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Strategies for the control of voluntary movements with one mechanical degree of freedom

Published online by Cambridge University Press:  04 February 2010

Gerald L. Gottlieb ,
Daniel M. Corcos  and
Gyan C. Agarwal
Gerald L. Gottlieb*
Affiliation:
Department of Physiology, Rush Medical College, Chicago, IL 60612*
Daniel M. Corcos
Affiliation:
Department of Physical Education, University of lllinois at Chicago, Chicago, IL 60680
Gyan C. Agarwal
Affiliation:
Departments of Electrical Engineening and Computer Science, and Bioengineering, University of lllinois at Chicago, Chicago, IL 60680 Electronic mail: [email protected]
*
* Please address all correspondence to Gerald L. Gottlieb
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Abstract

A theory is presented to explain how accurate, single-joint movements are controlled. The theory applies to movements across different distances, with different inertial loads, toward targets of different widths over a wide range of experimentally manipulated velocities. The theory is based on three propositions. (1) Movements are planned according to “strategies” of which there are at least two: a speed-insensitive (SI) and a speed-sensitive (SS) one. (2) These strategies can be equated with sets of rules for performing diverse movement tasks. The choice between SI and SS depends on whether movement speed and/or movement time (and hence appropriate muscle forces) must be constrained to meet task requirements. (3) The electromyogram can be interpreted as a low-pass filtered version of the controlling signal to the motoneuron pools. This controlling signal can be modelled as a rectangular excitation pulse in which modulation occurs in either pulse amplitude or pulse width. Movements to different distances and with loads are controlled by the SI strategy, which modulates pulse width. Movements in which speed must be explicitly regulated are controlled by the SS strategy, which modulates pulse amplitude. The distinction between the two movement strategies reconciles many apparent conflicts in the motor control literature.

Keywords

electromyogrammodelsmotor controlmovement strategiesmuscleneural controlvoluntary movements
Type
Target Articles
Information
Behavioral and Brain Sciences , Volume 12 , Issue 2 , June 1989 , pp. 189 - 210
Copyright
Copyright © Cambridge University Press 1989

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