Tuesday, May 7, 2024
5/7/2024
Project Summary Skilled inter-limb coordination is critically important for performance of many activities of daily living (ADL). In many patients with neurological disorders, such as stroke and cerebral palsy, impairments in bimanual coordination are often functionally greater than impairment of the more affected limb. Therefore, improving our understanding of neural mechanisms underlying bimanual control in typically-developed adults is critically important as a stepping stone towards creating more effective and targeted clinical interventions. While most of the existing bimanual research has focused on tasks in which each limb has independent goals, the proposed research will investigate how the brain controls two limbs when they share a common goal. We will test the hypothesis that cortical activity, in particular within the posterior parietal cortices (PPC), is differentially modulated to support common-goal bimanual coordination when the limbs are subjected to variable constraints and perturbations. We propose a series of experiments in which healthy adults will perform a virtual object manipulation task with the actions of two limbs. We will systematically vary the symmetry of bimanual actions in our virtual manipulation task by introducing persistent constraints or abrupt perturbations. These constraints and perturbation challenge the central nervous system to correctly perform the common-goal bimanual coordination. We expect greater performance error when the task is performed with constraints or perturbations applied to one limb (asymmetric) than both limbs (symmetric). Therefore, this experimental paradigm will enable us to quantify the behavioral changes of spatial-temporal inter-limb coordination in response to these constraints and perturbations, and investigate the underlying cortical activities using electroencephalography (EEG). Moreover, we will determine the causal role of bilateral intraparietal sulci (IPS) in bimanual common-goal coordination using transcranial magnetic stimulation (TMS) as a system identification tool to induce reversible virtual lesions. We will deliver continuous theta burst TMS or high intensity single pulse stimulation to medial IPS or a control region (i.e., anterior IPS) of either right or left cerebral hemispheres, and quantify the resulting deficit in bimanual coordination. Our findings have potential applications to translational research on sensorimotor rehabilitation to improve bimanual training paradigms in stroke bilateral therapies (i.e., common-goal coordination), and guide the design of non-invasive brain stimulation to enhance the outcome of these interventions. Our long-term goals are to (1) extend the investigation of neural control of common-goal inter-limb coordination to a broader cortical network by combining our unique experimental paradigm with functional magnetic resonance imaging, and (2) apply our experimental approach to study coordination of bimanual movements in individuals affected by sensorimotor deficits to design evidence-based, user-centered interventions.
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