The development of rapid online control in children with and without Developmental Coordination Disorder

The online control of manual actions is critical for the development of functional skills in children, not the least because demands on behaviour and complexity of the environment increase with age. When unexpected changes occur during the course of action, rapid online corrections are necessary to ensure that movement parameters (like force and timing) can be quickly updated. Developmentally, the motor network supporting online control is thought to mature rapidly over childhood; however, cross-sectional research suggests that the trajectory of change is not linear because the mode of control undergoes reorganisation during middle childhood. At the same time, development of frontal executive systems (particularly inhibition) may influence the way children enlist motor functions like online (predictive) control. Maturational theories that once considered these systems to be unitary in their development are now being challenged by a more parsimonious neuro-behavioural hypothesis—interactive specialization; this suggests behaviour can be strengthened and supported by the interaction of separate but overlapping neural networks. growing body of research indicates that online control processes may be disrupted for children with motor coordination problems (aka Developmental Coordination Disorder; DCD). As well, it has been widely reported that these children show problems related to executive function including tasks that involve response inhibition. It is argued here that deficits in predictive online control may be exacerbated under task conditions that require concurrent inhibitory control as when one is required to withhold a response to a compelling cue and move to an alternate location. However, there is not a clear picture of developmental change in the ability to couple motor and executive systems, nor of differences in growth patterns between typically developing children (TDC) and children with DCD. The purpose of my research was to address this knowledge gap by conducting cross-sectional and longitudinal studies of development to examine the unfolding interaction between online and executive systems in healthy and atypically developing children. Specifically, I examined how TDC and DCD groups corrected their arm movement mid-flight during a step-perturbation paradigm, and how a concurrent inhibitory load constrained their responses to a target shift.