Document Detail


Determinants of spatial and temporal coding by semicircular canal afferents.
MedLine Citation:
PMID:  15845995     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The vestibular semicircular canals are internal sensors that signal the magnitude, direction, and temporal properties of angular head motion. Fluid mechanics within the 3-canal labyrinth code the direction of movement and integrate angular acceleration stimuli over time. Directional coding is accomplished by decomposition of complex angular accelerations into 3 biomechanical components-one component exciting each of the 3 ampullary organs and associated afferent nerve bundles separately. For low-frequency angular motion stimuli, fluid displacement within each canal is proportional to angular acceleration. At higher frequencies, above the lower corner frequency, real-time integration is accomplished by viscous forces arising from the movement of fluid within the slender lumen of each canal. This results in angular velocity sensitive fluid displacements. Reflecting this, a subset of afferent fibers indeed report angular acceleration to the brain for low frequencies of head movement and report angular velocity for higher frequencies. However, a substantial number of afferent fibers also report angular acceleration, or a signal between acceleration and velocity, even at frequencies where the endolymph displacement is known to follow angular head velocity. These non-velocity-sensitive afferent signals cannot be attributed to canal biomechanics alone. The responses of non-velocity-sensitive cells include a mathematical differentiation (first-order or fractional) imparted by hair-cell and/or afferent complexes. This mathematical differentiation from velocity to acceleration cannot be attributed to hair cell ionic currents, but occurs as a result of the dynamics of synaptic transmission between hair cells and their primary afferent fibers. The evidence for this conclusion is reviewed below.
Authors:
Stephen M Highstein; Richard D Rabbitt; Gay R Holstein; Richard D Boyle
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, P.H.S.; Review    
Journal Detail:
Title:  Journal of neurophysiology     Volume:  93     ISSN:  0022-3077     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2005 May 
Date Detail:
Created Date:  2005-04-22     Completed Date:  2005-06-13     Revised Date:  2014-09-13    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2359-70     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Afferent Pathways / anatomy & histology,  physiology
Animals
Biomechanical Phenomena
Hair Cells, Vestibular / physiology
Head Movements / physiology
Humans
Labyrinthine Fluids / physiology
Motion Perception / physiology*
Neural Networks (Computer)
Reflex, Vestibulo-Ocular / physiology*
Semicircular Canals / cytology,  physiology*
Signal Transduction
Space Perception / physiology*
Synapses
Grant Support
ID/Acronym/Agency:
P01 DC-01837/DC/NIDCD NIH HHS; P01 DC001837/DC/NIDCD NIH HHS; R01 DC004928/DC/NIDCD NIH HHS; R01 DC004928-06/DC/NIDCD NIH HHS; R01 DC006685/DC/NIDCD NIH HHS; R01 DC006685-03/DC/NIDCD NIH HHS; R55 DC-05585/DC/NIDCD NIH HHS
Comments/Corrections

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