The Primate Superior Colliculus and its Sensory Inputs

Abstract

Let me begin by showing you a simplified diagram of the rhesus monkey visual system. The retinal fibers, as shown in Fig. 1, project to the superior colliculus and to the lateral geniculate nucleus. The geniculate in turn projects to visual cortex. From layer 5 cortical cells project down to the colliculus. What I want to emphasize is that the superior colliculus receives a dual projection; one directly from the retina and the other indirectly from visual cortex. If you look at this diagram do not take it as a literal proportional relationship of what the brain looks like. The superior colliculus is drawn big here simply because it is my point of focus. In reality, it is the smallest of these structures; in monkey its surface is only about five or six mm in diameter.