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Direct cortical control of muscle activation in voluntary arm movements: a model

Nature Neuroscience volume 3, pages 391–398 (2000)Cite this article

Abstract

What neural activity in motor cortex represents and how it controls ongoing movement remain unclear. Suggestions that cortex generates low-level muscle control are discredited by correlations with higher-level parameters of hand movement, but no coherent alternative exists. I argue that the view of low-level control is in principle correct, and that seeming contradictions result from overlooking known properties of the motor periphery. Assuming direct motor cortical activation of muscle groups and taking into account the state dependence of muscle-force production and multijoint mechanics, I show that cortical population output must correlate with hand kinematics in quantitative agreement with experimental observations. The model reinterprets the ‘neural population vector’ to afford unified control of posture, movement and force production.

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Figure 1: Mechanistic model of the motor periphery.
Figure 2: Composition of the MI signal, showing the signals for a 10-cm, 500-ms straight movement with a bell-shaped speed profile.
Figure 3: Predicted population vectors.
Figure 4: Effects of curvature on PV direction.
Figure 5: Statistical biases in cell classification.
Figure 6: Effects of kinematic scaling.

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Acknowledgements

I thank Zoubin Ghahramani and Stephen Scott for their suggestions.

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  1. Gatsby Computational Neuroscience Unit, University College London, 17 Queen Square, London, WC1N 3 AR, UK

    Emanuel Todorov

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Correspondence to Emanuel Todorov.

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Todorov, E. Direct cortical control of muscle activation in voluntary arm movements: a model. Nat Neurosci 3, 391–398 (2000). https://doi.org/10.1038/73964

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