configuration (cathode at T11/12, anode over the abdominal wall). Short-latency responses were recorded in the rectus femoris, medial hamstrings, tibialis anterior, and soleus muscles, bilaterally, in 11 neurologically intact participants. The response recruitment characteristics (maximal amplitude, motor threshold) and amplitude-matched onset latencies and paired-pulse suppression (35-ms interstimulus interval) were assessed with 1-ms current-controlled pulses at intensities up to 100 mA. The results showed that short-latency responses can be elicited with all bipolar electrode configurations. However, only with the cathode at T11/12 and the anode 10 cm cranially (∼T9), the maximum response amplitudes were statistical equivalent (P < 0.05) in the medial hamstrings, tibialis anterior, and soleus but not the rectus femoris, whereas motor thresholds were not significantly different across all muscles. The onset latency and paired-pulse suppression were also not significantly different across the tested electrode configurations, thereby confirming the reflex nature of the bipolar short-latency responses. We conclude that the bipolar configuration (cathode T11/12, anode ∼T9) produces reflex responses that are ostensibly similar to those evoked by the standard unipolar configuration. This provides an alternative approach for neuromodulation intervention.NEW & NOTEWORTHY Transcutaneous spinal stimulation with the identified bipolar electrode configuration may offer several advantages for neuromodulation interventions over commonly used unipolar configurations: there are no associated abdominal contractions, which improves the participant's comfort; additional dermatomes are not stimulated as when the anode is over the abdominal wall or iliac crest, which may have unwanted effects; and, due to a more localized electrical field, the bipolar configuration offers the possibility of targeting cord segments more selectively.
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Affiliation(s)
- Matthias J Krenn
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi.,Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, Mississippi
| | - Jose L Vargas Luna
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Winfried Mayr
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Dobrivoje S Stokic
- Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, Mississippi
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18
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Vernillo G, Temesi J, Martin M, Krüger RL, Millet GY. Spinal contribution to neuromuscular recovery differs between elbow-flexor and knee-extensor muscles after a maximal sustained fatiguing task. J Neurophysiol 2020; 124:763-773. [PMID: 32755359 DOI: 10.1152/jn.00273.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Data from studies of elbow-flexor (EF) or knee-extensor (KE) muscles suggest that a fatigue-related decrease in motoneuron excitability only occurs in EF. It is unknown how motoneuron excitability changes after sustained fatiguing maximal voluntary isometric contractions (MVICs) in EF and KE in the same participants. In two sessions, eight healthy men performed a 2-min MVIC of EF or KE to induce fatigue with brief MVICs before and six times after the 2-min MVIC. Electromyographic responses elicited by corticospinal tract stimulation at the transmastoid [cervicomedullary motor-evoked potential (CMEP)] or thoracic [thoracic motor-evoked potential (TMEP)] level were recorded from EF and KE, respectively. To account for muscle excitability, CMEPs and TMEPs were normalized to maximal M-wave (Mmax) elicited by peripheral nerve stimulation during each brief MVIC. Immediately after the 2-min MVIC, biceps brachii and brachioradialis CMEP/Mmax were 88% (SD 11%) (P = 0.026) and 87% (SD 12%) (P = 0.029) of pre-MVIC (PRE) values, respectively, and remained lower than PRE after 5 s of recovery [91% (SD 8%), P = 0.036 and 87% (SD 13%), P = 0.046, respectively]. No subsequent time points differed from PRE (all P ≥ 0.253). TMEP/Mmax for rectus femoris and vastus lateralis were not different from PRE at any time during the recovery period (all P > 0.050). A different recovery pattern in motoneuron excitability occurred in EF as it recovered by 60 s whereas KE motoneurons were unaffected by the fatiguing task. The present findings may contribute to better understand muscle-specific neurophysiological differences in spinal excitability.NEW & NOTEWORTHY By comparing the changes in motoneuron excitability in elbow-flexor and knee-extensor muscles after sustained fatiguing maximal voluntary contractions, this study shows that motoneuron recovery behavior depends on the muscle performing the exercise. A different recovery pattern in motoneuron excitability occurs in elbow flexors as it recovered by 60 s whereas knee extensors were unaffected by fatigue. This finding can help to increase understanding of the effect of a fatigue and subsequent recovery on neural processes.
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Affiliation(s)
- Gianluca Vernillo
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
| | - John Temesi
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Matthieu Martin
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Renata L Krüger
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Guillaume Y Millet
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Univ Lyon, UJM-Saint-Etienne, Inter-university Laboratory of Human Movement Biology, EA 7424, F-42023, Saint-Etienne, France.,Institut Universitaire de France (IUF)
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19
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Ansdell P, Brownstein CG, Škarabot J, Angius L, Kidgell D, Frazer A, Hicks KM, Durbaba R, Howatson G, Goodall S, Thomas K. Task‐specific strength increases after lower‐limb compound resistance training occurred in the absence of corticospinal changes in vastus lateralis. Exp Physiol 2020; 105:1132-1150. [DOI: 10.1113/ep088629] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 04/30/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Paul Ansdell
- Faculty of Health and Life SciencesNorthumbria University Newcastle upon Tyne UK
| | - Callum G. Brownstein
- Faculty of Health and Life SciencesNorthumbria University Newcastle upon Tyne UK
- Laboratoire Interuniversitaire de Biologie de la MotricitéUniversité Jean Monnet Saint Etienne, Université Lyon Lyon France
| | - Jakob Škarabot
- Faculty of Health and Life SciencesNorthumbria University Newcastle upon Tyne UK
- School of SportExercise and Health SciencesLoughborough University Loughborough UK
| | - Luca Angius
- Faculty of Health and Life SciencesNorthumbria University Newcastle upon Tyne UK
| | - Dawson Kidgell
- Department of PhysiotherapySchool of Primary and Allied Health CareFaculty of MedicineNursing and Health SciencesMonash University Melbourne Australia
| | - Ashlyn Frazer
- Department of PhysiotherapySchool of Primary and Allied Health CareFaculty of MedicineNursing and Health SciencesMonash University Melbourne Australia
| | - Kirsty M. Hicks
- Faculty of Health and Life SciencesNorthumbria University Newcastle upon Tyne UK
| | - Rade Durbaba
- Faculty of Health and Life SciencesNorthumbria University Newcastle upon Tyne UK
| | - Glyn Howatson
- Faculty of Health and Life SciencesNorthumbria University Newcastle upon Tyne UK
- Water Research GroupSchool of Biological SciencesNorth West University Potchefstroom South Africa
| | - Stuart Goodall
- Faculty of Health and Life SciencesNorthumbria University Newcastle upon Tyne UK
| | - Kevin Thomas
- Faculty of Health and Life SciencesNorthumbria University Newcastle upon Tyne UK
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20
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Brownstein CG, Souron R, Royer N, Singh B, Lapole T, Millet GY. Disparate kinetics of change in responses to electrical stimulation at the thoracic and lumbar level during fatiguing isometric knee extension. J Appl Physiol (1985) 2020; 128:159-167. [DOI: 10.1152/japplphysiol.00635.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The present study compared the fatigue-induced change of matched-amplitude thoracic evoked potential (TMEP) and lumbar evoked potential (LEP) following electrical stimulation. Ten participants performed a 3 × 3 min isometric knee extension contraction separated by 4 min of recovery at the level of EMG required to produce 50% maximal voluntary contraction (MVC) force at baseline. The TMEP and LEP were evoked during the ongoing contraction at baseline and every minute into the fatiguing protocol and during recovery. Both responses were also assessed during a transcranial magnetic stimulation (TMS) evoked silent period to elicit a TMS-TMEP and TMS-LEP to assess responses without the confounding influence of descending drive. The results displayed disparate kinetics of the TMS-TMEP and TMS-LEP throughout the fatiguing protocol. The TMS-TMEP was reduced at all time points during exercise ( P < 0.001), whereas the TMS-LEP was reduced at 2 min into set 1 and 1 min into sets 2 and 3 ( P ≤ 0.04). TMS-LEPs were higher than the TMS-TMEPs at most time points ( P ≤ 0.04). No change was observed in the TMEP or LEP. When evoked during the silent period, the reduction in TMEP is greater than the LEP during fatiguing isometric exercise. The disparate kinetics of change suggest that differential mechanisms are responsible for evoked responses to thoracic and lumbar stimulation. More research is required to identify the mechanisms responsible for the TMEP and LEP before precise inferences can be made on what fatigue-induced changes in these variables reflect. NEW & NOTEWORTHY Assessing spinal excitability using lumbar stimulation when measuring responses in lower limbs has been suggested as an alternative method that could circumvent the issues associated with thoracic stimulation. The present study compared responses to the two types of stimuli throughout a fatiguing protocol and demonstrated that lumbar evoked responses differ substantially from thoracic responses when measured in the absence of voluntary drive. These findings suggest that different mechanisms are responsible for evoked responses to thoracic and lumbar stimuli.
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Affiliation(s)
- Callum G. Brownstein
- Inter-university Laboratory of Human Movement Biology, University of Lyon, Jean Monnet University, Saint-Etienne, France
| | - Robin Souron
- Inter-university Laboratory of Human Movement Biology, University of Lyon, Jean Monnet University, Saint-Etienne, France
| | - Nicolas Royer
- Inter-university Laboratory of Human Movement Biology, University of Lyon, Jean Monnet University, Saint-Etienne, France
| | - Benjamin Singh
- Inter-university Laboratory of Human Movement Biology, University of Lyon, Jean Monnet University, Saint-Etienne, France
| | - Thomas Lapole
- Inter-university Laboratory of Human Movement Biology, University of Lyon, Jean Monnet University, Saint-Etienne, France
| | - Guillaume Y. Millet
- Inter-university Laboratory of Human Movement Biology, University of Lyon, Jean Monnet University, Saint-Etienne, France
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21
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Sustained Maximal Voluntary Contractions Elicit Different Neurophysiological Responses in Upper- and Lower-Limb Muscles in Men. Neuroscience 2019; 422:88-98. [DOI: 10.1016/j.neuroscience.2019.09.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 09/20/2019] [Accepted: 09/23/2019] [Indexed: 11/20/2022]
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Souron R, Baudry S, Millet GY, Lapole T. Vibration‐induced depression in spinal loop excitability revisited. J Physiol 2019; 597:5179-5193. [DOI: 10.1113/jp278469] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 08/14/2019] [Indexed: 01/24/2023] Open
Affiliation(s)
- Robin Souron
- Univ LyonUJM Saint‐EtienneInter‐university Laboratory of Human Movement Biology EA 7424 F‐42023 Saint‐Etienne France
| | - Stéphane Baudry
- Laboratory of Applied BiologyResearch Unit in Applied NeurophysiologyULB Neuroscience InstituteUniversité Libre de Bruxelles Brussels Belgium
| | - Guillaume Y. Millet
- Univ LyonUJM Saint‐EtienneInter‐university Laboratory of Human Movement Biology EA 7424 F‐42023 Saint‐Etienne France
| | - Thomas Lapole
- Univ LyonUJM Saint‐EtienneInter‐university Laboratory of Human Movement Biology EA 7424 F‐42023 Saint‐Etienne France
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Kennefick M, Burma JS, van Donkelaar P, McNeil CJ. The Time Course of Motoneuronal Excitability during the Preparation of Complex Movements. J Cogn Neurosci 2019; 31:781-790. [PMID: 30883285 DOI: 10.1162/jocn_a_01394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
For a simple RT task, movement complexity increases RT and also corticospinal excitability, as measured by the motor evoked potential (MEP) elicited by TMS of the motor cortex. However, it is unknown if complexity-related increases in corticospinal excitability during the preparation of movement are mediated at the cortical or spinal level. The purposes of this study were to establish a time course of motoneuronal excitability before prime mover activation and to assess task-dependent effects of complex movements on motoneuronal and cortical excitability in a simple RT paradigm. It was hypothesized that motoneuronal and cortical excitability would increase before prime mover activation and in response to movement complexity. In a seated position, participants completed ballistic elbow extension/flexion movements with their dominant arm to one, two, or three targets. TMS and transmastoid stimulation (TS) were delivered at 0%, 70%, 80% or 90% of mean premotor RT for each complexity level. Stimulus intensities were set to elicit MEPs and cervicomedullary MEPs (CMEPs) of ∼10% of the maximal M-wave in the triceps brachii. Compared with 0% RT, motoneuronal excitability (CMEP amplitude) was already 10% greater at 70% RT. CMEP amplitude also increased with movement complexity as both the two- and three-movement conditions had greater motoneuronal excitability than the one-movement condition (p < .038). Importantly, when normalized to the CMEP, there was no increase in MEP amplitude. This suggests that complexity-related increases in corticospinal excitability are likely to be mediated more by increased excitability at a motoneuronal than cortical level.
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Otieno LA, Opie GM, Semmler JG, Ridding MC, Sidhu SK. Intermittent single-joint fatiguing exercise reduces TMS-EEG measures of cortical inhibition. J Neurophysiol 2019; 121:471-479. [DOI: 10.1152/jn.00628.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fatiguing intermittent single-joint exercise causes an increase in corticospinal excitability and a decrease in intracortical inhibition when measured with peripherally recorded motor evoked potentials (MEPs) after transcranial magnetic stimulation (TMS). Combined TMS and electroencephalography (TMS-EEG) allows for more direct recording of cortical responses through the TMS-evoked potential (TEP). The aim of this study was to investigate the changes in the excitatory and inhibitory components of the TEP during fatiguing single-joint exercise. Twenty-three young (22 ± 2 yr) healthy subjects performed intermittent 30-s maximum voluntary contractions of the right first dorsal interosseous muscle, followed by a 30-s relaxation period repeated for a total of 15 min. Six single-pulse TMSs and one peripheral nerve stimulation (PNS) to evoke maximal M wave (Mmax) were applied during each relaxation period. A total of 90 TMS pulses and 5 PNSs were applied before and after fatiguing exercise to record MEP and TEP. The amplitude of the MEP (normalized to Mmax) increased during fatiguing exercise ( P < 0.001). There were no changes in local and global P30, N45, and P180 of TEPs during the development of intermittent single-joint exercise-induced fatigue. Global analysis, however, revealed a decrease in N100 peak of the TEP during fatiguing exercise compared with before fatiguing exercise ( P = 0.02). The decrease in N100 suggests a fatigue-related decrease in global intracortical GABAB-mediated inhibition. The increase in corticospinal excitability typically observed during single-joint fatiguing exercise may be mediated by a global decrease in intracortical inhibition. NEW & NOTEWORTHY Fatiguing intermittent single-joint exercise causes an increase in corticospinal excitability and a decrease in intracortical inhibition when measured with transcranial magnetic stimulation (TMS)-evoked potentials from the muscle. The present study provides new and direct cortical evidence, using TMS-EEG to demonstrate that during single-joint fatiguing exercise there is a global decrease in intracortical GABAB-mediated inhibition.
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Affiliation(s)
- Lavender A. Otieno
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
| | - George M. Opie
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
- Robinson Research Institute, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
| | - John G. Semmler
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
| | - Michael C. Ridding
- Robinson Research Institute, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
| | - Simranjit K. Sidhu
- Discipline of Physiology, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
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25
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Škarabot J, Ansdell P, Brownstein CG, Thomas K, Howatson G, Goodall S, Durbaba R. Electrical stimulation of human corticospinal axons at the level of the lumbar spinal segments. Eur J Neurosci 2019; 49:1254-1267. [PMID: 30589956 DOI: 10.1111/ejn.14321] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 11/27/2018] [Accepted: 12/18/2018] [Indexed: 12/16/2022]
Abstract
Electrical stimulation over the mastoids or thoracic spinous processes has been used to assess subcortical contribution to corticospinal excitability, but responses are difficult to evoke in the resting lower limbs or are limited to only a few muscle groups. This might be mitigated by delivering the stimuli lower on the spinal column, where the descending tracts contain a greater relative density of motoneurons projecting to lower limb muscles. We investigated activation of the corticospinal axons innervating tibialis anterior (TA) and rectus femoris (RF) by applying a single electrical stimulus over the first lumbar spinous process (LS). LS was paired with transcranial magnetic stimulation (TMS) at interstimulus intervals (ISIs) of -16 (TMS before LS) to 14 ms (LS before TMS). The relationship between muscle contraction strength (10%-100% maximal) and the amplitude of single-pulse TMS and LS responses was also investigated. Compared to the responses to TMS alone, responses to paired stimulation were significantly occluded in both muscles for ISIs ≥-8 ms (p ≤ 0.035), consistent with collision of descending volleys from TMS with antidromic volleys originating from LS. This suggests that TMS and LS activate some of the same corticospinal axons. Additionally, the amplitude of TMS and LS responses increased with increasing contraction strengths with no change in onset latency, suggesting responses to LS are evoked transsynaptically and have a monosynaptic component. Taken together, these experiments provide evidence that LS is an alternative method that could be used to discern segmental changes in the corticospinal tract when targeting lower limb muscles.
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Affiliation(s)
- Jakob Škarabot
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Paul Ansdell
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Callum G Brownstein
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Kevin Thomas
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Glyn Howatson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK.,Water Research Group, School of Environmental Sciences and Development, Northwest University, Potchefstroom, South Africa
| | - Stuart Goodall
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Rade Durbaba
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
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26
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Corticospinal excitability during fatiguing whole body exercise. PROGRESS IN BRAIN RESEARCH 2018; 240:219-246. [PMID: 30390833 DOI: 10.1016/bs.pbr.2018.07.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The corticospinal pathway is considered the primary conduit for voluntary motor control in humans. The efficacy of the corticospinal pathway to relay neural signals from higher brain areas to the locomotor muscle, i.e., corticospinal excitability, is subject to alterations during exercise. While the integrity of this motor pathway has historically been examined during single-joint contractions, a small number of investigations have recently focused on whole body exercise, such as cycling or rowing. Although differences in methodologies employed between these studies complicate the interpretation of the existing literature, it appears that the net excitability of the corticospinal pathway remains unaltered during fatiguing whole body exercise. Importantly, this lack of an apparent effect does not designate the absence of change, but a counterbalance of excitatory and inhibitory influences on the two components of the corticospinal pathway, namely the motor cortex and the spinal motoneurons. Specific emphasis is put on group III/IV afferent feedback from locomotor muscle which has been suggested to play a significant role in mediating these changes. Overall, this review aims at summarizing our limited understanding of how fatiguing whole body exercise influences the corticospinal pathway.
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Abstract
It is well known that prolonged passive muscle stretch reduces maximal muscle force production. There is a growing body of evidence suggesting that adaptations occurring within the nervous system play a major role in this stretch-induced force reduction. This article reviews the existing literature, and some new evidence, regarding acute neurophysiological changes in response to passive muscle stretching. We discuss the possible contribution of supra-spinal and spinal structures to the force reduction after passive muscle stretch. In summary, based on the recent evidence reviewed we propose a new hypothesis that a disfacilitation occurring at the motoneuronal level after passive muscle stretch is a major factor affecting the neural efferent drive to the muscle and, subsequently, its ability to produce maximal force.
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Finn HT, Rouffet DM, Kennedy DS, Green S, Taylor JL. Motoneuron excitability of the quadriceps decreases during a fatiguing submaximal isometric contraction. J Appl Physiol (1985) 2018; 124:970-979. [PMID: 29357479 DOI: 10.1152/japplphysiol.00739.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
During fatiguing voluntary contractions, the excitability of motoneurons innervating arm muscles decreases. However, the behavior of motoneurons innervating quadriceps muscles is unclear. Findings may be inconsistent because descending cortical input influences motoneuron excitability and confounds measures during exercise. To overcome this limitation, we examined effects of fatigue on quadriceps motoneuron excitability tested during brief pauses in descending cortical drive after transcranial magnetic stimulation (TMS). Participants ( n = 14) performed brief (~5-s) isometric knee extension contractions before and after a 10-min sustained contraction at ~25% maximal electromyogram (EMG) of vastus medialis (VM) on one ( n = 5) or two ( n = 9) days. Electrical stimulation over thoracic spine elicited thoracic motor evoked potentials (TMEP) in quadriceps muscles during ongoing voluntary drive and 100 ms into the silent period following TMS (TMS-TMEP). Femoral nerve stimulation elicited maximal M-waves (Mmax). On the 2 days, either large (~50% Mmax) or small (~15% Mmax) TMS-TMEPs were elicited. During the 10-min contraction, VM EMG was maintained ( P = 0.39), whereas force decreased by 52% (SD 13%) ( P < 0.001). TMEP area remained unchanged ( P = 0.9), whereas large TMS-TMEPs decreased by 49% (SD 28%) ( P = 0.001) and small TMS-TMEPs by 71% (SD 22%) ( P < 0.001). This decline was greater for small TMS-TMEPs ( P = 0.019; n = 9). Therefore, without the influence of descending drive, quadriceps TMS-TMEPs decreased during fatigue. The greater reduction for smaller responses, which tested motoneurons that were most active during the contraction, suggests a mechanism related to repetitive activity contributes to reduced quadriceps motoneuron excitability during fatigue. By contrast, the unchanged TMEP suggests that ongoing drive compensates for altered motoneuron excitability. NEW & NOTEWORTHY We provide evidence that the excitability of quadriceps motoneurons decreases with fatigue. Our results suggest that altered intrinsic properties brought about by repetitive activation of the motoneurons underlie their decreased excitability. Furthermore, we note that testing during voluntary contraction may not reflect the underlying depression of motoneuron excitability because of compensatory changes in ongoing voluntary drive. Thus, this study provides evidence that processes intrinsic to the motoneuron contribute to muscle fatigue of the knee extensors.
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Affiliation(s)
- Harrison T Finn
- Neuroscience Research Australia, Randwick, New South Wales , Australia.,University of New South Wales , Kensington, New South Wales , Australia
| | - David M Rouffet
- Victoria University , Melbourne, Victoria , Australia.,Australian Institute for Musculoskeletal Science, Victoria University , Melbourne , Australia.,Institute of Sport, Exercise, and Active Living, Victoria University , Melbourne , Australia
| | - David S Kennedy
- University of Sydney, Cumberland, New South Wales , Australia.,University of Technology , Ultimo, New South Wales , Australia
| | - Simon Green
- Western Sydney University, Campbelltown, New South Wales , Australia
| | - Janet L Taylor
- Neuroscience Research Australia, Randwick, New South Wales , Australia.,University of New South Wales , Kensington, New South Wales , Australia.,Edith Cowan University , Perth, Western Australia , Australia
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29
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Souron R, Besson T, McNeil CJ, Lapole T, Millet GY. An Acute Exposure to Muscle Vibration Decreases Knee Extensors Force Production and Modulates Associated Central Nervous System Excitability. Front Hum Neurosci 2017; 11:519. [PMID: 29118698 PMCID: PMC5660984 DOI: 10.3389/fnhum.2017.00519] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/11/2017] [Indexed: 01/25/2023] Open
Abstract
Local vibration (LV) has been recently validated as an efficient training method to improve muscle strength. Understanding the acute effects may help elucidate the mechanism(s). This study aimed to investigate the effects of a single bout of prolonged LV on knee extensor force production and corticospinal responsiveness of vastus lateralis (VL) and rectus femoris (RF) muscles in healthy young and old adults. Across two visits, 23 adult subjects (20-75 years old) performed pre- and post-test measurements, separated by 30-min of either rest (control; CON) or LV. Maximal voluntary contraction (MVC) force was assessed and transcranial magnetic stimulation (TMS) was used to evaluate cortical voluntary activation (VATMS) as well as the motor evoked potential (MEP) and silent period (SP). In 11 young adults, thoracic electrical stimulation was used to assess the thoracic motor evoked potential (TMEP). Although MVC decreased after both CON (-6.3 ± 4.4%, p = 0.01) and LV (-12.9 ± 7.7%, p < 0.001), the MVC loss was greater after LV (p = 0.001). Normalized maximal electromyographic (EMG) activity decreased after LV for both VL (-25.1 ± 10.7%) and RF (-20.9 ± 16.5%; p < 0.001), while it was unchanged after CON (p = 0.32). For RF, the TMEP and MEP/TMEP ratio decreased (p = 0.01) and increased (p = 0.01) after LV, respectively. Both measures were unchanged for VL (p = 0.27 and p = 0.15, respectively). No changes were reported for TMS-related parameters. These results confirm our hypothesis that modulations within the central nervous system would accompany the significant reduction of maximal voluntary force. A reduced motoneuron excitability seems to explain the decreased MVC after prolonged LV, as suggested by reductions in maximal EMG (all subjects) and TMEP area (data from 11 young subjects). A concomitant increased cortical excitability seems to compensate for lower excitability at the spinal level.
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Affiliation(s)
- Robin Souron
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Laboratoire Interuniversitaire de Biologie de la Motricité, UJM Saint-Etienne, University Lyon, Saint-Etienne, France
| | - Thibault Besson
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Laboratoire Interuniversitaire de Biologie de la Motricité, UJM Saint-Etienne, University Lyon, Saint-Etienne, France
| | - Chris J. McNeil
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Thomas Lapole
- Laboratoire Interuniversitaire de Biologie de la Motricité, UJM Saint-Etienne, University Lyon, Saint-Etienne, France
| | - Guillaume Y. Millet
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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30
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Kennedy DS, McNeil CJ, Gandevia SC, Taylor JL. Effects of fatigue on corticospinal excitability of the human knee extensors. Exp Physiol 2016; 101:1552-1564. [PMID: 27652591 DOI: 10.1113/ep085753] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 09/19/2016] [Indexed: 01/05/2023]
Abstract
NEW FINDINGS What is the central question of this study? Do group III and IV muscle afferents act at the spinal or cortical level to affect the ability of the central nervous system to drive quadriceps muscles during fatiguing exercise? What is the main finding and its importance? The excitability of the motoneurone pool of vastus lateralis was unchanged by feedback from group III and IV muscle afferents. In contrast, feedback from these afferents may contribute to inhibition at the cortex. However, the excitability of the corticospinal pathway was not directly affected by feedback from these afferents. These findings are important for understanding neural processes during fatiguing exercise. In upper limb muscles, changes in afferent feedback, motoneurone excitability, and motor cortical output can contribute to failure of the central nervous system to recruit muscles fully during fatigue. It is not known whether similar changes occur with fatigue of muscles in the lower limb. We assessed the corticospinal pathway to vastus lateralis during fatiguing sustained maximal voluntary contractions (MVCs) of the knee extensors and during firing of fatigue-sensitive group III/IV muscle afferents maintained by postexercise ischaemia after fatiguing MVCs of the knee extensors and, separately, the flexors. In two experiments, subjects (n = 9) performed brief knee extensor MVCs before and after 2-min sustained MVCs of the knee extensors (experiment 1) or knee flexors (experiment 2). During MVCs, motor evoked potentials (MEPs) were elicited by transcranial magnetic stimulation over the motor cortex and thoracic motor evoked potentials (TMEPs) by electrical stimulation over the thoracic spine. During the 2-min extensor contraction, the size of vastus lateralis MEPs normalized to the maximal M-wave increased (P < 0.05), but normalized TMEPs were unchanged (P = 0.16). After the 2-min MVC, maintained firing of group III/IV muscle afferents had no effect on vastus lateralis MEPs or TMEPs (P = 0.18 and P = 0.50, respectively). Likewise, after the 2-min knee flexor MVC, maintained firing of these afferents showed no effect on vastus lateralis MEPs or TMEPs (P = 0.69 and P = 0.34, respectively). Motoneurones of vastus lateralis do not become less excitable during fatiguing isometric MVCs. Moreover, fatigue-sensitive group III/IV muscle afferents fail to affect the overall excitability of vastus lateralis motoneurones during MVCs.
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Affiliation(s)
- David S Kennedy
- Neuroscience Research Australia, Randwick, NSW, Australia.,University of New South Wales, Kensington, NSW, Australia
| | - Chris J McNeil
- Neuroscience Research Australia, Randwick, NSW, Australia.,Centre for Heart, Lung and Vascular Health, School of Health & Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Simon C Gandevia
- Neuroscience Research Australia, Randwick, NSW, Australia.,University of New South Wales, Kensington, NSW, Australia
| | - Janet L Taylor
- Neuroscience Research Australia, Randwick, NSW, Australia.,University of New South Wales, Kensington, NSW, Australia
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31
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Group III/IV locomotor muscle afferents alter motor cortical and corticospinal excitability and promote central fatigue during cycling exercise. Clin Neurophysiol 2016; 128:44-55. [PMID: 27866119 DOI: 10.1016/j.clinph.2016.10.008] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 08/17/2016] [Accepted: 10/09/2016] [Indexed: 12/15/2022]
Abstract
OBJECTIVE To investigate the influence of group III/IV muscle afferents on the development of central fatigue and corticospinal excitability during exercise. METHODS Fourteen males performed cycling-exercise both under control-conditions (CTRL) and with lumbar intrathecal fentanyl (FENT) impairing feedback from leg muscle afferents. Transcranial magnetic- and cervicomedullary stimulation was used to monitor cortical versus spinal excitability. RESULTS While fentanyl-blockade during non-fatiguing cycling had no effect on motor-evoked potentials (MEPs), cervicomedullary-evoked motor potentials (CMEPs) were 13±3% higher (P<0.05), resulting in a decrease in MEP/CMEP (P<0.05). Although the pre- to post-exercise reduction in resting twitch was greater in FENT vs. CTRL (-53±3% vs. -39±3%; P<0.01), the reduction in voluntary muscle activation was smaller (-2±2% vs. -10±2%; P<0.05). Compared to the start of fatiguing exercise, MEPs and CMEPs were unchanged at exhaustion in CTRL. In contrast, MEPs and MEP/CMEP increased 13±3% and 25±6% in FENT (P<0.05). CONCLUSION During non-fatiguing exercise, group III/IV muscle afferents disfacilitate, or inhibit, spinal motoneurons and facilitate motor cortical cells. In contrast, during exhaustive exercise, group III/IV muscle afferents disfacilitate/inhibit the motor cortex and promote central fatigue. SIGNIFICANCE Group III/IV muscle afferents influence corticospinal excitability and central fatigue during whole-body exercise in humans.
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32
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Yacyshyn AF, Woo EJ, Price MC, McNeil CJ. Motoneuron responsiveness to corticospinal tract stimulation during the silent period induced by transcranial magnetic stimulation. Exp Brain Res 2016; 234:3457-3463. [DOI: 10.1007/s00221-016-4742-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 07/22/2016] [Indexed: 10/21/2022]
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33
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Weavil JC, Sidhu SK, Mangum TS, Richardson RS, Amann M. Fatigue diminishes motoneuronal excitability during cycling exercise. J Neurophysiol 2016; 116:1743-1751. [PMID: 27440242 DOI: 10.1152/jn.00300.2016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/15/2016] [Indexed: 11/22/2022] Open
Abstract
Exercise-induced fatigue influences the excitability of the motor pathway during single-joint isometric contractions. This study sought to investigate the influence of fatigue on corticospinal excitability during cycling exercise. Eight men performed fatiguing constant-load (80% Wpeak; 241 ± 13 W) cycling to exhaustion during which the percent increase in quadriceps electromyography (ΔEMG; vastus lateralis and rectus femoris) was quantified. During a separate trial, subjects performed two brief (∼45 s) nonfatiguing cycling bouts (244 ± 15 and 331 ± 23W) individually chosen to match the ΔEMG across bouts to that observed during fatiguing cycling. Corticospinal excitability during exercise was quantified by transcranial magnetic, electric transmastoid, and femoral nerve stimulation to elicit motor-evoked potentials (MEP), cervicomedullary evoked potentials (CMEP), and M waves in the quadriceps. Peripheral and central fatigue were expressed as pre- to postexercise reductions in quadriceps twitch force (ΔQtw) and voluntary quadriceps activation (ΔVA). Whereas nonfatiguing cycling caused no measureable fatigue, fatiguing cycling resulted in significant peripheral (ΔQtw: 42 ± 6%) and central (ΔVA: 4 ± 1%) fatigue. During nonfatiguing cycling, the area of MEPs and CMEPs, normalized to M waves, similarly increased in the quadriceps (∼40%; P < 0.05). In contrast, there was no change in normalized MEPs or CMEPs during fatiguing cycling. As a consequence, the ratio of MEP to CMEP was unchanged during both trials (P > 0.5). Therefore, although increases in muscle activation promote corticospinal excitability via motoneuronal facilitation during nonfatiguing cycling, this effect is abolished during fatigue. We conclude that the unaltered excitability of the corticospinal pathway from start of intense cycling exercise to exhaustion is, in part, determined by inhibitory influences on spinal motoneurons obscuring the facilitating effects of muscle activation.
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Affiliation(s)
- Joshua C Weavil
- Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah
| | - Simranjit K Sidhu
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah; Discipline of Physiology, University of Adelaide, Australia; and
| | - Tyler S Mangum
- Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah
| | - Russell S Richardson
- Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah; Department of Internal Medicine, University of Utah, Salt Lake City, Utah; Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Markus Amann
- Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah; Department of Internal Medicine, University of Utah, Salt Lake City, Utah; Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah
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34
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Aboodarda SJ, Copithorne DB, Power KE, Drinkwater E, Behm DG. Elbow flexor fatigue modulates central excitability of the knee extensors. Appl Physiol Nutr Metab 2015; 40:924-30. [PMID: 26300013 DOI: 10.1139/apnm-2015-0088] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The present study investigated the effects of exercise-induced elbow flexor fatigue on voluntary force output, electromyographic (EMG) activity and motoneurone excitability of the nonexercised knee extensor muscles. Eleven participants attended 3 testing sessions: (i) control, (ii) unilateral fatiguing elbow flexion and (iii) bilateral fatiguing elbow flexion (BiFlex). The nonfatigued knee extensor muscles were assessed with thoracic motor evoked potentials (TMEPs), maximal compound muscle action potential (Mmax), knee extensor maximal voluntary contractions (MVCs), and normalized EMG activity before and at 30 s, 3 min, and 5 min postexercise. BiFlex showed significantly lower (Δ = -18%, p = 0.03) vastus lateralis (VL) normalized EMG activity compared with the control session whereas knee extension MVC force did not show any statistical difference between the 3 conditions (p = 0.12). The TMEP·Mmax(-1) ratio measured at the VL showed a significantly higher value (Δ = +46%, p = 0.003) following BiFlex compared with the control condition at 30 s postexercise. The results suggest that the lower VL normalized EMG following BiFlex might have been due to a reduction in supraspinal motor output because spinal motoneuronal responses demonstrated substantially higher value (30 s postexercise) and peripheral excitability (compound muscle action potential) showed no change following BiFelex than control condition.
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Affiliation(s)
- Saied Jalal Aboodarda
- a School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL A1C 5S7, Canada
| | - David B Copithorne
- a School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL A1C 5S7, Canada
| | - Kevin E Power
- a School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL A1C 5S7, Canada
| | - Eric Drinkwater
- b School of Exercise and Health Sciences, Edith Cowan University, Perth, Australia
| | - David G Behm
- a School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL A1C 5S7, Canada
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35
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Weavil JC, Sidhu SK, Mangum TS, Richardson RS, Amann M. Intensity-dependent alterations in the excitability of cortical and spinal projections to the knee extensors during isometric and locomotor exercise. Am J Physiol Regul Integr Comp Physiol 2015; 308:R998-1007. [PMID: 25876651 DOI: 10.1152/ajpregu.00021.2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/08/2015] [Indexed: 11/22/2022]
Abstract
We investigated the role of exercise intensity and associated central motor drive in determining corticomotoneuronal excitability. Ten participants performed a series of nonfatiguing (3 s) isometric single-leg knee extensions (ISO; 10-100% of maximal voluntary contractions, MVC) and cycling bouts (30-160% peak aerobic capacity, W peak). At various exercise intensities, electrical potentials were evoked in the vastus lateralis (VL) and rectus femoris (RF) via transcranial magnetic stimulation (motor-evoked potentials, MEP), and electrical stimulation of both the cervicomedullary junction (cervicomedullary evoked potentials, CMEP) and the femoral nerve (maximal M-waves, M max). Whereas M max remained unchanged in both muscles (P > 0.40), voluntary electromyographic activity (EMG) increased in an exercise intensity-dependent manner for ISO and cycling exercise in VL and RF (both P < 0.001). During ISO exercise, MEPs and CMEPs progressively increased in VL and RF until a plateau was reached at ∼ 75% MVC; further increases in contraction intensity did not cause additional changes (P > 0.35). During cycling exercise, VL-MEPs and CMEPs progressively increased by ∼ 65% until a plateau was reached at W peak. In contrast, RF MEPs and CMEPs progressively increased by ∼ 110% throughout the tested cycling intensities without the occurrence of a plateau. Furthermore, alterations in EMG below the plateau influenced corticomotoneuronal excitability similarly between exercise modalities. In both exercise modalities, the MEP-to-CMEP ratio did not change with exercise intensity (P > 0.22). In conclusion, increases in exercise intensity and EMG facilitates the corticomotoneuronal pathway similarly in isometric knee extension and locomotor exercise until a plateau occurs at a submaximal exercise intensity. This facilitation appears to be primarily mediated by increases in excitability of the motoneuron pool.
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Affiliation(s)
- J C Weavil
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - S K Sidhu
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - T S Mangum
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - R S Richardson
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah; Department of Internal Medicine, University of Utah, Salt Lake City, Utah; Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Salt Lake City, Utah
| | - M Amann
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah; Department of Internal Medicine, University of Utah, Salt Lake City, Utah; Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Salt Lake City, Utah
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Gruet M, Temesi J, Brisswalter J, Millet G, Vergès S. Stimulation magnétique transcrânienne : application à la physiologie de l’exercice. Sci Sports 2014. [DOI: 10.1016/j.scispo.2014.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Zewdie ET, Roy FD, Okuma Y, Yang JF, Gorassini MA. Long-latency, inhibitory spinal pathway to ankle flexors activated by homonymous group 1 afferents. J Neurophysiol 2014; 111:2544-53. [PMID: 24671544 DOI: 10.1152/jn.00673.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inhibitory feedback from sensory pathways is important for controlling movement. Here, we characterize, for the first time, a long-latency, inhibitory spinal pathway to ankle flexors that is activated by low-threshold homonymous afferents. To examine this inhibitory pathway in uninjured, healthy participants, we suppressed motor-evoked potentials (MEPs), produced in the tibialis anterior (TA), by a prior stimulation to the homonymous common peroneal nerve (CPN). The TA MEP was suppressed by a triple-pulse stimulation to the CPN, applied 40, 50, and 60 ms earlier and at intensities of 0.5-0.7 times motor threshold (average suppression of test MEP was 33%). Whereas the triple-pulse stimulation was below M-wave and H-reflex threshold, it produced a long-latency inhibition of background muscle activity, approximately 65-115 ms after the CPN stimulation, a time period that overlapped with the test MEP. However, not all of the MEP suppression could be accounted for by this decrease in background muscle activity. Evoked responses from direct activation of the corticospinal tract, at the level of the brain stem or thoracic spinal cord, were also suppressed by low-threshold CPN stimulation. Our findings suggest that low-threshold muscle and cutaneous afferents from the CPN activate a long-latency, homonymous spinal inhibitory pathway to TA motoneurons. We propose that inhibitory feedback from spinal networks, activated by low-threshold homonymous afferents, helps regulate the activation of flexor motoneurons by the corticospinal tract.
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Affiliation(s)
- Ephrem T Zewdie
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada; Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Francois D Roy
- Department of Surgery, University of Alberta, Edmonton, Canada; Centre for Neuroscience, University of Alberta, Edmonton, Canada; Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Yoshino Okuma
- Centre for Neuroscience, University of Alberta, Edmonton, Canada
| | - Jaynie F Yang
- Department of Physical Therapy, University of Alberta, Edmonton, Canada; Centre for Neuroscience, University of Alberta, Edmonton, Canada; Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada; and
| | - Monica A Gorassini
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada; Centre for Neuroscience, University of Alberta, Edmonton, Canada; Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
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Vidor LP, Torres ILS, Medeiros LF, Dussán-Sarria JA, Dall'agnol L, Deitos A, Brietzke A, Laste G, Rozisky JR, Fregni F, Caumo W. Association of anxiety with intracortical inhibition and descending pain modulation in chronic myofascial pain syndrome. BMC Neurosci 2014; 15:42. [PMID: 24645677 PMCID: PMC3995110 DOI: 10.1186/1471-2202-15-42] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 03/12/2014] [Indexed: 01/03/2023] Open
Abstract
Background This study aimed to answer three questions related to chronic myofascial pain syndrome (MPS): 1) Is the motor cortex excitability, as assessed by transcranial magnetic stimulation parameters (TMS), related to state-trait anxiety? 2) Does anxiety modulate corticospinal excitability changes after evoked pain by Quantitative Sensory Testing (QST)? 3) Does the state-trait anxiety predict the response to pain evoked by QST if simultaneously receiving a heterotopic stimulus [Conditional Pain Modulation (CPM)]? We included females with chronic MPS (n = 47) and healthy controls (n = 11), aged 19 to 65 years. Motor cortex excitability was assessed by TMS, and anxiety was assessed based on the State-Trait Anxiety Inventory. The disability related to pain (DRP) was assessed by the Profile of Chronic Pain scale for the Brazilian population (B:PCP:S), and the psychophysical pain measurements were measured by the QST and CPM. Results In patients, trait-anxiety was positively correlated to intracortical facilitation (ICF) at baseline and after QST evoked pain (β = 0.05 and β = 0.04, respectively) and negatively correlated to the cortical silent period (CSP) (β = -1.17 and β = -1.23, respectively) (P <0.05 for all comparisons). After QST evoked pain, the DRP was positively correlated to ICF (β = 0.02) (P < 0.05). Pain scores during CPM were positively correlated with trait-anxiety when it was concurrently with high DRP (β = 0.39; P = 0.02). Controls’ cortical excitability remained unchanged after QST. Conclusions These findings suggest that, in chronic MPS, the imbalance between excitatory and inhibitory descending systems of the corticospinal tract is associated with higher trait-anxiety concurrent with higher DRP.
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Affiliation(s)
| | - Iraci L S Torres
- Post-Graduate Program in Medical Sciences, School of Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
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McNeil CJ, Butler JE, Taylor JL, Gandevia SC. Testing the excitability of human motoneurons. Front Hum Neurosci 2013; 7:152. [PMID: 23630483 PMCID: PMC3633937 DOI: 10.3389/fnhum.2013.00152] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 04/06/2013] [Indexed: 12/03/2022] Open
Abstract
The responsiveness of the human central nervous system can change profoundly with exercise, injury, disuse, or disease. Changes occur at both cortical and spinal levels but in most cases excitability of the motoneuron pool must be assessed to localize accurately the site of adaptation. Hence, it is critical to understand, and employ correctly, the methods to test motoneuron excitability in humans. Several techniques exist and each has its advantages and disadvantages. This review examines the most common techniques that use evoked compound muscle action potentials to test the excitability of the motoneuron pool and describes the merits and limitations of each. The techniques discussed are the H-reflex, F-wave, tendon jerk, V-wave, cervicomedullary motor evoked potential (CMEP), and motor evoked potential (MEP). A number of limitations with these techniques are presented.
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Affiliation(s)
- Chris J McNeil
- Neuroscience Research Australia Randwick, NSW, Australia ; School of Health and Exercise Sciences, University of British Columbia Kelowna, BC, Canada
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Corticospinal Responses to Sustained Locomotor Exercises: Moving Beyond Single-Joint Studies of Central Fatigue. Sports Med 2013; 43:437-49. [DOI: 10.1007/s40279-013-0020-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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41
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Gruet M, Temesi J, Rupp T, Levy P, Millet G, Verges S. Stimulation of the motor cortex and corticospinal tract to assess human muscle fatigue. Neuroscience 2013; 231:384-99. [DOI: 10.1016/j.neuroscience.2012.10.058] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 10/10/2012] [Accepted: 10/29/2012] [Indexed: 10/27/2022]
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Sidhu SK, Cresswell AG, Carroll TJ. Motor cortex excitability does not increase during sustained cycling exercise to volitional exhaustion. J Appl Physiol (1985) 2012; 113:401-9. [DOI: 10.1152/japplphysiol.00486.2012] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The excitability of the motor cortex increases as fatigue develops during sustained single-joint contractions, but there are no previous reports on how corticospinal excitability is affected by sustained locomotor exercise. Here we addressed this issue by measuring spinal and cortical excitability changes during sustained cycling exercise. Vastus lateralis (VL) and rectus femoris (RF) muscle responses to transcranial magnetic stimulation of the motor cortex (motor evoked potentials, MEPs) and electrical stimulation of the descending tracts (cervicomedullary evoked potentials, CMEPs) were recorded every 3 min from nine subjects during 30 min of cycling at 75% of maximum workload (Wmax), and every minute during subsequent exercise at 105% of Wmax until subjective task failure. Responses were also measured during nonfatiguing control bouts at 80% and 110% of Wmax prior to sustained exercise. There were no significant changes in MEPs or CMEPs ( P > 0.05) during the sustained cycling exercise. These results suggest that, in contrast to sustained single-joint contractions, sustained cycling exercise does not increase the excitability of motor cortical neurons. The contrasting corticospinal responses to the two modes of exercise may be due to differences in their associated systemic physiological consequences.
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Affiliation(s)
- Simranjit K. Sidhu
- School of Human Movement Studies, The University of Queensland, Brisbane, Queensland, Australia
| | - Andrew G. Cresswell
- School of Human Movement Studies, The University of Queensland, Brisbane, Queensland, Australia
| | - Timothy J. Carroll
- School of Human Movement Studies, The University of Queensland, Brisbane, Queensland, Australia
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Giesebrecht S, Martin PG, Gandevia SC, Taylor JL. Altered corticospinal transmission to the hand after maximum voluntary efforts. Muscle Nerve 2011; 43:679-87. [DOI: 10.1002/mus.21938] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2010] [Indexed: 11/10/2022]
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Petersen NC, Butler JE, Taylor JL, Gandevia SC. Probing the corticospinal link between the motor cortex and motoneurones: some neglected aspects of human motor cortical function. Acta Physiol (Oxf) 2010; 198:403-16. [PMID: 20003100 DOI: 10.1111/j.1748-1716.2009.02066.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This review considers the operation of the corticospinal system in primates. There is a relatively widespread cortical area containing corticospinal outputs to a single muscle and thus a motoneurone pool receives corticospinal input from a wide region of the cortex. In addition, corticospinal cells themselves have divergent intraspinal branches which innervate more than one motoneuronal pool but the synergistic couplings involving the many hand muscles are likely to be more diverse than can be accommodated simply by fixed patterns of corticospinal divergence. Many studies using transcranial magnetic stimulation of the human motor cortex have highlighted the capacity of the cortex to modify its apparent excitability in response to altered afferent inputs, training and various pathologies. Studies using cortical stimulation at 'very low' intensities which elicit only short-latency suppression of the discharge of motor units have revealed that the rapidly conducting corticospinal axons (stimulated at higher intensities) drive motoneurones in normal voluntary contractions. There are also major non-linearities generated at a spinal level in the relation between corticospinal output and the output from the motoneurone pool. For example, recent studies have revealed that the efficacy of the human corticospinal connection with motoneurones undergoes activity-dependent changes which influence the size of voluntary contractions. Hence, corticospinal drives must be sculpted continuously to compensate for the changing functional efficacy of the descending systems which activate the motoneurones. This highlights the need for proprioceptive monitoring of movements to ensure their accurate execution.
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Affiliation(s)
- N C Petersen
- Department of Exercise and Sport Sciences, University of Copenhagen, Denmark
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Giesebrecht S, Martin PG, Gandevia SC, Taylor JL. Facilitation and Inhibition of Tibialis Anterior Responses to Corticospinal Stimulation After Maximal Voluntary Contractions. J Neurophysiol 2010; 103:1350-6. [DOI: 10.1152/jn.00879.2009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The corticospinal pathway is the major pathway controlling human voluntary movements. After strong voluntary contractions, the efficacy of corticospinal transmission to elbow flexors is reduced for ∼90 s, and this limits motoneuronal output. This reduction may reflect activity-dependent changes at cortico-motoneuronal synapses. We investigated whether similar changes occur in a leg muscle, tibialis anterior (TA). Electrical stimuli over high thoracic vertebrae activated corticospinal axons to evoke an EMG response in TA (TMEP). Stimuli were delivered before and after short 10-s and prolonged 1-min maximal contractions (MVCs) of ankle dorsiflexors. In two studies, stimuli were given with the muscle relaxed. In other studies, stimuli were given during weak contraction. After a 10-s MVC ( study 1, n = 10), TMEPs increased immediately to 349 ± 335% (mean ± SD) of control values. By 1 min after contraction, TMEPs decreased to 38 ± 28% of control and remained depressed for >10 min. Facilitation (191 ± 133% control) and depression (18 ± 22% control) occurred over the same time course after the 1-min MVC ( study 2, n = 10). When tested during weak contraction ( study 3, n = 10), TMEPs showed less facilitation (131 ± 41% control) and less depression (67 ± 21% control) and responses returned to baseline over ∼15 min. In contrast to TMEPs, H-reflexes in TA were little changed after a 10-s MVC ( study 4, n = 7). Our findings reveal an immediate facilitation and subsequent longer-lasting depression in corticospinal transmission to TA, which originate at a premotoneuronal site. This behavior differs markedly from that in elbow flexor muscles and suggests that activity-dependent changes in the motor pathway may be muscle specific.
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Affiliation(s)
- Sabine Giesebrecht
- Prince of Wales Medical Research Institute and the University of New South Wales, Sydney, Australia
| | - Peter G. Martin
- Prince of Wales Medical Research Institute and the University of New South Wales, Sydney, Australia
| | - Simon C. Gandevia
- Prince of Wales Medical Research Institute and the University of New South Wales, Sydney, Australia
| | - Janet L. Taylor
- Prince of Wales Medical Research Institute and the University of New South Wales, Sydney, Australia
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Hoffman BW, Oya T, Carroll TJ, Cresswell AG. Increases in corticospinal responsiveness during a sustained submaximal plantar flexion. J Appl Physiol (1985) 2009; 107:112-20. [DOI: 10.1152/japplphysiol.91541.2008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Studying the responsiveness of specific central nervous system pathways to electrical or magnetic stimulation can provide important information regarding fatigue processes in the central nervous system. We investigated the changes in corticospinal responsiveness during a sustained submaximal contraction of the triceps surae. Comparisons were made between the size of motor-evoked potentials (MEPs) elicited by motor cortical stimulation and cervicomedullary motor-evoked potentials (CMEPs) elicited by magnetic stimulation of the descending tracts to determine the site of any change in corticospinal responsiveness. Participants maintained an isometric contraction of triceps surae at 30% of maximal voluntary contraction (MVC) for as long as possible on two occasions. Stimulation was applied to the motor cortex or the cervicomedullary junction at 1-min intervals during contraction until task failure. Peripheral nerve stimulation was also applied to evoke maximal M waves (Mmax) and a superimposed twitch. Additionally, MEPs and CMEPs were evoked during brief contractions at 80%, 90%, and 100% of MVC as a nonfatigue control. During the sustained contractions, MEP amplitude increased significantly in soleus (113%) and medial gastrocnemius (108%) muscles and, at task failure, matched MEP amplitude in the prefatigue MVC (∼20–25% Mmax). In contrast, CMEP amplitude increased significantly in medial gastrocnemius (51%), but not in soleus (63%) muscle and, at task failure, was significantly smaller than during prefatigue MVC (5–6% Mmax vs. 11–13% Mmax). The data indicate that cortical processes contribute substantially to the increase in corticospinal responsiveness during sustained submaximal contraction of triceps surae.
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