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Author Notes:

Corresponding Author: Lena Ting, The Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, 313 Ferst Drive, Atlanta, GA 30322-0535, 404-894-5216, 404-385-5044 (fax), lting@emory.edu

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Research Funding:

This work is supported by NIH NS058322 to Lena H. Ting, NSF IGERT and NSF Graduate Research Fellowships to SAC.

Voluntary and reactive recruitment of locomotor muscle synergies during perturbed walking

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Journal Title:

Journal of Neuroscience Nursing

Volume:

Volume 32, Number 35

Publisher:

, Pages 12237-12250

Type of Work:

Article | Post-print: After Peer Review

Abstract:

The modular control of muscles in groups, often referred to as muscle synergies, has been proposed to provide a motor repertoire of actions for the robust control of movement. However it is not clear whether muscle synergies identified in one task are also recruited by different neural pathways subserving other motor behaviors. We tested the hypothesis that voluntary and reactive modifications to walking in humans result from the recruitment of locomotor muscle synergies. We recorded the activity of 16 muscles in the right leg as subjects walked a 7.5 m path at two different speeds. To elicit a second motor behavior, midway through the path we imposed ramp and hold translation perturbations of the support surface in each of four cardinal directions. Variations in the temporal recruitment of locomotor muscle synergies could account for cycle-by-cycle variations in muscle activity across strides. Locomotor muscle synergies were also recruited in atypical phases of gait, accounting for both anticipatory gait modifications prior to perturbations and reactive feedback responses to perturbations. Our findings are consistent with the idea that a common pool of spatially-fixed locomotor muscle synergies can be recruited by different neural pathways, including the central pattern generator for walking, brainstem pathways for balance control, and cortical pathways mediating voluntary gait modifications. Together with electrophysiological studies, our work suggests that muscle synergies may provide a library of motor subtasks that can be flexibly recruited by parallel descending pathways to generate a variety of complex natural movements in the upper and lower limbs.

Copyright information:

© 2012 the authors

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