Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Spinal branching of corticospinal axons in the cat


Branching patterns of single corticospinal (CS) neurons were studied in the cat by activating these neurons antidromically from various regions of the spinal cord.

  1. 1.

    One hundred and ninety-three neurons were activated antidromically by microstimulation in the gray substance of the cervical cord and the majority of them were found in the forelimb area of the pericruciate cortex.

  2. 2.

    Branches to the lower levels of the spinal cord were found for 30% of the neurons projecting to the cervical gray matter.

  3. 3.

    The remaining 70% sent axons only to the cervical gray matter and some of them sent multiple branches to several segments in the cervical cord.

  4. 4.

    Only a few CS neurons located outside of the forelimb area could be activated from the cervical cord, but all of them also sent branches to the lower levels of the spinal cord. Neurons projecting to both the cervical cord and the lower levels were intermingled in the cortex with those projecting only to the cervical cord.

  5. 5.

    CS neurons activated from a given area of the cervical cord were often clustered together in a small area of the cortex, although some of these CS neurons sent their other branches to other parts of the spinal cord and neurons projecting to other parts were also intermingled among them.

  6. 6.

    The functional significance of multiple axonal branching of CS neurons is discussed in relation to cortical motor functions.

This is a preview of subscription content, log in to check access.


  1. Abzug, C., Maeda, M., Peterson, B.W., Wilson, V.J.: Cervical branching of lumbar vestibulospinal axons. J. Physiol. (Lond.) 243, 499–522 (1974)

  2. Anderson, P., Hagan, P.J., Phillips, C.G., Powell, T.P.S.: Mapping by microstimulation of overlapping projections from area 4 to motor units of the baboon's hand. Proc. roy. Soc. B 188, 31–60 (1975)

  3. Armand, J., Padel, Y., Smith, A.M.: Somatotopic organization of the corticospinal tract in cat motor cortex. Brain Res. 74, 209–227 (1974)

  4. Asanuma, H., Arnold, A.: Noxious effects of excessive currents used for intracortical microstimulation. Brain Res. 96, 103–107 (1975)

  5. Asanuma, H., Arnold, A., Zarzecki, P.: Further study on the excitation of Pyramidal Tract cells by intracortical microstimulation. Exp. Brain Res. (in press)

  6. 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)

  7. Asanuma, H., Sakata, H.: Functional organization of a cortical efferent system examined with focal depth stimulation in cat. J. Neurophysiol. 30, 35–54 (1967)

  8. Asanuma, H., Stoney, S.D. Jr., Abzug, C.: Relationship between afferent input and motor outflow in cat motorsensory cortex. J. Neurophysiol. 31, 670–681 (1968)

  9. Asanuma, H., Ward, J.E.: Patterns of contraction of distal forelimb muscles produced by intracortical stimulation in cats. Brain Res. 27, 97–109 (1971)

  10. BeMent, S.L., Ranck, J.B.: A quantitative study of electrical stimulation of central myelinated fibers. Exp. Neurol. 24, 147–170 (1969a)

  11. BeMent, S.L., Ranck, J.B.: A model for electrical stimulation of central myelinated fibers with monopolar electrodes. Exp. Neurol. 24, 171–186 (1969b)

  12. Brooks, V.B., Stoney, S.D.K.: Motor mechanisms: the role of the pyramidal system in motor control. Ann. Rev. Physiol. 33, 337–392 (1971)

  13. Chambers, W.W., Liu, C.N.: Cortico-spinal tract of the cat. J. comp. Neurol. 108, 23–55 (1957)

  14. Chang, H.T., Ruch, T.C., Ward, A.A. Jr.: Topographical representation of muscles in motor cortex in monkeys. J. Neurophysiol. 10, 39–56 (1947)

  15. Coombs, J.S., Curtis, D.R., Eccles, J.C.: The interpretation of spike potentials of motoneurones. J. Physiol. (Lond.) 139, 198–231 (1957)

  16. Darian-Smith, I., Phillips, G., Ryan, R.D.: Functional organization in the trigeminal main sensory and rostral spinal nuclei in the cat. J. Physiol. (Lond.) 168, 129–146 (1963)

  17. Dodge, R., Bott, E.A.: Antagonistic muscle action in voluntary flexion and extension. Psychol. Rev. 34, 241–272 (1927)

  18. Eccles, J.C., Eccles, R.M., Lundberg, A.: The convergence of monosynaptic excitatory afferents on to many different species of α-motoneurones. J. Phisiol. (Lond.) 137, 22–50 (1957)

  19. Eccles, R.M., Lundberg, A.: Integrative patterns of Ia synaptic actions on motoneurones of hip and knee muscles. J. Physiol. (Lond.) 144, 271–298 (1958)

  20. Endo, K., Araki, T., Yagi, N.: The distribution and pattern of axon branching of pyramidal tract cells. Brain Res. 57, 484–491 (1973)

  21. Hassler, R., Muhs-Clement, K.: Architektonischer Aufbau des sensomotorischen und parietalen Cortex der Katze. J. Hirnforsch. 6, 377–420 (1964)

  22. Hultborn, H., Jankowska, E., Lindström, S.: Relative contribution from different nerves to recurrent depression of Ia IPSPs in motoneurones. J. Physiol. (Lond.) 215, 637–664 (1971)

  23. Illert, M., Lundberg, A., Tanaka, R.: Disynaptic corticospinal effects in forelimb motoneurones in the cat. Brain Res. 75, 312–315 (1974)

  24. Jankowska, E., Padel, Y., Tanaka, R.: Projections of pyramidal tract cells to α-motoneurones innervating hindlimb muscles in the monkey. J. Physiol. (Lond.) 249; 637–667 (1975)

  25. 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 (1972)

  26. Jankowska, E., Smith, D.O.: Antidromic activation of Renshaw cells and their axonal projections. Acta. physiol. scand. 88, 198–214 (1973)

  27. Katz, B., Miledi, R.: Propagation of electric activity in motor nerve terminals. Proc. roy Soc. B 161, 453–482 (1965)

  28. Klüver, H., Barrera, E.: A method for the combined staining of cells and fibers in the nervous system. J. Neuropath. exp. Neurol 12, 400–403 (1953)

  29. 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)

  30. Leyton, A.S.F., Sherrington, C.S.: Observations on the excitable cortex of the chimpanzee, orang-utan and gorilla. Quart. J. exp. Physiol. 11, 135–222 (1917)

  31. Liu, C.M., Chambers, W.W.: An experimental study of the corticospinal system in the monkey (Macaca mulatta). J. comp. Neurol. 123, 257–284 (1964)

  32. Lloyd, D.P.C.: The spinal mechanisms of the pyramidal system in cats. J. Neurophysiol. 4, 525–546 (1941)

  33. Lundberg, A., Norrsell, U., Voorhoeve, P.: Effects from the sensorimotor cortex on ascending spinal pathways. Acta physiol. scand. 59, 462–473 (1963)

  34. Nyberg-Hansen, R., Brodal, A.: Sites of termination of corticospinal fibers in the cat. An experimental study with silver impregnation methods. J. comp. Neurol. 120, 369–391 (1963)

  35. Peterson, B.W., Maunz, R.A., Pitts, N.G., Mackel, R.G.: Patterns of projection and branching of reticulospinal neurons. Exp. Brain Res. 23, 333–351 (1975)

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

  37. Reed, A.F.: The nuclear masses in the cervical spinal cord of Macaca mulatta. J. comp. Neurol. 72, 187–206 (1940)

  38. Rexed, B.: A cytoarchitectonic atlas of the spinal cord in the cat. J. comp. Neurol. 100, 297–380 (1954)

  39. Roberts, W.J., Smith, D.O.: Analysis of threshold currents during microstimulation of fibers in the spinal cord. Acta physiol. scand. 89, 384–394 (1973)

  40. Romanes, G.J.: The motor cell columns of the lumbosacral spinal cord of the cat. J. comp. Neurol. 94, 313–358 (1951)

  41. Scheibel, M.E., Scheibel, A.B.: Terminal axonal patterns in cat spinal cord. I. The lateral corticospinal tract. Brain Res. 2, 333–350 (1966)

  42. Sherrington, C.S.: On nerve-tract degenerating secondarily to lesions of the cortex cerebri. J. Physiol. (Lond.) 10, 429–432 (1889)

  43. Sherrington, C.S.: Integrative Action of the Nervous System. New Haven and London: 1906

  44. Sterling, P., Kuypers, H.G.J.M.: Anatomical organization of the brachial spinal cord of the cat. II. The motoneuron plexus. Brain Res. 4, 16–32 (1967)

  45. Stoney, S.D., Jr., Thompson, W.D., Asanuma, H.: Excitation of pyramidal tract cells by intracortical microstimulation: effective extent of stimulating current. J. Neurophysiol. 31, 659–669 (1968)

  46. Thomas, R.C., Wilson, V.J.: Recurrent interactions between motoneurons of known location in the cervical cord of the cat. J. Neurophysiol. 30, 661–674 (1967)

  47. Thompson, F.J., Fernandez, J.J.: Patterns of cortical projection to hindlimb muscle motoneurone pools. Brain Res. 97, 33–46 (1975)

  48. Tsukahara, N., Fuller, D.R.G., Brooks, V.B.: Collateral pyramidal influences on the corticorubrospinal system. J. Neurophysiol. 31, 467–484 (1968)

  49. Verhaardt, W.J.C.: A Stereotaxic Atlas of the Cat. New York: Van Gorcum and Co. 1964

  50. Woolsey, C.N.: Organization of somatic sensory and motor areas of the cerebral cortex. In: Biological and Biochemical Bases of Behavior. (C.N. Woolsey and H.F. Harlow eds.). pp. 63–82. Madison, Wisc.: Univ. Wisconsin Press 1958

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Shinoda, Y., Arnold, A.P. & Asanuma, H. Spinal branching of corticospinal axons in the cat. Exp Brain Res 26, 215–234 (1976).

Download citation

Key words

  • Corticospinal neuron
  • Spinal axon branching
  • Microstimulation