Simulating closed- and open-loop voluntary movement: a nonlinear control-systems approach.

Full Abstract

In many recent human motor control models, including feedback-error learning and adaptive model theory (AMT), feedback control is used to correct errors while an inverse model is simultaneously tuned to provide accurate feedforward control. This popular and appealing hypothesis, based on a combination of psychophysical observations and engineering considerations, predicts that once the tuning of the inverse model is complete the role of feedback control is limited to the correction of disturbances. This hypothesis was tested by looking at the open-loop behavior of the human motor system during adaptation. An experiment was carried out involving 20 normal adult subjects who learned a novel visuomotor relationship on a pursuit tracking task with a steering wheel for input. During learning, the response cursor was periodically blanked, removing all feedback about the external system (i.e., about the relationship between hand motion and response cursor motion). Open-loop behavior was not consistent with a progressive transfer from closed- to open-loop control. Our recently developed computational model of the brain--a novel nonlinear implementation of AMT--was able to reproduce the observed closed- and open-loop results. In contrast, other control-systems models exhibited only minimal feedback control following adaptation, leading to incorrect open-loop behavior. This is because our model continues to use feedback to control slow movements after adaptation is complete. This behavior enhances the internal stability of the inverse model. In summary, our computational model is currently the only motor control model able to accurately simulate the closed- and open-loop characteristics of the experimental response trajectories.

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Author information

Author/s: Davidson, Paul R (PR); Jones, Richard D (RD); Andreae, John H (JH); Sirisena, Harsha R (HR);

Affiliation: Department of Electrical and Electronic Engineering, University of Canterbury, Christchurch, New Zealand.

Journal and publication information

Publication Type: Comparative Study; Journal Article

Journal: IEEE transactions on bio-medical engineering (IEEE Trans Biomed Eng), published in United States. (Language: eng)

Reference: 2002-Nov; vol 49 (issue 11) : pp 1242-52

Dates: Created 2002/11/26; Completed 2003/01/15; Revised 2006/11/15;

PMID: 12450354, status: MEDLINE (last retrieval date: 11/6/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adaptation, Biological - physiology
Computer Simulation
Feedback
Female
Humans
Learning - physiology
Male
Models, Biological

Movement - physiology
Muscle, Skeletal - physiology
Nonlinear Dynamics
Psychomotor Performance - physiology
Reproducibility of Results
Sensitivity and Specificity
Stochastic Processes
Vision - physiology

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