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Do the Corticospinal and Corticobulbar Tracts Mediate Functions in the Human Newborn?

Published online by Cambridge University Press:  18 September 2015

Harvey B. Sarnat
Harvey B. Sarnat*
Affiliation:
Departments of Paediatrics,Pathology and Clinical Neurosciences, University of Calgary Faculty of Medicine, Calgary
*
Alberta Children's Hospital, 1820 Richmond Road S.W., Calgary, Alberta, Canada T2T 5C7
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Abstract:

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Unlike the numerous dispersed bulbospinal pathways that are already well myelinated at term, the more compact corticospinal and corticobulbar tracts are only beginning their myelination cycle in late gestation and do not complete it until two years of age. During this same period, these pathways also develop extensive ramification of terminal axonal segments, growth of collateral axons, and proliferation of synapses. Despite their immaturity in the fullterm human newborn, several proposed functions may be attributed to the descending pathways from the neonatal cerebral cortex: a) a contribution to the differential development of passive muscle tone and resting postures; in general they function as an antagonist to the “subcorticospinal pathways” in mediating proximal flexion and distal extension, except for the rubrospinal tract which is probably synergistic with the corticospinal tract; b) enhancement of tactile reflexes originating in the brainstem and spinal cord, including suck and swallow; c) relay of epileptic activity of cortical origin; d) inhibition of complex stereotyped motor reflexes including many phenomena formerly termed “subtle seizures”; e) a possible influence on muscle maturation, particularly in relaying cerebellar impulses that modify the histochemical differentiation of myofibres. However, the bulbospinal tracts are probably more influential on muscle development. The corticospinal and corticobulbar tracts subserve different needs in the newborn than at older ages, but are functionally important pathways even at birth.

Type
Hypothesis
Information
Canadian Journal of Neurological Sciences , Volume 16 , Issue 2 , May 1989 , pp. 157 - 160
Copyright
Copyright © Canadian Neurological Sciences Federation 1989

References

REFERENCES

1.Rorke, LB, Riggs, HE. Myelination of the Brain in the Newborn. Philadelphia: JB Lippincott. 1969. 108p.Google Scholar
2.Yakovlev, PI, Lecours, A-R. The myelogenetic cycles of regional maturation of the brain. In: Minkowski, A, ed. Regional Development of the Brain in Early Life. Philadelphia: FA Davis. 1967. pp. 3–70.Google Scholar
3.Jane, JA, Yashon, D, DeMyer, W, et al. The contribution of the pre-central gyrus to the pyramidal tract of man. J Neurosurg 1967; 26: 244–248.CrossRefGoogle Scholar
4.Catsman-Berrevoets, CE, Kuypers, HGJM. Cells of origin of corti-cal projections to dorsal column nuclei, spinal cord and bulbar medial reticular formation in the rhesus monkey. Neurosci Lett 1976; 3: 245–252.CrossRefGoogle ScholarPubMed
5.Lawrence, DG, Hopkins, DA. The development of motor control in the rhesus monkey: Evidence concerning the role of corticomo-toneuronal connections. Brain 1976; 99: 235–254.CrossRefGoogle ScholarPubMed
6.Jones, EG, Wise, SP. Size, laminar, and columnar distribution of efferent cells in the sensory-motor cortex of monkeys. J Comp Neurol 1977; 175: 391–438.CrossRefGoogle ScholarPubMed
7.Stanfield, BB, O’Leary DDM. The transient corticospinal projec-tion from the occipital cortex during the postnatal development of the rat. J Comp Neurol 1985; 238: 236–248.CrossRefGoogle Scholar
8.Nathan, PW, Smith, MC. The rubrospinal and central tegmental tracts in man. Brain 1982; 105: 233–269.CrossRefGoogle ScholarPubMed
9.Lawrence, DG, Kuypers, HGJM. The functional organization of the motor system in the monkey. II. The effects of lesions of the descending brainstem pathways. Brain 1968; 91: 15–36.CrossRefGoogle Scholar
10.Holstege, JC, Kuypers, HGJM. Brainstem projections to spinal motoneurons: An update. Neuroscience 1987; 23: 809–821.CrossRefGoogle ScholarPubMed
11.Hakamada, S, Hayakawa, F, Kuno, K, et al. Development of the monsynaptic reflex pathway in the human spinal cord. Dev Brain Res 1988; 42: 239–246.CrossRefGoogle Scholar
12.Lawrence, DG, Kuypers, HGJM. The functional organization of the motor system in the monkey: I. The effects of bilateral pyramidal lesions. Brain 1968; 91: 1–14.CrossRefGoogle ScholarPubMed
13.Sarnat, HB. Anatomic and physiologic correlates of neurologic development in prematurity. In: Sarnat, HB, ed. Topics in Neonatal Neurology. Orlando, Florida. Grune and Stratton. 1984; pp. 1–25.Google Scholar
14.Sarnat, JB. Pathogenesis of decerebrate “seizures” in the premature infant with intraventricular hemorrhage. J Pediatr 1975; 87: 154–155.CrossRefGoogle ScholarPubMed
15.Amassian, VE, Ross, RJ. Developing role of sensorimotor cortex and pyramidal tract neurons in contact placing in kittens. J Physiol (Paris) 1978; 74: 165–184.Google ScholarPubMed
16.Batson, DE, Amassian, VE. A dynamic role of rubral neurons in contact placing by the adult cat. J Neurophysiol 1986; 56: 835–856.CrossRefGoogle ScholarPubMed
17.Kuypers, HGJM, Lawrence, DG. Cortical projections to the red nucleus and the brainstem in the rhesus monkey. Brain Res 1967; 4: 151–188.CrossRefGoogle Scholar
18.Tsukahara, N. Synaptic plasticity in the red nucleus and its possible behavioural correlates. In: Cotman, CW, ed. Synaptic Plasticity. New York, London: The Guilford Press. 1985; pp. 201–227.Google Scholar
19.Peiper, A. Cerebral Function in Infancy and Childhood. New York: Consultants Bureau; 1963.CrossRefGoogle Scholar
20.Modanlou, HD. Extension reflex of fingers in the newborn. Pediatr Neurol 1988; 4: 66–67.CrossRefGoogle ScholarPubMed
21.Szturm, T, Ireland, DJ, Jell, RM. Convergent effects from vestibu-lospinal tract and primary cutaneous afferent fibres on motoneurons to proximal lower limb flexor and extensor muscles in humans. Exp Neurol 1988; 99: 178–186.CrossRefGoogle ScholarPubMed
22.Danner, R, Shewmon, A, Sherman, MP. Seizures in an atelencephalic infant. Is the cortex essential for neonatal seizures? Arch Neurol 1985; 42: z1014–1016.CrossRefGoogle Scholar
23.Camfield, PR, Camfield, CS. Neonatal seizures: A commentary on selected aspects. J Child Neurol 1987; 2: 244–251.CrossRefGoogle ScholarPubMed
24.Mizrahi, EM, Kellaway, P. Characterization and classification of neonatal seizures. Neurology 1987; 37: 1837–1844.CrossRefGoogle ScholarPubMed
25.Sarnat, HB. Le cerveau influence-t-il le développement musculaire du foetus humain? Can J Neurol Sci 1985; 12: 111–120.CrossRefGoogle Scholar
26.Sarnat, HB. Cerebral dysgeneses and their influence on fetal muscle development. Brain Dev (Tokyo) 1986; 8: 495–499.CrossRefGoogle ScholarPubMed
27.Batton, RR III, Jayaraman, A, Ruggiero, D, et al. Fastigial efferent projections in the monkey: An autoradiographic study. J Comp Neurol 1977; 174: 281–306.CrossRefGoogle ScholarPubMed
28.Sarnat, HB, Alcalá, H. Human cerebellar hypoplasia. A syndrome of diverse causes. Arch Neurol 1980; 37: 300–305.CrossRefGoogle ScholarPubMed
29.Gilman, S. The mechanism of cerebellar hypotonia: An experimen-tal study in the monkey. Brain 1969; 92: 621–638.CrossRefGoogle Scholar