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Integration in descending motor pathways controlling the forelimb in the cat

3. Convergence on propriospinal neurones transmitting disynaptic excitation from the corticospinal tract and other descending tracts

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Summary

A previously described disynaptic pathway from cortex to forelimb motoneurones whose intercalated neurones were excited both from other descending pathways and from forelimb afferents (Illert et al., 1976a, b) has been further analysed, mainly with respect to the location of the relay cells and their axons.

Disynaptic EPSPs evoked in forelimb motoneurones by stimulation of the pyramid remained after complete transection of the corticospinal tract in C5 rostral to the forelimb segments but were abolished after a more rostral transection of the tract in the C2 segment. Corresponding findings were made with disynaptic rubral EPSPs after transection of the rubrospinal tract in these segments. It is concluded that disynaptic cortico-motoneuronal and rubro-motoneuronal excitation is relayed by propriospinal neurones originating in the C3–C4 segments. Other lesion experiments revealed that the axons of these propriospinal neurones descend to forelimb motoneurones in the ventrolateral part of the lateral funicle.

Spatial facilitation of transmission from the corticospinal and rubrospinal tracts after transection of them in C5 occurred with a time course showing monosynaptic convergence from these pathways on common propriospinal neurones.

Facilitation of disynaptic pyramidal EPSPs from the dorsal tegmentum remained after transection of the corticospinal tract at C5 but was abolished after a transection at C2. It is postulated that corticospinal and presumed tectospinal fibres converge onto common neurones in the propriospinal relay but evidence is also given for a more rostral relay (probably bulbar) with a similar convergence.

The oligo- (probably mono-)synaptic facilitation of the disynaptic pyramidal EPSP evoked by volleys in cutaneous and group I muscle afferents from the forelimb likewise remained after a C5 transection of the corticospinal tract but was abolished after an additional C5 lesion in the dorsal column. It is concluded that propriospinal relay cells receive excitatory action from forelimb afferents ascending in the dorsal column. Spatial facilitation experiments using three tests revealed that propriospinal neurones monosynaptically excited from both corticospinal and rubrospinal fibres also receive excitation from cutaneous forelimb afferents.

It is postulated that the propriospinal relay provides an important route for fast activation of forelimb motoneurones from the brain. The convergent monosynaptic excitation from several important motor centres in the brain is considered in relation to the general problem of the functional relationship between higher motor centres. The convergent action from forelimb afferents is taken to suggest that a descending command for a forelimb movement can be modified from the forelimb while on its way to the motoneurones.

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References

  • Allen, G.I., Tsukahara, N.: Cerebrocerebellar communication systems. Physiol. Rev. 54, 957–1006 (1974)

    Google Scholar 

  • Baldissera, F., Lundberg, A., Udo, M.: Stimulation of pre- and postsynaptic elements in the red nucleus. Exp. Brain Res. 15, 151–167 (1972a)

    Google Scholar 

  • Baldissera, F., Lundberg, A., Udo, M.: Activity evoked from the mesencephalic tegmentum in descending pathways other than the rubrospinal tract. Exp. Brain Res. 15, 133–150 (1972b)

    Google Scholar 

  • Bergmans, J., Illert, M., Jankowska, E., Lundberg, A.: Reticulospinal control of propriospinal neurones mediating disynaptic corticomotoneuronal excitation in the cat. Acta physiol. scand. 96, 5A (1976)

  • Eccles, J., Nicoll, R.A., Schwarz, D.W.F., Táboříková, H., Willey, T.J.: Reticulospinal neurons with and without monosynaptic inputs from cerebellar nuclei. J. Neurophysiol. 38, 513–530 (1975)

    Google Scholar 

  • Grillner, S., Hongo, T.: Vestibulospinal effects on motoneurones and interneurones in the lumbosacral cord. In: Basic Aspects of Central Vestibular Mechanisms (eds. A. Brodal and O. Pompeiano). Progress in Brain Res. 37, 244–262 (1972)

  • Illert, M., Lundberg, A., Padel, Y., Tanaka, R.: Convergence on propriospinal neurones which may mediate disynaptic corticospinal excitation to forelimb motoneurones in the cat. Brain Res. 93, 530–534 (1975a)

    Google Scholar 

  • Illert, M., Lundberg, A., Tanaka, R.: Integration in a disynaptic cortico-motoneuronal pathway to the forelimb in the cat. Brain Res. 93, 525–529 (1975b)

    Google Scholar 

  • Illert, M., Lundberg, A., Tanaka, R.: Integration in descending motor pathways controlling the forelimb in the cat. 1. Pyramidal effects on motoneurones. Exp. Brain Res. 26, 509–519 (1976a)

    Google Scholar 

  • Illert, M., Lundberg, A., Tanaka, R.: Integration in descending motor pathways controlling the forelimb in the cat. 2. Convergence on neurones mediating disynaptic cortico-motoneuronal excitation. Exp. Brain Res. 26, 521–540 (1976b)

    Google Scholar 

  • Ito, M., Udo, M., Mano, N., Kawai, N.: Synaptic action of the fastigiobulbar impulses upon neurones in the medullary reticular formation and vestibular nuclei. Exp. Brain Res. 11, 29–47 (1970)

    Google Scholar 

  • Jankowska, E., Roberts, W.J.: An electrophysiological demonstration of the axonal projections of single spinal interneurones in the cat. J. Physiol. (Lond.) 222, 597–622 (1972a)

    Google Scholar 

  • Jankowska, E., Roberts, W.J.: Synaptic actions of single interneurones mediating reciprocal Ia inhibition of motoneurones. J. Physiol. (Lond.) 222, 623–642 (1972b)

    Google Scholar 

  • Kostyuk, P.G.: Interneuronal mechanisms of interaction between descending and afferent signals in the spinal cord. In: Golgi Centennial Symposium. Proceedings (ed. M. Santini), pp. 247–259. New York: Raven Press 1975

    Google Scholar 

  • Lloyd, D.P.: Activity in neurons of the bulbospinal correlation system. J. Neurophysiol. 4, 115–134 (1941)

    Google Scholar 

  • Lundberg, A.: Integration in the reflex pathway. In: Muscular Afferents and Motor Control. Nobel Symposium I (ed. R. Granit), pp. 275–305. Stockholm: Almqvist and Wiksell 1966

    Google Scholar 

  • Lundberg, A.: The control of spinal mechanisms from the brain. In: The Nervous System, Vol. 1 (ed. D.B. Tower), pp. 253–265. New York: Raven Press 1975

    Google Scholar 

  • Peterson, B.W., Anderson, M.E., Filion, M.: Responses of ponto-medullary reticular neurons to cortical, tectal and cutaneous stimuli. Exp. Brain Res. 21, 19–44 (1974)

    Google Scholar 

  • Petras, J.M.: Cortical, tectal and tegmental fiber connections in the spinal cord of the cat. Brain Res. 6, 275–324 (1967)

    Google Scholar 

  • Phillips, C.G., Porter, R.: Corticospinal neurones. Their role in movement. London: Academic Press 1977

    Google Scholar 

  • Pogorelaya, N.C., Tarusina, V.N.: Experimental-morphological study of lateral funiculus propriospinal fibre terminals in cat cervical spinal cord. Neurophysiology (Kiev) 6, 44–51 (1974)

    Article  CAS  Google Scholar 

  • Shapovalov, A.I.: Neuronal organization and synaptic mechanisms of supraspinal motor control in vertebrates. Rev. Physiol. Biochem. Pharmacol. 72, 1–54 (1975)

    Google Scholar 

  • Sherrington, C.S.: The integrative action of the nervous system. New Haven and London: Yale University Press 1906

    Google Scholar 

  • Stewart, D.H., Preston, J.B., Whitlock, D.G.: Spinal pathways mediating motor cortex evoked excitability changes in segmental motoneurons in pyramidal cats. J. Neurophysiol. 31, 928–937 (1968)

    Google Scholar 

  • Szentágothai, J.: Propriospinal pathways and their synapses. In: Organization of the Spinal Cord (ed. J.C. Eccles and J.P. Schadé), Progress in Brain Res. Vol. 11, pp. 155–177. Amsterdam: Elsevier 1964

    Google Scholar 

  • Vasilenko, D.A., Kostyukov, A.I., Pilyavski, A.I.: Cortico- and rubrofugal activation of propriospinal interneurones sending axons into the dorsolateral funiculus of the cat spinal cord. Neurophysiology (Kiev) 4, 489–500 (1972)

    Google Scholar 

  • Vasilenko, D.A., Zadorozhny, A.G., Kostyuk, P.G.: Synaptic processes in spinal neurons monosynaptically activated from the pyramidal tract. Bull. exp. Biol. Med. USSR. 64, 20–25 (1967)

    Google Scholar 

  • Wilson, V.J.: The vestibular nuclei and spinal motor activity. J. psychiat. Res. 8, 259–272 (1971)

    Google Scholar 

  • 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. 32, 743–758 (1969)

    Google Scholar 

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Illert, M., Lundberg, A. & Tanaka, R. Integration in descending motor pathways controlling the forelimb in the cat. Exp Brain Res 29, 323–346 (1977). https://doi.org/10.1007/BF00236174

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