Noise, variability, and motor performance in developmental coordination disorder.

Variability and noise are a natural part of the neuromuscular system, and can occur at multiple levels. However, excessive neural noise in the motor system makes the problem of control much harder. Disruption of basic sensory inputs will exacerbate the problem, impacting one's sense of position in space (or body schema) and the ability of the motor system to predict its own dynamics. So-called predictive control is fundamental to movement efficiency and accuracy, but has been shown to be poorly developed in children with motor problems like developmental coordination disorder. These children manifest a core deficit in predictive control, which is expressed by high levels of variability across tasks, and at the level of movement kinematics, for example patterns of inter-limb coordination. As such, they rely heavily on feedback mechanisms to exert control, the outcome being slower and more laboured movements, and reduced responsiveness to changes in the environment. We discuss these issues of high variability and noise in developmental coordination disorder in relation to motor prediction, and with an eye to remediation. Issues of task scheduling and use of augmented feedback are important considerations for therapists when treating these children. © The Authors. Developmental Medicine & Child Neurology