Document Detail

Neural processing of gravito-inertial cues in humans. IV. Influence of visual rotational cues during roll optokinetic stimuli.
MedLine Citation:
PMID:  12522188     Owner:  NLM     Status:  MEDLINE    
Sensory systems often provide ambiguous information. For example, otolith organs measure gravito-inertial force (GIF), the sum of gravitational force and inertial force due to linear acceleration. However, according to Einstein's equivalence principle, a change in gravitational force due to tilt is indistinguishable from a change in inertial force due to translation. Therefore the central nervous system (CNS) must use other sensory cues to distinguish tilt from translation. For example, the CNS might use dynamic visual cues indicating rotation to help determine the orientation of gravity (tilt). This, in turn, might influence the neural processes that estimate linear acceleration, since the CNS might estimate gravity and linear acceleration such that the difference between these estimates matches the measured GIF. Depending on specific sensory information inflow, inaccurate estimates of gravity and linear acceleration can occur. Specifically, we predict that illusory tilt caused by roll optokinetic cues should lead to a horizontal vestibuloocular reflex compensatory for an interaural estimate of linear acceleration, even in the absence of actual linear acceleration. To investigate these predictions, we measured eye movements binocularly using infrared video methods in 17 subjects during and after optokinetic stimulation about the subject's nasooccipital (roll) axis (60 degrees /s, clockwise or counterclockwise). The optokinetic stimulation was applied for 60 s followed by 30 s in darkness. We simultaneously measured subjective roll tilt using a somatosensory bar. Each subject was tested in three different orientations: upright, pitched forward 10 degrees, and pitched backward 10 degrees. Five subjects reported significant subjective roll tilt (>10 degrees ) in directions consistent with the direction of the optokinetic stimulation. In addition to torsional optokinetic nystagmus and after nystagmus, we measured a horizontal nystagmus to the right during and following clockwise (CW) stimulation and to the left during and following counterclockwise (CCW) stimulation. These measurements match predictions that subjective tilt in the absence of real tilt should induce a nonzero estimate of interaural linear acceleration and, therefore, a horizontal eye response. Furthermore, as predicted, the horizontal response in the dark was larger for Tilters (n = 5) than for Non-Tilters (n = 12).
L H Zupan; D M Merfeld
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of neurophysiology     Volume:  89     ISSN:  0022-3077     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2003 Jan 
Date Detail:
Created Date:  2003-01-10     Completed Date:  2003-03-26     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  390-400     Citation Subset:  IM; S    
Jenks Vestibular Physiology Laboratory, Boston 02114, USA.
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MeSH Terms
Gravity Sensing / physiology*
Illusions / physiology
Middle Aged
Nystagmus, Optokinetic / physiology*
Otolithic Membrane / physiology
Reflex, Vestibulo-Ocular / physiology
Semicircular Canals / physiology
Visual Perception / physiology*
Grant Support

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