| The spinal generation of phases and cycle duration. | |
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MedLine Citation:
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PMID: 21333800 Owner: NLM Status: In-Data-Review |
Abstract/OtherAbstract:
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During walking, an increase in speed is accompanied by a decrease in the stance phase duration while the swing phase remains relatively invariant. By definition, the rhythm generator in the lumbar spinal cord controls cycle period, phase durations, and phase transitions. Our first aim was to determine if this asymmetry in the control of locomotor cycles is an inherent property of the central pattern generator (CPG). We recorded episodes of fictive locomotion, that is, locomotor patterns in absence of reafference, in decerebrate cats with or without a complete spinal transection (acute or chronic). In fictive locomotion, stance and swing phases typically correspond to extension and flexion, respectively. In the vast majority of locomotor episodes, cycle period varied more with extensor phase duration. This could be observed without phasic sensory feedback or supraspinal structures or pharmacology. In a few experiments, we stimulated the mesencephalic locomotor region or selected peripheral nerves during fictive locomotion and both could alter the phase/cycle period relationship. We conclude that there is a built-in asymmetry within the spinal rhythm generator for locomotion, which can be modified by extraneous factors. Locomotor and scratching rhythms are characterized by alternation of flexion and extension phases within one hindlimb, which are mediated by rhythm-generating circuitry within the spinal cord. Our second aim was to determine if rhythm generators for locomotion and scratch have similar control mechanisms in adult decerebrate cats. The regulation of cycle period during fictive scratching was evaluated, as were the effects of specific sensory inputs on phase durations and transitions during pinna-evoked fictive scratching. Results show that cycle period during fictive scratching varied predominantly with flexion phase duration, contrary to spontaneous fictive locomotion. Ankle dorsiflexion greatly increased extension phase duration and cycle period during fictive locomotion but did not alter cycle period during scratching. These data indicate that cycle period, phase durations, and phase transitions are not regulated similarly during fictive locomotion and scratching, with or without sensory inputs, providing evidence for the existence of distinct interneuronal components of rhythm generation within the mammalian spinal cord. |
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Authors:
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Jean-Pierre Gossard; Jennifer Sirois; Patrick Noué; Marie-Pascale Côté; Ariane Ménard; Hugues Leblond; Alain Frigon |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Progress in brain research Volume: 188 ISSN: 1875-7855 ISO Abbreviation: Prog. Brain Res. Publication Date: 2011 |
Date Detail:
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Created Date: 2011-02-21 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0376441 Medline TA: Prog Brain Res Country: Netherlands |
Other Details:
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Languages: eng Pagination: 15-29 Citation Subset: IM |
Copyright Information:
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Copyright © 2011 Elsevier B.V. All rights reserved. |
Affiliation:
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Groupe de Recherche sur le Systéme Nerveux Central, Département de Physiologie, Université de Montréal, Montreal, Quebec, Canada. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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