Interrelationships of the Visual Cortex and Superior Colliculus in the Cat

Abstract

IT is well known that in the mammal the retina is related in a well-organized manner with the lateral geniculate nucleus of the thalamus and with the visual cortex¹, on one hand, and with the superior colliculus² of the midbrain, on the other. In addition, a projection from the visual and other cortical areas to the tectum has been demonstrated³. Apart from a recent investigation in the rat⁴ there is no evidence, however, to indicate whether the projection of the cortex on the tectum is topically organized and in particular whether the parts of the cortex and tectum related to a specific part of the retina are interconnected. This problem of the interrelationships of the visual cortex and the superior colliculus has been investigated in the cat in three stages by determining, first, the detailed projection of the retina on the lateral geniculate nucleus and the superior colliculus; secondly, the organization of the projection of the lateral geniculate nucleus on the visual cortex (and thereby the representation of the retina in the cortex); and finally, the manner of termination of the cortical efferent fibres to the superior colliculus.