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Otolith and canal reflexes in human standing.
J Physiol. 2005 Feb 15; 563(Pt 1):229-34.JP

Abstract

We used galvanic vestibular stimulation (GVS) to identify human balance reflexes of the semicircular canals and otolith organs. The experiment used a model of vestibular signals arising from GVS modulation of the net signal from vestibular afferents. With the head upright, the model predicts that the GVS-evoked canal signal indicates lateral head rotation while the otolith signal indicates lateral tilt or acceleration. Both signify body sway transverse to the head. With the head bent forward, the model predicts that the canal signal indicates body spin about a vertical axis but the otolith signal still signifies lateral body motion. Thus, we compared electromyograms (EMG) in the leg muscles and body sway evoked by GVS when subjects stood with the head upright or bent forward. With the head upright, GVS evoked a large sway in the direction of the anodal electrode. This response was abolished with the head bent forward leaving only small, oppositely directed, transient responses at the start and end of the stimulus. With the head upright, GVS evoked short-latency (60-70 ms), followed by medium-latency (120 ms) EMG responses, of opposite polarity. Bending the head forward abolished the medium-latency but preserved the short-latency response. This is compatible with GVS evoking separate otolithic and canal reflexes, indicating that balance is controlled by independent canal and otolith reflexes, probably through different pathways. We propose that the short-latency reflex and small transient sway are driven by the otolith organs and the medium-latency response and the large sway are driven by the semicircular canals.

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Authors+Show Affiliations

Cathers I
Prince of Wales Medical Research Institute and University of New South Wales, Sydney, Australia.
Day BL
No affiliation info available
Fitzpatrick RC
No affiliation info available

MeSH

AdultAnkle JointElectric StimulationElectromyographyHumansMiddle AgedMovementMuscle ContractionMuscle, SkeletalOtolithic MembranePhysical StimulationPostural BalancePostureReflexSemicircular Canals

Pub Type(s)

Clinical Trial
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15618274

Citation

Cathers, Ian, et al. "Otolith and Canal Reflexes in Human Standing." The Journal of Physiology, vol. 563, no. Pt 1, 2005, pp. 229-34.
Cathers I, Day BL, Fitzpatrick RC. Otolith and canal reflexes in human standing. J Physiol. 2005;563(Pt 1):229-34.
Cathers, I., Day, B. L., & Fitzpatrick, R. C. (2005). Otolith and canal reflexes in human standing. The Journal of Physiology, 563(Pt 1), 229-34.
Cathers I, Day BL, Fitzpatrick RC. Otolith and Canal Reflexes in Human Standing. J Physiol. 2005 Feb 15;563(Pt 1):229-34. PubMed PMID: 15618274.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Otolith and canal reflexes in human standing. AU - Cathers,Ian, AU - Day,Brian L, AU - Fitzpatrick,Richard C, Y1 - 2004/12/23/ PY - 2004/12/25/pubmed PY - 2005/6/25/medline PY - 2004/12/25/entrez SP - 229 EP - 34 JF - The Journal of physiology JO - J Physiol VL - 563 IS - Pt 1 N2 - We used galvanic vestibular stimulation (GVS) to identify human balance reflexes of the semicircular canals and otolith organs. The experiment used a model of vestibular signals arising from GVS modulation of the net signal from vestibular afferents. With the head upright, the model predicts that the GVS-evoked canal signal indicates lateral head rotation while the otolith signal indicates lateral tilt or acceleration. Both signify body sway transverse to the head. With the head bent forward, the model predicts that the canal signal indicates body spin about a vertical axis but the otolith signal still signifies lateral body motion. Thus, we compared electromyograms (EMG) in the leg muscles and body sway evoked by GVS when subjects stood with the head upright or bent forward. With the head upright, GVS evoked a large sway in the direction of the anodal electrode. This response was abolished with the head bent forward leaving only small, oppositely directed, transient responses at the start and end of the stimulus. With the head upright, GVS evoked short-latency (60-70 ms), followed by medium-latency (120 ms) EMG responses, of opposite polarity. Bending the head forward abolished the medium-latency but preserved the short-latency response. This is compatible with GVS evoking separate otolithic and canal reflexes, indicating that balance is controlled by independent canal and otolith reflexes, probably through different pathways. We propose that the short-latency reflex and small transient sway are driven by the otolith organs and the medium-latency response and the large sway are driven by the semicircular canals. SN - 0022-3751 UR - https://www.unboundmedicine.com/medline/citation/15618274/Otolith_and_canal_reflexes_in_human_standing_ DB - PRIME DP - Unbound Medicine ER -