Time evolution of the organization of multi-muscle postural responses to sudden changes in the external force applied at the trunk level

doi:10.1016/j.neulet.2008.04.052

Neuroscience Letters

Volume 438, Issue 2, 20 June 2008, Pages 238-241

https://doi.org/10.1016/j.neulet.2008.04.052 Get rights and content

Abstract

We studied muscle activation patterns in response to perturbations of posture (sudden changes in the external force applied to the thorax) during two time intervals corresponding to pre-programmed postural reactions and voluntary corrections of posture. A hypothesis was tested that a set of postural muscles could be used to form stable groups (M-modes) whose composition changes in different time intervals after a perturbation. Perturbations were applied at the sternum level to standing subjects at an unexpected time. Principal component analysis with factor extraction allowed to identify sets of three factors (M-modes) during the two time intervals, 80–180 ms (T₁) and 250–450 ms (T₂) after the perturbation. The composition of M-modes was similar within each time interval across subjects and perturbations but differed significantly between T₁ and T₂. In particular, M-modes during T₁ were characterized by more co-contraction patterns. The results suggest that the neural controller is able to rearrange M-mode composition in real time based on a safety-efficacy trade-off. The results also support the idea that M-modes represent synergies in the muscle space, while they may be used as elemental variables to form synergies at a higher hierarchical level to produce desired mechanical effects.

Section snippets

Acknowledgments

The study was in part supported by NIH grants AG-018751 and NS-035032. The authors are grateful to Elena Shapkova and Alexandra Shapkova for their assistance during the experiment and to Alessander Danna-dos-Santos for his help with data processing.

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Time evolution of the organization of multi-muscle postural responses to sudden changes in the external force applied at the trunk level

Abstract

Section snippets

Acknowledgments

Neurosci. Lett.

Shared and specific muscle synergies in natural motor behaviors

Proc. Natl. Acad. Sci. U.S.A.

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Exp. Brain Res.

Muscle modes and synergies during voluntary body sway

Exp. Brain Res.

Influence of stimulus parameters on human postural responses

J. Neurophysiol.

Coordination of locomotion with voluntary movements in humans

J. Neurosci.

Five basic muscle activation patterns account for muscle activity during human locomotion

J. Physiol.

Interaction of involuntary post-contraction activity with locomotor movements

Exp. Brain. Res.