Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)

Planning and executing coordinated movement is remarkably complex, yet appears to take very little conscious effort beyond the initial decision to achieve a desired goal. Despite this apparent simplicity, such movements require a complex series of sensorimotor transformations that make use of visual, proprioceptive, cutaneous, and vestibular information. The complexity of the underlying planning and execution processes is made clear by the challenges faced by patients with sensorimotor deficits who have difficulty carrying out simple activities of daily living. My research makes use of the KINARM robot system to gain a better understanding of these planning and executions processes. We use this device to assess movement trajectories under varying sensory feedback conditions and apply perturbations during these trajectories to probe the ability to make on-line corrections. In addition, we use transcranial magnetic stimulation (TMS) to examine the contribution of different cortical and subcortical sites to the planning and execution processes. Finally, by having participants perform these tasks while standing, we can also determine how movement planning and on-line corrections interact with anticipatory and reactive postural adjustments. By these means, we can obtain a comprehensive picture of the integrated planning and execution of upper limb movements in a standing posture and the putative contributions from specific brain sites thought to be involved in these processes. One of the key features of movement planning is its predictive nature. This is observed both within the features of limb movements themselves as well as in the anticipatory nature of postural adjustments prior to movement onset. How these predictive mechanisms are affected by the complexity of the movement and the extent to which attentional processes contribute is currently poorly understood. In addition, it is not known how different neural circuits which contribute to limb movement planning and execution also influence or are influenced postural control centres in the brain. Thus, the objectives of the current proposal are to examine 1) the interaction between standing postural control and upper limb movements; 2) the role attention plays in these interactions; 3) the contribution of anticipatory versus reactive postural responses to perturbed and unperturbed upper limb movements; and 4) the different manner in which parietal and supplementary motor areas and lateral cerebellum contribute to these processes. The experiments proposed in this application will allow us to better understand the planning and execution processes of upper limb movements, how they are integrated with standing postural control, and the role played by parietal and supplementary motor areas and the lateral cerebellum in this integration. This information can be used to better inform current theories of limb motor control.