Summary
The projection of individual pyramidal tract (PT) neurons from the hindlimb area in the precentral gyrus of the cerebral cortex to the lumbar spinal cord was studied in the monkey by systematically searching for sites within identified regions of the spinal gray from which the PT neurons could be antidromically activated by local stimulation. All investigated neurons belonged to the fast conducting fraction of PT neurons. The following results were obtained.
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1.
Each PT neuron could be activated from more than one region of the spinal gray matter, including identified spinal motor nuclei and areas dorsomedial to these nuclei, but not the intermediate nucleus or regions dorsal to it. “Passage areas” and “termination areas” were defined.
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2.
Half of the PT neurons with termination areas within motor nuclei had these areas in more than one nucleus. There were thus strong suggestions for synaptic contacts of some PT neurons with motoneurons of more than one muscle.
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3.
Four groups of three or four neurons were recorded simultaneously by the same cortical electrode. Comparisons of passage and termination areas within groups revealed both similarities and differences in projections of neighboring neurons. Every neuron was activated from some region(s) where others of the group were not. Common passage areas, or passage and termination areas, for two or three neurons of a group within at least one motor nucleus were found for all groups. Termination areas in the same motor nucleus have been found for the majority of the neurons of only one group. These common projection areas are compatible with, but do not prove, that a group of adjacent PT neurons has common target cells in the spinal cord.
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References
Abzug, C., Maeda, M., Peterson, B.W., Wilson, V.J.: Cervical branching of lumbar vestibulospinal axons. J Physiol (Lond) 243, 499–522 (1974)
Araki, T., Endo, K., Kawai, Y., Ito, K., Shigenaga, Y.: Supraspinal control of slow and fast spinal motoneurons of the cat. Progr Brain Res 44, 413–432 (1976)
Asanuma, H., Sakata, H.: Functional organization of a cortical efferent system examined with focal depth stimulation in cat. J Neurophysiol 30, 35–54 (1967)
Asanuma, H., Rosén, I.: Topographical organization of cortical efferent zones projecting to distal forelimb muscles in the monkey. Exp Brain Res 14, 243–256 (1972)
Bonin, G. von, Bailey, P.: The Neocortex of Macaca mulatta. Urbana: University of Illinois Press 1947
Coulter, J.D., Jones, E.G.: Differential distribution of corticospinal projections from individual cytoarchitectonic fields in the monkey. Brain Res 129, 335–340 (1977)
Evarts, E.V.: Representation of movements and muscles by pyramidal tract neurons of the precentral motor cortex. In: Symposium on “Neurophysical basis of normal and abnormal motor activities” (eds. D.P. Purpura and M.D. Yahr), pp. 215–251. Hewlett: Raven Press 1967
Fetz, E.E., Cheney, P.D., German, D.C.: Corticomotoneuronal connections of precentral cells detected by postspike averages of EMG activity in behaving monkeys. Brain Res 114, 505–510 (1976)
Illert, M., Lundberg, A., Tanaka, R.: 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. Exp Brain Res 29, 323–346 (1977)
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)
Jankowska, E., Roberts, W.J.: Synaptic actions of single interneurones mediating reciprocal Ia inhibition of motoneurones. J Physiol (Lond) 222, 623–642 (1972b)
Jankowska, E., Lindstrom, S.: Morphology of interneurones mediating Ia reciprocal inhibition of motoneurones in the spinal cord of the cat. J Physiol (Lond) 226, 805–823 (1972)
Jankowska, E., Padel, Y., Tanaka, R.: Projections of pyramidal tract cells to alpha-motoneurones innervating hindlimb muscles in the monkey. J Physiol (Lond) 249, 637–667 (1975)
Jankowska, E., Padel, Y., Tanaka, R.: Disynaptic inhibition of spinal motoneurones from the motor cortex in the monkey. J Physiol (Lond) 258, 467–487 (1976)
Kandel, E.R., Frazier, W.T., Waziri, R., Coggeshall, R.E.: Direct and common connections among identified neurones in aplysia. J Neurophysiol 30, 1352–1376 (1967)
Kostyuk, P.G., Maisky, V.A.: Propriospinal projections in the lumbar spinal cord of the cat. Brain Res 39, 530–535 (1972)
Kuypers, H.G.J.M., Brinkman, J.: Precentral projections to different parts of the spinal intermediate zone in the rhesus monkey. Brain Res 24, 29–48 (1970)
Landgren, S., Phillips, C., Porter, R.: Minimal synaptic actions of pyramidal impulses on some alpha motoneurones of the baboon's hand and forearm. J Physiol (Lond) 161, 91–111 (1962)
Liu, C.M., Chambers, W.W.: An experimental study of the corticospinal system in the monkey (Manaca mulatta). J Comp Neurol 123, 257–284 (1964)
Mendell, L.M., Henneman, E.: Terminals of single Ia fibers: Distribution within a pool of 300 homonymous motor neurons. Science 160, 96–98 (1968)
Mendell, L.M., Henneman, E.: Terminals of single Ia fibers: Location, density and distribution within a pool of 300 homonymous motoneurons. J Neurophysiol 34, 171–187 (1971)
Porter, R., Hore, J.: Time course of minimal cortico-motoneuronal excitatory postsynaptic potentials in lumbar motoneurons of monkey. J Neurophysiol 32, 443–451 (1969)
Scheibel, M.E., Scheibel, A.B.: Terminal axonal patterns in cat spinal cord. I. The lateral corticospinal tract. Brain Res 2, 333–350 (1966)
Shinoda, Y., Arnold, A.P., Asanuma, H.: Spinal branching of corticospinal axons in the cat. Exp Brain Res 26, 215–234 (1976)
Shinoda, Y., Zarzecki, P., Asanuma, H.: Spinal branching of pyramidal tract neurons in the monkey. Exp Brain Res. 34, 59–72 (1979)
Stoney, S.D., Thompson, W.D., Asanuma, H.: Excitation of pyramidal tract cells by intracortical microstimulation: Effective extent of stimulating current. J Neurophysiol 31, 659–669 (1968)
Tamarova, Z.A., Shapovalov, A.I., Karamyan, O.A. Kurchavyi, G.G.: Cortico-pyramidal and cortico-extrapyramidal synaptic influences on lumbar motoneurons in monkeys. Neurophysiol (Kiev) 4, 587–596 (1972)
Thomas, R.C., Wilson, V.J.: Precise localization of Renshaw cells with a new marking technique. Nature (Lond) 206, 211–213 (1965)
Tsukahara, N., Fuller, D.R.G., Brooks, V.B.: Collateral pyramidal influences on the corticorubrospinal system. J Neurophysiol 31, 467–484 (1968)
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Asanuma, H., Zarzecki, P., Jankowska, E. et al. Projection of individual pyramidal tract neurons to lumbar motor nuclei of the monkey. Exp Brain Res 34, 73–89 (1979). https://doi.org/10.1007/BF00238342
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DOI: https://doi.org/10.1007/BF00238342