THe proposed experiments are designed to investigate the relationship between recovery of motor function following injury to the CNS and the anatomical plasticity specifically collateral sprouting, of the remaining undamaged systems. The methods used will be behavioral and anatomical. The hypothesis underlying these experiments is that converging systems are not equipotential but that they are ordered hierarchically and therefore that the pattern of recovery will be defined by one of the systems which remains. We propose also to examine the relationship between recovery or sparing of function and anatomical plasticity after neonatal lesion to determine to what extent limitations placed on recovery or sprouting develop postnatally.