抄録
Generally speaking, the neonatal brain is more resistant to damage compared to the adult brain, but the mechanism of functional reorganization after neonatal brain damage remains still elusive. We studied this problem by evaluating the restoration of the motor function in rats. Five Whistar rats received large unilateral decortications on the right side at the 5th day after birth (first lesion). The forelimb movements were observed using Reach and Grasp task. The performance of affected forelimb was recovered, although it was still poorer compared with that of intact limbs. After 6 weeks, the sensorimotor area of the remaining hemisphere was removed (second lesion). The function of both forelimb movements severely impaired once after the second lesion. To clarify how the descending commands form the remaining hemisphere reach forelimb motoneurons on the ipsilateral side, anterograde tracing studies were performed using biotinylated dextran amine. We have found that the sensorimotor cortex on the remaining side issued aberrant projections to various structures, such as contralateral red nucleus, contralateral pontine nucleus, ipsilateral dorsal column nucleus and ipsilateral spinal cord gray matter. We have concluded that the functional restoration was observed after neonatal unilateral decortications and that the aberrant projections may be involved in restoration of the affected forelimb movements. [J Physiol Sci. 2007;57 Suppl:S70]
