Is sprouting the result of a persistent neonatal connection?

The present study aims to test the hypothesis that early neonatal connections might account for certain sprouting phenomena in the central nervous system. Fink-Heimer's method for degenerating axons, electron microscopy and autoradiography were used to trace the neonatal corticofugal projections from the sensorimotor cortex (SMC) of albino rats. The results showed that neonatal corticofugal projections to the superior colliculus, red nucleus and spinal cord were unilateral and could not explain the bilateral corticofugal projections to these areas soon after neonatal SMC lesions [8, 10, 12, 13]. The presence of a neonatal contralateral corticopontine projection is also not sufficient to account for the presence of a contralateral corticopontine projection seen after neonatal unilateral SMC lesion, but might account for the contralateral corticopontine projection seen after neonatal unilateral cerebellar hemispherectomy [11].