The long-term goal of the proposed research is the increased understanding of the role of the cerebral cortex in the neural control of eye movement. The major aid during the requested grant period will be the clarification of the interaction of the posterior parietal cortex and the cortex of the frontal eye fields in the control of purposive, visually-guided eye movements. Two general lines of investigation are proposed. In the first, the activity of single neurons in the inferior parietal lobule will be studied in monkeys that have been trained to perform oculomotor and visual attention tasks. The axonal projection targets of neurons in the inferior bank of the intraparietal sulcus will be determined using antidromic activation. The functional properties of neurons which project to the frontal eye fields or the superior colliculus will be characterized. In the course of studying the functional properties of these neurons behavioral tasks which emphasize the performance of visually-evoked saccadic eye movements and also the neural coding of spatial relationships in extrapersonal space will be emphasized. The second are of investigation is a series of neuroanatomical experiments which are directed at discovering the details of the neural connectivity of the parietal association cortex with other cortical and subcortical regions of the brain in monkeys. The anterograde transport of tritiated amino acids and the retrograde transport of two fluorescent dyes will be used to provide new information about the pathways from the frontal eye fields and the inferior parietal lobule to the brainstem oculomotor system that are involved in the control of the visual pursuit of moving objects. These experiments will aid in the understanding of how the brain initiates and controls voluntary eye movements, how that control is impaired by disease and injury, and how the process of partial recovery of function occurs after some strokes and injuries. The results of these studies will increase our understanding of the basic mechanisms of the neural control of behavior, which will in turn aid in the understanding of congenital and acquired disorders of nervous system function. In addition, these studies will eventually contribute to improved tools for diagnosis and for the evaluation of nervous system function in patients following stroke or trauma, and also in the many progressive conditions which are known to affect oculomotor control.
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