Cargando…
Extensive Cortical Convergence to Primate Reticulospinal Pathways
Early evolution of the motor cortex included development of connections to brainstem reticulospinal neurons; these projections persist in primates. In this study, we examined the organization of corticoreticular connections in five macaque monkeys (one male) using both intracellular and extracellula...
Autores principales: | , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Society for Neuroscience
2021
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7880280/ https://www.ncbi.nlm.nih.gov/pubmed/33268548 http://dx.doi.org/10.1523/JNEUROSCI.1379-20.2020 |
_version_ | 1783650675099435008 |
---|---|
author | Fisher, Karen M. Zaaimi, Boubker Edgley, Steve A. Baker, Stuart N. |
author_facet | Fisher, Karen M. Zaaimi, Boubker Edgley, Steve A. Baker, Stuart N. |
author_sort | Fisher, Karen M. |
collection | PubMed |
description | Early evolution of the motor cortex included development of connections to brainstem reticulospinal neurons; these projections persist in primates. In this study, we examined the organization of corticoreticular connections in five macaque monkeys (one male) using both intracellular and extracellular recordings from reticular formation neurons, including identified reticulospinal cells. Synaptic responses to stimulation of different parts of primary motor cortex (M1) and supplementary motor area (SMA) bilaterally were assessed. Widespread short latency excitation, compatible with monosynaptic transmission over fast-conducting pathways, was observed, as well as longer latency responses likely reflecting a mixture of slower monosynaptic and oligosynaptic pathways. There was a high degree of convergence: 56% of reticulospinal cells with input from M1 received projections from M1 in both hemispheres; for SMA, the equivalent figure was even higher (70%). Of reticulospinal neurons with input from the cortex, 78% received projections from both M1 and SMA (regardless of hemisphere); 83% of reticulospinal cells with input from M1 received projections from more than one of the tested M1 sites. This convergence at the single cell level allows reticulospinal neurons to integrate information from across the motor areas of the cortex, taking account of the bilateral motor context. Reticulospinal connections are known to strengthen following damage to the corticospinal tract, such as after stroke, partially contributing to functional recovery. Extensive corticoreticular convergence provides redundancy of control, which may allow the cortex to continue to exploit this descending pathway even after damage to one area. SIGNIFICANCE STATEMENT The reticulospinal tract (RST) provides a parallel pathway for motor control in primates, alongside the more sophisticated corticospinal system. We found extensive convergent inputs to primate reticulospinal cells from primary and supplementary motor cortex bilaterally. These redundant connections could maintain transmission of voluntary commands to the spinal cord after damage (e.g., after stroke or spinal cord injury), possibly assisting recovery of function. |
format | Online Article Text |
id | pubmed-7880280 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Society for Neuroscience |
record_format | MEDLINE/PubMed |
spelling | pubmed-78802802021-02-16 Extensive Cortical Convergence to Primate Reticulospinal Pathways Fisher, Karen M. Zaaimi, Boubker Edgley, Steve A. Baker, Stuart N. J Neurosci Research Articles Early evolution of the motor cortex included development of connections to brainstem reticulospinal neurons; these projections persist in primates. In this study, we examined the organization of corticoreticular connections in five macaque monkeys (one male) using both intracellular and extracellular recordings from reticular formation neurons, including identified reticulospinal cells. Synaptic responses to stimulation of different parts of primary motor cortex (M1) and supplementary motor area (SMA) bilaterally were assessed. Widespread short latency excitation, compatible with monosynaptic transmission over fast-conducting pathways, was observed, as well as longer latency responses likely reflecting a mixture of slower monosynaptic and oligosynaptic pathways. There was a high degree of convergence: 56% of reticulospinal cells with input from M1 received projections from M1 in both hemispheres; for SMA, the equivalent figure was even higher (70%). Of reticulospinal neurons with input from the cortex, 78% received projections from both M1 and SMA (regardless of hemisphere); 83% of reticulospinal cells with input from M1 received projections from more than one of the tested M1 sites. This convergence at the single cell level allows reticulospinal neurons to integrate information from across the motor areas of the cortex, taking account of the bilateral motor context. Reticulospinal connections are known to strengthen following damage to the corticospinal tract, such as after stroke, partially contributing to functional recovery. Extensive corticoreticular convergence provides redundancy of control, which may allow the cortex to continue to exploit this descending pathway even after damage to one area. SIGNIFICANCE STATEMENT The reticulospinal tract (RST) provides a parallel pathway for motor control in primates, alongside the more sophisticated corticospinal system. We found extensive convergent inputs to primate reticulospinal cells from primary and supplementary motor cortex bilaterally. These redundant connections could maintain transmission of voluntary commands to the spinal cord after damage (e.g., after stroke or spinal cord injury), possibly assisting recovery of function. Society for Neuroscience 2021-02-03 /pmc/articles/PMC7880280/ /pubmed/33268548 http://dx.doi.org/10.1523/JNEUROSCI.1379-20.2020 Text en Copyright © 2021 Fisher et al. https://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed. |
spellingShingle | Research Articles Fisher, Karen M. Zaaimi, Boubker Edgley, Steve A. Baker, Stuart N. Extensive Cortical Convergence to Primate Reticulospinal Pathways |
title | Extensive Cortical Convergence to Primate Reticulospinal Pathways |
title_full | Extensive Cortical Convergence to Primate Reticulospinal Pathways |
title_fullStr | Extensive Cortical Convergence to Primate Reticulospinal Pathways |
title_full_unstemmed | Extensive Cortical Convergence to Primate Reticulospinal Pathways |
title_short | Extensive Cortical Convergence to Primate Reticulospinal Pathways |
title_sort | extensive cortical convergence to primate reticulospinal pathways |
topic | Research Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7880280/ https://www.ncbi.nlm.nih.gov/pubmed/33268548 http://dx.doi.org/10.1523/JNEUROSCI.1379-20.2020 |
work_keys_str_mv | AT fisherkarenm extensivecorticalconvergencetoprimatereticulospinalpathways AT zaaimiboubker extensivecorticalconvergencetoprimatereticulospinalpathways AT edgleystevea extensivecorticalconvergencetoprimatereticulospinalpathways AT bakerstuartn extensivecorticalconvergencetoprimatereticulospinalpathways |