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Canlı K, Van Oijen J, Van Oosterwijck J, Meeus M, Van Oosterwijck S, De Meulemeester K. Influence of sensory retraining on cortical reorganization in peripheral neuropathy: A systematic review. PM R 2024; 16:888-907. [PMID: 38155585 DOI: 10.1002/pmrj.13126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 11/19/2023] [Accepted: 12/14/2023] [Indexed: 12/30/2023]
Abstract
OBJECTIVE This study systematically reviewed the literature about sensory retraining effect in comparison to other rehabilitative techniques on cortical reorganization in patients with peripheral neuropathic pain. TYPE: Systematic review. LITERATURE SURVEY After an electronic search of PubMed, Web of Science, and Embase, risk of bias was assessed using the revised Cochrane risk of bias tool for randomized controlled trials and the ROBINS-1 (Risk of bias in non-randomized studies-of interventions) for non-randomized studies of intervention. METHODOLOGY The strength of conclusion was determined using the evidence-based guideline development approach. SYNTHESIS Limited evidence indicates a higher increase in cortical inhibition and a higher reduction in cortical activation during a motor task of the affected hemisphere after graded motor imagery compared to wait-list. Higher reductions in map volume (total excitability of the cortical representation) of the affected hemisphere after peripheral electrical stimulation (PES) were observed when compared to transcranial direct current stimulation (tDCS) or to sham treatment with limited evidence. No other differences in cortical excitability and representation of the affected and non-affected hemisphere were observed when comparing mirror therapy with sham therapy or tDCS, PES with sham therapy or tDCS, and graded motor imagery with wait-list. CONCLUSIONS Graded motor imagery and PES result in higher cortical excitability reductions of the affected hemisphere compared to wait-list, tDCS and sham treatment, respectively.
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Affiliation(s)
- Kübra Canlı
- Faculty of Physical Therapy and Rehabilitation, Hacettepe University, Ankara, Türkiye
| | - Joris Van Oijen
- Department of Rehabilitation Sciences, Spine, Pain and Head Research Unit Ghent, Ghent University, Ghent, Belgium
| | - Jessica Van Oosterwijck
- Department of Rehabilitation Sciences, Spine, Pain and Head Research Unit Ghent, Ghent University, Ghent, Belgium
- Pain in Motion International Research Group, Brussels, Belgium
| | - Mira Meeus
- Department of Rehabilitation Sciences, Spine, Pain and Head Research Unit Ghent, Ghent University, Ghent, Belgium
- Pain in Motion International Research Group, Brussels, Belgium
- Research Group MOVANT, Department of Rehabilitation Sciences and Physiotherapy (REVAKI), University of Antwerp, Antwerpen, Belgium
| | - Sophie Van Oosterwijck
- Department of Rehabilitation Sciences, Spine, Pain and Head Research Unit Ghent, Ghent University, Ghent, Belgium
- Pain in Motion International Research Group, Brussels, Belgium
- Research Foundation-Flanders (FWO), Brussels, Belgium
| | - Kayleigh De Meulemeester
- Department of Rehabilitation Sciences, Spine, Pain and Head Research Unit Ghent, Ghent University, Ghent, Belgium
- Pain in Motion International Research Group, Brussels, Belgium
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Mao L, Lu X, Yu C, Yin K. Physiological and Neural Changes with Rehabilitation Training in a 53-Year Amputee: A Case Study. Brain Sci 2022; 12:brainsci12070832. [PMID: 35884639 PMCID: PMC9313058 DOI: 10.3390/brainsci12070832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 05/25/2022] [Accepted: 05/30/2022] [Indexed: 02/05/2023] Open
Abstract
Many people who received amputation wear sEMG prostheses to assist in their daily lives. How these prostheses promote muscle growth and change neural activity remains elusive. We recruited a subject who had his left hand amputated for over 53 years to participate in a six-week rehabilitation training using an sEMG prosthesis. We tracked the muscle growth of his left forearm and changes in neural activity over six weeks. The subject showed an increase in fast muscle fiber in his left forearm during the training period. In an analysis of complex networks of neural activity, we observed that the α-band network decreased in efficiency but increased in its capability to integrate information. This could be due to an expansion of the network to accommodate new movements enabled by rehabilitation training. Differently, we found that in the β-band network, a band frequency related to motor functions, the efficiency of the network initially decreased but started to increase after approximately three weeks. The ability to integrate network information showed an opposite trend compared with its efficiency. rMT values, a measure that negatively correlates with cortical excitability, showed a sharp decrease in the first three weeks, suggesting an increase in cortical excitability. In the last three weeks, there was little to no change. These data indicate that rehabilitation training promoted fast muscle fiber growth and introduced neural activity changes in the subject during the first three weeks of training. Our study gave insights into how rehabilitation training with an sEMG prosthesis could lead to physiological and neural changes in amputees.
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Affiliation(s)
- Lin Mao
- Nanjing Research Institute of Electronic Technology, Nanjing 210019, China; (L.M.); (C.Y.)
| | - Xiao Lu
- Department of Rehabilitation Medicine, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029, China;
| | - Chao Yu
- Nanjing Research Institute of Electronic Technology, Nanjing 210019, China; (L.M.); (C.Y.)
| | - Kuiying Yin
- Nanjing Research Institute of Electronic Technology, Nanjing 210019, China; (L.M.); (C.Y.)
- Correspondence:
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Gunduz ME, Pinto CB, Saleh Velez FG, Duarte D, Pacheco-Barrios K, Lopes F, Fregni F. Motor Cortex Reorganization in Limb Amputation: A Systematic Review of TMS Motor Mapping Studies. Front Neurosci 2020; 14:314. [PMID: 32372907 PMCID: PMC7187753 DOI: 10.3389/fnins.2020.00314] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 03/17/2020] [Indexed: 12/16/2022] Open
Abstract
Purpose: The purpose of this systematic review is to evaluate motor cortex reorganization in amputees as indexed by transcranial magnetic stimulation (TMS) cortical mapping and its relationship with phantom limb pain (PLP). Methods: Pubmed database were systematically searched. Three independent researchers screened the relevant articles, and the data of motor output maps, including the number of effective stimulation sites, center of gravity (CoG) shift, and their clinical correlations were extracted. We calculated a pooled CoG shift for motor cortex TMS mapping. Results: The search yielded 468 articles, 11 were included. Three studies performed correlation between the cortical changes and PLP intensity, and only one study compared cortical mapping changes between amputees with pain and without pain. Results showed (i) enlarged excitable area and a shift of CoG of neighboring areas toward the deafferented limb area; (ii) no correlation between motor cortex reorganization and level of pain and (iii) greater cortical reorganization in patients with PLP compared to amputation without pain. Conclusion: Our review supports the evidence for cortical reorganization in the affected hemisphere following an amputation. The motor cortex reorganization could be a potential clinical target for prevention and treatment response of PLP.
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Affiliation(s)
- Muhammed Enes Gunduz
- Laboratory of Neuromodulation & Center for Clinical Research Learning, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA, United States
| | - Camila Bonin Pinto
- Laboratory of Neuromodulation & Center for Clinical Research Learning, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA, United States
| | - Faddi Ghassan Saleh Velez
- Laboratory of Neuromodulation & Center for Clinical Research Learning, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA, United States
| | - Dante Duarte
- Laboratory of Neuromodulation & Center for Clinical Research Learning, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA, United States
| | - Kevin Pacheco-Barrios
- Laboratory of Neuromodulation & Center for Clinical Research Learning, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA, United States.,Unidad de Investigación Para la Generación y Síntesis de Evidencias en Salud, Universidad San Ignacio de Loyola, Lima, Peru
| | - Fernanda Lopes
- Laboratory of Neuromodulation & Center for Clinical Research Learning, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA, United States
| | - Felipe Fregni
- Laboratory of Neuromodulation & Center for Clinical Research Learning, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA, United States
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Nardone R, Versace V, Sebastianelli L, Brigo F, Christova M, Scarano GI, Saltuari L, Trinka E, Hauer L, Sellner J. Transcranial magnetic stimulation in subjects with phantom pain and non-painful phantom sensations: A systematic review. Brain Res Bull 2019; 148:1-9. [DOI: 10.1016/j.brainresbull.2019.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 03/03/2019] [Accepted: 03/05/2019] [Indexed: 12/18/2022]
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Jono Y, Iwata Y, Mizusawa H, Hiraoka K. Change in Excitability of Corticospinal Pathway and GABA-Mediated Inhibitory Circuits of Primary Motor Cortex Induced by Contraction of Adjacent Hand Muscle. Brain Topogr 2016; 29:834-846. [PMID: 27251710 DOI: 10.1007/s10548-016-0499-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 05/24/2016] [Indexed: 11/29/2022]
Abstract
The present study examined whether the excitability of the corticospinal pathway and the GABA-mediated inhibitory circuits of the primary motor cortex that project onto the corticospinal neurons in the tonically contracting hand muscle are changed by tonic contraction of the adjacent hand muscle. The motor evoked potential (MEP) and cortical silent period (CSP) in the tonically contracting hand muscle were obtained while the adjacent hand muscle was either tonically contracting or at rest. The MEP and CSP of the first dorsal interosseous (FDI) muscle elicited across the scalp sites where the MEP is predominantly elicited in the FDI muscle were decreased by tonic contraction of the abductor digiti minimi (ADM) muscle. The centers of the area of the MEP and the duration of the CSP in the FDI muscle elicited across the sites where the MEP is predominantly elicited in the FDI muscle were lateral to those in the FDI muscle elicited across the sites where the MEP is elicited in both the FDI and ADM muscles. They were also lateral to those in the ADM muscle elicited either across the sites where the MEP is predominantly elicited in the ADM muscle, or across the sites where the MEP is elicited in both the FDI and ADM muscles. The decrease in the corticospinal excitability and the excitability of the GABA-mediated inhibitory circuits of the primary motor cortex that project onto the corticospinal neurons in the FDI muscle may be due either to (1) the interaction between the activity of the lateral area of the FDI representation and the descending drive to the ADM muscle, or (2) the decreased susceptibility of the primary motor area that predominantly projects onto the corticospinal neurons in the FDI muscle, which also plays a role in independent finger movement when both the FDI and ADM muscles act together as synergists.
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Affiliation(s)
- Yasutomo Jono
- Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, 3-7-30 Habikino, Habikino, Osaka, 583-8555, Japan
| | - Yasuyuki Iwata
- Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, 3-7-30 Habikino, Habikino, Osaka, 583-8555, Japan
| | - Hiroki Mizusawa
- Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, 3-7-30 Habikino, Habikino, Osaka, 583-8555, Japan
| | - Koichi Hiraoka
- College of Health and Human Sciences, Osaka Prefecture University, Habikino, Osaka, Japan.
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Hermsen A, Haag A, Duddek C, Balkenhol K, Bugiel H, Bauer S, Mylius V, Menzler K, Rosenow F. Test–retest reliability of single and paired pulse transcranial magnetic stimulation parameters in healthy subjects. J Neurol Sci 2016; 362:209-16. [DOI: 10.1016/j.jns.2016.01.039] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 12/28/2015] [Accepted: 01/20/2016] [Indexed: 10/22/2022]
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Batista e Sá VW, Gomes MK, Rangel MLS, Sanchez TA, Moreira FA, Hoefle S, Souto IB, da Cunha AJLA, Fontana AP, Vargas CD. Primary Motor Cortex Representation of Handgrip Muscles in Patients with Leprosy. PLoS Negl Trop Dis 2015. [PMID: 26203653 PMCID: PMC4512691 DOI: 10.1371/journal.pntd.0003944] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Leprosy is an endemic infectious disease caused by Mycobacterium leprae that predominantly attacks the skin and peripheral nerves, leading to progressive impairment of motor, sensory and autonomic function. Little is known about how this peripheral neuropathy affects corticospinal excitability of handgrip muscles. Our purpose was to explore the motor cortex organization after progressive peripheral nerve injury and upper-limb dysfunction induced by leprosy using noninvasive transcranial magnetic stimulation (TMS). METHODS In a cross-sectional study design, we mapped bilaterally in the primary motor cortex (M1) the representations of the hand flexor digitorum superficialis (FDS), as well as of the intrinsic hand muscles abductor pollicis brevis (APB), first dorsal interosseous (FDI) and abductor digiti minimi (ADM). All participants underwent clinical assessment, handgrip dynamometry and motor and sensory nerve conduction exams 30 days before mapping. Wilcoxon signed rank and Mann-Whitney tests were performed with an alpha-value of p<0.05. FINDINGS Dynamometry performance of the patients' most affected hand (MAH), was worse than that of the less affected hand (LAH) and of healthy controls participants (p = 0.031), confirming handgrip impairment. Motor threshold (MT) of the FDS muscle was higher in both hemispheres in patients as compared to controls, and lower in the hemisphere contralateral to the MAH when compared to that of the LAH. Moreover, motor evoked potential (MEP) amplitudes collected in the FDS of the MAH were higher in comparison to those of controls. Strikingly, MEPs in the intrinsic hand muscle FDI had lower amplitudes in the hemisphere contralateral to MAH as compared to those of the LAH and the control group. Taken together, these results are suggestive of a more robust representation of an extrinsic hand flexor and impaired intrinsic hand muscle function in the hemisphere contralateral to the MAH due to leprosy. CONCLUSION Decreased sensory-motor function induced by leprosy affects handgrip muscle representation in M1.
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Affiliation(s)
- Vagner Wilian Batista e Sá
- Núcleo de Pesquisas em Fisioterapia, Universidade Castelo Branco, Rio de Janeiro, Rio de Janeiro, Brazil
- Programa de Pós-Graduação em Clínica Médica, Hospital Universitário Clementino Fraga Filho e Departamento de Medicina de Família e Comunidade/Faculdade de Medicina da Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
- Laboratório de Neurobiologia II, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail: (VWBeS); (CDV)
| | - Maria Katia Gomes
- Programa de Pós-Graduação em Clínica Médica, Hospital Universitário Clementino Fraga Filho e Departamento de Medicina de Família e Comunidade/Faculdade de Medicina da Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Maria Luíza Sales Rangel
- Laboratório de Neurobiologia II, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Tiago Arruda Sanchez
- Programa de Pós-Graduação em Clínica Médica, Hospital Universitário Clementino Fraga Filho e Departamento de Medicina de Família e Comunidade/Faculdade de Medicina da Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Filipe Azaline Moreira
- Programa de Pós-Graduação em Clínica Médica, Hospital Universitário Clementino Fraga Filho e Departamento de Medicina de Família e Comunidade/Faculdade de Medicina da Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Sebastian Hoefle
- Laboratório de Neurobiologia II, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
- Cognitive and Behavioral Neuroscience Unit and Neuroinformatics Workgroup, D'Or Institute for Research and Education, Rio de Janeiro, Brazil
| | - Inaiacy Bittencourt Souto
- Programa de Pós-Graduação em Clínica Médica, Hospital Universitário Clementino Fraga Filho e Departamento de Medicina de Família e Comunidade/Faculdade de Medicina da Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Antônio José Ledo Alves da Cunha
- Programa de Pós-Graduação em Clínica Médica, Hospital Universitário Clementino Fraga Filho e Departamento de Medicina de Família e Comunidade/Faculdade de Medicina da Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ana Paula Fontana
- Programa de Pós-Graduação em Clínica Médica, Hospital Universitário Clementino Fraga Filho e Departamento de Medicina de Família e Comunidade/Faculdade de Medicina da Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Claudia Domingues Vargas
- Laboratório de Neurobiologia II, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
- Instituto de Neurologia Deolindo Couto da Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail: (VWBeS); (CDV)
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Surgical leg rotation: cortical neuroplasticity assessed through brain mapping using transcranial magnetic stimulation. Int J Rehabil Res 2015; 37:323-33. [PMID: 25153790 PMCID: PMC4213133 DOI: 10.1097/mrr.0000000000000075] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Rotationplasty (Borggreve-Van Nes operation) is a rare limb salvage procedure, most often applied to children presenting with sarcoma of the distal femur. In type A1 operation, the distal thigh is removed and the proximal tibia is axially rotated by 180°, remodeled, grafted onto the femoral stump, and then prosthetized. The neurovascular bundle is spared. The rotated ankle then works as a knee. The foot plantar and dorsal flexors act as knee extensors and flexors, respectively. Functional results may be excellent. Cortical neuroplasticity was studied in three men (30–31 years) who were operated on the left lower limb at ages between 7 and 11 years and were fully autonomous with a custom-made prosthesis, as well as in three age–sex matched controls. The scalp stimulation coordinates, matching the patients’ brain MRI spots, were digitized through a ‘neuronavigation’ optoelectronic system, in order to guide the transcranial magnetic stimulation coil, thus ensuring spatial precision during the procedure. Through transcranial magnetic stimulation driven by neuronavigation, the cortical representations of the contralateral soleus and vastus medialis muscles were studied in terms of amplitude of motor evoked potentials (MEPs) and centering and width of the cortical areas from which the potentials could be evoked. Map centering on either hemisphere did not differ substantially across muscles and participants. In the operated patients, MEP amplitudes, the area from which MEPs could be evoked, and their product (volume) were larger for the muscles of the unaffected side compared with both the rotated soleus muscle (average effect size 0.75) and the muscles of healthy controls (average effect size 0.89). In controls, right–left differences showed an effect size of 0.38. In no case did the comparisons reach statistical significance (P>0.25). Nevertheless, the results seem consistent with cortical plasticity reflecting strengthening of the unaffected leg and a combination of cross-education and skill training of the rotated leg.
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Jono Y, Chujo Y, Nomura Y, Tani K, Nikaido Y, Hatanaka R, Hiraoka K. The effect of tonic contraction of the finger muscle on the motor cortical representation of the contracting adjacent muscle. Somatosens Mot Res 2015; 32:114-21. [PMID: 25874638 DOI: 10.3109/08990220.2014.994738] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
This study examined the effect of tonic contraction of the finger muscle on the motor cortical representation of the contracting adjacent muscle. A representation map of the motor evoked potential (MEP) in the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles was obtained with the subject at rest or during tonic contraction of the ADM muscle while the FDI muscle was tonically contracted. The center of gravity (COG) of the MEP map in the FDI muscle shifted medially during contraction of the ADM muscle. Motor cortical excitability in the motor cortical representation of the FDI muscle that did not overlap with the motor cortical representation of the ADM muscle was suppressed, but motor cortical excitability in the motor cortical representation of the FDI muscle overlapping with the motor cortical representation of the ADM muscle was not suppressed during contraction of the ADM muscle. The motor cortical representation of the FDI muscle not overlapping with the motor cortical representation of the ADM muscle was located lateral to that of the FDI muscle that did overlap with the motor cortical representation of the ADM muscle. Medial shift of the COG of the motor cortical representation of the contracting finger muscle induced by tonic contraction of the adjacent finger muscle must be due to suppression of motor cortical excitability in the lateral part of the representation, which is not shared by the adjacent representation.
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Affiliation(s)
- Yasutomo Jono
- Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University , Habikino City, Osaka , Japan and
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Methods for estimating cortical motor representation size and location in navigated transcranial magnetic stimulation. J Neurosci Methods 2014; 232:125-33. [DOI: 10.1016/j.jneumeth.2014.05.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 05/14/2014] [Accepted: 05/15/2014] [Indexed: 11/20/2022]
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Age-related weakness of proximal muscle studied with motor cortical mapping: a TMS study. PLoS One 2014; 9:e89371. [PMID: 24586726 PMCID: PMC3931763 DOI: 10.1371/journal.pone.0089371] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 01/17/2014] [Indexed: 11/30/2022] Open
Abstract
Aging-related weakness is due in part to degeneration within the central nervous system. However, it is unknown how changes to the representation of corticospinal output in the primary motor cortex (M1) relate to such weakness. Transcranial magnetic stimulation (TMS) is a noninvasive method of cortical stimulation that can map representation of corticospinal output devoted to a muscle. Using TMS, we examined age-related alterations in maps devoted to biceps brachii muscle to determine whether they predicted its age-induced weakness. Forty-seven right-handed subjects participated: 20 young (22.6±0.90 years) and 27 old (74.96±1.35 years). We measured strength as force of elbow flexion and electromyographic activation of biceps brachii during maximum voluntary contraction. Mapping variables included: 1) center of gravity or weighted mean location of corticospinal output, 2) size of map, 3) volume or excitation of corticospinal output, and 4) response density or corticospinal excitation per unit area. Center of gravity was more anterior in old than in young (p<0.001), though there was no significant difference in strength between the age groups. Map size, volume, and response density showed no significant difference between groups. Regardless of age, center of gravity significantly predicted strength (β = −0.34, p = 0.005), while volume adjacent to the core of map predicted voluntary activation of biceps (β = 0.32, p = 0.008). Overall, the anterior shift of the map in older adults may reflect an adaptive change that allowed for the maintenance of strength. Laterally located center of gravity and higher excitation in the region adjacent to the core in weaker individuals could reflect compensatory recruitment of synergistic muscles. Thus, our study substantiates the role of M1 in adapting to aging-related weakness and subtending strength and muscle activation across age groups. Mapping from M1 may offer foundation for an examination of mechanisms that preserve strength in elderly.
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Ngomo S, Mercier C, Roy JS. Cortical mapping of the infraspinatus muscle in healthy individuals. BMC Neurosci 2013; 14:52. [PMID: 23617624 PMCID: PMC3652754 DOI: 10.1186/1471-2202-14-52] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 04/20/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND While cortical representations of intrinsic hand muscles have been extensively studied in healthy individuals, little is known about the representation of proximal upper limb muscles. Improving our understanding of normal shoulder function is important, given that shoulder musculoskeletal disorders affect approximately 20% of the population and are suspected to involve changes in central motor representations. The purpose of the study is to describe the motor representation (motor evoked potentials (MEP) amplitude at the hotspot, map area, normalized map volume and center of gravity) of the infraspinatus muscle in healthy individuals, and to explore the potential influence of hand dominance on this representation (i.e. symmetry of the excitability and of the location of motor map between sides), as well as the effect of age and gender on motor excitability. RESULTS Fifteen healthy participants took part in this study. No significant asymmetry between sides was observed for motor excitability (p = 0.14), map area (p = 0.73) and normalized map volume (p = 0.34). Moreover, no side x intensity interaction was found (p = 0.54), indicating similar stimulus response properties. No difference between sides was found in the location of infraspinatus motor representation, either in the mediolateral or anteroposterior axis (p > 0.10). Neither age nor gender influenced aMT (p > 0.58) or MEP size (p > 0.61). CONCLUSIONS As the cortical representation of infraspinatus muscles was found to be symmetric between sides, both in terms of excitability and location, comparisons between the intact and affected side could be performed in clinical studies, regardless of whether the dominant or non-dominant side is affected. The next step will be to characterize corticospinal excitability and map parameters in populations with shoulder disorders.
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Affiliation(s)
- Suzy Ngomo
- Department of Rehabilitation, Faculty of Medicine, Laval University, Quebec City, QC, G1R 1P5, Canada
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Freitas C, Farzan F, Pascual-Leone A. Assessing brain plasticity across the lifespan with transcranial magnetic stimulation: why, how, and what is the ultimate goal? Front Neurosci 2013; 7:42. [PMID: 23565072 PMCID: PMC3613699 DOI: 10.3389/fnins.2013.00042] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 03/09/2013] [Indexed: 12/30/2022] Open
Abstract
Sustaining brain and cognitive function across the lifespan must be one of the main biomedical goals of the twenty-first century. We need to aim to prevent neuropsychiatric diseases and, thus, to identify and remediate brain and cognitive dysfunction before clinical symptoms manifest and disability develops. The brain undergoes a complex array of changes from developmental years into old age, putatively the underpinnings of changes in cognition and behavior throughout life. A functionally “normal” brain is a changing brain, a brain whose capacity and mechanisms of change are shifting appropriately from one time-point to another in a given individual's life. Therefore, assessing the mechanisms of brain plasticity across the lifespan is critical to gain insight into an individual's brain health. Indexing brain plasticity in humans is possible with transcranial magnetic stimulation (TMS), which, in combination with neuroimaging, provides a powerful tool for exploring local cortical and brain network plasticity. Here, we review investigations to date, summarize findings, and discuss some of the challenges that need to be solved to enhance the use of TMS measures of brain plasticity across all ages. Ultimately, TMS measures of plasticity can become the foundation for a brain health index (BHI) to enable objective correlates of an individual's brain health over time, assessment across diseases and disorders, and reliable evaluation of indicators of efficacy of future preventive and therapeutic interventions.
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Affiliation(s)
- Catarina Freitas
- Department of Neurology, Division of Cognitive Neurology, Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School Boston, MA, USA
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