|
|
||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia, United States
* To whom correspondence should be addressed. E-mail: lting{at}emory.edu.
Postural control is a natural behavior that requires the spatial and temporal coordination of multiple muscles. Complex muscle activation patterns characterizing postural responses suggest the need for independent muscle control. However, our previous work shows that postural responses in cats can be robustly reproduced by the activation of a few muscle synergies (Ting and Macpherson 2005; Torres-Oviedo et al. 2006). We now investigate whether a similar simplification structure is used for human postural control. We hypothesized that a few muscle synergies could account for the inter-trial variability in automatic postural responses from different perturbation directions, as well as different postural strategies. Postural responses to multidirectional support-surface translations in 16 muscles of the lower back and leg were analyzed in nine healthy subjects. Six or fewer muscle synergies were required to reproduce the postural responses of each subject. The composition and temporal activation of several muscle synergies identified across all subjects were consistent with the previously identified "ankle" and "hip" strategies in human postural responses. Moreover, inter-trial variability in muscle activation patterns was successfully reproduced by modulating the activity of the various muscle synergies. This suggests that trial-to-trial variations in the activation of individual muscles are correlated, and moreover, represent variations in the amplitude of descending neural commands that activate individual muscle synergies. Finally, composition and temporal activation of most of the muscle synergies were similar across subjects. These results suggest that muscles synergies represent a general simplification strategy underlying muscle coordination in postural tasks.
This article has been cited by other articles:
![]() |
H. J. Chiel, L. H. Ting, O. Ekeberg, and M. J. Z. Hartmann The Brain in Its Body: Motor Control and Sensing in a Biomechanical Context J. Neurosci., October 14, 2009; 29(41): 12807 - 12814. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. J. Valero-Cuevas, M. Venkadesan, and E. Todorov Structured Variability of Muscle Activations Supports the Minimal Intervention Principle of Motor Control J Neurophysiol, July 1, 2009; 102(1): 59 - 68. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. D. J. Welch and L. H. Ting A Feedback Model Explains the Differential Scaling of Human Postural Responses to Perturbation Acceleration and Velocity J Neurophysiol, June 1, 2009; 101(6): 3294 - 3309. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. A. Leonard, R. H. Brown, and P. J. Stapley Reaching to Multiple Targets When Standing: The Spatial Organization of Feedforward Postural Adjustments J Neurophysiol, April 1, 2009; 101(4): 2120 - 2133. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. C. K. Cheung, A. d'Avella, and E. Bizzi Adjustments of Motor Pattern for Load Compensation Via Modulated Activations of Muscle Synergies During Natural Behaviors J Neurophysiol, March 1, 2009; 101(3): 1235 - 1257. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Kiemel, A. J. Elahi, and J. J. Jeka Identification of the Plant for Upright Stance in Humans: Multiple Movement Patterns From a Single Neural Strategy J Neurophysiol, December 1, 2008; 100(6): 3394 - 3406. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. D. J. Welch and L. H. Ting A Feedback Model Reproduces Muscle Activity During Human Postural Responses to Support-Surface Translations J Neurophysiol, February 1, 2008; 99(2): 1032 - 1038. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. A. Overduin, A. d'Avella, J. Roh, and E. Bizzi Modulation of Muscle Synergy Recruitment in Primate Grasping J. Neurosci., January 23, 2008; 28(4): 880 - 892. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |