Document Detail


A unified view of quiet and perturbed stance: simultaneous co-existing excitable modes.
MedLine Citation:
PMID:  15740840     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
When standing quietly, human upright stance is typically approximated as a single segment inverted pendulum. In contrast, investigations which perturb upright stance with support surface translations or visual driving stimuli have shown that the body behaves like a two-segment pendulum, displaying both in-phase and anti-phase patterns between the upper and lower body. Here we present evidence that a single-segment characterization of quiet stance is inadequate. Similar to perturbed stance, quiet stance has simultaneously co-existing in-phase and anti-phase patterns. Subjects stood with eyes closed in three sensory conditions: a fixed surface, a foam surface, and a sway-referenced surface. Spectral analysis showed that the body behaved like a multi-link pendulum with two co-existing modes. The angles of the trunk and leg segments were in-phase for frequencies below 1 Hz and anti-phase for frequencies above 1Hz. The shift from in-phase to anti-phase sway showed an abrupt change for the fixed and foam surfaces, but a gradual change for the sway-referenced condition with the trunk showing a phase lead over the legs. The coexistence of in-phase and anti-phase patterns during quiet stance suggests that the ankle and hip strategies are not extremes along a behavioral continuum of mixed strategies. They are "simultaneously co-existing excitable modes", both always present, but one of which may predominate depending upon the characteristics of the available sensory information, task or perturbation.
Authors:
Robert Creath; Tim Kiemel; Fay Horak; Robert Peterka; John Jeka
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.     Date:  2004-12-19
Journal Detail:
Title:  Neuroscience letters     Volume:  377     ISSN:  0304-3940     ISO Abbreviation:  Neurosci. Lett.     Publication Date:  2005 Mar 
Date Detail:
Created Date:  2005-03-02     Completed Date:  2005-05-03     Revised Date:  2014-01-27    
Medline Journal Info:
Nlm Unique ID:  7600130     Medline TA:  Neurosci Lett     Country:  Ireland    
Other Details:
Languages:  eng     Pagination:  75-80     Citation Subset:  IM; S    
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MeSH Terms
Descriptor/Qualifier:
Adult
Female
Humans
Male
Photic Stimulation / methods
Postural Balance / physiology*
Posture / physiology*
Psychomotor Performance / physiology*
Grant Support
ID/Acronym/Agency:
1R01NS046065/NS/NINDS NIH HHS; AG17960/AG/NIA NIH HHS; DC-01849/DC/NIDCD NIH HHS; NS35070/NS/NINDS NIH HHS; R01 AG006457/AG/NIA NIH HHS; R01AG06457/AG/NIA NIH HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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