Document Detail


Restoration of 3D vestibular sensation in rhesus monkeys using a multichannel vestibular prosthesis.
MedLine Citation:
PMID:  21888961     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Profound bilateral loss of vestibular hair cell function can cause chronically disabling loss of balance and inability to maintain stable vision during head and body movements. We have previously shown that chinchillas rendered bilaterally vestibular-deficient via intratympanic administration of the ototoxic antibiotic gentamicin regain a more nearly normal 3-dimensional vestibulo-ocular reflex (3D VOR) when head motion information sensed by a head-mounted multichannel vestibular prosthesis (MVP) is encoded via rate-modulated pulsatile stimulation of vestibular nerve branches. Despite significant improvement versus the unaided condition, animals still exhibited some 3D VOR misalignment (i.e., the 3D axis of eye movement responses did not precisely align with the axis of head rotation), presumably due to current spread between a given ampullary nerve's stimulating electrode(s) and afferent fibers in non-targeted branches of the vestibular nerve. Assuming that effects of current spread depend on relative orientation and separation between nerve branches, anatomic differences between chinchilla and human labyrinths may limit the extent to which results in chinchillas accurately predict MVP performance in humans. In this report, we describe the MVP-evoked 3D VOR measured in alert rhesus monkeys, which have labyrinths that are larger than chinchillas and temporal bone anatomy more similar to humans. Electrodes were implanted in five monkeys treated with intratympanic gentamicin to bilaterally ablate vestibular hair cell mechanosensitivity. Eye movements mediated by the 3D VOR were recorded during passive sinusoidal (0.2-5 Hz, peak 50°/s) and acceleration-step (1000°/s(2) to 150°/s) whole-body rotations in darkness about each semicircular canal axis. During constant 100 pulse/s stimulation (i.e., MVP powered ON but set to stimulate each ampullary nerve at a constant mean baseline rate not modulated by head motion), 3D VOR responses to head rotation exhibited profoundly low gain [(mean eye velocity amplitude)/(mean head velocity amplitude) < 0.1] and large misalignment between ideal and actual eye movements. In contrast, motion-modulated sinusoidal MVP stimuli elicited a 3D VOR with gain 0.4-0.7 and axis misalignment of 21-38°, and responses to high-acceleration transient head rotations exhibited gain and asymmetry closer to those of unilaterally gentamicin-treated animals (i.e., with one intact labyrinth) than to bilaterally gentamicin-treated animals without MVP stimulation. In comparison to responses observed under similar conditions in chinchillas, acute responses to MVP stimulation in rhesus macaque monkeys were slightly better aligned to the desired rotation axis. Responses during combined rotation and prosthetic stimulation were greater than when either stimulus was presented alone, suggesting that the central nervous system uses MVP input in the context of multisensory integration. Considering the similarity in temporal bone anatomy and VOR performance between rhesus monkeys and humans, these observations suggest that an MVP will likely restore a useful level of vestibular sensation and gaze stabilization in humans.
Authors:
Chenkai Dai; Gene Y Fridman; Natan S Davidovics; Bryce Chiang; Joong Ho Ahn; Charles C Della Santina
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2011-08-26
Journal Detail:
Title:  Hearing research     Volume:  281     ISSN:  1878-5891     ISO Abbreviation:  Hear. Res.     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-11-04     Completed Date:  2012-02-24     Revised Date:  2014-09-14    
Medline Journal Info:
Nlm Unique ID:  7900445     Medline TA:  Hear Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  74-83     Citation Subset:  IM    
Copyright Information:
Copyright © 2011 Elsevier B.V. All rights reserved.
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MeSH Terms
Descriptor/Qualifier:
Acceleration
Animals
Disease Models, Animal
Electric Stimulation
Eye Movements
Female
Gentamicins
Head Movements
Macaca mulatta
Male
Neural Prostheses*
Orientation
Postural Balance*
Prosthesis Design
Prosthesis Implantation*
Reflex, Vestibulo-Ocular*
Rotation
Time Factors
Vestibular Diseases / chemically induced,  physiopathology,  therapy*
Vestibular Function Tests
Vestibule, Labyrinth / innervation*
Grant Support
ID/Acronym/Agency:
5F32DC009917/DC/NIDCD NIH HHS; K08 DC006216/DC/NIDCD NIH HHS; K08 DC006216-05/DC/NIDCD NIH HHS; K08DC6216/DC/NIDCD NIH HHS; R01 DC002390-15/DC/NIDCD NIH HHS; R01 DC009255/DC/NIDCD NIH HHS; R01 DC009255-02S1/DC/NIDCD NIH HHS; R01 DC009255-03/DC/NIDCD NIH HHS; R01DC0255/DC/NIDCD NIH HHS; R01DC2390/DC/NIDCD NIH HHS
Chemical
Reg. No./Substance:
0/Gentamicins
Comments/Corrections

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