Summary
This study has described the organization of EMG activities among the muscles of a standing subject's legs during rapid postural adjustments (95–120 ms latencies). Adjustments were elicited by the horizontal translation of both feet (causing antero-posterior sway), by the synchronous vertical displacement of both feet (causing changes in height) and by the reciprocal vertical displacement of the feet (causing a locomotor-like motion of the legs and lateral sway of the body). The resulting patterns of EMG activity were highly specific for each kind of displacement, and all subjects completely reorganized the pattern of activity from one form to another within the first trials, even immediately following unexpected stimulus changes.
The organization of EMG activities during reciprocal vertical displacements was qualitatively quite similar to those observed during the comparable swing and stance phases of the locomotor step cycle; flexor muscles of the ankle and knee (those being shortened by the displacement) contracted in the upwardly displaced leg while extensor muscles were active in the downwardly displaced leg. This pattern was in marked contrast to the activation of lengthening muscles during synchronous vertical and antero-posterior sway displacements. Finally, electrical cutaneous stimulation of the dorsum of one foot during reciprocal vertical displacements always enhanced the EMG activity of the agonist leg muscles, in-phase with the vertical movement.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Bernstein, N.: Coordination and Regulation of Movements. New York: Pergamon Press 1967
Duysens, J., Pearson, K.G.: The role of cutaneous afferents from the distal hindlimb in the regulation of the step cycle of thalamic cats. Exp. Brain Res. 24, 245–255 (1976)
Engberg, I., Lundberg, A.: An electromyographic analysis of muscular activity in the hindlimb of the cat during unrestrained locomotion. Acta Physiol. Scand. 75, 614–630 (1969)
Forssberg, H., Grillner, S., Rossignol, S.: Phase-dependent reflex reversal during walking in chronic spinal cats. Brain Res. 85, 103–107 (1975)
Forssberg, H., Grillner, S., Rossignol, S.: Phasic gain control of reflexes from the dorsum of the paw during spinal locomotion. Brain Res. 132, 121–139 (1977)
Gelfand, I.M., Gurfinkel, V.S., Fomin, S.V., Tsetlin, M.L.: Models of the Structural-Functional Organization of Certain Biological Systems, Chap. 9, pp. 329–345. Cambridge: MIT Press 1971
Grillner, S.: Locomotion in vertebrates: central mechanisms and reflex interaction. Physiol. Rev. 55, 247–304 (1975)
Herman, R., Wirta, R., Bampton, S., Finley, F.R.: Human solutions to locomotion. I. Single limb analysis. In: Neural control of locomotion (eds. Herman, Grillner, Stein, Stuart), pp. 13–49 New York: Plenum Press 1976
Kots, Ya.M., Zhukov, V.I.: Supraspinal control over segmental centers of antagonist muscles in man. III. Tuning of spinal reciprocal inhibition system during organization preceding voluntary movement. Biophysics 16, 1085–1091 (1971)
Lisin, V.V., Frankstein, S.I., Rechtmann, M.B.: The influence of locomotion on flexor reflex of the hindlimb in cat and man. Exp. Neurol. 38, 180–183 (1973)
Nashner, L.M.: Vestibular and reflex control of normal standing. In: Control of posture and locomotion (eds. Stein, Pearson, Smith, Redford), pp. 291–308. New York: Plenum Press 1973
Nashner, L.M.: Adapting reflexes controlling the human posture. Exp. Brain Res. 26, 59–72 (1976)
Nashner, L.M.: Fixed patterns of rapid postural responses among leg muscles during stance. Exp. Brain Res. 30, 13–24 (1977)
Nashner, L.M., Berthoz, A.: Visual contribution to rapid motor responses during posture control. Brain Res. 150, 403–407 (1978)
Wetzel, M.D., Stuart, D.G.: Ensemble characteristics of cat locomotion and its neural control. In: Progress in neurobiology, Vol. 7, pp. 1–98. London: Pergamon Press 1976
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Nashner, L.M., Woollacott, M. & Tuma, G. Organization of rapid responses to postural and locomotor-like perturbations of standing man. Exp Brain Res 36, 463–476 (1979). https://doi.org/10.1007/BF00238516
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00238516