Low dimensionality of supraspinally induced force fields

A. D'Avella, E. Bizzi

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

Recent experiments using electrical and N-methyl-D-aspartate microstimulation of the spinal cord gray matter and cutaneous stimulation of the hindlimb of spinalized frogs have provided evidence for a modular organization of the frog's spinal cord circuitry. A 'module' is a functional unit in the spinal cord circuitry that generates a specific motor output by imposing a specific pattern of muscle activation. The output of a module can be characterized as a force field: the collection of the isometric forces generated at the ankle over different locations in the leg's workspace. Different modules can be combined independently so that their force fields linearly sum. The goal of this study was to ascertain whether the force fields generated by the activation of supraspinal structures could result from combinations of a small number of modules. We recorded a set of force fields generated by the electrical stimulation of the vestibular nerve in seven frogs, and we performed a principal component analysis to study the dimensionality of this set. We found that 94% of the total variation of the data is explained by the first five principal components, a result that indicates that the dimensionality of the set of fields evoked by vestibular stimulation is low. This result is compatible with the hypothesis that vestibular fields are generated by combinations of a small number of spinal modules.

Original languageEnglish
Pages (from-to)7711-7714
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume95
Issue number13
DOIs
Publication statusPublished - Jun 23 1998

Fingerprint

Anura
Spinal Cord
Vestibular Nerve
N-Methylaspartate
Hindlimb
Principal Component Analysis
Ankle
Electric Stimulation
Leg
Muscles
Skin
Gray Matter

ASJC Scopus subject areas

  • General
  • Genetics

Cite this

Low dimensionality of supraspinally induced force fields. / D'Avella, A.; Bizzi, E.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 95, No. 13, 23.06.1998, p. 7711-7714.

Research output: Contribution to journalArticle

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