The overall goal of our laboratory research is to understand the signals that the nervous system uses to control movements. We are specifically interested in reaching movements, and the participation of one structure, the cerebellum, in the guidance and control of reaching. Cerebellar damage, although causing little cognitive deficits, results in severe deficits in making accurate coordinated reaching movements. Our proposal is to study one of the input systems to the cerebellum, the climbing fiber system, to understand information that it supplies to the cerebellum about movements. We are specifically interested in how motor signals modify the information carried by the climbing fibers, that is, how does output affect input? We have developed a reaching paradigm for cats, that allows us to record from the inferior olive, the source of the climbing fiber system, while the cats reach out to grasp a lever to receive pureed chicken with cod liver oil, a high preference food for cats. During the lever retrieval small perturbations of the arm are introduced with a servo motor. The cats quickly learn to adjust to the perturbation to receive the food. We are interested in the performance of the climbing fiber system during the period of adjustment. Other experiments will be performed in acute anesthetized preparations to define the circuitry responsible for climbing fiber response modification. With advances in technology, there has been much interest in robotics and prosthetic devices. Although we don't feel that mimicking cerebellar action exactly could be accomplished in the foreseeable future, it is quite possible that the overall scheme of motor control used by the nervous system will be valuable in developing efficient robotic devices. No machine can reach out and grasp an object as smoothly or accurately as a human, and this is a basic goal of robotics. It is also one of the movements most needed by paralyzed humans. Another possible application of our research is in neurosurgery. We are located at a Neurological Institute and interact with neurosurgeons on practical problems encountered in the operating room. We have recently completed anatomical work with Drs. Sonntag and Pappas on Bell's Cruciate Palsey, a selective paralysis of the upper limbs. There are suggestions from that work that the paralysis is due to disruption of the cerebellar circuits studied by this proposal.