Effect of altered neck sensory feedback on brain plasticity and upper limb sensorimotor integration

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Sensorimotor integration (SMI) is the ability of the central nervous system to integrate sensory information from different body parts and formulate appropriate motor outputs to muscles. Effective SMI is essential when learning new skills and when performing tasks at home and in the workplace. In this age of technology use, neck pain and fatigue are very common, yet we have limited understanding about how altered neck sensory input impacts upper limb SMI. My work has found that neck muscle fatigue impairs our ability to know exactly where our arm is located in 3D space, makes us worse at learning new movement skills, and alters the way the brain adapts when learning those skills. We think this is because changes in neck sensory input interferes with our body schema (a map providing awareness of the position of our body parts in relation to one another). The cerebellum is a brain structure critical for accurate and coordinated movement, and maintaining an accurate body schema. My work suggests that altered neck input affects the way the cerebellum does its job. In my proposed research program, I am using novel techniques, some of them developed and validated in my own lab, to study how changing neck sensory input, using neck muscle vibration, affects SMI from the arm; how this affects motor commands to the arm muscles; and how the cerebellum integrates eye and hand movements. I am using virtual reality (VR), where the participant looks at an avatar's arm that appears as if it is their own arm. In a series of experiments, the visual feedback of the size and/or speed of the avatar's arm will be subtly altered so that participants have to rely on their own body schema to accurately perform an aiming task. I expect that neck muscle vibration prior to VR will lead to worse performance because the neck vibration will distort the accuracy of the body schema. This work will significantly advance our understanding of how altered sensory input from the neck impacts upper limb SMI, and the effect on the brain's control of movement, and how we learn new actions. Moreover, this knowledge has important real life implications. For instance, there are a number of common workplace tasks that require precise upper limb movements while the neck is in an awkward posture, or is susceptible to fatigue, such as overhead work by mechanics or assembly line workers; or precision work by surgeons, dentists, and hygienists. On a daily basis, we utilize the body schema to accurately reach for controls while driving, play skilled sport or interact with technology. Neck fatigue and/or altered neck postures are often present during these tasks. If altered neck input impacts speed and accuracy of upper limb performance, it has the potential to lead to errors which impact the health and productivity of Canadian workers. This research can lead to improved strategies for workplace and technology design to decrease injuries and improve performance at work and in VR environments.