Experimental Brain Research

, Volume 92, Issue 1, pp 173–182 | Cite as

Feedforward postural stabilization in a distal bimanual unloading task

  • P. Kaluzny
  • M. Wiesendanger


The aim of the present study was to investigate postural adjustments and positional stability in a bimanual unloading task, involving essentially the index finger, in order to test whether proactive adjustments are also observed in distal body segments. A second goal of the study was to evaluate the concept of a central command that would be responsible for coupling movement and posture. The positional disturbance of the right load-bearing index finger of healthy human subjects was studied under two types of manipulations: passive, i.e., imposed, unloading and active unloading, by the subject's left index finger. It was found that, in such a distal task, positional stabilization of the load-bearing finger was much better (by a factor of 6) in the active situation than the passive situation. This improvement was greater than previously reported for a proximal task. An electromyogram (EMG) analysis of the mostly implicated dorsal interosseous muscles revealed a typical unloading reflex in the passive situation (reactive mode) and a suppression of EMG before unloading onset in the active situation (proactive mode). Averaged records showed an almost perfect synchronization between the EMG suppression in the load-bearing interosseous muscle and the onset of the EMG burst of the unloading index finger. A trial-by-trial analysis, however, revealed a considerable scatter in intervals of the two EMG events, with a tendency of the activity burst in the left finger to occur slightly before the suppression of EMG in the load-bearing muscle. No positive correlation was found between the precision of synchronization (intervals near zero time) and the accuracy of performance, i.e., positional stability of the unloaded finger. Although the trial-by-trial variability was large, it is suggested that at least some of this variability is caused by a nonsteady state of motoneuronal excitability. In view of the low-pass property of the muscle, the observed variability in synchronization may be sufficiently precise to maintain the hypothesis of a central temporal coupling of the events in the two hands through a common command. However, the lack of a correlation between the degree of synchronization and the performance in stability argues rather in favor of separate commands to the two hands that select the parameters in the spatial domain. Finally, an intermanual EMG or torque analysis is proposed that might be useful in assessing the accuracy in goal achievement, i.e., the maintenance of a stable finger position in spite of the “internal” perturbation.

Key words

Bimanual task Anticipatory postural adjustment Distal movements Unloading reflex Human 


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  1. Bazalgette D, Zattara M, Bathien N, Bouisset S, Rondot P (1986) Postural adjustments associated with rapid voluntary arm movements in patients with Parkinson's disease. Adv Neurol 45: 371–374Google Scholar
  2. Dufossé M, Hugon M, Massion J (1985) Postural forearm changes induced by predictable in time or voluntary triggered unloading in man. Exp Brain Res 60: 330–334Google Scholar
  3. Forget R, Lamarre Y (1990) Anticipatory postural adjustment in the absence of normal peripheral feedback. Brain Res 508: 176–179Google Scholar
  4. Gahéry Y (1987) Associated movements, postural adjustments and synergies: some comments about the history and significance of three motor concepts. Arch Ital Biol 125: 345–360Google Scholar
  5. Gurfinkel VS, Elner AM (1988) Participation of secondary motor area of the frontal lobe in organization of postural components of voluntary movements in man (in Russian). Neirofiziologiia 20: 7–14Google Scholar
  6. Hess WR (1943) Teleokinetisches und ereismatisches Kräftesystem in der Biomotorik. Helv Physiol Pharmacol Acta 1: C62-C63Google Scholar
  7. Hess WR (1981) Biological order and brain organization. In: Akert K (eds) Selected works of W.R. Hess. Springer, Berlin Heidelberg New York, pp 265–268Google Scholar
  8. Houk JC, Rymer WZ (1981) Neural control of muscle length and tension. In: Brooks VB (ed) Handbook of physiology (vol 2, part 1). Am Physiol Soc pp 257–323Google Scholar
  9. Hugon M, Massion J, Wiesendanger M (1982) Anticipatory pos- tural changes induced by active unloading and comparison with passive unloading in man. Pflügers Arch 393: 292–296Google Scholar
  10. Johansson RS, Westling GR (1988) Programmed and triggered actions to rapid load changes during precision grip. Exp Brain Res 71: 72–86Google Scholar
  11. MacNeilage PF (1990) Grasping in modern primates: the evolutionary context. In: Goodale MA (ed) Vision and action: the control of grasping. Ablex, Norwood, NJ pp 1–13Google Scholar
  12. Massion J (1992) Movement, posture and equilibrium: interaction and coordination. Prog Neurobiol 38: 35–56CrossRefPubMedGoogle Scholar
  13. Massion J, Viallet F, Massarino R, Khalil R (1989) La région de l'aire motrice supplémentaire est impliquée dans la coordination entre posture et mouvement chez l'Homme. C R Acad Sci [III] 308: 417–423Google Scholar
  14. Nashner LM, Shumway-Cook A, Marin O (1983) Stance posture control in select groups of children with cerebral palsy: deficits in sensory organization and muscular coordination. Exp Brain Res 49: 393–409Google Scholar
  15. Paulignan Y, Dufossé M, Hugon M, Massion J (1989) Acquisition of co-ordination between posture and movement in a bimanual task. Exp Brain Res 77: 337–348Google Scholar
  16. Rogers MW, Kukulka CG, Soderberg GL (1987) Postural adjustments preceding rapid arm movements in parkinsonian subjects. Neurosci Lett 75: 246–251Google Scholar
  17. Schmidt RA, Zelaznik H, Hawkins B, Frank JS, Quin JT (1979) Motor output variability: a theory for the accuracy of rapid motor acts. Psychol Rev 86: 415–449Google Scholar
  18. Viallet F, Massion J, Massarino R, Khalil R (1987) Performance of a bimanual load-lifting task by parkinsonian patients. J Neurol Neurosurg Psychiatry 50: 1274–1283Google Scholar
  19. Viallet F, Massion J, Massarino R, Khalil R (1992) Coordination between posture and movement in a bimanual load-lifting task: putative role of a mesial region including the supplementary motor area. Exp Brain Res 88: 674–684Google Scholar

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • P. Kaluzny
    • 1
  • M. Wiesendanger
    • 1
  1. 1.Institut de PhysiologieUniversité de FribourgFribourgSwitzerland

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