Summary
In anesthetized albino rabbits, ampullary branches of the vestibular nerve were stimulated electrically. Prominent and stable reflex contraction was induced in extra-ocular muscles by applying single current pulses of relatively long duration, 3–5 msec. Survey with a glass microelectrode revealed that, during application of relatively wide pulses to a canal, primary vestibular fibers discharged impulses repetitively at a rate as high as 300–1400/sec and that after being transmitted across second-order vestibular neurons these impulses built up summated EPSPs in oculomotor neurons, large enough to trigger off motoneuronal discharges. From each semicircular canal, prominent reflex contraction was evoked selectively in two muscles; from the anterior canal in the ipsilateral superior rectus and contralateral inferior oblique; from the horizontal canal in the ipsilateral medial rectus and contralateral lateral rectus; and from the posterior canal in the ipsilateral superior oblique and contralateral inferior rectus. Acute lesion experiments indicated that signals for this excitation reached IIIrd and IVth nuclei via three different pathways; from the anterior canal through the ipsilateral brachium conjunctivum, from the horizontal canal through the ipsilateral fasciculus longitudinalis medialis and from the posterior canal through the contralateral fasciculus longitudinalis medialis.
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Baker, R.G., Mano, N., Shimazu, H.: Postsynaptic potentials in abducens motoneurons induced by vestibular stimulation. Brain Res. 15, 577–580 (1969)
Baker, R., Precht, W., Berthoz, A.: Synaptic connections to trochlear motoneurons determined by individual vestibular nerve branch stimulation in the cat. Brain Res. 64, 402–406 (1974)
Brodal, A., Høivik, B.: Site and mode of termination of primary vestibulo-cerebellar fibres in the oat. Arch. ital. Biol. 102, 1–21 (1964)
Brodal, A., Pompeiano, O.: The vestibular nuclei in the cat. J. Anat. (Lond.) 91, 438–454 (1957)
Cohen, B., Suzuki, J., Bender, M.B.: Eye movement from semicircular canal nerve stimulation in the cat. Ann. oto-rhino-laryng. 73, 153–170 (1964)
Gacek, R.R.: The course and central termination of first order neurones supplying vestibular endorgans in the cat. Acta oto-laryng. (Stockh.) 254, 1–66 (1969)
Graybiel, A.M., Hartwieg, E.A.: Some efferent connections of the oculomotor complex in the cat: an experimental study with tracer techniques. Brain Res. 81, 543–551 (1974)
Highstein, S.M.: The organization of the vestibulo-ocular and trochlear reflex pathways in the rabbit. Exp. Brain Res. 17, 285–300 (1973a)
Highstein, S.M.: Synaptic linkage in the vestibulo-ocular and cerebello-vestibular pathways to the VIth nucleus in the rabbit. Exp. Brain Res. 17, 301–314 (1973b)
Highstein, S.M., Ito, M., Tsuchiya, T.: Synaptic linkage in the vestibulo-ocular reflex pathway of rabbit. Exp. Brain Res. 13, 306–326 (1971)
Iggo, A., Muir, A.R.: The structure and function of a slowly adapting touch corpuscle in hairy skin. J. Physiol. (Lond.) 200, 763–796 (1969)
Ito, M., Hongo, T., Okada, Y.: Vestibular-evoked postsynaptic potentials in Deiters neurones. Exp. Brain Res. 7, 214–230 (1969)
Ito, M., Nisimaru, N., Yamamoto, M.: The neural pathways mediating reflex contraction of extraocular muscles during semicircular canal stimulation in rabbits. Brain Res. 55, 183–188 (1973a)
Ito, M., Nisimaru, N., Yamamoto, M.: The neural pathways relaying reflex inhibition from semicircular canals to extraocular muscles of rabbits. Brain Res. 55, 189–193 (1973b)
Ito, M., Nisimaru, N., Yamamoto, M.: Specific neural connections for the cerebellar control of vestibulo-ocular reflexes. Brain Res. 60, 238–247 (1973c)
Katz, B.: Depolarization of sensory terminals and the initiation of impulses in the muscle spindle. J. Physiol. (Lond.) 111, 261–282 (1950)
Kawai, N., Ito, M., Nozue, M.: Postsynaptic influences on the vestibular non-Deiters nuclei from primary vestibular nerve. Exp. Brain Res. 8, 190–200 (1969)
Lorente de Nó, R.: Vestibulo-ocular reflex arc. Arch. Neurol. Psychiat. (Chic.) 30, 245–291 (1933)
Lowenstein, O.: The effect of galvanic polarization on the impulse discharge from sense endings in the isolated labyrinth of the thornback ray. J. Physiol. (Lond.) 127, 104–117 (1955)
McMaster, R.D., Weiss, A.H., Carpenter, M.B.: Vestibular projections to the nuclei of the extraocular muscles. Degeneration resulting from discrete partial lesions of the vestibular nuclei in the monkey. Amer. J. Anat. 118, 163–194 (1966)
Precht, W., Baker, R.: Synaptic organization of the vestibulo-trochlear pathway. Exp. Brain Res. 14, 158–184 (1972)
Precht, W., Llinás, R.: Functional organization of the vestibular afferents to the cerebellar cortex of frog and cat. Exp. Brain Res. 9, 30–52 (1969)
Precht, W., Shimazu, H.: Functional connections of tonic and kinetic vestibular neurons with primary vestibular afferents. J. Neurophysiol. 28, 1014–1028 (1965)
Schwindt, P.C., Richter, A., Precht, W.: Short latency utricular and canal input to ipsilateral abducens motoneurones. Brain Res. 60, 259–262 (1973)
Suzuki, J., Goto, K., Tokumasu, K., Cohen, B.: Implantation of electrodes near individual vestibular nerve branches in mammals. Ann. oto-rhino-laryng. 78, 815–827 (1969a)
Suzuki, J., Tokumasu, K., Goto, K.: Eye movements from single utricular nerve stimulation in the cat. Acta oto-laryng. (Stockh.) 68, 350–363 (1969b)
Szentágothai, J.: The elementary vestibulo-ocular reflex arc. J. Neurophysiol. 13, 395–407 (1950)
Tarlov, E.: Organization of vestibulo-oculomotor projections in the cat. Brain Res. 20, 159–179 (1970)
Wilson, V.J., Wylie, R.M., Marco, L.A.: Synaptic inputs to cells in the medial vestibular nucleus. J. Neurophysiol. 31, 176–185 (1968)
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This work was supported by a grant from Educational Ministry of Japan (844021).
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Ito, M., Nisimaru, N. & Yamamoto, M. Pathways for the vestibulo-ocular reflex excitation arising from semicircular canals of rabbits. Exp Brain Res 24, 257–271 (1976). https://doi.org/10.1007/BF00235014
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DOI: https://doi.org/10.1007/BF00235014