A critical question that must be answered before we understand the control of sensoryguided saccades is that of how the spatial (anatomical) code of saccade direction and amplitude contained in the superior colliculus (SC) is transformed into the temporal signals required by motoneurons for the generation of saccadic movements. The long-range goals of the proposed research are directed toward the solution of this improtant problem. Chronic unit recording, microstimulation , and reversible deactivation methods will be used to study the role of the SC and brainstem recipients of inputs from the SC in the control of saccadic eye movements. More specifically, the goals of the project are to: a) Perform a detailed analysis of the alterations in saccade direction and amplitude occurring during reversible deactivation of small regions of the SC before and after unilateral removal of the frontal eye fields (FEFs). b) Characterize the saccaderelated discharges of neurons in tectorecipient areas by: 1) plotting the movement fields of neurons displaying saccaderelated activity; 2) quantifying the relationship between saccaderelated neural activity and saccadic velocity (vectorial velocity as well as component velocity); 3) determining the effects of varying the initial fixation position upon saccaderelated bursts; and 4) determining the effects of deactiviation of neurons in the SC upon the discharge of neurons with saccaderelated activity. c) Examine the connections between SC and neurons in PPRF, cMRF and NRTP using orthodromic and antidromic stimulation methods. d) Determine whether or not specific functional classes of neurons isolated in the PPRF, cMRF and NRTP receive inputs from specific types of collicular neurons using dual recording methods and cross correlation analysis. e) Study the effects of localized reversible deactiviation of small regions in the PPRF, cMRF and NRTP upon the latency, duration, direction, velocity, and amplitude of saccadic eye movements.