Theoretical Models of Motor Control and Motor Learning

摘要

The ease with which one is able to walk, talk, manipulate objects and play sports belies the fact that generating coordinated movement is a tremendously complex task. We have to control our bodies through a muscular system that is highly redundant, nonlinear and unreliable. Furthermore, we are reliant on sensory feedback that is also unreliable and substantially delayed. Yet many tasks that robotic systems achieve either cumbersomely or not at all are routine to us. Expert performers push the limits of performance even further. Our advantage over synthetic manipulators and – arguably – a professional sportsperson’s advantage over a rookie, lies not so much in the hardware performing the task, but in the way it is controlled. A theoretical approach to motor control and motor learning seeks to explain regularities in behavior in terms of underlying principles. This typically entails formulating mathematical models that describe the mechanics of the body or task, the way in which appropriate motor commands are selected, or the way in which prior experience infl uences future behavior. Many theories are mechanstic in nature – appealing to computations or plasticity occurring at the level of individual neurons or synapses in order to explain observations at the behavioral level. More abstract theories may not necessarily refer to any specifi c neural substrate but instead seek to explain behavior in terms of the way in which information can be represented and transformed. In both approaches, predictions about behavior stem largely from constraints imposed by the assumed circuitry or algorithm. Note that these two modelling approaches are similar to the implementational and algorithmic levels of analysis discussed by Marr (1982). An alternative approach is to set aside questions about mechanism or algorithms and attempt to characterize and understand motor system function purely at the behavioral level. The sheer fl exibility of the motor system makes it seem unlikely that underlying mechanisms place a signifi cant constraint on the kinds of movement that can be generated. Instead, it seems that regularities in behavior are mostly dictated by ... mostly dictated by features of 1 THEORETICAL MODELS OF MOTOR CONTROL AND MOTOR LEARNING