Document Detail


High-velocity angular vestibulo-ocular reflex adaptation to position error signals.
MedLine Citation:
PMID:  20588093     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND AND PURPOSE: Vestibular rehabilitation strategies including gaze stabilization exercises have been shown to increase gain of the angular vestibulo-ocular reflex (aVOR) using a retinal slip error signal (ES). The identification of additional ESs capable of promoting substitution strategies or aVOR adaptation is an important goal in the management of vestibular hypofunction. Position ESs have been shown to increase both aVOR gain and recruitment of compensatory saccades (CSs) during passive whole body rotation. This may be a useful compensatory strategy for gaze instability during active head rotation as well. In vestibular rehabilitation, the imaginary target exercise is often prescribed to improve gaze stability. This exercise uses a position ES; however, the mechanism for its effect has not been investigated. We compared aVOR gain adaptation using 2 types of small position ES: constant versus incremental.
METHODS: Ten subjects with normal vestibular function were assessed with unpredictable and active head rotations before and after a 20-minute training session. Subjects performed 9 epochs of 40 active, high-velocity head impulses using a position ES stimulus to increase aVOR gain.
RESULTS: Five subjects demonstrated significant aVOR gain increases with the constant-position ES (mean, 2%; range, -18% to 12%) compared with another 5 subjects showing significant aVOR gain increases to the incremental-position ES (mean, 3.7%; range, -2% to 22.6%). There was no difference in aVOR gain adaptation or CS recruitment between the 2 paradigms.
DISCUSSION AND CONCLUSION: These findings suggest that some subjects can increase their aVOR gain in response to high-velocity active head movement training using a position ES. The primary mechanism for this seems to be aVOR gain adaptation because CS use was not modified. The overall low change in aVOR gain adaptation with position ES suggests that retinal slip is a more powerful aVOR gain modifier.
Authors:
Matthew Scherer; Michael C Schubert
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  Journal of neurologic physical therapy : JNPT     Volume:  34     ISSN:  1557-0584     ISO Abbreviation:  J Neurol Phys Ther     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-06-30     Completed Date:  2010-10-01     Revised Date:  2010-12-03    
Medline Journal Info:
Nlm Unique ID:  101193365     Medline TA:  J Neurol Phys Ther     Country:  United States    
Other Details:
Languages:  eng     Pagination:  82-6     Citation Subset:  IM    
Affiliation:
Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Maryland, USA.
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological / physiology*
Adult
Head Movements / physiology*
Humans
Middle Aged
Reflex, Vestibulo-Ocular / physiology*
Rotation
Vestibular Function Tests
Grant Support
ID/Acronym/Agency:
K23 DC007926-04/DC/NIDCD NIH HHS; K23DC007926/DC/NIDCD NIH HHS

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


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