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EPSPs of masseter motoneurons evoked by stimulation of low-threshold infraorbital nerve afferents in cat

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Stimulation of the infraorbital nerve at strengths 1.4–2.5 times higer than the threshold of excitation of A fibers in cats anesthetized with chloralose and pentobarbital evoked EPSPs with an amplitude up to 3.0 mV and a duration of 9–15 msec in 69% of masseter motoneurons after 1.5–3.0 msec. These EPSPs were complex and formed by summation of simpler short-latency and long-latency EPSPs. The short-latency EPSPs appeared in response to infraorbital nerve stimulation at 1.1–1.5 thresholds and had a slow rate of rise (2.5–4.5 msec, mean 3.7±0.4 msec), low amplitude (under 2.0 mV), and short duration (5–6 msec). Their latent period varied from 1.5 to 3.0 msec (mean 2.1±0.2 msec). The shortness of the latent period and its constancy during stimulation of the nerve at increasing strength, and also the character of development of facilitation and inhibition of the EPSP during high-frequency stimulation suggests that these EPSPs are monosynaptic. The slow rate of rise suggested that these EPSPs arise on distal dendrites of the motoneurons. Long-latency EPSPs appeared 7–9 msec after stimulation of the infraorbital nerve at 1.1–1.5 thresholds. Their amplitude reached 1.5–2.0 mV and their duration 7–9 msec. The long duration of the latent period combined with low ability to reproduce high-frequency stimulation (up to 30/sec) points to the polysynaptic origin of these EPSPs.

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Literature cited

  1. 1.

    E. V. Gura, Yu. P. Limanskii, and A. I. Pilyavskii, "Synaptic potentials of masseter motoneurons," Neirofiziologiya,1, 262 (1969).

  2. 2.

    K. E. Aström, "On the central course of afferent fibers in the trigeminal, facial, glossopharyngeal, and vagal nerves and their nuclei in the mouse," Acta Physiol. Scand.,29, Suppl. 106, 209 (1953).

  3. 3.

    J. N. Barrett and W. E. Crill, "Influence of dendritic location and membrane properties on the effectiveness of synapses on cat motoneurones," J. Physiol. (London),293, 325 (1974).

  4. 4.

    I. Darian-Smith, "Neurone activity in the cat's trigeminal main sensory nucleus elicited by graded afferent stimulation," J. Physiol. (London),153, 52 (1960).

  5. 5.

    R. W. Dykes, "Afferent fibers from mustacial vibrissae of cats and seals," J. Neurophysiol.,38, 650 (1975).

  6. 6.

    J. Eisenman, S. Landgren, and D. Novin, "Functional organization in the main sensory trigeminal nucleus and the rostral subdivision of the nucleus of the spinal trigeminal tract in the cat," Acta Physiol. Scand.,59, Suppl. 214, 1 (1963).

  7. 7.

    W. M. Falls and J. S. King, "The facial motor nucleus of the opossum: cytology and axosomatic synapses," J. Comp. Neurol.,167, 177 (1976).

  8. 8.

    L. J. Goldberg and Y. Nakamura, "Lingually induced inhibition of masseteric motoneurones," Experientia,24, 371 (1968).

  9. 9.

    K. M. Gottschaldt, A. Iggo, and D. W. Young, "Functional characteristics of mechanoreceptors in sinus hair follicles of the cat," J. Physiol. (London),235, 287 (1973).

  10. 10.

    J. F. Hahn, "Stimulus-response relationships in first-order sensory fibers from cat vibrissae," J. Physiol. (London),213, 215 (1971).

  11. 11.

    J. B. Hursh, "Conduction velocity and diameter of nerve fibers," Amer. J. Physiol.127, 131 (1939).

  12. 12.

    Y. Kawamura and M. Takata, "The role of trigeminal afferents in the control of masseter motoneuron activity," in: Oral-Facial Sensory and Motor Mechanisms, New York (1971), pp. 333–348.

  13. 13.

    F. W. L. Kerr, "Structural relation of the trigeminal spinal tract to upper cervical roots and the solitary nucleus in the cat," Exp. Neurol.,4, 134 (1961).

  14. 14.

    L. Kidokoro, K. Kubota, S. Shuto, and R. Sumino, "Reflex organization of cat masticatory muscles," J. Neurophysiol.,31, 695 (1968).

  15. 15.

    K. Kubota and J. M. Brookheart, "Recurrent facilitation of frog motoneurons," J. Neurophysiol.,26, 877 (1963).

  16. 16.

    A. B. Odutola, "Cell grouping and Golgi architecture of the hypoglossal nucleus of the rat," Exp. Neurol.,52, 356 (1976).

  17. 17.

    M. Rall, "Distinguishing theoretical synaptic potentials computed for different soma-dendritic distributions of synaptic input," J. Neurophysiol.,30, 1138 (1967).

  18. 18.

    M. Rall, T. G. Smith, K. Frank, R. E. Burke, and P. G. Nelson, "Dendritic location of synapses and possible mechanisms for the monosynaptic EPSP in motoneurons," J. Neurophysiol.,30, 1169 (1967).

  19. 19.

    G. J. Romanes, "The motor pools of the spinal cord," Prog. Brain Res.,11, 93 (1964).

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Additional information

A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 9, No. 6, pp. 583–591, November–December, 1977.

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Limanskii, Y.P., Gura, E.V. EPSPs of masseter motoneurons evoked by stimulation of low-threshold infraorbital nerve afferents in cat. Neurophysiology 9, 441–447 (1977). https://doi.org/10.1007/BF01063521

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  • Short Duration
  • Latent Period
  • Slow Rate
  • Pentobarbital
  • Nerve Stimulation