The primate superior colliculus and the control of saccadic eye movements

The superior colliculus is a brainstem structure playing a critical role in orienting movements of the head, pinnae, and eyes. The superior colliculus acts as an important intermediary between sensory and motor signals, issuing motor commands that are translated into the appropriate temporal code required by the motoneuron pools. Collicular cells are broadly tuned with respect to the direction and amplitude of the movements they initiate, and a large population of collicular neurons is active before each movement, How information is extracted from the spatial and temporal profile of the active population and how the translation of the motor command progresses from the anatomically (spatially) organized map of saccade direction and amplitude found in the colliculus to the level of the temporally-coded motoneuron commands are important, but unsolved, problems, This review considers this spatial-to-temporal transformation, a prime motivating problem in oculomotor research. Recent findings have led to alterations of previously held views of the role of the primate superior colliculus in generating movements that orient our sense organs toward visual, auditory, and tactile stimuli. Some of these most current findings are presented in this review.