Evidence for a crossed corticorubral projection in cats with one cerebral hemisphere removed neonatally.

Tritiated amino acids were injected into the right pericruciate cortex and the projections to the red nucleus were mapped autoradiographically in 10 intact and 6 adult cats with one cerebral hemisphere (left side) removed neonatally. In the intact cats only projections to the ipsilateral red nuclei were seen. The terminals were distributed along the entire rostrocaudal extent, but the density of the label was greater in the ventral and medial aspects of the nucleus. In the hemispherectomized cats projections to both red nuclei were found. The topography of the terminals was similar to that seen in intact animals. This finding, together with other changes which we have described, suggests that an extensive structural reorganization may occur after removal of one cerebral hemisphere in cats.