### Abstract

We use an approach rooted in the recent theory of synergies to analyze possible co-variation between two hypothetical control variables involved in finger force production based on the equilibrium-point (EP) hypothesis. These control variables are the referent coordinate (R) and apparent stiffness (C) of the finger. We tested a hypothesis that inter-trial co-variation in the {R; C} space during repeated, accurate force production trials stabilizes the fingertip force. This was expected to correspond to a relatively low amount of inter-trial variability affecting force and a high amount of variability keeping the force unchanged. We used the "inverse piano" apparatus to apply small and smooth positional perturbations to fingers during force production tasks. Across trials, R and C showed strong co-variation with the data points lying close to a hyperbolic curve. Hyperbolic regressions accounted for over 99% of the variance in the {R; C} space. Another analysis was conducted by randomizing the original {R; C} data sets and creating surrogate data sets that were then used to compute predicted force values. The surrogate sets always showed much higher force variance compared to the actual data, thus reinforcing the conclusion that finger force control was organized in the {R; C} space, as predicted by the EP hypothesis, and involved co-variation in that space stabilizing total force.

Original language | English (US) |
---|---|

Pages (from-to) | 150-161 |

Number of pages | 12 |

Journal | Neuroscience |

Volume | 315 |

DOIs | |

State | Published - Feb 19 2016 |

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### All Science Journal Classification (ASJC) codes

- Neuroscience(all)

### Cite this

*Neuroscience*,

*315*, 150-161. https://doi.org/10.1016/j.neuroscience.2015.12.012

}

*Neuroscience*, vol. 315, pp. 150-161. https://doi.org/10.1016/j.neuroscience.2015.12.012

**Synergies in the space of control variables within the equilibrium-point hypothesis.** / Ambike, S.; Mattos, D.; Zatsiorsky, V. M.; Latash, M. L.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Synergies in the space of control variables within the equilibrium-point hypothesis

AU - Ambike, S.

AU - Mattos, D.

AU - Zatsiorsky, V. M.

AU - Latash, M. L.

PY - 2016/2/19

Y1 - 2016/2/19

N2 - We use an approach rooted in the recent theory of synergies to analyze possible co-variation between two hypothetical control variables involved in finger force production based on the equilibrium-point (EP) hypothesis. These control variables are the referent coordinate (R) and apparent stiffness (C) of the finger. We tested a hypothesis that inter-trial co-variation in the {R; C} space during repeated, accurate force production trials stabilizes the fingertip force. This was expected to correspond to a relatively low amount of inter-trial variability affecting force and a high amount of variability keeping the force unchanged. We used the "inverse piano" apparatus to apply small and smooth positional perturbations to fingers during force production tasks. Across trials, R and C showed strong co-variation with the data points lying close to a hyperbolic curve. Hyperbolic regressions accounted for over 99% of the variance in the {R; C} space. Another analysis was conducted by randomizing the original {R; C} data sets and creating surrogate data sets that were then used to compute predicted force values. The surrogate sets always showed much higher force variance compared to the actual data, thus reinforcing the conclusion that finger force control was organized in the {R; C} space, as predicted by the EP hypothesis, and involved co-variation in that space stabilizing total force.

AB - We use an approach rooted in the recent theory of synergies to analyze possible co-variation between two hypothetical control variables involved in finger force production based on the equilibrium-point (EP) hypothesis. These control variables are the referent coordinate (R) and apparent stiffness (C) of the finger. We tested a hypothesis that inter-trial co-variation in the {R; C} space during repeated, accurate force production trials stabilizes the fingertip force. This was expected to correspond to a relatively low amount of inter-trial variability affecting force and a high amount of variability keeping the force unchanged. We used the "inverse piano" apparatus to apply small and smooth positional perturbations to fingers during force production tasks. Across trials, R and C showed strong co-variation with the data points lying close to a hyperbolic curve. Hyperbolic regressions accounted for over 99% of the variance in the {R; C} space. Another analysis was conducted by randomizing the original {R; C} data sets and creating surrogate data sets that were then used to compute predicted force values. The surrogate sets always showed much higher force variance compared to the actual data, thus reinforcing the conclusion that finger force control was organized in the {R; C} space, as predicted by the EP hypothesis, and involved co-variation in that space stabilizing total force.

UR - http://www.scopus.com/inward/record.url?scp=84952881659&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84952881659&partnerID=8YFLogxK

U2 - 10.1016/j.neuroscience.2015.12.012

DO - 10.1016/j.neuroscience.2015.12.012

M3 - Article

C2 - 26701299

AN - SCOPUS:84952881659

VL - 315

SP - 150

EP - 161

JO - Neuroscience

JF - Neuroscience

SN - 0306-4522

ER -