Abstract

The superior colliculus (SC) has been known as a critical neural structure in controlling saccadic (rapid) eye movements. The locations of visual stimuli, common targets of saccadic eye movements, are registered in place code by the retina and by various areas of the visual cortex. Motor commands to acquire these targets by reorienting the gaze line, on the other hand, are represented in the temporal pattern of neural discharges. Thus, the neural signal is thought to undergo a spatial-to-temporal transformation, and the SC is considered to play a critical roles for this transformation. Despite the intensive neurophysiological and pharmacological studies, roles of collicular neurons are not fully understood in relation to this transformation, and a few computational models appeared trying to make sense out of these incomplete biological data. We reviewed key aspects of the patterns of neural discharges of various saccade-related neurons of the SC and of brain stem areas that are known to be involved in generation of saccades, focusing on the spatial-to-temporal transformation. We also reviewed various models of saccade generation, and proposed further studies to better understand neural mechanisms for saccade generation.