The major goal of the proposed experiments is to test the general hypothesis that individual frontal motor areas function in motor learning as well as motor performance. The experiments will test three hypotheses that primary and non-primary frontal motor areas to learning. The first hypothesis is that there is a component of discharge modulation in motor cortex uniquely related to the motor learning process itself. The second hypothesis is that motor learning occurs in association with a functional reorganization of motor cortex that supports newly learned motor behaviors. The third hypothesis that individual frontal motor areas subserve different roles in motor learning. In the proposed experiments, neural activity, EMG, and movement kinematics will be recorded in monkeys during two types of visuomotor learning tasks that involve planar arm reaching movements. The first task will require the monkey to adapt either the extent or direction of the reaching movement when the compatibility between a visual position feedback signal and the amplitude or direction of arm movement is altered. Activity during adaptation will be compared to that obtained before and after adaptation and to trials that control for changes in kinematics and target location. The second task will investigate motor learning that requires the establishment of new spatiotemporal patterns of muscle activity when monkeys learn new sequences of reaching movements. In both tasks, recordings will be made using both single microelectrodes and chronically implanted microwires, which will permit the simultaneous and continued evaluation of multiple motor sites in identical behavioral conditions. Reorganization of the functional relationships of motor cortex neurons with each other, with their target muscles or with encoded kinematic variables will be examined using cross correlation techniques. Electrical stimulation methods will also be used to evaluate changes in cortical output. The proposed studies will demonstrate the potential for learning-related reorganization in each of three major subdivisions of motor cortex and the circumstances under which they change. In addition they will clarify the role of motor cortex in controlling the direction and extent of simple and sequential movements. These results have direct relevance to understanding the role of the motor cortex in the development of movement disorders, in functional recovery after damage and may assist in developing neurorehabilitation strategies. Finally, they may help to identify common cortical processes related to learning.
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