Effects of altered input from the neck on upper limb sensorimotor integration

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Most of us have had the experience of reaching for an object and missing, or had days when we make more typos than usual while on our computers. What we may not have considered is that these experiences may be the consequences of altered sensorimotor integration (SMI) due to altered sensory input from our necks. SMI is the ability of the central nervous system (CNS) 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. Yet we understand very little about how changing the sensory input from the neck impacts SMI of the upper limb, and this affects the brain’s control of movement and how we learn new actions. Recently my lab has found that neck muscle fatigue impairs our ability to know exactly where our arm is located in 3D space. We have also found that individuals with chronic changes in neck input due to pain or stiffness are worse at learning new movement skills and have worse spatial awareness. We think this is because changes in sensory input from the neck interferes with our body schema (a map providing awareness of the position of our body parts in relation to one another). An accurate body schema is critical for producing accurate and coordinated movement. Part of the brain called the cerebellum is really important for eye-hand coordination and adapting the position and movements of our body to maintain the correct representation of our body schema with respect to our changing visual experience as we look around. My work suggests that the altered neck input is affecting the way the cerebellum does its job. I am studying how changing sensory input from the neck, using neck muscle fatigue and awkward postures, affects SMI from the arm and how this affects the motor commands to the arm muscles. We are also looking at how the cerebellum integrates eye and hand movements. There are a number of common tasks in workplaces 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, playing skilled sport or interacting with technology. Neck fatigue and/or altered neck postures are often present during these tasks. If altered neck input impacts the speed and accuracy of upper limb performance, it has the potential to lead to errors which impact the health and productivity of Canadian workers. The knowledge gained from this work will improve our understanding how neck fatigue and altered postures impact motor skill training and performance at work, sport and leisure. In our age of technology, this work has great potential to improve strategies for workplace and technology design to decrease injury risk and improve performance.