CHANGES IN RETROGRADELY LABELED NEURONS IN THE RED NUCLEUS AND CORTEXAFTER DEPLETION OF MOTONEURONS BY AXOTOMY IN NEONATAL RATS

Following nerve injury to the sciatic nerve in neonatal rats many moto neurones die, so that the target of the rubrospinal and corticospinal cord is altered. Retrograde labelling of neurones terminating in this region shows that, in the red nucleus as well as cerebral cortex, ther e is a significant reduction in labelled neurones on the side contrala teral to the nerve injury. Thus neurones in the brain that give rise t o descending fibres are influenced by the altered environment in the s pinal cord following axotomy at birth.