Bilateral pericruciate cortical innervation of the red nucleus in cats with adult or neonatal cerebral hemispherectomy.
We studied remodeling of the remaining corticorubral projections in adult cats sustaining a left cerebral hemispherectomy in adulthood or neonatally using cortical injections of [3H]leucine-proline. Injection sites and terminal fields were reconstructed from autoradiography-processed tissue. In all cats, the label filled similar extents of ares 4 gamma and 3a of the right frontal cortex. We used sections at 8 coronal planes throughout the red nucleus (RN) for computer-assisted analysis of visually estimated density and topography of distribution of terminal label, and for calculation of RN cross-sectional area. Additionally, at 3 coronal planes we further quantified terminal label using computerized procedures (number of particles for surface area). In all lesioned cats we found terminal label in the RN contralateral to the injection site with a topographic distribution similar to that of the RN ipsilateral to the injection in normal or lesioned cats and in absence of any significant shrinkage of the nucleus. The difference between the 2 age-at-lesion groups was that in the cats with neonatal ablation the density of contralateral terminal label was about double that seen in adult-lesioned subjects. However, the amount of contralateral labeling in adult-lesioned cats was substantial and represented a significant increase over the minimal labeling seen in normal cats. There were no differences between groups in labeling or size of the RN ipsilateral to the injection site. For reasons discussed, we interpret the label on the side of the hemispherectomy as representative of reinnervation of the cortically deafferented RN by crossing collaterals of fibers arising in the remaining motor cortex and not as lesion-sustained persistent prenatal connections.
Villablanca
J R
JR
Department of Psychiatry, UCLA Medical School 90024.
Fómez-Pinilla
F
F
Sonnier
B J
BJ
Hovda
D A
DA
D000375:Aging / Q000502:physiology*; D000818:Animals; D001345:Autoradiography; D002415:Cats; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology*; D002541:Cerebral Decortication; D005260:Female; D007930:Leucine; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D009473:Neuronal Plasticity; D011392:Proline; D012012:Red Nucleus / Q000166:cytology / Q000502:physiology*
D011392:Proline; D007930:Leucine