A critical question which must be answered in order to understand how the CNS controls visually-guided saccades is that of how the spatial code of saccade direction and amplitude contained in the superior colliculus is tranformed into the appropriate temporal signals necessary to control the burst durations of oculomotor neurons during saccades. This problem has not received serious experimental attention since precise information about saccade direction and amplitude is likely to be encoded by the spatial location of the population of neurons active in the superior colliculus rather than the pattern of spike activity originating from individual neurons. The proposed research projects are all directed at this important question. We propose to 1) describe, anatomically, the region of superior colliculus which is metabolically active before particular saccades; 2) examine the functional interactions which occur in this active population by reversibly blocking the activity of a small region of the normally active population; and 3) determine what changes occur in the response properties of neurons in nuclei which receive a descending collicular input. Collectively, information derived from these experiments should represent a significant approach to the question of how information about saccade direction and amplitude, contained in the spatial pattern of superior colliculus activity, is converted into appropriate signals for each of the extraocular muscles. In a broader sense, results of these studies will be important in attempts to describe the neural events which intervene between the central processing of sensory information and the central programming of motor outputs.
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