DIENCEPHALIC MECHANISMS OF VISUOMOTOR INTEGRATION

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The broad objective of this proposal is to provide insights into the neural mechanisms underlying the generation of voluntary movement toward sensory goals. The ease with which we respond to sensory cues belies a high degree of computational complexity and it is now known that a highly distributed neural network, involving main brain areas, underlies this ability. Fundamental to our understanding of this process is a determination of how activity in this network is orchestrated so that actions are both timely and appropriate for a given set of circumstances. Understanding how the sensory to motor linkage is gated by behavioral context represents a major experimental challenge, but one that will ultimately lead to a more fundamental understanding of both normal and pathological sensorimotor behavior. In this regard, there is a growing appreciation that dysfunction, such as that observed with Parkinson's disease, or sensory neglect syndromes, is not of purely motor or sensory origin, but instead, a complex sensorimotor disturbance. The proposed study uses the awake behaving primate preparation, vision, and the oculomotor system as a model for sensorimotor function and focuses on activity in oculomotor thalamus as a potential important locus at the sensorimotor interface. Based on its anatomical relationships to cortical and subcortical visuomotor areas, oculomotor thalamus has been suggested to play the role of "central controller" in this broadly distributed network. Using extracellular single-unit recording and a series of behavioral tasks designed to test different aspects of sensorimotor function, the proposed experiments seek to elucidate the relative contributions of oculomotor thalamus to sensory- driven motor behavior.