The human hand possesses a rich repertoire of dexterous movements, much of which can be lost after stroke. Our recent large-scale longitudinal stroke study (2017, 2018) showed that most patients never fully regained hand dexterity despite substantial recovery of hand strength. We further provided evidence that strength and dexterity recovery depend on separable descending neural pathways. These findings highlight the critical need to specifically target hand dexterity in rehabilitation, as the hand function relies heavily on the dexterous component. In this project, we investigate behavioral and neural mechanisms of hand dexterity, its impairment after stroke, and key factors for recovery.

We have developed a sensitive device to track very subtle finger forces in 3D. Using this device, we can dissect different compare different components of finger dexterity, and directly compare finger individuation and precision grip, two traditional paradigms that have been used as proxies for hand dexterity. We strive to answer the questions of what are the critical components of hand dexterity and what brain pathways support these components, and how do they interact in learning and rehabilitation. To answer these questions, we also utilize brain imaging of high-resolution diffusion imaging and tractography method, as well as brain stimulation using transcranial magnetic stimulation (TMS)

We recently trained a cohort of chronic stroke patients with a piano-keyboard like tasks and showed the patients improved their finger individuation ability after one week of training. We thus aim at designing effective training tasks for patients to improve all components of hand dexterity(2020).