Document Detail

Asymmetry in vestibular responses to cross-coupled stimulus.
MedLine Citation:
PMID:  21336829     Owner:  NLM     Status:  MEDLINE    
Head turns performed while rotating about another axis result in a cross-coupled stimulus (CCS) to the vestibular system. The CCS causes a tumbling sensation, and the magnitude of the tumbling sensation is dependent on the type of head turn (HT) that is performed. Asymmetric CCS responses to different rotational directions are widely acknowledged, yet poorly understood. The objective of this study was to: 1) correctly describe the asymmetries in responses to different configurations of CCS stimulation and 2) test two previously proposed hypotheses for explaining the asymmetries, dominant direction, and dominant end position. The dominant direction hypothesis states that the tumbling sensations evoked by the CCS will be more intense for certain directions of the tumbling sensation than for others. The dominant end position hypothesis states that head turns ending in the nose-up position result in more intense sensations than those ending on the side positions. Subjects performed four types of 60-degree yaw head turns while lying horizontally on a centrifuge. Subjects were either supine or prone, while rotating clockwise or counterclockwise. Three experimental conditions were tested: clockwise supine (n = 33); counterclockwise supine (n = 10); and clockwise prone (n = 10). Subjective tumbling intensity scores were recorded for each head turn. Head turns to the left are dominant for clockwise supine centrifugation (P < 0.0001) and head turns to the right are dominant for counterclockwise supine centrifugation (P = 0.0020), matching what is expected from previous studies. However, for prone centrifugation, head turns to the left are more intense than head turns to the right (P = 0.0078), refuting the dominant direction hypothesis. The dominant end position effect is small in magnitude and cannot by itself explain the asymmetries. For every test condition, there is a dominant direction, but the dominant direction is not just a function of the HT and centrifuge rotation directions, instead it is also dependent on the subject's orientation on the centrifuge. An alternative perceived danger hypothesis that matches the data from all three experiments is proposed.
Jaime Mateus; Jorge Cañizales; Andrew N Hearn; Laurence R Young
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2011-02-19
Journal Detail:
Title:  Experimental brain research     Volume:  209     ISSN:  1432-1106     ISO Abbreviation:  Exp Brain Res     Publication Date:  2011 Apr 
Date Detail:
Created Date:  2011-03-14     Completed Date:  2011-07-25     Revised Date:  2013-12-13    
Medline Journal Info:
Nlm Unique ID:  0043312     Medline TA:  Exp Brain Res     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  561-9     Citation Subset:  IM    
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MeSH Terms
Head Movements / physiology
Orientation / physiology*
Reflex, Vestibulo-Ocular / physiology
Space Perception / physiology
Vestibule, Labyrinth / physiology*

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