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Altered regulation of Ia afferent input during voluntary contraction in humans with spinal cord injury

Sensory input converging on the spinal cord contributes to the control of movement. Although sensory pathways reorganize following spinal cord injury (SCI), the extent to which sensory input from Ia afferents is regulated during voluntary contraction after the injury remains largely unknown. To addr...

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Autores principales: Chen, Bing, Perez, Monica A
Formato: Online Artículo Texto
Lenguaje:English
Publicado: eLife Sciences Publications, Ltd 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9451536/
https://www.ncbi.nlm.nih.gov/pubmed/36069767
http://dx.doi.org/10.7554/eLife.80089
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author Chen, Bing
Perez, Monica A
author_facet Chen, Bing
Perez, Monica A
author_sort Chen, Bing
collection PubMed
description Sensory input converging on the spinal cord contributes to the control of movement. Although sensory pathways reorganize following spinal cord injury (SCI), the extent to which sensory input from Ia afferents is regulated during voluntary contraction after the injury remains largely unknown. To address this question, the soleus H-reflex and conditioning of the H-reflex by stimulating homonymous [depression of the soleus H-reflex evoked by common peroneal nerve (CPN) stimulation, D1 inhibition] and heteronymous (d), [monosynaptic Ia facilitation of the soleus H-reflex evoked by femoral nerve stimulation (FN facilitation)] nerves were tested at rest, and during tonic voluntary contraction in humans with and without chronic incomplete SCI. The soleus H-reflex size increased in both groups during voluntary contraction compared with rest, but to a lesser extent in SCI participants. Compared with rest, the D1 inhibition decreased during voluntary contraction in controls but it was still present in SCI participants. Further, the FN facilitation increased in controls but remained unchanged in SCI participants during voluntary contraction compared with rest. Changes in the D1 inhibition and FN facilitation were correlated with changes in the H-reflex during voluntary contraction, suggesting an association between outcomes. These findings provide the first demonstration that the regulation of Ia afferent input from homonymous and heteronymous nerves is altered during voluntary contraction in humans with SCI, resulting in lesser facilitatory effect on motor neurons.
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spelling pubmed-94515362022-09-08 Altered regulation of Ia afferent input during voluntary contraction in humans with spinal cord injury Chen, Bing Perez, Monica A eLife Neuroscience Sensory input converging on the spinal cord contributes to the control of movement. Although sensory pathways reorganize following spinal cord injury (SCI), the extent to which sensory input from Ia afferents is regulated during voluntary contraction after the injury remains largely unknown. To address this question, the soleus H-reflex and conditioning of the H-reflex by stimulating homonymous [depression of the soleus H-reflex evoked by common peroneal nerve (CPN) stimulation, D1 inhibition] and heteronymous (d), [monosynaptic Ia facilitation of the soleus H-reflex evoked by femoral nerve stimulation (FN facilitation)] nerves were tested at rest, and during tonic voluntary contraction in humans with and without chronic incomplete SCI. The soleus H-reflex size increased in both groups during voluntary contraction compared with rest, but to a lesser extent in SCI participants. Compared with rest, the D1 inhibition decreased during voluntary contraction in controls but it was still present in SCI participants. Further, the FN facilitation increased in controls but remained unchanged in SCI participants during voluntary contraction compared with rest. Changes in the D1 inhibition and FN facilitation were correlated with changes in the H-reflex during voluntary contraction, suggesting an association between outcomes. These findings provide the first demonstration that the regulation of Ia afferent input from homonymous and heteronymous nerves is altered during voluntary contraction in humans with SCI, resulting in lesser facilitatory effect on motor neurons. eLife Sciences Publications, Ltd 2022-09-07 /pmc/articles/PMC9451536/ /pubmed/36069767 http://dx.doi.org/10.7554/eLife.80089 Text en © 2022, Chen and Perez https://creativecommons.org/licenses/by/4.0/This article is distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use and redistribution provided that the original author and source are credited.
spellingShingle Neuroscience
Chen, Bing
Perez, Monica A
Altered regulation of Ia afferent input during voluntary contraction in humans with spinal cord injury
title Altered regulation of Ia afferent input during voluntary contraction in humans with spinal cord injury
title_full Altered regulation of Ia afferent input during voluntary contraction in humans with spinal cord injury
title_fullStr Altered regulation of Ia afferent input during voluntary contraction in humans with spinal cord injury
title_full_unstemmed Altered regulation of Ia afferent input during voluntary contraction in humans with spinal cord injury
title_short Altered regulation of Ia afferent input during voluntary contraction in humans with spinal cord injury
title_sort altered regulation of ia afferent input during voluntary contraction in humans with spinal cord injury
topic Neuroscience
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9451536/
https://www.ncbi.nlm.nih.gov/pubmed/36069767
http://dx.doi.org/10.7554/eLife.80089
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