DESCRIPTION (Adapted from Applicant's Abstract): The overall goal of this research is to understand how the nervous system controls limb movements. The limb movement that we have chosen to study is reaching to grasp an object - a complex task that requires using sensory information to coordinate muscles of the entire limb. The survival of many species, including humans, depends upon performing the reach-to-grasp with speed and accuracy. Despite the importance of the reach-to-grasp, little is known about its control, since few studies have recorded from the nervous system during the reach-to-grasp. Our laboratory has recorded neural activity of single cells in the brains of cats and monkeys while they reach to grasp an object. The data demonstrate that major divisions of the nervous system (intermediate cerebellum and related structures) are involved in control of the grasp but not the reach. That is, different parts of the nervous system control different parts of the movement; this represents an important advance to our understanding of motor control. The research outlined in this proposal will identify parts of the nervous system that control the reach during the reach-to-grasp. Control of the shoulder and muscles of the upper arm depends upon pathways originating in the reticular formation. We will record from neurons in the reticular formation of cats and monkeys while they make the reach-to-grasp and provide information about how reaching is controlled. Anatomical studies will identify neural structures providing input to reticular regions controlling the reach, and we will conduct additional recording studies in those structures to understand how they contribute to the reach-to-grasp. The data will provide the first detailed outline of neural systems controlling a complex forelimb movement and also provide valuable information about how different regions of the brain work together to make movements smooth and precise. Knowledge of how the nervous system controls movement will help us understand, and possibly treat, the diseases and injuries that affect movement and detract from the lives of many people.