PHS Force coordination in grasping is severely impaired in individuals with certain neurological and musculoskeletal diseases. Basic understanding of the development of force coordination is essential for the rehabilitation and restoration of hand function in these individuals. The objective of the present proposal is to better understand the mechanisms underlying the spatial and temporal coordination of multiple grip forces during grasping. This objective will be pursued by examining involuntary corrective force responses to perturbations to stable force sharing patterns during five-digit grasps. A novel procedure will be introduced that elicits transient force changes in individual digits, disrupting the force sharing pattern. The specific aims of the proposal are to determine the effects of varying 1) force perturbation parameters (digit perturbed, direction of force) and 2) initial force sharing pattern on the involuntary corrective force responses developed to compensate for the perturbation. Our preliminary data suggests that involuntary corrective responses are involved. We will test that the corrective force responses will be dependent upon the function role of the perturbed digit in maintaining grasp stability. [unreadable] [unreadable]