Effects of prior and future movements on current actions

The ability to interact with the surrounding environment is fundamental to most human activities. This ability depends on the seamless integration of sensory, cognitive, and motor functions. We know much about these basic processes from studying the properties of individual movements that are disconnected from other movements that have been made in the past, or that will be made in the future. Creating a sequence of movements is a major part of achieving a goal, but it is not yet well understood how motor control systems are able to plan multiple movements while ensuring that those plans do not interfere with each other. Recent work in my laboratory has explored the effect that prior movements have on current ones, showing that people are slower to make movements that repeat the direction of a prior action. We have also studied the effect of upcoming (planned) movements on current ones, showing spill-over effects that are not easily explained by the idea that people simply plan the most economical series of actions. The studies outlined in this proposal seek to further explore both of these phenomena so that we might better understand how action sequencing works in humans. The studies will use 3D motion analysis to explore interactions between (1) past and current movements, and (2) future and current movements. The studies will look for evidence of response slowing (reaction time) and changes in movement path (trajectory), both of which would suggest interaction between multiple movement plans. For each phenomenon, experiments are proposed that will flesh out the scope and breadth of the previously documented behaviours. Next, experiments are proposed that will explore competing hypotheses about the mechanisms that might explain these observations. Finally, plans for future directions beyond the scope of the current grant cycle are outlined. Throughout the proposal, the role of highly qualified personnel (HQP) will be explained. Several HQP have played a critical role in the discoveries made to date, and HQP are critical for the completion of the studies outlined in this proposal. Understanding the nature of human movement is important in many sectors, and the HQP that will train in my laboratory will be in a strong position to contribute to the betterment of life for Canadians. Improved knowledge of human action could lead to (1) improved rehabilitation programs for individuals with neurological disorders, (2) improved techniques for training individuals to perform new skills, (3) improved prosthetic devices that are controlled by signals recorded from the nervous system, and (4) better design of tasks and devices that minimize the risk of potentially harmful movement errors.