The construction of movement by the spinal cord

Abstract

We used a computational analysis to identify the basic elements with which the vertebrate spinal cord constructs one complex behavior. This analysis extracted a small set of muscle synergies from the range of muscle activations generated by cutaneous stimulation of the frog hindlimb. The flexible combination of these synergies was able to account for the large number of different motor patterns produced by different animals. These results therefore demonstrate one strategy used by the vertebrate nervous system to produce movement in a computationally simple manner.

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Figure 1: Muscle activation patterns evoked from cutaneous stimulation of the frog hindlimb.
Figure 2: Example of muscle covariation patterns within evoked responses.
Figure 3: The contribution of each muscle synergy to responses evoked from different regions of the skin surface for three different animals (a, b, c).
Figure 4: The ability of synergies from sites on the rostral and caudal margins of the hindlimb to explain responses evoked from other skin regions.

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Acknowledgements

We thank Sandro Mussa–Ivaldi and Andrea d'Avella for reading versions of this manuscript and Simon Giszter, Peter Dayan, Kuno Wyler and James Galagan for suggestions. M.C.T. was supported by a HHMI predoctoral fellowship. This research was supported by NIH NS09343 and ONR N00014–95–I0445 to E.B.

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Correspondence to Emilio Bizzi.

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