Anatomical sparing in the superior colliculus of hemispherectomized monkeys

Using the monkey as a model for human hemispherectomy, the effects of early removal of a whole cerebral hemisphere on the cytoarchitecture and cytochr ome oxidase histochemistry of the superior colliculus (SC) were evaluated. Results show that the SC ipsilateral to the cortical lesion suffers a 29.9% average volume reduction and a 32.7% total loss of neurons compared to the contralateral SC. Neuronal densities and metabolic activity are similar in normal and hemispherectomized monkeys. Furthermore, the ipsi- and contrale sional SC receive retinal inputs as revealed with intraocular injections of tritiated proline. These data suggest that the superior colliculus retains functional capabilities following hemispherectomy in monkey. (C) 2001 Else vier Science B.V. All rights reserved.