An Optimization Principle for Determining Movement Duration
Open Access
- 1 June 2006
- journal article
- Published by American Physiological Society in Journal of Neurophysiology
- Vol. 95 (6), 3875-3886
- https://doi.org/10.1152/jn.00751.2005
Abstract
Movement duration is an integral component of motor control, but nearly all extant optimization models of motor planning prefix duration instead of explaining it. Here we propose a new optimization principle that predicts movement duration. The model assumes that the brain attempts to minimize movement duration under the constraint of meeting an accuracy criterion. The criterion is task and context dependent but is fixed for a given task and context. The model determines a unique duration as a trade-off between speed (time optimality) and accuracy (acceptable endpoint scatter). We analyzed the model for a linear motor plant, and obtained a closed-form equation for determining movement duration. By solving the equation numerically with specific plant parameters for the eye and arm, we found that the model can reproduce saccade duration as a function of amplitude (the main sequence), and arm-movement duration as a function of the ratio of target distance to size (Fitts's law). In addition, it explains the dependency of peak saccadic speed on amplitude and the dependency of saccadic duration on initial eye position. Furthermore, for arm movements, the model predicts a scaling relationship between peak velocity and distance and a reduction in movement duration with a moderate increase in viscosity. Finally, for a linear plant, our model predicts a neural control signal identical to that of the minimum-variance model set to the same movement duration. This control signal is a smooth function of time (except at the endpoint), in contrast to the discontinuous bang–bang control found in the time-optimal control literature. We suggest that one aspect of movement planning, as revealed by movement duration, may be to assign an endpoint accuracy criterion for a given task and context.Keywords
This publication has 32 references indexed in Scilit:
- Flexible strategies for sensory integration during motor planningNature Neuroscience, 2005
- Different Predictions by the Minimum Variance and Minimum Torque-Change Models on the Skewness of Movement Velocity ProfilesNeural Computation, 2004
- Optimal feedback control as a theory of motor coordinationNature Neuroscience, 2002
- Towards a mathematical foundation of minimum-variance theoryJournal of Physics A: General Physics, 2002
- Minimum Muscle-Tension Change Trajectories Predicted by Using a 17-Muscle Model of the Monkey's ArmJournal of Motor Behavior, 1996
- Processing visual feedback information for movement control.Journal of Experimental Psychology: Human Perception and Performance, 1981
- Inhibition of afferent transmission in cuneate nucleus during voluntary movement in the catBrain Research, 1972
- Movement control in skilled motor performance.Psychological Bulletin, 1968
- Processing of visual feedback in rapid movements.Journal of Experimental Psychology, 1968
- Information capacity of discrete motor responses.Journal of Experimental Psychology, 1964