The bliss (not the problem) of motor abundance (not redundancy)
- 2k Downloads
Motor control is an area of natural science exploring how the nervous system interacts with other body parts and the environment to produce purposeful, coordinated actions. A central problem of motor control—the problem of motor redundancy—was formulated by Nikolai Bernstein as the problem of elimination of redundant degrees-of-freedom. Traditionally, this problem has been addressed using optimization methods based on a variety of cost functions. This review draws attention to a body of recent findings suggesting that the problem has been formulated incorrectly. An alternative view has been suggested as the principle of abundance, which considers the apparently redundant degrees-of-freedom as useful and even vital for many aspects of motor behavior. Over the past 10 years, dozens of publications have provided support for this view based on the ideas of synergic control, computational apparatus of the uncontrolled manifold hypothesis, and the equilibrium-point (referent configuration) hypothesis. In particular, large amounts of “good variance”—variance in the space of elements that has no effect on the overall performance—have been documented across a variety of natural actions. “Good variance” helps an abundant system to deal with secondary tasks and unexpected perturbations; its amount shows adaptive modulation across a variety of conditions. These data support the view that there is no problem of motor redundancy; there is bliss of motor abundance.
KeywordsMotor redundancy Principle of abundance Synergy Referent configuration
Preparation of this paper was in part supported by NIH grant NS-035032.
- Bernstein NA (1930) A new method of mirror cyclographie and its application towards the study of labor movements during work on a workbench. Hyg, Saf Pathol Labor 5:3–9, and 6:3–11 (in Russian)Google Scholar
- Bernstein NA (1967) The co-ordination and regulation of movements. Pergamon Press, OxfordGoogle Scholar
- Feldman AG (1966) Functional tuning of nervous system with control of movement or maintenance of a steady posture. II. Controllable parameters of the muscles. Biophysics 11:565–578Google Scholar
- Gelfand IM, Latash ML (1998) On the problem of adequate language in movement science. Mot Control 2:306–313Google Scholar
- Kugler PN, Turvey MT (1987) Information, natural law, and the self-assembly of rhythmic movement. Erlbaum, Hillsdale, NJGoogle Scholar
- Latash ML (2000) There is no motor redundancy in human movements. There is motor abundance. Mot Control 4:257–259Google Scholar
- Latash ML (2010) Motor synergies and the equilibrium-point hypothesis. Mot Control 14:294–322Google Scholar
- Latash ML, Scholz JP, Schöner G (2007) Toward a new theory of motor synergies. Mot Control 11:276–308Google Scholar
- Shadmehr R, Wise SP (2005) The computational neurobiology of reaching and pointing. MIT Press, Cambridge, MAGoogle Scholar