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Wilkins EW, Young RJ, Houston D, Kawana E, Lopez Mora E, Sunkara MS, Riley ZA, Poston B. Non-Dominant Hemisphere Excitability Is Unaffected during and after Transcranial Direct Current Stimulation of the Dominant Hemisphere. Brain Sci 2024; 14:694. [PMID: 39061434 PMCID: PMC11274959 DOI: 10.3390/brainsci14070694] [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: 06/06/2024] [Revised: 07/05/2024] [Accepted: 07/10/2024] [Indexed: 07/28/2024] Open
Abstract
Transcranial direct current stimulation (tDCS) increases primary motor cortex (M1) excitability and improves motor performance when applied unilaterally to the dominant hemisphere. However, the influence of tDCS on contralateral M1 excitability both during and after application has not been quantified. The purpose was to determine the influence of tDCS applied to the dominant M1 on the excitability of the contralateral non-dominant M1. This study employed a double-blind, randomized, SHAM-controlled, within-subject crossover experimental design. Eighteen young adults performed two experimental sessions (tDCS, SHAM) in counterbalanced order separated by a one-week washout. Transcranial magnetic stimulation (TMS) was used to quantify the excitability of the contralateral M1 to which anodal tDCS was applied for 20 min with a current strength of 1 mA. Motor evoked potential (MEP) amplitudes were assessed in 5 TMS test blocks (Pre, D5, D10, D15, and Post). The Pre and Post TMS test blocks were performed immediately before and after tDCS application, whereas the TMS test blocks performed during tDCS were completed at the 5, 10, and 15 min stimulation timepoints. MEPs were analyzed with a 2 condition (tDCS, SHAM) × 5 test (Pre, D5, D10, D15, Post) within-subject ANOVA. The main effect for condition (p = 0.213), the main effect for test (p = 0.502), and the condition × test interaction (p = 0.860) were all not statistically significant. These results indicate that tDCS does not modulate contralateral M1 excitability during or immediately after application, at least under the current set of common tDCS parameters of stimulation.
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Affiliation(s)
- Erik W. Wilkins
- Department of Kinesiology and Nutrition Sciences, University of Nevada, Las Vegas, NV 89154, USA;
- Interdisciplinary Ph.D. Program in Neuroscience, University of Nevada, Las Vegas, NV 89154, USA;
| | - Richard J. Young
- Interdisciplinary Ph.D. Program in Neuroscience, University of Nevada, Las Vegas, NV 89154, USA;
| | - Daniel Houston
- School of Medicine, University of Nevada, Las Vegas, NV 89154, USA; (D.H.); (E.K.); (E.L.M.)
| | - Eric Kawana
- School of Medicine, University of Nevada, Las Vegas, NV 89154, USA; (D.H.); (E.K.); (E.L.M.)
| | - Edgar Lopez Mora
- School of Medicine, University of Nevada, Las Vegas, NV 89154, USA; (D.H.); (E.K.); (E.L.M.)
| | - Meghana S. Sunkara
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284, USA;
| | - Zachary A. Riley
- Department of Kinesiology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA;
| | - Brach Poston
- Department of Kinesiology and Nutrition Sciences, University of Nevada, Las Vegas, NV 89154, USA;
- Interdisciplinary Ph.D. Program in Neuroscience, University of Nevada, Las Vegas, NV 89154, USA;
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de Albuquerque LL, Pantovic M, Wilkins EW, Morris D, Clingo M, Boss S, Riley ZA, Poston B. Exploring the Influence of Inter-Trial Interval on the Assessment of Short-Interval Intracortical Inhibition. Bioengineering (Basel) 2024; 11:645. [PMID: 39061727 PMCID: PMC11274151 DOI: 10.3390/bioengineering11070645] [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: 04/18/2024] [Revised: 06/05/2024] [Accepted: 06/17/2024] [Indexed: 07/28/2024] Open
Abstract
Short-interval intracortical inhibition (SICI) is a common paired-pulse transcranial magnetic stimulation (TMS) measure used to assess primary motor cortex (M1) interneuron activity in healthy populations and in neurological disorders. Many of the parameters of TMS stimulation to most accurately measure SICI have been determined. However, one TMS parameter that has not been investigated is the time between SICI trials (termed inter-trial interval; ITI). This is despite a series of single-pulse TMS studies which have reported that motor evoked potential (MEP) amplitude were suppressed for short, but not long ITIs in approximately the initial ten trials of a TMS block of 20-30 trials. The primary purpose was to examine the effects of ITI on the quantification of SICI at rest. A total of 23 healthy adults completed an experimental session that included four SICI trial blocks. Each block utilized a different ITI (4, 6, 8, and 10 s) and was comprised of a total of 26 SICI trials divided into three epochs. ANOVA revealed that the main effects for ITI and epoch as well as their interaction were all non-statistically significant for SICI. We conclude that the shorter (4-6 s) ITIs used in studies investigating SICI should not alter the interpretation of M1 activity, while having the advantages of being more comfortable to participants and reducing the experimental time needed to evaluate perform single and paired-pulse TMS experiments.
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Affiliation(s)
- Lidio Lima de Albuquerque
- School of Health and Applied Human Sciences, University of North Carolina Wilmington, Wilmington, NC 28403, USA;
| | - Milan Pantovic
- Health and Human Performance Department, Utah Tech University, St. George, UT 84770, USA;
| | - Erik W. Wilkins
- Department of Kinesiology and Nutrition Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154, USA;
| | - Desiree Morris
- School of Medicine, University of Nevada-Las Vegas, Las Vegas, NV 89154, USA; (D.M.); (M.C.)
| | - Mitchell Clingo
- School of Medicine, University of Nevada-Las Vegas, Las Vegas, NV 89154, USA; (D.M.); (M.C.)
| | - Sage Boss
- School of Life Sciences, University of Nevada-Las Vegas, Las Vegas, NV 89154, USA;
| | - Zachary A. Riley
- Department of Kinesiology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA;
| | - Brach Poston
- Department of Kinesiology and Nutrition Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154, USA;
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Crouzier M, Avrillon S, Hug F, Cattagni T. Horizontal foot orientation affects the distribution of neural drive between gastrocnemii during plantarflexion, without changing neural excitability. J Appl Physiol (1985) 2024; 136:786-798. [PMID: 38205551 DOI: 10.1152/japplphysiol.00536.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 12/21/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
The distribution of activation among muscles from the same anatomical group can be affected by the mechanical constraints of the task, such as limb orientation. For example, the distribution of activation between the gastrocnemius medialis (GM) and lateralis (GL) muscles during submaximal plantarflexion depends on the orientation of the foot in the horizontal plane. The neural mechanisms behind these modulations are not known. The overall aim of this study was to determine whether the excitability of the two gastrocnemius muscles is differentially affected by changes in foot orientation. Nineteen males performed isometric plantarflexions with their foot internally (toes-in) or externally (toes-out) rotated. GM and GL motor unit discharge characteristics were estimated from high-density surface electromyography to estimate neural drive. GM and GL corticospinal excitability and intracortical activity were assessed using transcranial magnetic stimulation through motor-evoked potentials. The efficacy of synaptic transmission between Ia-afferent fibers and α-motoneurons of the GM and GL was evaluated through the Hoffmann reflex. We observed a differential change in neural drive between GM (toes-out > toes-in) and GL (toes-out < toes-in). However, there was no foot orientation-related modulation in corticospinal excitability of the GM or GL, either at the cortical level or through modulation of the efficacy of Ia-α-motoneuron transmission. These results demonstrate that change in the motor pathway excitability is not the mechanism controlling the different distribution of neural drive between GM and GL with foot orientation.NEW & NOTEWORTHY Horizontal foot orientation affects the distribution of neural drive between the gastrocnemii during plantarflexion. There is no foot orientation-related modulation in the corticospinal excitability of the gastrocnemii, either at the cortical level or through modulation of the efficacy of Ia-α-motoneuron transmission. Change in motor pathway excitability is not the mechanism controlling the different distribution of neural drive between gastrocnemius medialis and lateralis with foot orientation.
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Affiliation(s)
- Marion Crouzier
- Nantes University, Movement - Interactions - Performance, MIP, UR-4334, Nantes, France
| | - Simon Avrillon
- Department of Bioengineering, Faculty of Engineering, Imperial College London, London, United Kingdom
| | - François Hug
- Université Côte d'Azur, LAMHESS, Nice, France
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Thomas Cattagni
- Nantes University, Movement - Interactions - Performance, MIP, UR-4334, Nantes, France
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Moraes VH, Vargas CD, Ramalho BL, Matsuda RH, Souza VH, Imbiriba LA, Garcia MAC. Effect of muscle length in a handgrip task on corticomotor excitability of extrinsic and intrinsic hand muscles under resting and submaximal contraction conditions. Scand J Med Sci Sports 2023; 33:2524-2533. [PMID: 37642219 DOI: 10.1111/sms.14477] [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: 01/07/2023] [Revised: 07/10/2023] [Accepted: 08/13/2023] [Indexed: 08/31/2023]
Abstract
The neurophysiological mechanisms underlying muscle force control for different wrist postures still need to be better understood. To further elucidate these mechanisms, the present study aimed to investigate the effects of wrist posture on the corticospinal excitability by transcranial magnetic stimulation (TMS) of extrinsic (flexor [FCR] and extensor carpi radialis [ECR]) and intrinsic (flexor pollicis brevis (FPB)) muscles at rest and during a submaximal handgrip strength task. Fourteen subjects (24.06 ± 2.28 years) without neurological or motor disorders were included. We assessed how the wrist posture (neutral: 0°; flexed: +45°; extended: -45°) affects maximal handgrip strength (HGSmax ) and the motor evoked potentials (MEP) amplitudes during rest and active muscle contractions. HGSmax was higher at 0° (133%) than at -45° (93.6%; p < 0.001) and +45° (73.9%; p < 0.001). MEP amplitudes were higher for the FCR at +45° (83.6%) than at -45° (45.2%; p = 0.019) and at +45° (156%; p < 0.001) and 0° (146%; p = 0.014) than at -45° (106%) at rest and active condition, respectively. Regarding the ECR, the MEP amplitudes were higher at -45° (113%) than at +45° (60.8%; p < 0.001) and 0° (72.6%; p = 0.008), and at -45° (138%) than +45° (96.7%; p = 0.007) also at rest and active conditions, respectively. In contrast, the FPB did not reveal any difference among wrist postures and conditions. Although extrinsic and intrinsic hand muscles exhibit overlapping cortical representations and partially share the same innervation, they can be modulated differently depending on the biomechanical constraints.
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Affiliation(s)
- Victor Hugo Moraes
- Laboratório de Neurociências e Reabilitação, Instituto de Neurologia Deolindo Couto, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Laboratório de Neurobiologia do Movimento do Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Departamento de Biociências e Atividades Físicas, Escola de Educação Física e Desportos, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Claudia D Vargas
- Laboratório de Neurociências e Reabilitação, Instituto de Neurologia Deolindo Couto, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Laboratório de Neurobiologia do Movimento do Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Bia L Ramalho
- Laboratório de Neurociências e Reabilitação, Instituto de Neurologia Deolindo Couto, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Centro de Pesquisa, Inovação e Difusão em Neuromatemática (NeuroMat), Instituto de Matemática e Estatística, Universidade de São Paulo, São Paulo, Brazil
| | - Renan H Matsuda
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
- Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Victor H Souza
- Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
- Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
- Programa de Pós-Graduação em Ciências da Reabilitação e Desempenho Físico-Funcional, Faculdade de Fisioterapia, Universidade Federal de Juiz de Fora, Juiz de Fora, Brazil
| | - Luis Aureliano Imbiriba
- Departamento de Biociências e Atividades Físicas, Escola de Educação Física e Desportos, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marco Antonio C Garcia
- Laboratório de Neurociências e Reabilitação, Instituto de Neurologia Deolindo Couto, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Programa de Pós-Graduação em Ciências da Reabilitação e Desempenho Físico-Funcional, Faculdade de Fisioterapia, Universidade Federal de Juiz de Fora, Juiz de Fora, Brazil
- Grupo de Estudos em Neuro Biomecânica, Faculdade de Fisioterapia, Universidade Federal de Juiz de Fora, Juiz de Fora, Brazil
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Pantovic M, Boss R, Noorda KJ, Premyanov MI, Aynlender DG, Wilkins EW, Boss S, Riley ZA, Poston B. The Influence of Different Inter-Trial Intervals on the Quantification of Intracortical Facilitation in the Primary Motor Cortex. Bioengineering (Basel) 2023; 10:1278. [PMID: 38002401 PMCID: PMC10669180 DOI: 10.3390/bioengineering10111278] [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: 10/10/2023] [Revised: 10/29/2023] [Accepted: 10/30/2023] [Indexed: 11/26/2023] Open
Abstract
Intracortical facilitation (ICF) is a paired-pulse transcranial magnetic stimulation (TMS) measurement used to quantify interneuron activity in the primary motor cortex (M1) in healthy populations and motor disorders. Due to the prevalence of the technique, most of the stimulation parameters to optimize ICF quantification have been established. However, the underappreciated methodological issue of the time between ICF trials (inter-trial interval; ITI) has been unstandardized, and different ITIs have never been compared in a paired-pulse TMS study. This is important because single-pulse TMS studies have found motor evoked potential (MEP) amplitude reductions over time during TMS trial blocks for short, but not long ITIs. The primary purpose was to determine the influence of different ITIs on the measurement of ICF. Twenty adults completed one experimental session that involved 4 separate ICF trial blocks with each utilizing a different ITI (4, 6, 8, and 10 s). Two-way ANOVAs indicated no significant ITI main effects for test MEP amplitudes, condition-test MEP amplitudes, and therefore ICF. Accordingly, all ITIs studied provided nearly identical ICF values when averaged over entire trial blocks. Therefore, it is recommended that ITIs of 4-6 s be utilized for ICF quantification to optimize participant comfort and experiment time efficiency.
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Affiliation(s)
- Milan Pantovic
- Health and Human Performance Department, Utah Tech University, St. George, UT 84770, USA;
| | - Rhett Boss
- School of Medicine, University of Nevada-Las Vegas, Las Vegas, NV 89154, USA; (R.B.); (K.J.N.); (M.I.P.); (D.G.A.)
| | - Kevin J. Noorda
- School of Medicine, University of Nevada-Las Vegas, Las Vegas, NV 89154, USA; (R.B.); (K.J.N.); (M.I.P.); (D.G.A.)
| | - Mario I. Premyanov
- School of Medicine, University of Nevada-Las Vegas, Las Vegas, NV 89154, USA; (R.B.); (K.J.N.); (M.I.P.); (D.G.A.)
| | - Daniel G. Aynlender
- School of Medicine, University of Nevada-Las Vegas, Las Vegas, NV 89154, USA; (R.B.); (K.J.N.); (M.I.P.); (D.G.A.)
| | - Erik W. Wilkins
- Department of Kinesiology and Nutrition Sciences, University of Nevada-Las Vegas, Las Vegas, NV 89154, USA;
| | - Sage Boss
- School of Life Sciences, University of Nevada-Las Vegas, Las Vegas, NV 89154, USA;
| | - Zachary A. Riley
- Department of Kinesiology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA;
| | - Brach Poston
- Department of Kinesiology and Nutrition Sciences, University of Nevada-Las Vegas, Las Vegas, NV 89154, USA;
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Tazoe T, Perez MA. Abnormal changes in motor cortical maps in humans with spinal cord injury. J Physiol 2021; 599:5031-5045. [PMID: 34192806 PMCID: PMC9109877 DOI: 10.1113/jp281430] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 06/28/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The functional role of motor cortical reorganization following spinal cord injury (SCI) remains largely unknown. Here, we tested motor maps in a hand muscle at rest and during voluntary contraction of the hand with and without voluntary contraction of a proximal arm muscle. Motor map area in participants with SCI decreased during hand voluntary contraction and further decreased during additional contraction of a proximal arm muscle compared with rest. In contrast, motor map area in controls increased during the same motor tasks. Participants with SCI with more severe sensory deficits in the hand showed larger decreases in motor map area. Ten minutes of hand muscle-tendon vibration increased the motor map area during voluntary contraction in SCI participants. These novel findings suggest that abnormal changes in motor cortical maps during voluntary contraction after SCI can be reshaped by sensory input, knowledge that can have implications for rehabilitation. ABSTRACT Motor cortical representations reorganize following cervical spinal cord injury (SCI). The functional role of this reorganization remains largely unknown. Using neuronavigated transcranial magnetic stimulation, we examined motor cortical maps during voluntary contraction in humans with chronic cervical SCI and age-matched controls. We constructed motor maps in the first dorsal interosseous (FDI) muscle at rest and during voluntary contraction of the FDI with and without voluntary contraction of the biceps brachi (BB). The role of sensory input into this reorganization was examined by muscle-tendon vibration. We found that, at rest, motor maps were larger in SCI (22.3 cm2 ) compared with control (12.6 cm2 , P < 0.001) participants. Motor map area increased during voluntary contraction of the FDI (120.7%) and further increased during contraction of the BB (143.9%) compared with rest in control subjects; however, motor map area decreased during voluntary contraction of the FDI (69.5%) and further decreased during contraction of the BB (55.5%) in individuals with SCI. SCI participants with larger decreases in map area during voluntary contraction of the FDI were those with larger sensory deficits in the hand and 10 min of hand muscle-tendon vibration increased motor map area. These results provide the first evidence of abnormal changes in motor cortical maps in humans with chronic SCI during voluntary contraction, suggesting that sensory input can help to reshape this reorganization.
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Affiliation(s)
- Toshiki Tazoe
- Arms + Hands Lab, Shirley Ryan AbilityLab, Northwestern
University, Chicago, IL 60611 and Hines Veterans Affairs Medical Center, Chicago, IL
60141, USA
- Neural Prosthesis Project, Department of Brain and
Neurosciences, Tokyo Metropolitan Institute of Medial Science, Tokyo 156-8506,
Japan
| | - Monica A. Perez
- Arms + Hands Lab, Shirley Ryan AbilityLab, Northwestern
University, Chicago, IL 60611 and Hines Veterans Affairs Medical Center, Chicago, IL
60141, USA
- The Miami Project to Cure Paralysis, Department of
Neurological Surgery, University of Miami, Miami FL 33136 and Bruce W. Carter
Department of Veterans Affairs Medical Center, Miami, FL 33125, USA
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Geed S, Grainger M, Harris-Love ML, Lum PS, Dromerick AW. Shoulder position and handedness differentially affect excitability and intracortical inhibition of hand muscles. Exp Brain Res 2021; 239:1517-1530. [PMID: 33751158 PMCID: PMC8317198 DOI: 10.1007/s00221-021-06077-w] [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] [Accepted: 03/03/2021] [Indexed: 10/22/2022]
Abstract
Individuals with stroke show distinct differences in hand function impairment when the shoulder is in adduction, within the workspace compared to when the shoulder is abducted, away from the body. To better understand how shoulder position affects hand control, we tested the corticomotor excitability and intracortical control of intrinsic and extrinsic hand muscles important for grasp in twelve healthy individuals. Motor evoked potentials (MEP) using single and paired-pulse transcranial magnetic stimulation were elicited in extensor digitorum communis (EDC), flexor digitorum superficialis (FDS), first dorsal interosseous (FDI), and abductor pollicis brevis (APB). The shoulder was fully supported in horizontal adduction (ADD) or abduction (ABD). Separate mixed-effect models were fit to the MEP parameters using shoulder position (or upper-extremity [UE] side) as fixed and participants as random effects. In the non-dominant UE, EDC showed significantly greater MEPs in shoulder ABD than ADD. In contrast, the dominant side EDC showed significantly greater MEPs in ADD compared to ABD; %facilitation of EDC on dominant side showed significant stimulus intensity x position interaction, EDC excitability was significantly greater in ADD at 150% of the resting threshold. Intrinsic hand muscles of the dominant UE received significantly more intracortical inhibition (SICI) when the shoulder was in ADD compared to ABD; there was no position-dependent modulation of SICI on the non-dominant side. Our findings suggest that these resting-state changes in hand muscle excitabilities reflect the natural statistics of UE movements, which in turn may arise from as well as shape the nature of shoulder-hand coupling underlying UE behaviors.
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Affiliation(s)
- Shashwati Geed
- Center for Brain Plasticity and Recovery, Department of Rehabilitation Medicine, Georgetown University Medical Center, Washington, DC, USA.
- Neuroscience Research Center, MedStar National Rehabilitation Hospital, 102 Irving St. NW, 1060, Washington, DC, 0010, USA.
| | - Megan Grainger
- Neuroscience Research Center, MedStar National Rehabilitation Hospital, 102 Irving St. NW, 1060, Washington, DC, 0010, USA
| | - Michelle L Harris-Love
- Neuroscience Research Center, MedStar National Rehabilitation Hospital, 102 Irving St. NW, 1060, Washington, DC, 0010, USA
| | - Peter S Lum
- Neuroscience Research Center, MedStar National Rehabilitation Hospital, 102 Irving St. NW, 1060, Washington, DC, 0010, USA
- Department of Bioengineering, The Catholic University of America, Washington, DC, USA
| | - Alexander W Dromerick
- Center for Brain Plasticity and Recovery, Department of Rehabilitation Medicine, Georgetown University Medical Center, Washington, DC, USA
- Neuroscience Research Center, MedStar National Rehabilitation Hospital, 102 Irving St. NW, 1060, Washington, DC, 0010, USA
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Rossi A, Feurra M, Rossi S, Santarnecchi E, Ginanneschi F. Impact of β-range-induced oscillatory activity on human input-output relationship of the corticospinal pathway. Neurol Res 2021; 43:496-502. [PMID: 33441044 DOI: 10.1080/01616412.2020.1870358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Objective: The aim of the study was to show that short-lasting (90 s) transcranial alternating current stimulation (tACS) at 20 Hz delivered over the left primary motor cortex (M1) is able to change the shape of recruitment curve of the corticospinal pathway.Methods: The corticospinal pathway was studied during tACS by means of the relationship between the intensity of transcranial magnetic stimulation (TMS) delivered over the left M1 and corresponding motor evoked potentials (MEPs) recorded from the right first dorsal interosseus muscle (FDI), in nine healthy subjects. In order to extract characteristics of the input-output relationship that have particular physiological relevance, data were fitted to the Boltzmann sigmoidal function by the Levenberg-Marquardt nonlinear, least mean squares algorithm.Results: The β-rhythm tACS influenced the shape and parameters of the input-output relation, so that the initial segment of the conditioned curve (from threshold to 30% of maximum muscle size) diverged, while the subsequent segment converged to overlap the unconditioned control curve.Discussion: β-rhythm tACS conditions only a definite subset of corticospinal elements influencing less than 30% of the entire motoneuronal pool. The fact that β-rhythm tACS mainly affects the most excitable motoneurons could explain the observed antikinetic effect of the tACS at β-rhythm applied in the motor regions.
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Affiliation(s)
- Alessandro Rossi
- Department of Medical, Surgery and Neurological Sciences, Brain Investigation and Neuromodulation Lab (Si-bin Lab), University of Siena, Siena, Italy
| | - Matteo Feurra
- Centre for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University, Higher School of Economics, Moscow, Russia
| | - Simone Rossi
- Department of Medical, Surgery and Neurological Sciences, Brain Investigation and Neuromodulation Lab (Si-bin Lab), University of Siena, Siena, Italy
| | - Emiliano Santarnecchi
- Department of Medical, Surgery and Neurological Sciences, Brain Investigation and Neuromodulation Lab (Si-bin Lab), University of Siena, Siena, Italy.,Berenson-Allen Center for Non-Invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Federica Ginanneschi
- Department of Medical, Surgery and Neurological Sciences, Brain Investigation and Neuromodulation Lab (Si-bin Lab), University of Siena, Siena, Italy
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Saidane Y, Parry R, Belkhiria C, Jebara SB, Driss T, de Marco G. Effects of Mental Effort on Premotor Muscle Activity and Maximal Grip Force. J Mot Behav 2020; 53:234-242. [PMID: 32468962 DOI: 10.1080/00222895.2020.1770179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The present study sought to evaluate how mental effort modulates premotor activity within forearm muscles in the context of an isometric grasping task. Muscle activity of the flexor digitorum superficialis (FDS) and extensor digitorum communis (EDC) was recorded during the application of maximum grip forces in nineteen healthy adult subjects. Each subject was examined under two experimental conditions: 1) spontaneous initiation of grasp (SI) and 2) focused concentration preceding the initiation of grasp (CA). Two novel parameters, the mean premotor duration (MPD) and the mean premotor power (MPP) were used to distinguish patterns of muscle activity. Here we tested the hypothesis was maximal grip strength is primed by muscle activity during the premotor phase. Our results demonstrate that MPD for each muscle group was significantly longer in the CA condition than for the SI condition (BF10 = 491497) and that MPP was significantly greater in EDC than in FDS (BF10 = 4305). Furthermore, both the MPD and MPP of the EDC were significantly correlated with maximum grip force. These results suggest that the increase of premotor activity consequent to the mental effort (focused concentration) may support internal biomechanical and physiological mechanisms which serve to enhance patterns of neuromuscular synergies.
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Affiliation(s)
- Yosra Saidane
- Laboratoire COSIM, Ecole Supérieure de Communication de Tunis, Université de Carthage Route de Raoued, Cite El Ghazala, Ariana, Tunisie
| | - Ross Parry
- Centre de Recherches sur le Sport et le Mouvement, UFR STAPS, UPL, Université Paris Nanterre, Nanterre, France.,COMUE, Université Paris Lumières, Paris, France
| | - Chama Belkhiria
- Centre de Recherches sur le Sport et le Mouvement, UFR STAPS, UPL, Université Paris Nanterre, Nanterre, France
| | - Sofia Ben Jebara
- Laboratoire COSIM, Ecole Supérieure de Communication de Tunis, Université de Carthage Route de Raoued, Cite El Ghazala, Ariana, Tunisie
| | - Tarak Driss
- Centre de Recherches sur le Sport et le Mouvement, UFR STAPS, UPL, Université Paris Nanterre, Nanterre, France.,COMUE, Université Paris Lumières, Paris, France
| | - Giovanni de Marco
- Centre de Recherches sur le Sport et le Mouvement, UFR STAPS, UPL, Université Paris Nanterre, Nanterre, France.,COMUE, Université Paris Lumières, Paris, France
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Yacyshyn AF, Kuzyk S, Jakobi JM, McNeil CJ. The effects of forearm position and contraction intensity on cortical and spinal excitability during a submaximal force steadiness task of the elbow flexors. J Neurophysiol 2020; 123:522-528. [PMID: 31774348 DOI: 10.1152/jn.00349.2019] [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: 11/22/2022] Open
Abstract
Elbow flexor force steadiness is less with the forearm pronated (PRO) compared with neutral (NEU) or supinated (SUP) and may relate to neural excitability. Although not tested in a force steadiness paradigm, lower spinal and cortical excitability was observed separately for biceps brachii in PRO, possibly dependent on contractile status at the time of assessment. This study aimed to investigate position-dependent changes in force steadiness as well as spinal and cortical excitability at a variety of contraction intensities. Thirteen males (26 ± 7 yr; means ± SD) performed three blocks (PRO, NEU, and SUP) of 24 brief (~6 s) isometric elbow flexor contractions (5, 10, 25 or 50% of maximal force). During each contraction, transcranial magnetic stimulation or transmastoid stimulation was delivered to elicit a motor-evoked potential (MEP) or cervicomedullary motor-evoked potential (CMEP), respectively. Force steadiness was lower in PRO compared with NEU and SUP (P ≤ 0.001), with no difference between NEU and SUP. Similarly, spinal excitability (CMEP/maximal M wave) was lower in PRO than NEU (25 and 50% maximal force; P ≤ 0.010) and SUP (all force levels; P ≤ 0.004), with no difference between NEU and SUP. Cortical excitability (MEP/CMEP) did not change with forearm position (P = 0.055); however, a priori post hoc testing for position showed excitability was 39.8 ± 38.3% lower for PRO than NEU at 25% maximal force (P = 0.006). The data suggest that contraction intensity influences the effect of forearm position on neural excitability and that reduced spinal and, to a lesser extent, cortical excitability could contribute to lower force steadiness in PRO compared with NEU and SUP.NEW & NOTEWORTHY To address conflicting reports about the effect of forearm position on spinal and cortical excitability of the elbow flexors, we examine the influence of contraction intensity. For the first time, excitability data are considered in a force steadiness context. Motoneuronal excitability is lowest in pronation and this disparity increases with contraction intensity. Cortical excitability exhibits a similar pattern from 5 to 25% of maximal force. Lower corticospinal excitability likely contributes to relatively poor force steadiness in pronation.
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Affiliation(s)
- Alexandra F Yacyshyn
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Samantha Kuzyk
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Jennifer M Jakobi
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Chris J McNeil
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
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11
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Runnalls KD, Ortega-Auriol P, McMorland AJC, Anson G, Byblow WD. Effects of arm weight support on neuromuscular activation during reaching in chronic stroke patients. Exp Brain Res 2019; 237:3391-3408. [PMID: 31728596 DOI: 10.1007/s00221-019-05687-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 11/07/2019] [Indexed: 12/14/2022]
Abstract
To better understand how arm weight support (WS) can be used to alleviate upper limb impairment after stroke, we investigated the effects of WS on muscle activity, muscle synergy expression, and corticomotor excitability (CME) in 13 chronic stroke patients and 6 age-similar healthy controls. For patients, lesion location and corticospinal tract integrity were assessed using magnetic resonance imaging. Upper limb impairment was assessed using the Fugl-Meyer upper extremity assessment with patients categorised as either mild or moderate-severe. Three levels of WS were examined: low = 0, medium = 50 and high = 100% of full support. Surface EMG was recorded from 8 upper limb muscles, and muscle synergies were decomposed using non-negative matrix factorisation from data obtained during reaching movements to an array of 14 targets using the paretic or dominant arm. Interactions between impairment level and WS were found for the number of targets hit, and EMG measures. Overall, greater WS resulted in lower EMG levels, although the degree of modulation between WS levels was less for patients with moderate-severe compared to mild impairment. Healthy controls expressed more synergies than patients with moderate-severe impairment. Healthy controls and patients with mild impairment showed more synergies with high compared to low weight support. Transcranial magnetic stimulation was used to elicit motor-evoked potentials (MEPs) to which stimulus-response curves were fitted as a measure of corticomotor excitability (CME). The effect of WS on CME varied between muscles and across impairment level. These preliminary findings demonstrate that WS has direct and indirect effects on muscle activity, synergies, and CME and warrants further study in order to reduce upper limb impairment after stroke.
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Affiliation(s)
- Keith D Runnalls
- Movement Neuroscience Laboratory, Department of Exercise Sciences, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Pablo Ortega-Auriol
- Movement Neuroscience Laboratory, Department of Exercise Sciences, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Angus J C McMorland
- Movement Neuroscience Laboratory, Department of Exercise Sciences, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, University of Auckland, Auckland, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Greg Anson
- Movement Neuroscience Laboratory, Department of Exercise Sciences, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Winston D Byblow
- Movement Neuroscience Laboratory, Department of Exercise Sciences, University of Auckland, Auckland, New Zealand.
- Centre for Brain Research, University of Auckland, Auckland, New Zealand.
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12
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Kosugi A, Castagnola E, Carli S, Ricci D, Fadiga L, Taoka M, Iriki A, Ushiba J. Fast Electrophysiological Mapping of Rat Cortical Motor Representation on a Time Scale of Minutes during Skin Stimulation. Neuroscience 2019; 414:245-254. [PMID: 31301365 DOI: 10.1016/j.neuroscience.2019.07.011] [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: 11/26/2018] [Revised: 07/01/2019] [Accepted: 07/02/2019] [Indexed: 10/26/2022]
Abstract
The topographic map of motor cortical representation, called the motor map, is not invariant, but can be altered by motor learning, neurological injury, and functional recovery from injury. Although much attention has been paid to short-term changes of the motor map, robust measures have not been established. The existing mapping methods are time-consuming, and the obtained maps are confounded by time preference. The purpose of this study was to examine the dynamics of the motor map on a timescale of minutes during transient somatosensory input by a fast motor mapping technique. We applied 32-channel micro-electrocorticographic electrode arrays to the rat sensorimotor cortex for cortical stimulation, and the topographic profile of motor thresholds in forelimb muscle was identified by fast motor mapping. Sequential motor maps were obtained every few minutes before, during, and just after skin stimulation to the dorsal forearm using a wool buff. During skin stimulation, the motor map expanded and the center of gravity of the map was shifted caudally. The expansion of the map persisted for at least a few minutes after the end of skin stimulation. Although the motor threshold of the hotspot was not changed, the area in which it was decreased appeared caudally to the hotspot, which may be in the somatosensory cortex. The present study demonstrated rapid enlargement of the forelimb motor map in the order of a few minutes induced by skin stimulation. This helps to understand the spatial dynamism of motor cortical representation that is modulated rapidly by somatosensory input.
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Affiliation(s)
- Akito Kosugi
- Graduate School of Science and Technology, Keio University, Kanagawa, Japan; Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan; Laboratory for Symbolic Cognitive Development, RIKEN Center for Biosystems Dynamics Research, Saitama, Japan
| | - Elisa Castagnola
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy; Center for Sensorimotor Neural Engineering, San Diego State University, San Diego, CA, United States
| | - Stefano Carli
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy
| | - Davide Ricci
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy
| | - Luciano Fadiga
- Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia, Ferrara, Italy; Section of Human Physiology, University of Ferrara, Ferrara, Italy
| | - Miki Taoka
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan; Laboratory for Symbolic Cognitive Development, RIKEN Center for Biosystems Dynamics Research, Saitama, Japan
| | - Atsushi Iriki
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan; Laboratory for Symbolic Cognitive Development, RIKEN Center for Biosystems Dynamics Research, Saitama, Japan
| | - Junichi Ushiba
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Kanagawa, Japan; Keio Institute of Pure and Applied Sciences, Keio University, Kanagawa, Japan.
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13
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Forman DA, Abdel-Malek D, Bunce CMF, Holmes MWR. Muscle length and joint angle influence spinal but not corticospinal excitability to the biceps brachii across forearm postures. J Neurophysiol 2019; 122:413-423. [PMID: 31116661 DOI: 10.1152/jn.00620.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Forearm rotation (supination/pronation) alters corticospinal excitability to the biceps brachii, but it is unclear whether corticospinal excitability is influenced by joint angle, muscle length, or both. Thus the purpose of this study was to separately examine elbow joint angle and muscle length on corticospinal excitability. Corticospinal excitability to the biceps and triceps brachii was measured using motor evoked potentials (MEPs) elicited via transcranial magnetic stimulation. Spinal excitability was measured using cervicomedullary motor evoked potentials (CMEPs) elicited via transmastoid electrical stimulation. Elbow angles were manipulated with a fixed biceps brachii muscle length (and vice versa) across five unique postures: 1) forearm neutral, elbow flexion 90°; 2) forearm supinated, elbow flexion 90°; 3) forearm pronated, elbow flexion 90°; 4) forearm supinated, elbow flexion 78°; and 5) forearm pronated, elbow flexion 113°. A musculoskeletal model determined biceps brachii muscle length for postures 1-3, and elbow joint angles (postures 4-5) were selected to maintain biceps length across forearm orientations. MEPs and CMEPs were elicited at rest and during an isometric contraction of 10% of maximal biceps muscle activity. At rest, MEP amplitudes to the biceps were largest during supination, which was independent of elbow joint angle. CMEP amplitudes were not different when the elbow was fixed at 90° but were largest in pronation when muscle length was controlled. During an isometric contraction, there were no significant differences across forearm postures for either MEP or CMEP amplitudes. These results highlight that elbow joint angle and biceps brachii muscle length can each independently influence spinal excitability. NEW & NOTEWORTHY Changes in upper limb posture can influence the responsiveness of the central nervous system to artificial stimulations. We established a novel approach integrating neurophysiology techniques with biomechanical modeling. Through this approach, the effects of elbow joint angle and biceps brachii muscle length on corticospinal and spinal excitability were assessed. We demonstrate that spinal excitability is uniquely influenced by joint angle and muscle length, and this highlights the importance of accounting for muscle length in neurophysiological studies.
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Affiliation(s)
- Davis A Forman
- Faculty of Science, University of Ontario Institute of Technology , Oshawa, Ontario , Canada
| | - Daniel Abdel-Malek
- Faculty of Health Sciences, University of Ontario Institute of Technology , Oshawa, Ontario , Canada
| | - Christopher M F Bunce
- Faculty of Health Sciences, University of Ontario Institute of Technology , Oshawa, Ontario , Canada
| | - Michael W R Holmes
- Faculty of Applied Health Sciences, Brock University , St. Catharines, Ontario , Canada
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14
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Dongés SC, Taylor JL, Nuzzo JL. Elbow angle modulates corticospinal excitability to the resting biceps brachii at both spinal and supraspinal levels. Exp Physiol 2019; 104:546-555. [PMID: 30690803 DOI: 10.1113/ep087472] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 01/25/2019] [Indexed: 01/22/2023]
Abstract
NEW FINDINGS What is the central question of this study? Corticospinal excitability to biceps brachii is known to modulate according to upper-limb posture. Here, cervicomedullary stimulation was used to investigate potential spinal contributions to elbow angle-dependent changes in corticospinal excitability at rest. What is the main finding and its importance? At more extended elbow angles, biceps responses to cervicomedullary stimulation were decreased, whereas cortically evoked responses (normalized to cervicomedullary-evoked responses) were increased. Results suggest decreased spinal excitability but increased cortical excitability as the elbow is placed in a more extended position, an effect that is unlikely to be attributable to cutaneous stretch receptor activation. ABSTRACT Corticospinal excitability to biceps brachii is known to modulate according to upper-limb posture. In study 1, our aim was to investigate potential spinal contributions to this modulation and the independent effect of elbow angle. Biceps responses to transcranial magnetic stimulation (motor evoked potentials; MEPs) and electrical cervicomedullary stimulation (cervicomedullary motor evoked potentials; CMEPs) were measured at five elbow angles ranging from full extension to 130 deg of flexion. In study 2, possible contributions of cutaneous stretch receptors to elbow angle-dependent excitability changes were investigated by eliciting MEPs and CMEPs in three conditions of skin stretch about the elbow (stretch to mimic full extension, no stretch or stretch to mimic flexion). Each study had 12 participants. Evoked potentials were acquired at rest, with participants seated, the shoulder flexed 90 deg and forearm supinated. The MEPs and CMEPs were normalized to maximal compound muscle action potentials. In study 1, as the elbow was moved to more extended positions, there were no changes in MEPs (P = 0.963), progressive decreases in CMEPs (P < 0.0001; CMEPs at 130 deg flexion ∼220% of full extension) and increases in the MEP/CMEP ratio (P = 0.019; MEP/CMEP at 130 deg flexion ∼20% of full extension). In study 2, there were no changes in MEPs (P = 0.830) or CMEPs (P = 0.209) between skin stretch conditions. Therefore, although results suggest a decrease in spinal and an increase in supraspinal excitability at more extended angles, the mechanism for these changes in corticospinal excitability to biceps is not cutaneous stretch receptor feedback.
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Affiliation(s)
| | - Janet L Taylor
- Neuroscience Research Australia, Sydney, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia.,Edith Cowan University, Perth, WA, Australia
| | - James L Nuzzo
- Neuroscience Research Australia, Sydney, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
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15
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Corticospinal excitability, assessed through stimulus response curves, is phase-, task-, and muscle-dependent during arm cycling. Neurosci Lett 2019; 692:100-106. [DOI: 10.1016/j.neulet.2018.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 10/11/2018] [Accepted: 11/01/2018] [Indexed: 11/20/2022]
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16
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Collins BW, Pearcey GE, Buckle NC, Power KE, Button DC. Neuromuscular fatigue during repeated sprint exercise: underlying physiology and methodological considerations. Appl Physiol Nutr Metab 2018; 43:1166-1175. [DOI: 10.1139/apnm-2018-0080] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Neuromuscular fatigue occurs when an individual’s capacity to produce force or power is impaired. Repeated sprint exercise requires an individual to physically exert themselves at near-maximal to maximal capacity for multiple short-duration bouts, is extremely taxing on the neuromuscular system, and consequently leads to the rapid development of neuromuscular fatigue. During repeated sprint exercise the development of neuromuscular fatigue is underlined by a combination of central and peripheral fatigue. However, there are a number of methodological considerations that complicate the quantification of the development of neuromuscular fatigue. The main goal of this review is to synthesize the results from recent investigations on the development of neuromuscular fatigue during repeated sprint exercise. Hence, we summarize the overall development of neuromuscular fatigue, explain how recovery time may alter the development of neuromuscular fatigue, outline the contributions of peripheral and central fatigue to neuromuscular fatigue, and provide some methodological considerations for quantifying neuromuscular fatigue during repeated sprint exercise.
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Affiliation(s)
- Brandon W. Collins
- BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, NL A1C 5S7, Canada
| | - Gregory E.P. Pearcey
- Rehabilitation Neuroscience Laboratory and Centre for Biomedical Research, University of Victoria, Victoria, BC V8W 2Y2, Canada
- Human Discovery Science, International Collaboration on Repair Discoveries (ICORD), Vancouver, BC V5Z 1M9, Canada
| | - Natasha C.M. Buckle
- School of Human Kinetics and Recreation and BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, NL A1C 5S7, Canada
| | - Kevin E. Power
- School of Human Kinetics and Recreation and BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, NL A1C 5S7, Canada
| | - Duane C. Button
- School of Human Kinetics and Recreation and BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, NL A1C 5S7, Canada
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17
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Ding Q, Patten C. External biomechanical constraints impair maximal voluntary grip force stability post-stroke. Clin Biomech (Bristol, Avon) 2018; 57:26-34. [PMID: 29894857 DOI: 10.1016/j.clinbiomech.2018.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 04/23/2018] [Accepted: 06/04/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND Grip strength is frequently measured as a global indicator of motor function. In clinical populations, such as hemiparesis post-stroke, grip strength is associated with upper-extremity motor impairment, function, and ability to execute activities of daily living. However, biomechanical configuration of the distal arm and hand may influence the magnitude and stability of maximal voluntary grip force and varies across studies. The influence of distal arm/hand biomechanical configuration on grip force remains unclear. Here we investigated how biomechanical configuration of the distal arm/hand influence the magnitude and trial-to-trial variability of maximal grip force performed in similar positions with variations in external constraint. METHODS We studied three groups of 20 individuals: healthy young, healthy older, and individuals post-stroke. We tested maximal voluntary grip force in 4 conditions: 1: self-determined/"free"; 2: standard; 3: fixed arm-rest; 4: gripper fixed to arm-rest, using an instrumented grip dynamometer in both dominant/non-dominant and non-paretic/paretic hands. FINDINGS Regardless of hand or group, maximal voluntary grip force was highest when the distal limb was most constrained (i.e., Condition 4), followed by the least constrained (i.e., Condition 1) (Cohen's f = 0.52, P's < 0.001). Coefficient of variation among three trials was greater in the paretic hand compared with healthy individuals, particularly in more (Conditions 3 and 4) compared to less (Conditions 1 and 2) constrained conditions (Cohen's f = 0.29, P's < 0.05). INTERPRETATION These findings have important implications for design of rehabilitation interventions and devices. Particularly in individuals post-stroke, external biomechanical constraints increase maximal voluntary grip force variability while fewer biomechanical constraints yield more stable performance.
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Affiliation(s)
- Qian Ding
- Neural Control of Movement Lab, Malcolm Randall VA Medical Center (151A), Gainesville, FL 32608, USA; Rehabilitation Sciences Doctoral Program, Department of Physical Therapy, University of Florida, Gainesville, FL 32608, USA
| | - Carolynn Patten
- Biomechanics and Neural Control of Movement Lab, University of California, Davis School of Medicine, Northern California VA Health Care System, Sacramento, CA 95817, USA.
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18
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Eckert NR, Poston B, Riley ZA. Differential processing of nociceptive input within upper limb muscles. PLoS One 2018; 13:e0196129. [PMID: 29694394 PMCID: PMC5918997 DOI: 10.1371/journal.pone.0196129] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 04/06/2018] [Indexed: 12/03/2022] Open
Abstract
The cutaneous silent period is an inhibitory evoked response that demonstrates a wide variety of responses in muscles of the human upper limb. Classically, the cutaneous silent period results in a characteristic muscle pattern of extensor inhibition and flexor facilitation within the upper limb, in the presence of nociceptive input. The aims of the current study were: 1) to primarily investigate the presence and characteristics of the cutaneous silent period response across multiple extensor and flexor muscles of the upper limb, and 2) to secondarily investigate the influence of stimulation site on this nociceptive reflex response. It was hypothesized that the cutaneous silent period would be present in all muscles, regardless of role (flexion/extension) or the stimulation site. Twenty-two healthy, university-age adults (14 males; 8 females; 23 ± 5 yrs) participated in the study. Testing consisted of three different stimulation sites (Digit II, V, and II+III nociceptive stimulation) during a low intensity, sustained muscle contraction, in which, 7 upper limb muscles were monitored via surface EMG recording electrodes. Distal muscles of the upper limb presented with the earliest reflex onset times, longest reflex duration, and lowest level of EMG suppression when compared to the more proximal muscles, regardless of extensor/flexor role. Additionally, the greatest overall inhibitory influence was expressed within the distal muscles. In conclusion, the present study provides a new level of refinement within the current understanding of the spinal organization associated with nociceptive input processing and the associated motor control of the upper limb. Subsequently, these results have further implications on the impact of nociception on supraspinal processing.
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Affiliation(s)
- Nathanial R Eckert
- Department of Kinesiology, University of Indianapolis, Indianapolis, IN, United States of America
| | - Brach Poston
- Department of Kinesiology and Nutrition Sciences, University of Nevada-Las Vegas, Las Vegas, NV, United States of America
| | - Zachary A Riley
- Department of Kinesiology, Indiana University-Purdue University, Indianapolis, IN, United States of America
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19
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Collins BW, Button DC. The effect of shoulder position on motor evoked and maximal muscle compound action potentials of the biceps brachii. Neurosci Lett 2018; 665:206-211. [DOI: 10.1016/j.neulet.2017.12.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 11/21/2017] [Accepted: 12/07/2017] [Indexed: 11/30/2022]
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20
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Collins BW, Cadigan EWJ, Stefanelli L, Button DC. Corticospinal excitability of the biceps brachii is shoulder position dependent. J Neurophysiol 2017; 118:3242-3251. [DOI: 10.1152/jn.00527.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/27/2017] [Accepted: 08/28/2017] [Indexed: 01/17/2023] Open
Abstract
The purpose of this study was to examine the effect of shoulder position on corticospinal excitability (CSE) of the biceps brachii during rest and a 10% maximal voluntary contraction (MVC). Participants ( n = 9) completed two experimental sessions with four conditions: 1) rest, 0° shoulder flexion; 2) 10% MVC, 0° shoulder flexion; 3) rest, 90° shoulder flexion; and 4) 10% MVC, 90° shoulder flexion. Transcranial magnetic, transmastoid electrical, and Erb’s point stimulation were used to induce motor-evoked potentials (MEPs), cervicomedullary MEPs (CMEPs), and maximal muscle compound potentials (Mmax), respectively, in the biceps brachii in each condition. At rest, MEP, CMEP, and Mmax amplitudes increased ( P < 0.01) by 509.7 ± 118.3%, 113.3 ± 28.3%, and 155.1 ± 47.9%, respectively, at 90° compared with 0°. At 10% MVC, MEP amplitudes did not differ ( P = 0.08), but CMEP and Mmax amplitudes increased ( P < 0.05) by 32.3 ± 10.5% and 127.9 ± 26.1%, respectively, at 90° compared with 0°. MEP/Mmax increased ( P < 0.01) by 224.0 ± 99.1% at rest and decreased ( P < 0.05) by 51.3 ± 6.7% at 10% MVC at 90° compared with 0°. CMEP/Mmax was not different ( P = 0.22) at rest but decreased ( P < 0.01) at 10% MVC by 33.6 ± 6.1% at 90° compared with 0°. EMG increased ( P < 0.001) by 8.3 ± 2.0% at rest and decreased ( P < 0.001) by 21.4 ± 4.4% at 10% MVC at 90° compared with 0°. In conclusion, CSE of the biceps brachii was dependent on shoulder position, and the pattern of change was altered within the state in which it was measured. The position-dependent changes in Mmax amplitude, EMG, and CSE itself all contribute to the overall change in CSE of the biceps brachii. NEW & NOTEWORTHY We demonstrate that when the shoulder is placed into two common positions for determining elbow flexor force and activation, corticospinal excitability (CSE) of the biceps brachii is both shoulder position and state dependent. At rest, when the shoulder is flexed from 0° to 90°, supraspinal factors predominantly alter CSE, whereas during a slight contraction, spinal factors predominantly alter CSE. Finally, the normalization techniques frequently used by researchers to investigate CSE may under- and overestimate CSE when shoulder position is changed.
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Affiliation(s)
- Brandon Wayne Collins
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Memorial University, St. John’s, Newfoundland and Labrador, Canada
| | - Edward W. J. Cadigan
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Memorial University, St. John’s, Newfoundland and Labrador, Canada
| | - Lucas Stefanelli
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Memorial University, St. John’s, Newfoundland and Labrador, Canada
| | - Duane C. Button
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Memorial University, St. John’s, Newfoundland and Labrador, Canada
- BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, Newfoundland and Labrador, Canada
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21
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Forman DA, Richards M, Forman GN, Holmes MWR, Power KE. Changes in Corticospinal and Spinal Excitability to the Biceps Brachii with a Neutral vs. Pronated Handgrip Position Differ between Arm Cycling and Tonic Elbow Flexion. Front Hum Neurosci 2016; 10:543. [PMID: 27826236 PMCID: PMC5078689 DOI: 10.3389/fnhum.2016.00543] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 10/13/2016] [Indexed: 12/04/2022] Open
Abstract
The purpose of this study was to examine the influence of neutral and pronated handgrip positions on corticospinal excitability to the biceps brachii during arm cycling. Corticospinal and spinal excitability were assessed using motor evoked potentials (MEPs) elicited via transcranial magnetic stimulation (TMS) and cervicomedullary-evoked potentials (CMEPs) elicited via transmastoid electrical stimulation (TMES), respectively. Participants were seated upright in front on arm cycle ergometer. Responses were recorded from the biceps brachii at two different crank positions (6 and 12 o'clock positions relative to a clock face) while arm cycling with neutral and pronated handgrip positions. Responses were also elicited during tonic elbow flexion to compare/contrast the results to a non-rhythmic motor output. MEP and CMEP amplitudes were significantly larger at the 6 o'clock position while arm cycling with a neutral handgrip position compared to pronated (45.6 and 29.9%, respectively). There were no differences in MEP and CMEP amplitudes at the 12 o'clock position for either handgrip position. For the tonic contractions, MEPs were significantly larger with a neutral vs. pronated handgrip position (32.6% greater) while there were no difference in CMEPs. Corticospinal excitability was higher with a neutral handgrip position for both arm cycling and tonic elbow flexion. While spinal excitability was also higher with a neutral handgrip position during arm cycling, no difference was observed during tonic elbow flexion. These findings suggest that not only is corticospinal excitability to the biceps brachii modulated at both the supraspinal and spinal level, but that it is influenced differently between rhythmic arm cycling and tonic elbow flexion.
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Affiliation(s)
- Davis A. Forman
- School of Human Kinetics and Recreation, Memorial University of NewfoundlandSt. John’s, NL, Canada
- Faculty of Health Sciences, University of Ontario Institute of TechnologyOshawa, ON, Canada
| | - Mark Richards
- School of Human Kinetics and Recreation, Memorial University of NewfoundlandSt. John’s, NL, Canada
| | - Garrick N. Forman
- Faculty of Health Sciences, University of Ontario Institute of TechnologyOshawa, ON, Canada
| | - Michael W. R. Holmes
- Faculty of Health Sciences, University of Ontario Institute of TechnologyOshawa, ON, Canada
| | - Kevin E. Power
- School of Human Kinetics and Recreation, Memorial University of NewfoundlandSt. John’s, NL, Canada
- Faculty of Medicine, Memorial University of NewfoundlandSt. John’s, NL, Canada
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22
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Posture interacts with arm weight support to modulate corticomotor excitability to the upper limb. Exp Brain Res 2016; 235:97-107. [PMID: 27639400 DOI: 10.1007/s00221-016-4775-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 09/09/2016] [Indexed: 10/21/2022]
Abstract
The use of arm weight support (WS) to optimize movement quality may be an avenue for improved upper limb stroke rehabilitation; however, the underlying neurophysiological effects of WS are not well understood. Rehabilitation exercises may be performed when sitting or standing, but the interaction of posture with WS has not been examined until now. We explored the effect of posture with WS on corticomotor excitability (CME) in healthy adults. Thirteen participants performed static shoulder abduction in two postures (sitting and standing) at three levels of WS (0, 45, and 90 % of full support). Transcranial magnetic stimulation of primary motor cortex was used to elicit motor-evoked potentials (MEPs) in eight upper limb muscles. Stimulus-response (SR) curves were fitted to the MEP data using nonlinear regression. Whole-body posture interacted with WS to influence tonic activity and CME in all muscles examined. SR curve parameters revealed greater CME when standing compared to sitting for upper arm muscles, but lower CME to the shoulder, forearm, and hand. Distal to the shoulder, tonic activity and CME were modulated independent of any explicit differences in task requirements. Overall, these results support a model of integrated upper limb control influenced by whole-body posture and WS. These findings have implications for the application of WS in settings such as upper limb rehabilitation after stroke.
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The effects of upper limb posture and a sub-maximal gripping task on corticospinal excitability to muscles of the forearm. J Electromyogr Kinesiol 2016; 27:95-101. [DOI: 10.1016/j.jelekin.2016.02.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 01/19/2016] [Accepted: 02/16/2016] [Indexed: 11/22/2022] Open
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Nuzzo JL, Trajano GS, Barry BK, Gandevia SC, Taylor JL. Arm posture-dependent changes in corticospinal excitability are largely spinal in origin. J Neurophysiol 2016; 115:2076-82. [PMID: 26864764 DOI: 10.1152/jn.00885.2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 02/06/2016] [Indexed: 11/22/2022] Open
Abstract
Biceps brachii motor evoked potentials (MEPs) from cortical stimulation are influenced by arm posture. We used subcortical stimulation of corticospinal axons to determine whether this postural effect is spinal in origin. While seated at rest, 12 subjects assumed several static arm postures, which varied in upper-arm (shoulder flexed, shoulder abducted, arm hanging to side) and forearm orientation (pronated, neutral, supinated). Transcranial magnetic stimulation over the contralateral motor cortex elicited MEPs in resting biceps and triceps brachii, and electrical stimulation of corticospinal tract axons at the cervicomedullary junction elicited cervicomedullary motor evoked potentials (CMEPs). MEPs and CMEPs were normalized to the maximal compound muscle action potential (Mmax). Responses in biceps were influenced by upper-arm and forearm orientation. For upper-arm orientation, biceps CMEPs were 68% smaller (P= 0.001), and biceps MEPs 31% smaller (P= 0.012), with the arm hanging to the side compared with when the shoulder was flexed. For forearm orientation, both biceps CMEPs and MEPs were 34% smaller (both P< 0.046) in pronation compared with supination. Responses in triceps were influenced by upper-arm, but not forearm, orientation. Triceps CMEPs were 46% smaller (P= 0.007) with the arm hanging to the side compared with when the shoulder was flexed. Triceps MEPs and biceps and triceps MEP/CMEP ratios were unaffected by arm posture. The novel finding is that arm posture-dependent changes in corticospinal excitability in humans are largely spinal in origin. An interplay of multiple reflex inputs to motoneurons likely explains the results.
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Affiliation(s)
- James L Nuzzo
- Neuroscience Research Australia, Randwick, New South Wales, Australia; School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia; and
| | - Gabriel S Trajano
- Neuroscience Research Australia, Randwick, New South Wales, Australia
| | - Benjamin K Barry
- Neuroscience Research Australia, Randwick, New South Wales, Australia; School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia; and
| | - Simon C Gandevia
- Neuroscience Research Australia, Randwick, New South Wales, Australia; Prince of Wales Clinical School, University of New South Wales, Kensington, New South Wales, Australia
| | - Janet L Taylor
- Neuroscience Research Australia, Randwick, New South Wales, Australia; School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia; and
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25
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Papegaaij S, Taube W, van Keeken HG, Otten E, Baudry S, Hortobágyi T. Postural challenge affects motor cortical activity in young and old adults. Exp Gerontol 2015; 73:78-85. [PMID: 26615878 DOI: 10.1016/j.exger.2015.11.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 10/27/2015] [Accepted: 11/23/2015] [Indexed: 11/18/2022]
Abstract
When humans voluntarily activate a muscle, intracortical inhibition decreases. Such a decrease also occurs in the presence of a postural challenge and more so with increasing age. Here, we examined age-related changes in motor cortical activity during postural and non-postural contractions with varying levels of postural challenge. Fourteen young (age 22) and twelve old adults (age 70) performed three conditions: (1) voluntary contraction of the soleus muscle in sitting and (2) leaning forward while standing with and (3) without being supported. Subthreshold transcranial magnetic stimulation was applied to the soleus motor area suppressing ongoing EMG, as an index of motor cortical activity. The area of EMG suppression was ~60% smaller (p<0.05) in unsupported vs. supported leaning and sitting, with no difference between these latter two conditions (p>0.05). Even though in absolute terms young compared with old adults leaned farther (p=0.018), there was no age effect or an age by condition interaction in EMG suppression. Leaning closer to the maximum without support correlated with less EMG suppression (rho=-0.44, p=0.034). We conclude that the critical factor in modulating motor cortical activity was postural challenge and not contraction aim or posture. Age did not affect the motor control strategy as quantified by the modulation of motor cortical activity, but the modulation appeared at a lower task difficulty with increasing age.
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Affiliation(s)
- Selma Papegaaij
- University of Groningen, University Medical Center Groningen, Center for Human Movement Sciences, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands.
| | - Wolfgang Taube
- University of Fribourg, Department of Medicine, Ch. du Musée 8, CH-1700, Fribourg, Switzerland
| | - Helco G van Keeken
- University of Groningen, University Medical Center Groningen, Center for Human Movement Sciences, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands
| | - Egbert Otten
- University of Groningen, University Medical Center Groningen, Center for Human Movement Sciences, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands
| | - Stéphane Baudry
- Université Libre de Bruxelles, Faculty for Motor Sciences, Laboratory of Applied Biology, CP 640, Route de Lennik 808, 1070 Brussels, Belgium
| | - Tibor Hortobágyi
- University of Groningen, University Medical Center Groningen, Center for Human Movement Sciences, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands; Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-upon-Tyne NE1 8ST, United Kingdom
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26
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Excitability of the infraspinatus, but not the middle deltoid, is affected by shoulder elevation angle. Exp Brain Res 2015; 233:1837-43. [DOI: 10.1007/s00221-015-4255-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 03/11/2015] [Indexed: 11/26/2022]
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Runnalls KD, Anson G, Wolf SL, Byblow WD. Partial weight support differentially affects corticomotor excitability across muscles of the upper limb. Physiol Rep 2014; 2:2/12/e12183. [PMID: 25501435 PMCID: PMC4332194 DOI: 10.14814/phy2.12183] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Partial weight support may hold promise as a therapeutic adjuvant during rehabilitation after stroke by providing a permissive environment for reducing the expression of abnormal muscle synergies that cause upper limb impairment. We explored the neurophysiological effects of upper limb weight support in 13 healthy young adults by measuring motor‐evoked potentials (MEPs) from transcranial magnetic stimulation (TMS) of primary motor cortex and electromyography from anterior deltoid (AD), biceps brachii (BB), extensor carpi radialis (ECR), and first dorsal interosseous (FDI). Five levels of weight support, varying from none to full, were provided to the arm using a commercial device (Saebo Mobile Arm Support). For each level of support, stimulus–response (SR) curves were derived from MEPs across a range of TMS intensities. Weight support affected background EMG activity in each of the four muscles examined (P <0.0001 for each muscle). Tonic background activity was primarily reduced in the AD. Weight support had a differential effect on the size of MEPs across muscles. After curve fitting, the SR plateau for ECR increased at the lowest support level (P =0.004). For FDI, the SR plateau increased at the highest support level (P =0.0003). These results indicate that weight support of the proximal upper limb modulates corticomotor excitability across the forearm and hand. The findings support a model of integrated control of the upper limb and may inform the use of weight support in clinical settings. Partial weight support of the arm may hold promise as a therapeutic adjuvant during stroke rehabilitation, but little is known about its neurophysiological effects. We measured EMG activity and motor‐evoked potentials from TMS during variable weight support in healthy adults. Weight support had a differential effect on the size of MEPs across muscles, indicating support of the proximal upper limb modulates corticomotor excitability across the forearm and hand.
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Affiliation(s)
- Keith D Runnalls
- Movement Neuroscience Laboratory, Department of Sport and Exercise Science, University of Auckland, Auckland, New Zealand Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Greg Anson
- Movement Neuroscience Laboratory, Department of Sport and Exercise Science, University of Auckland, Auckland, New Zealand Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Steven L Wolf
- Department of Rehabilitation Medicine, Emory University School of Medicine, Atlanta, Georgia Atlanta VA Center of Excellence in Visual and Neurocognitive Rehabilitation, Atlanta, Georgia
| | - Winston D Byblow
- Movement Neuroscience Laboratory, Department of Sport and Exercise Science, University of Auckland, Auckland, New Zealand Centre for Brain Research, University of Auckland, Auckland, New Zealand
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28
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Neural summation in human motor cortex by subthreshold transcranial magnetic stimulations. Exp Brain Res 2014; 233:671-7. [PMID: 25399245 DOI: 10.1007/s00221-014-4146-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 11/10/2014] [Indexed: 10/24/2022]
Abstract
Integration of diverse synaptic inputs is a basic neuronal operation that relies on many neurocomputational principles, one of which is neural summation. However, we lack empirical understanding of neuronal summation in the human brains in vivo. Here, we explored the effect of neural summation on the motor cortex using two subthreshold pulses of transcranial magnetic stimulation (TMS), each with intensities ranging from 60 to 95% of the resting motor threshold (RMT) and interstimulus interval (ISI) varying from 1 to 25 ms. We found that two subthreshold TMS pulses can produce suprathreshold motor response when ISIs were less than 10 ms, most prominent at 1, 1.5 and 3 ms. This facilitatory, above-threshold response was evident when the intensity of the subthreshold pulses was above 80% of RMT but was absent as the intensity was 70% or below. Modeling of the summation data across intensity suggested that they followed an exponential function with excellent model fitting. Understanding the constraints for inducing summation of subthreshold stimulations to generate above-threshold response may have implications in modeling neural operations and potential clinical applications.
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29
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Papegaaij S, Taube W, Hogenhout M, Baudry S, Hortobágyi T. Age-related decrease in motor cortical inhibition during standing under different sensory conditions. Front Aging Neurosci 2014; 6:126. [PMID: 24971063 PMCID: PMC4054792 DOI: 10.3389/fnagi.2014.00126] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 05/28/2014] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Although recent studies point to the involvement of the primary motor cortex in postural control, it is unknown if age-related deterioration of postural control is associated with changes in motor cortical circuits. We examined the interaction between age and sensory condition in the excitability of intracortical motor pathways as indexed by short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) during standing. METHODS We used magnetic brain stimulation to evoke SICI and ICF in 11 young (range 21-25 years) and 12 healthy old adults (range 60-74 years) while they stood on a rigid platform or foam, with the eyes open or closed. RESULTS There was an overall age-related 43% reduction in SICI (p = 0.001). SICI lessened when standing on foam in old (31%) but not in young (1%) adults (condition × group interaction, p = 0.049). This reduction was associated with increases in center of pressure velocity (r = -0.648, p = 0.043). Age (p = 0.527) and sensory conditions (p = 0.325) did not affect ICF. CONCLUSION Motor cortical circuits controlling leg muscles are modulated differently in healthy old vs. young adults during upright posture. Future experiments will clarify whether this difference mediates impaired postural control or serves as a compensatory mechanism to counteract postural instability.
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Affiliation(s)
- Selma Papegaaij
- Center for Human Movement Sciences, University of Groningen, University Medical Center Groningen Groningen, Netherlands
| | - Wolfgang Taube
- Movement and Sports Science, Department of Medicine, University of Fribourg Fribourg, Switzerland
| | - Margot Hogenhout
- Center for Human Movement Sciences, University of Groningen, University Medical Center Groningen Groningen, Netherlands
| | - Stéphane Baudry
- Laboratory of Applied Biology, Faculty for Motor Sciences, Université Libre de Bruxelles Brussels, Belgium
| | - Tibor Hortobágyi
- Center for Human Movement Sciences, University of Groningen, University Medical Center Groningen Groningen, Netherlands ; Faculty of Health and Life Sciences, Northumbria University Newcastle Upon Tyne, UK
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Bączyk M, Pettersson LG, Jankowska E. Facilitation of ipsilateral actions of corticospinal tract neurons on feline motoneurons by transcranial direct current stimulation. Eur J Neurosci 2014; 40:2628-40. [PMID: 24835584 DOI: 10.1111/ejn.12623] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 04/07/2014] [Accepted: 04/15/2014] [Indexed: 02/03/2023]
Abstract
Ipsilateral actions of pyramidal tract (PT) neurons are weak but may, if strengthened, compensate for deficient crossed PT actions following brain damage. The purpose of the present study was to examine whether transcranial direct current stimulation (tDCS) can strengthen ipsilateral PT (iPT) actions; in particular, those relayed by reticulospinal neurons co-excited by axon collaterals of fibres descending in the iPT and contralateral PT (coPT) and of reticulospinal neurons descending in the medial longitudinal fascicle (MLF). The effects of tDCS were assessed in acute experiments on deeply anaesthetized cats by comparing postsynaptic potentials evoked in hindlimb motoneurons and discharges recorded from their axons in a ventral root, before, during and after tDCS. tDCS was consistently found to facilitate joint actions of the iPT and coPT, especially when they were stimulated together with the MLF. Both excitatory postsynaptic potentials and inhibitory postsynaptic potentials evoked in motoneurons and the ensuing ventral root discharges were facilitated, even though the facilitatory effects of tDCS were not sufficient for activation of motoneurons by iPT neurons alone. Facilitation outlasted single tDCS periods by at least a few minutes, and the effects evoked by repeated tDCS by up to 2 h. The results of this study thus indicate that tDCS may increase the contribution of iPT actions to the recovery of motor functions after injuries to coPT neurons, and thereby assist rehabilitation, provided that corticoreticular and reticulospinal connections are preserved.
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Affiliation(s)
- Marcin Bączyk
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 11, Box 432, 405 30, Gothenburg, Sweden; Department of Neurobiology, University School of Physical Education, 61-871, Poznań, Poland
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31
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Hand muscles corticomotor excitability in hereditary spastic paraparesis type 4. Neurol Sci 2014; 35:1287-91. [PMID: 24648003 DOI: 10.1007/s10072-014-1707-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Accepted: 02/27/2014] [Indexed: 10/25/2022]
Abstract
Transcranial magnetic stimulation (TMS) studies on the pathways to the upper limbs have revealed inconsistent results in patients harboring mutations in SPAST/SPG4 gene, responsible for the commonest form of hereditary spastic paraplegia (HSP). This paper is addressed to study the corticomotor excitability of the pathways to the upper limbs in SPG4 subjects. We assessed the corticomotor excitability of hand muscles in 12 subjects belonging to 7 unrelated SPG4 families and in 12 control subjects by stimulus-response curve [input-output (I-O) curve]. All the parameters of the recruitment curve (threshold, V50, slope and plateau) did not differ significantly from those of the controls. Presence of upper limb hyper-reflexia did not influence the results of I-O curve. Considering the multiplicity of possible genes/loci accounting for pure HSPs, performing TMS analyses could be helpful in differential diagnosis of pure HSPs in the absence of other clinical or neuroimaging tools.
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32
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Corticomotor excitability of arm muscles modulates according to static position and orientation of the upper limb. Clin Neurophysiol 2014; 125:2046-54. [PMID: 24630543 DOI: 10.1016/j.clinph.2014.02.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 02/08/2014] [Accepted: 02/13/2014] [Indexed: 11/21/2022]
Abstract
OBJECTIVE We investigated how multi-joint changes in static upper limb posture impact the corticomotor excitability of the posterior deltoid (PD) and biceps brachii (BIC), and evaluated whether postural variations in excitability related directly to changes in target muscle length. METHODS The amplitude of individual motor evoked potentials (MEPs) was evaluated in each of thirteen different static postures. Four functional postures were investigated that varied in shoulder and elbow angle, while the forearm was positioned in each of three orientations. Posture-related changes in muscle lengths were assessed using a biomechanical arm model. Additionally, M-waves were evoked in the BIC in each of three forearm orientations to assess the impact of posture on recorded signal characteristics. RESULTS BIC-MEP amplitudes were altered by shoulder and elbow posture, and demonstrated robust changes according to forearm orientation. Observed changes in BIC-MEP amplitudes exceeded those of the M-waves. PD-MEP amplitudes changed predominantly with shoulder posture, but were not completely independent of influence from forearm orientation. CONCLUSIONS Results provide evidence that overall corticomotor excitability can be modulated according to multi-joint upper limb posture. SIGNIFICANCE The ability to alter motor pathway excitability using static limb posture suggests the importance of posture selection during rehabilitation aimed at retraining individual muscle recruitment and/or overall coordination patterns.
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Influence of position and stimulation parameters on intracortical inhibition and facilitation in human tongue motor cortex. Brain Res 2014; 1557:83-9. [PMID: 24534367 DOI: 10.1016/j.brainres.2014.02.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/17/2014] [Accepted: 02/07/2014] [Indexed: 12/15/2022]
Abstract
Paired-pulse transcranial magnetic stimulation (ppTMS) can be used to assess short-interval intracortical inhibitory (SICI) and facilitatory (ICF) networks. Many methodological parameters may however influence the outcome. The aim of the study was to examine the influence of body positions (recline and supine), inter-stimulus intervals (ISI) between the test stimulus (TS) and conditioning stimulus (CS) and intensities of the TS and CS on the degree of SICI and ICF. In studies 1 and 2, fourteen and seventeen healthy volunteers participated respectively. ppTMS was applied over the "hot-spot" of the tongue motor cortex and motor evoked potentials (MEPs) were recorded from contralateral tongue muscles. In study 1, single pulse and three ppTMS ISIs, 2, 10, and 15ms, were applied 8 times each in three blocks (TS: 120%, 140% and 160% of resting motor threshold (rMT); CS: 80% of rMT) in two different body positions (recline and supine) randomly. In study 2, single pulse and four ppTMS ISIs, 2, 2.5, 3, and 3.5ms, were applied 8 times each in randomized order in two blocks (CS: 70% and 80% of rMT; TS: 120% of rMT). There was a significant effect of body position (P=0.049), TS intensities (P<0.001) and ISIs (P<0.001) and interaction between intensity and ISIs (P=0.042) in study 1. In study 2, there was a significant effect of ISI (P<0.001) but not CS intensity (P=0.984) on MEP amplitude. These results may be applied in future studies on the mechanisms of cortical plasticity in the tongue motor pathways using ppTMS and SICI and ICF.
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Suzuki M, Kirimoto H, Sugawara K, Watanabe M, Shimizu S, Ishizaka I, Yamada S, Matsunaga A, Fukuda M, Onishi H. Induction of cortical plasticity for reciprocal muscles by paired associative stimulation. Brain Behav 2014; 4:822-32. [PMID: 25365805 PMCID: PMC4212109 DOI: 10.1002/brb3.280] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 07/27/2014] [Accepted: 08/18/2014] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Paired associative stimulation (PAS) is widely used to induce plasticity in the human motor cortex. Although reciprocal inhibition of antagonist muscles plays a fundamental role in human movements, change in cortical circuits for reciprocal muscles by PAS is unknown. METHODS We investigated change in cortical plasticity for reciprocal muscles during PAS. PAS consisted of 200 pairs of peripheral electric stimulation of the right median nerve at the wrist at a frequency of 0.25 Hz followed by transcranial magnetic stimulation of the left M1 at the midpoint between the center of gravities of the flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles. Measures of motor cortical excitability included resting motor threshold (RMT), GABAA-mediated short-interval intracortical inhibition (SICI), and GABAB-mediated long-interval intracortical inhibition (LICI). RESULTS Motor evoked potential amplitude-conditioned LICI for the FCR muscle was significantly decreased after PAS (P = 0.020), whereas that for the ECR muscle was significantly increased (P = 0.033). Changes in RMT and SICI for the FCR and ECR muscles were not significantly different before and after PAS. Corticospinal excitability for both reciprocal muscles was increased during PAS, but GABAB-mediated cortical inhibitory functions for the agonist and antagonist muscles were reciprocally altered after PAS. CONCLUSION These results implied that the cortical excitability for reciprocal muscles including GABAB-ergic inhibitory systems within human M1 could be differently altered by PAS.
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Affiliation(s)
- Makoto Suzuki
- Graduate School of Medical Sciences, Kitasato University Kanagawa, Japan ; School of Allied Health Sciences, Kitasato University Kanagawa, Japan
| | - Hikari Kirimoto
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare Niigata, Japan
| | - Kazuhiro Sugawara
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare Niigata, Japan
| | - Makoto Watanabe
- School of Allied Health Sciences, Kitasato University Kanagawa, Japan
| | - Shinobu Shimizu
- School of Allied Health Sciences, Kitasato University Kanagawa, Japan
| | - Ikuyo Ishizaka
- School of Allied Health Sciences, Kitasato University Kanagawa, Japan
| | - Sumio Yamada
- Department of Rehabilitation Science, Nagoya University Graduate School of Medicine Nagoya, Japan
| | - Atsuhiko Matsunaga
- Graduate School of Medical Sciences, Kitasato University Kanagawa, Japan ; School of Allied Health Sciences, Kitasato University Kanagawa, Japan
| | - Michinari Fukuda
- Graduate School of Medical Sciences, Kitasato University Kanagawa, Japan ; School of Allied Health Sciences, Kitasato University Kanagawa, Japan
| | - Hideaki Onishi
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare Niigata, Japan
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Bolzoni F, Bączyk M, Jankowska E. Subcortical effects of transcranial direct current stimulation in the rat. J Physiol 2013; 591:4027-42. [PMID: 23774279 DOI: 10.1113/jphysiol.2013.257063] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Transcranial direct current stimulation (tDCS) affects neurons at both cortical and subcortical levels. The subcortical effects involve several descending motor systems but appeared to be relatively weak, as only small increases in the amplitude of subcortically initiated descending volleys and a minute shortening of latencies of these volleys were found. The aim of the present study was therefore to evaluate the consequences of facilitation of these volleys on the ensuing muscle activation. The experiments were carried out on deeply anaesthetized rats without neuromuscular blockade. Effects of tDCS were tested on EMG potentials recorded from neck muscles evoked by weak (20-60 μA) single, double or triple stimuli applied in the medial longitudinal fascicle (MLF) or in the red nucleus (RN). Short latencies of these potentials were compatible with monosynaptic or disynaptic actions of reticulospinal and disynaptic or trisynaptic actions of rubrospinal neurons on neck motoneurons. Despite only weak effects on indirect descending volleys, the EMG responses from both the MLF and the RN were potently facilitated by cathodal tDCS and depressed by anodal tDCS. Both the facilitation and the depression developed relatively rapidly (within the first minute) but both outlasted tDCS and were present for up to 1 h after tDCS. The study thus demonstrates long-lasting effects of tDCS on subcortical neurons in the rat, albeit evoked by an opposite polarity of tDCS to that found to be effective on subcortical neurons in the cat investigated in the preceding study, or for cortical neurons in the humans.
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Affiliation(s)
- F Bolzoni
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
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36
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Adams RA, Shipp S, Friston KJ. Predictions not commands: active inference in the motor system. Brain Struct Funct 2013; 218:611-43. [PMID: 23129312 PMCID: PMC3637647 DOI: 10.1007/s00429-012-0475-5] [Citation(s) in RCA: 356] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 10/25/2012] [Indexed: 12/04/2022]
Abstract
The descending projections from motor cortex share many features with top-down or backward connections in visual cortex; for example, corticospinal projections originate in infragranular layers, are highly divergent and (along with descending cortico-cortical projections) target cells expressing NMDA receptors. This is somewhat paradoxical because backward modulatory characteristics would not be expected of driving motor command signals. We resolve this apparent paradox using a functional characterisation of the motor system based on Helmholtz's ideas about perception; namely, that perception is inference on the causes of visual sensations. We explain behaviour in terms of inference on the causes of proprioceptive sensations. This explanation appeals to active inference, in which higher cortical levels send descending proprioceptive predictions, rather than motor commands. This process mirrors perceptual inference in sensory cortex, where descending connections convey predictions, while ascending connections convey prediction errors. The anatomical substrate of this recurrent message passing is a hierarchical system consisting of functionally asymmetric driving (ascending) and modulatory (descending) connections: an arrangement that we show is almost exactly recapitulated in the motor system, in terms of its laminar, topographic and physiological characteristics. This perspective casts classical motor reflexes as minimising prediction errors and may provide a principled explanation for why motor cortex is agranular.
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Affiliation(s)
- Rick A Adams
- The Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London, WC1N 3BG, UK.
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Tyč F, Boyadjian A, Allam N, Brasil-Neto JP. Abnormal acute changes in upper limb muscle cortical representation areas in the patients with writer's cramp during co-activation of distal and proximal muscles. Acta Physiol (Oxf) 2012; 206:195-207. [PMID: 22574750 DOI: 10.1111/j.1748-1716.2012.02451.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 01/22/2012] [Accepted: 05/03/2012] [Indexed: 11/27/2022]
Abstract
AIM We analysed cortical muscle representation areas during single muscle activation and during the co-activation of several upper arm muscles in the patients with writer's cramp to determine the possible occurrence of abnormal dynamic somatotopic changes in M1, in addition to the static map abnormalities already described in this form of dystonia. METHODS Using transcranial magnetic stimulation, we assessed cortical representations of medial deltoid, extensor carpi radialis and the first dorsal interosseus muscles in eight patients with writer's cramp and in eight healthy control subjects. Cortical maps were obtained during distal muscles' activation either in isolation or in conjunction with voluntary medial deltoid co-activation. RESULTS This study showed a difference in the organization of cortical representations of these muscles between the patients with dystonia and control subjects. The first dorsal interosseus and the extensor carpi radialis cortical representation areas were larger in the dystonic group. The cortical representations became larger when the medial deltoid was simultaneously co-activated, and this effect was not observed in the control group. In the dystonic group, the three cortical muscle representations largely overlapped and their centres of gravity were closer. CONCLUSION Patients with dystonia showed not only a different spatial organization of muscle cortical representation areas, but also abnormal acute somatotopic changes during proximal muscle co-activation. Task-specific motor impairment in writer's cramp may result not only from lack of cortical inhibition and the well-known anomalous cortical organization observed in these patients, but also from abnormal patterns of proximo-distal functional muscle coupling.
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Affiliation(s)
| | | | | | - J. P. Brasil-Neto
- Laboratório de Neurociências e Comportamento; Universidade de Brasilia (UnB); Distrito Federal; Brasil
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Suzuki M, Kirimoto H, Onishi H, Yamada S, Tamaki H, Maruyama A, Yamamoto JI. Reciprocal changes in input–output curves of motor evoked potentials while learning motor skills. Brain Res 2012; 1473:114-23. [DOI: 10.1016/j.brainres.2012.07.043] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 07/23/2012] [Indexed: 11/15/2022]
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Rossi A, Rossi S, Ginanneschi F. Activity-dependent changes in intrinsic excitability of human spinal motoneurones produced by natural activity. J Neurophysiol 2012; 108:2473-80. [PMID: 22933724 DOI: 10.1152/jn.00477.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The current study was designed to evaluate activity-dependent changes intrinsic to the spinal motoneurones (MNs) associated with sustained contractions. The excitability of spinal MNs (reflected by the antidromically evoked F-wave) innervating the abductor digiti minimi muscle (ADM) was measured in 12 healthy subjects following maximum voluntary contractions (MVCs) of ADM lasting 5 s, 15 s, 30 s, and 60 s. Upon cessation of the contractions, F-waves showed a depression, which increased in depth and duration with increasing duration of contraction. Following a 5-s contraction, there was a 20% decrease, which waned in 2 min, whereas a 60-s contraction produced a 40% decrease and waned in over 15 min. The changes in excitability of peripheral motor axons produced by the MVCs were measured by recording an ADM compound muscle action potential (CMAP) of ~50% of maximum to a constant ulnar nerve electrical stimulation. On cessation of the contractions, there was a prominent decrease in size of the CMAP: following a 5-s MVC, it produced a 10% decrease in the size of the test CMAP, which recovered in 2 min, whereas following a 60-s MVC, it produced a 30% decrease, which recovered in over 15 min. Statistical analysis (correntropy) showed a high-order mutual dependence between F-wave and CMAP, and both were significantly dependent on MVC duration. Because of the parallel excitability changes in peripheral axons and spinal MNs, our interpretation is that intrinsic excitability of the axon initial segment (i.e., where the action potential is generated) and peripheral axon segments changed in a similar, activity-dependent manner.
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Affiliation(s)
- Alessandro Rossi
- Department of Neurological, Neurosurgical and Behavioral Sciences, University of Siena, Siena, Italy.
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The effect of changes in joint angle on the characteristics of physiological tremor. J Electromyogr Kinesiol 2012; 22:954-60. [PMID: 22608278 DOI: 10.1016/j.jelekin.2012.04.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 03/14/2012] [Accepted: 04/20/2012] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Physiological tremor, as a whole, can be influenced by changes in muscle activity. However, the origin of low-frequency physiological tremor oscillations has yet to be conclusively determined. It is possible that by experimentally manipulating muscular activity, a better determination of the origin of those low-frequency oscillations can be achieved. It was demonstrated that changes in joint angle modify characteristics of muscular activity. As such, we hypothesize that changes in wrist-joint angle will alter the characteristics of low-frequency physiological tremor oscillations. OBJECTIVE Assess the influence of changes in joint angle of the wrist on characteristics of physiological finger tremor. METHODS Physiological finger tremor was recorded (n = 25) using a laser displacement system while the arm and hand were supported. The relative angle between the dorsum of the hand and the forearm was altered between conditions (135°, 180°, 225° and 270°), while the hand and the finger remained parallel to the ground. EMG of the extensors and flexors were also recorded. RESULTS Tremor amplitude was significantly altered by changes in wrist-joint angle. This was especially the case for lower frequency oscillations. In addition, electromyography properties of forearm muscles were also significantly modified by changes in wrist-joint angles. CONCLUSIONS This study demonstrates that changes in wrist-joint angle modify the characteristics of physiological finger tremor. This should be taken into account when interpreting tremor data as well as when developing tools to minimize tremor.
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Hoffmann G, Schmit BD, Kahn JH, Kamper DG. Effect of sensory feedback from the proximal upper limb on voluntary isometric finger flexion and extension in hemiparetic stroke subjects. J Neurophysiol 2011; 106:2546-56. [PMID: 21832028 DOI: 10.1152/jn.00522.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study investigated the potential influence of proximal sensory feedback on voluntary distal motor activity in the paretic upper limb of hemiparetic stroke survivors and the potential effect of voluntary distal motor activity on proximal muscle activity. Ten stroke subjects and 10 neurologically intact control subjects performed maximum voluntary isometric flexion and extension, respectively, at the metacarpophalangeal (MCP) joints of the fingers in two static arm postures and under three conditions of electrical stimulation of the arm. The tasks were quantified in terms of maximum MCP torque [MCP flexion (MCP(flex)) or MCP extension (MCP(ext))] and activity of targeted (flexor digitorum superficialis or extensor digitorum communis) and nontargeted upper limb muscles. From a previous study on the MCP stretch reflex poststroke, we expected stroke subjects to exhibit a modulation of voluntary MCP torque production by arm posture and electrical stimulation and increased nontargeted muscle activity. Posture 1 (flexed elbow, neutral shoulder) led to greater MCP(flex) in stroke subjects than posture 2 (extended elbow, flexed shoulder). Electrical stimulation did not influence MCP(flex) or MCP(ext) in either subject group. In stroke subjects, posture 1 led to greater nontargeted upper limb flexor activity during MCP(flex) and to greater elbow flexor and extensor activity during MCP(ext). Stroke subjects exhibited greater elbow flexor activity during MCP(flex) and greater elbow flexor and extensor activity during MCP(ext) than control subjects. The results suggest that static arm posture can modulate voluntary distal motor activity and accompanying muscle activity in the paretic upper limb poststroke.
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Affiliation(s)
- Gilles Hoffmann
- Sensory Motor Performance Program, Rehabilitation Institute of Chicago, 345 E. Superior St., Suite 1406, Chicago, IL 60611, USA.
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Soteropoulos DS, Perez MA. Physiological changes underlying bilateral isometric arm voluntary contractions in healthy humans. J Neurophysiol 2011; 105:1594-602. [PMID: 21273315 DOI: 10.1152/jn.00678.2010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Many bilateral motor tasks engage simultaneous activation of distal and proximal arm muscles, but little is known about their physiological interactions. Here, we used transcranial magnetic stimulation to examine motor-evoked potentials (MEPs), interhemispheric inhibition at a conditioning-test interval of 10 (IHI(10)) and 40 ms (IHI(40)), and short-interval intracortical inhibition (SICI) in the left first dorsal interosseous (FDI) muscle during isometric index finger abduction. The right side remained at rest or performed isometric voluntary contraction with the FDI, biceps or triceps brachii, or the tibialis anterior. Left FDI MEPs were suppressed to a similar extent during contraction of the right FDI and biceps and triceps brachii but remained unchanged during contraction of the right tibialis anterior. IHI(10) and IHI(40) were decreased during contraction of the right biceps and triceps brachii compared with contraction of the right FDI. SICI was increased during activation of the right biceps and triceps brachii and decreased during activation of the right FDI. The present results indicate that an isometric voluntary contraction with either a distal or a proximal arm muscle, but not a foot dorsiflexor, decreases corticospinal output in a contralateral active finger muscle. Transcallosal inhibitory effects were strong during bilateral activation of distal hand muscles and weak during simultaneous activation of a distal and a proximal arm muscle, whereas GABAergic intracortical activity was modulated in the opposite manner. These findings suggest that in intact humans crossed interactions at the level of the motor cortex involved different physiological mechanisms when bilateral distal hand muscles are active and when a distal and a proximal arm muscle are simultaneously active.
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Affiliation(s)
- Demetris S Soteropoulos
- Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
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Tyč F, Boyadjian A. Plasticity of motor cortex induced by coordination and training. Clin Neurophysiol 2010; 122:153-62. [PMID: 21168091 DOI: 10.1016/j.clinph.2010.05.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 05/05/2010] [Accepted: 05/24/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE To study the modifications induced by training of a coordinated movement on the primary motor cortex (M1) maps of one proximal muscle and one distal muscle activated alone and during their co-contraction. METHODS Six healthy female sport students performed a 6-week training program during which they were trained in darts 3-4 times a week. At the end each subject had made more than 1200 throws. Transcranial magnetic stimulation (TMS) was used to map the proximal medial deltoid (MD) and the distal brachio-radialis (BR) muscle representations on M1. Motor evoked potentials (MEPs) amplitude and excitability curves were used to test corticomotor excitability. RESULTS The cortical representation areas of each muscle separately increased after training. The cortical representation and the excitability curve of the BR muscle increased during co-activation with the MD. Combining co-contraction and training produced a further enlargement of the M1 representation of the BR muscle. CONCLUSIONS The enlargement of the BR representation in M1 suggests the development of overlapping zones specifying functional synergies between distal and proximal muscles. SIGNIFICANCE Our findings support the idea that training of a coordinated movement involving several muscles and joints requires an activity-dependent coupling of cortical networks.
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Affiliation(s)
- F Tyč
- Laboratoire Plasticité et Physio-Pathologie de la Motricité, UMR 6196, CNRS, 31 Chemin J. Aiguier, 13402 Marseille Cedex 20, France.
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Raptis H, Burtet L, Forget R, Feldman AG. Control of wrist position and muscle relaxation by shifting spatial frames of reference for motoneuronal recruitment: possible involvement of corticospinal pathways. J Physiol 2010; 588:1551-70. [PMID: 20231141 PMCID: PMC2876809 DOI: 10.1113/jphysiol.2009.186858] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2010] [Accepted: 03/09/2010] [Indexed: 11/08/2022] Open
Abstract
It has previously been established that muscles become active in response to deviations from a threshold (referent) position of the body or its segments, and that intentional motor actions result from central shifts in the referent position. We tested the hypothesis that corticospinal pathways are involved in threshold position control during intentional changes in the wrist position in humans. Subjects moved the wrist from an initial extended to a final flexed position (and vice versa). Passive wrist muscle forces were compensated with a torque motor such that wrist muscle activity was equalized at the two positions. It appeared that motoneuronal excitability tested by brief muscle stretches was also similar at these positions. Responses to mechanical perturbations before and after movement showed that the wrist threshold position was reset when voluntary changes in the joint angle were made. Although the excitability of motoneurons was similar at the two positions, the same transcranial magnetic stimulus (TMS) elicited a wrist extensor jerk in the extension position and a flexor jerk in the flexion position. Extensor motor-evoked potentials (MEPs) elicited by TMS at the wrist extension position were substantially bigger compared to those at the flexion position and vice versa for flexor MEPs. MEPs were substantially reduced when subjects fully relaxed wrist muscles and the wrist was held passively in each position. Results suggest that the corticospinal pathway, possibly with other descending pathways, participates in threshold position control, a process that pre-determines the spatial frame of reference in which the neuromuscular periphery is constrained to work. This control strategy would underlie not only intentional changes in the joint position, but also muscle relaxation. The notion that the motor cortex may control motor actions by shifting spatial frames of reference opens a new avenue in the analysis and understanding of brain function.
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Affiliation(s)
- Helli Raptis
- Department of Physiology, University of Montreal, Montreal, QC, H3S 2J4, Canada.
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Rossi A, Biasella A, Scarselli C, Piu P, Ginanneschi F. Influence of activity-induced axonal hypoexcitability on transmission of descending and segmental signals. Brain Res 2009; 1320:47-59. [PMID: 20026312 DOI: 10.1016/j.brainres.2009.12.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 12/04/2009] [Accepted: 12/07/2009] [Indexed: 01/21/2023]
Abstract
In this experiment, the changes in excitability of motor axons produced after natural activity were measured in nine healthy subjects using 1 min of maximal voluntary contractions (MVC) of the abductor digiti minimi (ADM) by studying the relationship between stimulus intensity applied to the ulnar nerve and the size of the ADM compound muscle action potential (CMAP). On cessation of the contraction, there was a prominent right-shift of the input-output curve: the intensity required to produce a control CMAP approximately 60% of maximum, generated a post-contraction response approximately 25% of maximum. Similar changes occurred in the input-output curves obtained by recording the ulnar nerve volley evoked by same test stimulus for CMAP. Motor-evoked potential (MEP) and F-waves (and H-reflex in one subject) were recorded from ADM before and after 1 min of MVC. On cessation of contraction, the MEP input-output curves exhibited a significant right-shift: the stimulus required to evoke a pre-contraction maximum MEP ( approximately 60% of maximum CMAP) generated a post-contraction response approximately 65% of initial values. One minute of MVC produced similar decreases of F ( approximately 35%)- and H ( approximately 30%)-ADM responses. All responses recovered their control value in 15-20 min after the end of contraction. The almost identical depressive effect produced by 1 min of MVC on peripherally and centrally generated muscle responses suggests a common conditioning factor. These findings are discussed within the context of activity-induced motor axonal hyperpolarizion.
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Affiliation(s)
- Alessandro Rossi
- Clinical Neurophysiology, Department of Neurological Neurosurgical and Behavioural Sciences, University of Siena, Viale Bracci 1, 53100 Siena, Italy.
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Bensmail D, Sarfeld AS, Fink GR, Nowak DA. Intermanual transfer of sensorimotor memory for grip force when lifting objects: the role of wrist angulation. Clin Neurophysiol 2009; 121:402-7. [PMID: 20004612 DOI: 10.1016/j.clinph.2009.11.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 11/04/2009] [Accepted: 11/08/2009] [Indexed: 10/20/2022]
Abstract
OBJECTIVE To investigate the mechanisms underlying the intermanual transfer of sensorimotor memory when lifting an object. METHODS Twenty healthy subjects grasped and lifted an object with constant mechanical properties with the right hand (RH) first and then with the left hand (LH). Ten of the subjects lifted the object with the RH in a regular wrist angulation (WA), followed by lifts with the LH in a regular WA. The remaining 10 subjects lifted the object with the RH in a hyper-flexed WA, followed by lifts with the LH in a regular WA. RESULTS Subjects generated greater peak grip force (GF) rates, grip and lift forces when lifting the object with the wrist in a regular WA compared to lifts with the wrist in hyper-flexion. Importantly, subjects transferred the predictive scaling of GF from the RH to the LH, regardless of the WA. CONCLUSIONS Biomechanical properties of the object do not seem to be used by the CNS as a first line information to evaluate GF when handling an object or transferring information about the grasp to the opposite hemisphere. SIGNIFICANCE The predictive scaling of GF rather reflects an internal sense of effort than an internal representation of the mechanical object properties.
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Affiliation(s)
- Djamel Bensmail
- Department of Neurology, University Hospital, University of Cologne, Cologne, Germany
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Bensmail D, Sarfeld AS, Fink GR, Nowak DA. Sensorimotor processing in the grip-lift task: the impact of maximum wrist flexion/extension on force scaling. Clin Neurophysiol 2009; 120:1588-95. [PMID: 19577513 DOI: 10.1016/j.clinph.2009.05.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Revised: 05/04/2009] [Accepted: 05/05/2009] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To evaluate the effect of wrist angulation on the grip force (GF) scaling in healthy subjects. METHODS The first experiment investigated if hyperflexion or hyperextension of the wrist affects the scaling of GF. Subjects performed sets of 10 lifts with the wrist positioned in (i) a self-chosen, regular, slightly extended angulation, (ii) a hyperextended angulation and (iii) a hyperflexed angulation. The second experiment tested if wrist angulation applied during a preceding lift influenced GF scaling when lifting the object with a predefined wrist angulation. RESULTS Compared with the regular and hyperflexed wrist angulations, subjects generated an overshoot of GF when lifting the object with the wrist hyperextended. Irrespective of the wrist angulation applied in the preceding lift, subjects generated an overshoot of GF when lifting the object with the wrist hyperextended, but not during lifts with the wrist in a regular or hyperflexed angulation. CONCLUSIONS We demonstrate that a change in the horizontal angulation of the wrist of the grasping hand interferes with the scaling of GF. SIGNIFICANCE We interpret these data to reflect a very basic strategic response of the motor system to changes in the geometry of the hand in order to ensure grasp stability.
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Affiliation(s)
- Djamel Bensmail
- Department of Physical Medicine and Rehabilitation, Hôpital R. Poincaré, Garches, AP-HP, University of Versailles Saint-Quentin, Versailles, France
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Increase in corticospinal excitability of limb and trunk muscles according to maintenance of neck flexion. Neurosci Lett 2009; 461:235-9. [PMID: 19545609 DOI: 10.1016/j.neulet.2009.06.047] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 06/03/2009] [Accepted: 06/16/2009] [Indexed: 10/20/2022]
Abstract
The effect of maintenance of neck flexion on corticospinal excitability of limb and trunk muscles was investigated using transcranial magnetic stimulation (TMS). Nine healthy young subjects participated in this experiment. Every measurement was performed with subjects sitting on a chair. Target muscles were the first dorsal interosseous (FDI), biceps brachii (BB), triceps brachii (TB), rectus abdominis (RA), erector spinae (ES), rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GcM) on the right side. TMS was applied to the left primary motor cortex, and motor evoked potential (MEP) was measured from the muscles listed above. Optimal stimulus location and resting motor threshold (RMT) were identified for each target muscle, and stimulus intensity used was 120% of RMT. MEPs of the target muscle were recorded with the chin resting on a chin support (chin-on condition) with neck in 20 degrees of flexion, and with voluntary maintenance of the neck flexion posture (chin-off condition). Amplitude and latency of MEP and background activity of target muscles were analyzed. For FDI, BB, TB, ES, and RF, amplitude of MEP increased and latency shortened in the chin-off compared with the chin-on condition. No significant difference in background activity of each target muscle was found between the two conditions. Corticospinal excitability of limb and trunk muscles was selectively enhanced while neck flexion was maintained.
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Abstract
Stimulus-triggered averaging (StTA) of electromyographic (EMG) activity is a form of intracortical microstimulation that enables documentation in awake animals of the sign, magnitude, latency, and distribution of output effects from cortical and brainstem areas to motoneurons of different muscles. In this study, we show that the properties of effects in StTAs are stable and mostly independent of task conditions. StTAs of EMG activity from 24 forelimb muscles were collected from two male rhesus monkeys while they performed three tasks: (1) an isometric step tracking wrist task, (2) an isometric whole-arm push-pull task, and (3) a reach-to-grasp task. Layer V sites in primary motor cortex were identified and microstimuli were applied (15 muA) at a low rate (15 Hz). Our results show that the sign of effects (facilitation or suppression) in StTAs of EMG activity are remarkably stable in the presence of joint angle position changes (96% stable), whole-arm posture changes (97% stable), and across fundamentally different types of tasks such as arm push-pull versus reach-to-grasp (81% stable). Furthermore, comparing effects across different phases of a task also yielded remarkable stability (range, 84-96%). At different shoulder, elbow, and wrist angles, the magnitudes of effects in individual muscles were highly correlated. Our results demonstrate that M1 output effects obtained with StTA of EMG activity are highly stable across widely varying joint angles and motor tasks. This study further validates the use of StTA for mapping and other studies of cortical motor output.
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Mazzocchio R, Gelli F, Del Santo F, Popa T, Rossi A. Effects of posture-related changes in motor cortical output on central oscillatory activity of pathological origin in humans. Brain Res 2008; 1223:65-72. [PMID: 18597745 DOI: 10.1016/j.brainres.2008.05.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 05/13/2008] [Accepted: 05/13/2008] [Indexed: 10/22/2022]
Abstract
Changes in shoulder position influence motor cortical outflow to Abductor Digiti Minimi (ADM) muscle in healthy humans. We examined whether these changes may affect finger tremor of central origin. Subjects had their shoulder positioned in two different configurations: 30 degrees horizontal adduction (ANT) and 30 degrees horizontal abduction (POST) with respect to neutral position at 0 degrees in the horizontal plane. In healthy subjects, patients with Parkinsonian tremor (PT) and essential tremor (ET), transcranial magnetic stimulation (TMS) of the motor cortex was performed under resting and active conditions in ANT and POST. PT, ET and physiological tremor (PhT) were studied by accelerometric recordings from the little finger and by EMG activity from ADM and Extensor Carpi Radialis (ECR) in ANT and POST. In healthy and ET subjects, ADM motor evoked responses (MEPs) to TMS were smaller under resting, but larger under active conditions in POST. In PT patients, MEPs showed no difference at rest in ANT but were lower during ADM activation in POST. PT decreased, whereas ET increased in POST. These changes were paralleled by a decrease in PT EMG power and an increase in ET EMG power in POST. In PhT, there was no difference in tremor amplitude between ANT and POST. PT decrease and ET increase in POST parallel the changes in motor cortical outflow to ADM induced by modification of shoulder position under active conditions. This may be evidence for altered premotor-motor interaction at cortical level in PT, and for a role of the motor cortex in generating ET.
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Affiliation(s)
- Riccardo Mazzocchio
- Sezione di Neurofisiologia Clinica, Dipartimento di Scienze Neurologiche e del Comportamento, Universita' di Siena, Viale Bracci I, Siena, Italy.
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