The Superior Colliculus and Visual Thalamus

Abstract

Understanding how the brain uses the information it receives from the eye has been a primary subject of inquiry for a host of laboratories. We now know that the impulses generated in the retina are transmitted to a variety of subcortical nuclei, each designed to evaluate a specific aspect of the visual information present within a visual scene. For example, some of these nuclei sense levels of ambient light to control reflex responses and diurnal rhythms. But the neural computations that give rise to what we normally think of as “seeing,” including the ability to detect, orient to, and analyze elements of a visual scene, are carried out by numerous brain regions dedicated to various aspects of these functions. Chief among them are the superior colliculus, a midbrain structure that transforms sensory (including non-visual) signals into the motor commands for orienting, and the lateral geniculate nucleus, a thalamic structure that serves as the entry point into the cascade of areas dedicated to processing visual features. What has been learned about these two areas, and about how they are specialized to perform their distinct sensory functions, is discussed in depth.