Experimental Brain Research

, Volume 126, Issue 3, pp 289–306

The uncontrolled manifold concept: identifying control variables for a functional task

Authors

  • J. P. Scholz
    • Physical Therapy Department and Interdisciplinary Neuroscience Program, 307 McKinly Laboratory, University of Delaware, Newark, DE 19716, USA, e-mail: jpscholz@udel.edu, Fax: +1-302-831-4234
  • Gregor Schöner
    • CNRS, Centre de Recherche en Neurosciences Cognitives, Marseille, France
Research Article

DOI: 10.1007/s002210050738

Cite this article as:
Scholz, J. & Schöner, G. Exp Brain Res (1999) 126: 289. doi:10.1007/s002210050738

Abstract

 The degrees of freedom problem is often posed by asking which of the many possible degrees of freedom does the nervous system control? By implication, other degrees of freedom are not controlled. We give an operational meaning to ”controlled” and ”uncontrolled” and describe a method of analysis through which hypotheses about controlled and uncontrolled degrees of freedom can be tested. In this conception, control refers to stabilization, so that lack of control implies reduced stability. The method was used to analyze an experiment on the sit-to-stand transition. By testing different hypotheses about the controlled variables, we systematically approximated the structure of control in joint space. We found that, for the task of sit-to-stand, the position of the center of mass in the sagittal plane was controlled. The horizontal head position and the position of the hand were controlled less stably, while vertical head position appears to be no more controlled than joint motions.

Key words Motor controlTrajectory formationCoordinationHuman

Copyright information

© Springer-Verlag Berlin Heidelberg 1999