Document Detail

Retention of adaptive control over varying intervals: prevention of slip- induced backward balance loss during gait.
MedLine Citation:
PMID:  16407423     Owner:  NLM     Status:  MEDLINE    
Stability improvements made in a single acquisition session with merely five slips in walking are sufficient to prevent backward balance loss (BLOB) at the end of session, but not after 12 mo. The purpose of this study was to determine whether the effect of an enhanced single acquisition session would be retainable if tested sooner, at intervals of < or =4 mo. Twenty-four young subjects were exposed to blocks of slip, nonslip, and both types of trials during walking at their preferred speed in the acquisition session. In each of the four follow-up sessions around 1 wk, 2 wk, 1 mo, and 4 mo later, these same subjects experienced only a single slip after eight to 13 unperturbed walking trials in an otherwise identical setup. Gait stability was obtained as the shortest distance between the measured center of mass (COM) state (position and velocity) and the mathematically predicted threshold for BLOB at pre- and postslip, corresponding to the instants of touchdown of the slipping limb and liftoff of the contralateral limb, respectively. During the acquisition session, pre- and postslip stability improved significantly, resulting in a reduction of BLOB from 100% in the first slip (S1) to 0% in the last slip (S24), with improvements converging to a steady state, that enabled all of the subjects to avoid BLOB, regardless of whether a slip occurred. During retest sessions, subjects' preslip stability was not different from that in S24, but was greater than that in S1. Their postslip stability was also greater than that in S1 but less than that in S24, resulting in BLOB at a 40% level. No difference was found in any of these aspects between each follow-up session. These adaptive changes were associated with a range of individual differences, varying from no detectable deterioration in all aspects (n = 8) to a consistent BLOB in all follow-ups (n = 3). Our findings demonstrated the extent of plasticity of the CNS, characterized by rapid acquisition of a stable COM state under unpredictable slip conditions and retention of such improvements for months, resulting in a reduced occurrence of unintended backward falling.
T Bhatt; E Wang; Y-C Pai
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural     Date:  2006-01-11
Journal Detail:
Title:  Journal of neurophysiology     Volume:  95     ISSN:  0022-3077     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2006 May 
Date Detail:
Created Date:  2006-04-17     Completed Date:  2006-06-28     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2913-22     Citation Subset:  IM    
Department of Physical Therapy, University of Illinois at Chicago, 1919 West Taylor St., Room 426 (M/C 898) Chicago, IL 60612, USA.
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MeSH Terms
Adaptation, Physiological*
Analysis of Variance
Biomechanics / methods
Follow-Up Studies
Gait / physiology*
Postural Balance*
Psychomotor Performance / physiology*
Retention (Psychology) / physiology*
Time Factors
Walking / physiology*
Grant Support
2R01 AG-16727/AG/NIA NIH HHS

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

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