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A review of mechanical and synaptic processes in otolith transduction of sound and vibration for clinical VEMP testing.

Abstract

Older studies of mammalian otolith physiology have focused mainly on sustained responses to low-frequency (<50 Hz) or maintained linear acceleration. So the otoliths have been regarded as accelerometers. Thus evidence of otolithic activation and high-precision phase locking to high-frequency sound and vibration appears to be very unusual. However, those results are exactly in accord with a substantial body of knowledge of otolith function in fish and frogs. It is likely that phase locking of otolith afferents to vibration is a general property of all vertebrates. This review examines the literature about the activation and phase locking of single otolithic neurons to air-conducted sound and bone-conducted vibration, in particular the high precision of phase locking shown by mammalian irregular afferents that synapse on striolar type I hair cells by calyx endings. Potassium in the synaptic cleft between the type I hair cell receptor and the calyx afferent ending may be responsible for the tight phase locking of these afferents even at very high discharge rates. Since frogs and fish do not possess full calyx endings, it is unlikely that they show phase locking with such high precision and to such high frequencies as has been found in mammals. The high-frequency responses have been modeled as the otoliths operating in a seismometer mode rather than an accelerometer mode. These high-frequency otolithic responses constitute the neural basis for clinical vestibular-evoked myogenic potential tests of otolith function.

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  • Publisher Full Text
  • Authors+Show Affiliations

    ,

    Vestibular Research Laboratory, School of Psychology, the University of Sydney, New South Wales, Australia.

    ,

    Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia.

    ,

    The Meniere's Laboratory, Sydney Medical School, University of Sydney, New South Wales, Australia.

    ,

    The Meniere's Laboratory, Sydney Medical School, University of Sydney, New South Wales, Australia.

    ,

    Vestibular Research Laboratory, School of Psychology, the University of Sydney, New South Wales, Australia.

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    School of Biomedical Sciences and Pharmacy, The University of Newcastle and Hunter Medical Research Institute. Newcastle, New South Wales, Australia.

    School of Biomedical Sciences and Pharmacy, The University of Newcastle and Hunter Medical Research Institute. Newcastle, New South Wales, Australia.

    Source

    Journal of neurophysiology 122:1 2019 Jul 01 pg 259-276

    Pub Type(s)

    Journal Article

    Language

    eng

    PubMed ID

    31042414

    Citation

    Curthoys, Ian S., et al. "A Review of Mechanical and Synaptic Processes in Otolith Transduction of Sound and Vibration for Clinical VEMP Testing." Journal of Neurophysiology, vol. 122, no. 1, 2019, pp. 259-276.
    Curthoys IS, Grant JW, Pastras CJ, et al. A review of mechanical and synaptic processes in otolith transduction of sound and vibration for clinical VEMP testing. J Neurophysiol. 2019;122(1):259-276.
    Curthoys, I. S., Grant, J. W., Pastras, C. J., Brown, D. J., Burgess, A. M., Brichta, A. M., & Lim, R. (2019). A review of mechanical and synaptic processes in otolith transduction of sound and vibration for clinical VEMP testing. Journal of Neurophysiology, 122(1), pp. 259-276. doi:10.1152/jn.00031.2019.
    Curthoys IS, et al. A Review of Mechanical and Synaptic Processes in Otolith Transduction of Sound and Vibration for Clinical VEMP Testing. J Neurophysiol. 2019 Jul 1;122(1):259-276. PubMed PMID: 31042414.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - A review of mechanical and synaptic processes in otolith transduction of sound and vibration for clinical VEMP testing. AU - Curthoys,Ian S, AU - Grant,J Wally, AU - Pastras,Christopher J, AU - Brown,Daniel J, AU - Burgess,Ann M, AU - Brichta,Alan M, AU - Lim,Rebecca, Y1 - 2019/05/01/ PY - 2019/5/3/pubmed PY - 2019/5/3/medline PY - 2019/5/3/entrez KW - phase locking KW - sound KW - utricle KW - vestibular KW - vibration SP - 259 EP - 276 JF - Journal of neurophysiology JO - J. Neurophysiol. VL - 122 IS - 1 N2 - Older studies of mammalian otolith physiology have focused mainly on sustained responses to low-frequency (<50 Hz) or maintained linear acceleration. So the otoliths have been regarded as accelerometers. Thus evidence of otolithic activation and high-precision phase locking to high-frequency sound and vibration appears to be very unusual. However, those results are exactly in accord with a substantial body of knowledge of otolith function in fish and frogs. It is likely that phase locking of otolith afferents to vibration is a general property of all vertebrates. This review examines the literature about the activation and phase locking of single otolithic neurons to air-conducted sound and bone-conducted vibration, in particular the high precision of phase locking shown by mammalian irregular afferents that synapse on striolar type I hair cells by calyx endings. Potassium in the synaptic cleft between the type I hair cell receptor and the calyx afferent ending may be responsible for the tight phase locking of these afferents even at very high discharge rates. Since frogs and fish do not possess full calyx endings, it is unlikely that they show phase locking with such high precision and to such high frequencies as has been found in mammals. The high-frequency responses have been modeled as the otoliths operating in a seismometer mode rather than an accelerometer mode. These high-frequency otolithic responses constitute the neural basis for clinical vestibular-evoked myogenic potential tests of otolith function. SN - 1522-1598 UR - https://www.unboundmedicine.com/medline/citation/31042414/A_review_of_mechanical_and_synaptic_processes_in_otolith_transduction_of_sound_and_vibration_for_clinical_VEMP_testing L2 - http://www.physiology.org/doi/full/10.1152/jn.00031.2019?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -