A bilateral cortical projection to the superior colliculus in the cat.

Projections from the cerebral cortex to the superior colliculus (SC) of the cat have been determined by injecting horseradish peroxidase (HRP) unilaterally into SC. In addition to labelled cells found in the visual areas ipsilateral to the injection site, HRP-positive neurones were observed in the lateral bank of the suprasylvian sulcus of both hemispheres. This region, the suprasylvian fringe, which is part of the auditory cortex, apparently projects bilaterally to the SC.