The spatial localization of saccade targets. II. Activity of superior colliculus neurons preceding compensatory saccades

to brief visual targets presented in an oth-erwise darkened room. Single-unit activity was recorded from the superior colliculus (SC) during the performance of two tasks for which successful completion was contingent on the combination of retinal-error and eye-position signals. The first task required suc-cessive eye movements to serially flashed tar-gets, each of which was extinguished prior to the initial eye movement. In the second task, electrical stimulation of the SC, delivered during the interval between target offset and saccade onset, drove the eyes to another po-sition in the orbit, thereby requiring a com-pensatory saccade. The major purpose of thi