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Ipsilateral Motor Evoked Potentials as a Measure of the Reticulospinal Tract in Age-Related Strength Changes
Background: The reticulospinal tract (RST) is essential for balance, posture, and strength, all functions which falter with age. We hypothesized that age-related strength reductions might relate to differential changes in corticospinal and reticulospinal connectivity. Methods: We divided 83 particip...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Frontiers Media S.A.
2021
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7966512/ https://www.ncbi.nlm.nih.gov/pubmed/33746734 http://dx.doi.org/10.3389/fnagi.2021.612352 |
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author | Maitland, Stuart Baker, Stuart N. |
author_facet | Maitland, Stuart Baker, Stuart N. |
author_sort | Maitland, Stuart |
collection | PubMed |
description | Background: The reticulospinal tract (RST) is essential for balance, posture, and strength, all functions which falter with age. We hypothesized that age-related strength reductions might relate to differential changes in corticospinal and reticulospinal connectivity. Methods: We divided 83 participants (age 20–84) into age groups <50 (n = 29) and ≥50 (n = 54) years; five of which had probable sarcopenia. Transcranial Magnetic Stimulation (TMS) was applied to the left cortex, inducing motor evoked potentials (MEPs) in the biceps muscles bilaterally. Contralateral (right, cMEPs) and ipsilateral (left, iMEPs) MEPs are carried by mainly corticospinal and reticulospinal pathways respectively; the iMEP/cMEP amplitude ratio (ICAR) therefore measured the relative importance of the two descending tracts. Grip strength was measured with a dynamometer and normalized for age and sex. Results: We found valid iMEPs in 74 individuals (n = 44 aged ≥50, n = 29 < 50). Younger adults had a significant negative correlation between normalized grip strength and ICAR (r = −0.37, p = 0.045); surprisingly, in older adults, the correlation was also significant, but positive (r = 0.43, p = 0.0037). Discussion: Older individuals who maintain or strengthen their RST are stronger than their peers. We speculate that reduced RST connectivity could predict those at risk of age-related muscle weakness; interventions that reinforce the RST could be a candidate for treatment or prevention of sarcopenia. |
format | Online Article Text |
id | pubmed-7966512 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-79665122021-03-18 Ipsilateral Motor Evoked Potentials as a Measure of the Reticulospinal Tract in Age-Related Strength Changes Maitland, Stuart Baker, Stuart N. Front Aging Neurosci Neuroscience Background: The reticulospinal tract (RST) is essential for balance, posture, and strength, all functions which falter with age. We hypothesized that age-related strength reductions might relate to differential changes in corticospinal and reticulospinal connectivity. Methods: We divided 83 participants (age 20–84) into age groups <50 (n = 29) and ≥50 (n = 54) years; five of which had probable sarcopenia. Transcranial Magnetic Stimulation (TMS) was applied to the left cortex, inducing motor evoked potentials (MEPs) in the biceps muscles bilaterally. Contralateral (right, cMEPs) and ipsilateral (left, iMEPs) MEPs are carried by mainly corticospinal and reticulospinal pathways respectively; the iMEP/cMEP amplitude ratio (ICAR) therefore measured the relative importance of the two descending tracts. Grip strength was measured with a dynamometer and normalized for age and sex. Results: We found valid iMEPs in 74 individuals (n = 44 aged ≥50, n = 29 < 50). Younger adults had a significant negative correlation between normalized grip strength and ICAR (r = −0.37, p = 0.045); surprisingly, in older adults, the correlation was also significant, but positive (r = 0.43, p = 0.0037). Discussion: Older individuals who maintain or strengthen their RST are stronger than their peers. We speculate that reduced RST connectivity could predict those at risk of age-related muscle weakness; interventions that reinforce the RST could be a candidate for treatment or prevention of sarcopenia. Frontiers Media S.A. 2021-03-03 /pmc/articles/PMC7966512/ /pubmed/33746734 http://dx.doi.org/10.3389/fnagi.2021.612352 Text en Copyright © 2021 Maitland and Baker. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Neuroscience Maitland, Stuart Baker, Stuart N. Ipsilateral Motor Evoked Potentials as a Measure of the Reticulospinal Tract in Age-Related Strength Changes |
title | Ipsilateral Motor Evoked Potentials as a Measure of the Reticulospinal Tract in Age-Related Strength Changes |
title_full | Ipsilateral Motor Evoked Potentials as a Measure of the Reticulospinal Tract in Age-Related Strength Changes |
title_fullStr | Ipsilateral Motor Evoked Potentials as a Measure of the Reticulospinal Tract in Age-Related Strength Changes |
title_full_unstemmed | Ipsilateral Motor Evoked Potentials as a Measure of the Reticulospinal Tract in Age-Related Strength Changes |
title_short | Ipsilateral Motor Evoked Potentials as a Measure of the Reticulospinal Tract in Age-Related Strength Changes |
title_sort | ipsilateral motor evoked potentials as a measure of the reticulospinal tract in age-related strength changes |
topic | Neuroscience |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7966512/ https://www.ncbi.nlm.nih.gov/pubmed/33746734 http://dx.doi.org/10.3389/fnagi.2021.612352 |
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