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. 1994 Jul 15;478(Pt 2):363–372. doi: 10.1113/jphysiol.1994.sp020257

Task-dependent reflex responses and movement illusions evoked by galvanic vestibular stimulation in standing humans.

R Fitzpatrick 1, D Burke 1, S C Gandevia 1
PMCID: PMC1155693  PMID: 7965852

Abstract

1. To identify the vestibular contribution to human standing, responses in leg muscles evoked by galvanic vestibular stimulation were studied. Step impulses of current were applied between the mastoid processes of normal subjects and the effects on the soleus and tibialis anterior electromyograms (EMGs), ankle torque, and body sway were identified by post-stimulus averaging. The responses were measured when subjects stood on a stable platform or on an unstable platform and the effects of eye closure were also assessed. Responses were also recorded during voluntary contraction of the leg muscles and when subjects balanced a load equivalent to their own body in a situation where vestibular postural reflexes would not be useful. 2. At a mean post-stimulus latency of 56 ms, there were reciprocal changes in soleus and tibialis anterior muscle activity followed, at 105 ms, by larger responses of opposite sign. These were termed the short- and middle-latency responses, respectively. Both responses increased with stimulus intensity, but the short-latency response had a higher threshold. The early response had a similar latency to EMG responses evoked by rapid postural perturbations. Both responses were larger when the eyes were closed, but eye closure was associated with increased sway and EMG activity, and the responses were of similar magnitude when scaled to background EMG level. 3. Both short- and middle-latency EMG responses in soleus and tibialis anterior muscles produced small transient postural sways. The transient changes in EMG activity were followed by a larger prolonged sway which was not attributable to the activity in these muscles but rather to reflex or volitional adjustments to movements at other body segments. When subjects were prevented from swaying, the galvanic stimulus produced illusory movements in the opposite direction to the sway evoked when standing, and it is possible that the prolonged sway is a reaction to the illusion of sway. 4. The short- and middle-latency responses were modified during different postural tasks according to the dependence on vestibular reflexes. When the support platform was unstable, the EMG responses to galvanic stimulation were larger. There were no vestibular-evoked responses when seated subjects made voluntary contractions of the leg muscles or when they stood upright with the trunk supported, using the ankles to balance a body-like load.(ABSTRACT TRUNCATED AT 400 WORDS)

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Selected References

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  1. Allum J. H., Pfaltz C. R. Visual and vestibular contributions to pitch sway stabilization in the ankle muscles of normals and patients with bilateral peripheral vestibular deficits. Exp Brain Res. 1985;58(1):82–94. doi: 10.1007/BF00238956. [DOI] [PubMed] [Google Scholar]
  2. Black F. O., Shupert C. L., Horak F. B., Nashner L. M. Abnormal postural control associated with peripheral vestibular disorders. Prog Brain Res. 1988;76:263–275. doi: 10.1016/s0079-6123(08)64513-6. [DOI] [PubMed] [Google Scholar]
  3. Britton T. C., Day B. L., Brown P., Rothwell J. C., Thompson P. D., Marsden C. D. Postural electromyographic responses in the arm and leg following galvanic vestibular stimulation in man. Exp Brain Res. 1993;94(1):143–151. doi: 10.1007/BF00230477. [DOI] [PubMed] [Google Scholar]
  4. Eklund G. General features of vibration-induced effects on balance. Ups J Med Sci. 1972;77(2):112–124. doi: 10.1517/03009734000000016. [DOI] [PubMed] [Google Scholar]
  5. Fitzpatrick R. C., Taylor J. L., McCloskey D. I. Ankle stiffness of standing humans in response to imperceptible perturbation: reflex and task-dependent components. J Physiol. 1992 Aug;454:533–547. doi: 10.1113/jphysiol.1992.sp019278. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Greenwood R., Hopkins A. Muscle responses during sudden falls in man. J Physiol. 1976 Jan;254(2):507–518. doi: 10.1113/jphysiol.1976.sp011242. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Grillner S., Hongo T., Lund S. Convergent effects on alpha motoneurones from the vestibulospinal tract and a pathway descending in the medial longitudinal fasciculus. Exp Brain Res. 1971 Jun 29;12(5):457–479. doi: 10.1007/BF00234243. [DOI] [PubMed] [Google Scholar]
  8. Horstmann G. A., Dietz V. The contribution of vestibular input to the stabilization of human posture: a new experimental approach. Neurosci Lett. 1988 Dec 19;95(1-3):179–184. doi: 10.1016/0304-3940(88)90653-2. [DOI] [PubMed] [Google Scholar]
  9. Iles J. F., Pisini J. V. Vestibular-evoked postural reactions in man and modulation of transmission in spinal reflex pathways. J Physiol. 1992 Sep;455:407–424. doi: 10.1113/jphysiol.1992.sp019308. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Jones G. M., Watt D. G. Muscular control of landing from unexpected falls in man. J Physiol. 1971 Dec;219(3):729–737. doi: 10.1113/jphysiol.1971.sp009685. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Lund S., Broberg C. Effects of different head positions on postural sway in man induced by a reproducible vestibular error signal. Acta Physiol Scand. 1983 Feb;117(2):307–309. doi: 10.1111/j.1748-1716.1983.tb07212.x. [DOI] [PubMed] [Google Scholar]
  12. Nashner L. M. Adapting reflexes controlling the human posture. Exp Brain Res. 1976 Aug 27;26(1):59–72. doi: 10.1007/BF00235249. [DOI] [PubMed] [Google Scholar]
  13. Nashner L. M., Wolfson P. Influence of head position and proprioceptive cues on short latency postural reflexes evoked by galvanic stimulation of the human labyrinth. Brain Res. 1974 Feb 22;67(2):255–268. doi: 10.1016/0006-8993(74)90276-5. [DOI] [PubMed] [Google Scholar]
  14. Tokita T., Ito Y., Takagi K. Modulation by head and trunk positions of the vestibulo-spinal reflexes evoked by galvanic stimulation of the labyrinth. Observations by labyrinthine evoked EMG. Acta Otolaryngol. 1989 May-Jun;107(5-6):327–332. doi: 10.3109/00016488909127516. [DOI] [PubMed] [Google Scholar]
  15. Wilson V. J., Yoshida M. Comparison of effects of stimulation of Deiters' nucleus and medial longitudinal fasciculus on neck, forelimb, and hindlimb motoneurons. J Neurophysiol. 1969 Sep;32(5):743–758. doi: 10.1152/jn.1969.32.5.743. [DOI] [PubMed] [Google Scholar]

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