Document Detail

Postural feedback scaling deficits in Parkinson's disease.
MedLine Citation:
PMID:  19741108     Owner:  NLM     Status:  MEDLINE    
Many differences in postural responses have been associated with age and Parkinson's disease (PD), but until now there has been no quantitative model to explain these differences. We developed a feedback control model of body dynamics that could reproduce the postural responses of young subjects, elderly subjects, and subjects with PD, and we investigated whether the postural impairments of subjects with PD can be described as an abnormal scaling of postural feedback gain. Feedback gains quantify how the nervous system generates compensatory joint torques based on kinematic responses. Seven subjects in each group experienced forward postural perturbations to seven different backward support surface translations ranging from 3- to 15-cm amplitudes and with a constant duration of 275 ms. Ground reaction forces and joint kinematics were measured to obtain joint torques from inverse dynamics. A full-state feedback controller with a two-segment body dynamic model was used to simulate joint kinematics and kinetics in response to perturbations. Results showed that all three subject groups gradually scaled postural feedback gains as a function of perturbation amplitudes, and the scaling started even before the maximum allowable ankle torque was reached. This result implies that the nervous system takes body dynamics into account and adjusts postural feedback gains to accommodate biomechanical constraints. PD subjects showed significantly smaller than normal ankle feedback gain with low scaling and larger hip feedback gain, which led to an early violation of the flat-foot constraint and unusually small (bradykinetic) postural responses. Our postural feedback control model quantitatively described the postural abnormality of the patients with PD as abnormal feedback gains and reduced ability to modify postural feedback gain with changes in postural challenge.
Seyoung Kim; Fay B Horak; Patricia Carlson-Kuhta; Sukyung Park
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2009-09-09
Journal Detail:
Title:  Journal of neurophysiology     Volume:  102     ISSN:  1522-1598     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2009 Nov 
Date Detail:
Created Date:  2009-11-05     Completed Date:  2010-01-25     Revised Date:  2014-09-22    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2910-20     Citation Subset:  IM    
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MeSH Terms
Biomechanical Phenomena
Case-Control Studies
Computer Simulation
Feedback, Physiological / physiology*
Joints / innervation
Middle Aged
Models, Biological
Parkinson Disease / physiopathology*
Postural Balance / physiology*
Posture / physiology*
Statistics as Topic
Young Adult
Grant Support

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

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