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Optimal sensorimotor transformations for balance


Here we have identified a sensorimotor transformation that is used by a mammalian nervous system to produce a multijoint motor behavior. Using a simple biomechanical model, a delayed-feedback rule based on an optimal tradeoff between postural error and neural effort explained patterns of muscle activation in response to a sudden loss of balance in cats. Following the loss of large sensory afferents, changes in these muscle-activation patterns reflected an optimal reweighting of sensory feedback gains to minimize postural instability. Specifically, a loss of center-of-mass-acceleration information, which allowed for a rapid initial rise in the muscle activity in intact animals, was absent after large-fiber sensory neuropathy. Our results demonstrate that a simple and flexible neural feedback control strategy coordinates multiple muscles over time via a small set of extrinsic, task-level variables during complex multijoint natural movements.

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Figure 1: Example of muscle-activation patterns evoked during balance corrections to support-surface motion in the horizontal plane.
Figure 2: Simple feedback model of postural control used to predict muscle activity during balance responses.
Figure 3: Comparison of recorded and simulated muscle activation and CoM kinematics.
Figure 4: Summary of model (TSyID) fits and parameter values (mean ± s.d.) for all muscles in four cats.
Figure 5: Robustness of the feedback model to varying perturbation characteristics.
Figure 6: Comparison of recorded and simulated muscle activation and CoM kinematics following large-fiber neuropathy.


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We thank J.M. Macpherson and P.J. Stapley for use of the data and helpful comments, R.J. Peterka for his technical guidance, A. Koenig for help with the simulations, and J.L. McKay for his insightful editorial assistance. This work was supported by Whitaker Grant RG–02–0747.

Author information




D.B.L. developed and validated the TSyID and DQR formulations, performed the simulations and data analysis and contributed to writing the manuscript. L.H.T. conceptualized the model, developed the dual-ramp perturbations, participated in experiments, supervised the research and wrote the manuscript.

Corresponding author

Correspondence to Lena H Ting.

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Lockhart, D., Ting, L. Optimal sensorimotor transformations for balance. Nat Neurosci 10, 1329–1336 (2007).

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