Letter | Published:

Direct control of paralysed muscles by cortical neurons

Nature volume 456, pages 639642 (04 December 2008) | Download Citation

Abstract

A potential treatment for paralysis resulting from spinal cord injury is to route control signals from the brain around the injury by artificial connections. Such signals could then control electrical stimulation of muscles, thereby restoring volitional movement to paralysed limbs1,2,3. In previously separate experiments, activity of motor cortex neurons related to actual or imagined movements has been used to control computer cursors and robotic arms4,5,6,7,8,9,10, and paralysed muscles have been activated by functional electrical stimulation11,12,13. Here we show that Macaca nemestrina monkeys can directly control stimulation of muscles using the activity of neurons in the motor cortex, thereby restoring goal-directed movements to a transiently paralysed arm. Moreover, neurons could control functional stimulation equally well regardless of any previous association to movement, a finding that considerably expands the source of control signals for brain-machine interfaces. Monkeys learned to use these artificial connections from cortical cells to muscles to generate bidirectional wrist torques, and controlled multiple neuron–muscle pairs simultaneously. Such direct transforms from cortical activity to muscle stimulation could be implemented by autonomous electronic circuitry, creating a relatively natural neuroprosthesis. These results are the first demonstration that direct artificial connections between cortical cells and muscles can compensate for interrupted physiological pathways and restore volitional control of movement to paralysed limbs.

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Acknowledgements

We thank L. Shupe for programming assistance, C. Kent and L. Miller for advice on nerve block, C. Kirby, A. Price and K. McElwain for animal care, and A. Jackson, Y. Nishimura and A. Richardson for comments on the manuscript. This work was supported by grants from the National Institutes of Health.

Author Contributions C.T.M. and E.E.F. conceived and designed the experiments, C.T.M. and S.I.P. performed the experiments, and C.T.M. and E.E.F. wrote the paper.

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  1. Department of Physiology & Biophysics and Washington National Primate Research Center, University of Washington, Seattle, Washington 98195, USA

    • Chet T. Moritz
    • , Steve I. Perlmutter
    •  & Eberhard E. Fetz

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Correspondence to Chet T. Moritz.

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    Supplementary Information

    This files contains Supplementary Figures S1-S4 with Legends, Supplementary Methods, Supplementary Results, Supplementary Discussion and Supplementary References.

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https://doi.org/10.1038/nature07418

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