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The CPGs for Limbed Locomotion–Facts and Fiction

The neuronal networks that generate locomotion are well understood in swimming animals such as the lamprey, zebrafish and tadpole. The networks controlling locomotion in tetrapods remain, however, still enigmatic with an intricate motor pattern required for the control of the entire limb during the...

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Autores principales: Grillner, Sten, Kozlov, Alexander
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8198624/
https://www.ncbi.nlm.nih.gov/pubmed/34070932
http://dx.doi.org/10.3390/ijms22115882
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author Grillner, Sten
Kozlov, Alexander
author_facet Grillner, Sten
Kozlov, Alexander
author_sort Grillner, Sten
collection PubMed
description The neuronal networks that generate locomotion are well understood in swimming animals such as the lamprey, zebrafish and tadpole. The networks controlling locomotion in tetrapods remain, however, still enigmatic with an intricate motor pattern required for the control of the entire limb during the support, lift off, and flexion phase, and most demandingly when the limb makes contact with ground again. It is clear that the inhibition that occurs between bursts in each step cycle is produced by V2b and V1 interneurons, and that a deletion of these interneurons leads to synchronous flexor–extensor bursting. The ability to generate rhythmic bursting is distributed over all segments comprising part of the central pattern generator network (CPG). It is unclear how the rhythmic bursting is generated; however, Shox2, V2a and HB9 interneurons do contribute. To deduce a possible organization of the locomotor CPG, simulations have been elaborated. The motor pattern has been simulated in considerable detail with a network composed of unit burst generators; one for each group of close synergistic muscle groups at each joint. This unit burst generator model can reproduce the complex burst pattern with a constant flexion phase and a shortened extensor phase as the speed increases. Moreover, the unit burst generator model is versatile and can generate both forward and backward locomotion.
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spelling pubmed-81986242021-06-14 The CPGs for Limbed Locomotion–Facts and Fiction Grillner, Sten Kozlov, Alexander Int J Mol Sci Review The neuronal networks that generate locomotion are well understood in swimming animals such as the lamprey, zebrafish and tadpole. The networks controlling locomotion in tetrapods remain, however, still enigmatic with an intricate motor pattern required for the control of the entire limb during the support, lift off, and flexion phase, and most demandingly when the limb makes contact with ground again. It is clear that the inhibition that occurs between bursts in each step cycle is produced by V2b and V1 interneurons, and that a deletion of these interneurons leads to synchronous flexor–extensor bursting. The ability to generate rhythmic bursting is distributed over all segments comprising part of the central pattern generator network (CPG). It is unclear how the rhythmic bursting is generated; however, Shox2, V2a and HB9 interneurons do contribute. To deduce a possible organization of the locomotor CPG, simulations have been elaborated. The motor pattern has been simulated in considerable detail with a network composed of unit burst generators; one for each group of close synergistic muscle groups at each joint. This unit burst generator model can reproduce the complex burst pattern with a constant flexion phase and a shortened extensor phase as the speed increases. Moreover, the unit burst generator model is versatile and can generate both forward and backward locomotion. MDPI 2021-05-30 /pmc/articles/PMC8198624/ /pubmed/34070932 http://dx.doi.org/10.3390/ijms22115882 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Review
Grillner, Sten
Kozlov, Alexander
The CPGs for Limbed Locomotion–Facts and Fiction
title The CPGs for Limbed Locomotion–Facts and Fiction
title_full The CPGs for Limbed Locomotion–Facts and Fiction
title_fullStr The CPGs for Limbed Locomotion–Facts and Fiction
title_full_unstemmed The CPGs for Limbed Locomotion–Facts and Fiction
title_short The CPGs for Limbed Locomotion–Facts and Fiction
title_sort cpgs for limbed locomotion–facts and fiction
topic Review
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8198624/
https://www.ncbi.nlm.nih.gov/pubmed/34070932
http://dx.doi.org/10.3390/ijms22115882
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