Bilateral synergies in foot force production tasks

Nejc Sarabon, Goran Markovic, Pavle Mikulic, Mark Latash

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We analysed the effects of task symmetry during bilateral accurate force production tasks performed by the two feet. In particular, we tested a hypothesis that bilateral deficit would lead to higher indices of synergies defined as co-varied adjustments in the two forces across trials that reduced total force variability. The subjects produced steady-state force followed by a quick force pulse into the target. The two feet could be acting both into plantar flexion and into dorsiflexion (symmetrical tasks), or in opposite directions (asymmetrical task). We used the framework of the uncontrolled manifold hypothesis to quantify two variance components, one of which did not change total force (V UCM), while the other did (V ORT). Synergy indices during the asymmetrical task were higher than in either symmetrical task. The difference was due to higher V UCM (compared to the symmetrical plantar flexion task) or lower V ORT (compared to the symmetrical dorsiflexion task). The synergy index showed a drop (anticipatory synergy adjustment, ASA) starting 100-150 ms prior to the force pulse initiation. The ASA tended to be shorter and of a smaller magnitude for the asymmetrical task. This is the first demonstration of bilateral synergies during accurate force production by the legs. We conclude that bilateral deficit has no or weak effects on two-leg synergies. The results fit the earlier introduced scheme with two groups of neural variables defining average performance of a redundant system and patterns of co-variation among its elemental variables, respectively.

Original languageEnglish (US)
Pages (from-to)121-130
Number of pages10
JournalExperimental Brain Research
Volume227
Issue number1
DOIs
StatePublished - May 1 2013

Fingerprint

Advisory Committees
Foot
Leg
Direction compound

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

Cite this

Sarabon, Nejc ; Markovic, Goran ; Mikulic, Pavle ; Latash, Mark. / Bilateral synergies in foot force production tasks. In: Experimental Brain Research. 2013 ; Vol. 227, No. 1. pp. 121-130.
@article{f4fdfc1aab474effae9c52e7b12b6471,
title = "Bilateral synergies in foot force production tasks",
abstract = "We analysed the effects of task symmetry during bilateral accurate force production tasks performed by the two feet. In particular, we tested a hypothesis that bilateral deficit would lead to higher indices of synergies defined as co-varied adjustments in the two forces across trials that reduced total force variability. The subjects produced steady-state force followed by a quick force pulse into the target. The two feet could be acting both into plantar flexion and into dorsiflexion (symmetrical tasks), or in opposite directions (asymmetrical task). We used the framework of the uncontrolled manifold hypothesis to quantify two variance components, one of which did not change total force (V UCM), while the other did (V ORT). Synergy indices during the asymmetrical task were higher than in either symmetrical task. The difference was due to higher V UCM (compared to the symmetrical plantar flexion task) or lower V ORT (compared to the symmetrical dorsiflexion task). The synergy index showed a drop (anticipatory synergy adjustment, ASA) starting 100-150 ms prior to the force pulse initiation. The ASA tended to be shorter and of a smaller magnitude for the asymmetrical task. This is the first demonstration of bilateral synergies during accurate force production by the legs. We conclude that bilateral deficit has no or weak effects on two-leg synergies. The results fit the earlier introduced scheme with two groups of neural variables defining average performance of a redundant system and patterns of co-variation among its elemental variables, respectively.",
author = "Nejc Sarabon and Goran Markovic and Pavle Mikulic and Mark Latash",
year = "2013",
month = "5",
day = "1",
doi = "10.1007/s00221-013-3494-4",
language = "English (US)",
volume = "227",
pages = "121--130",
journal = "Experimental Brain Research",
issn = "0014-4819",
publisher = "Springer Verlag",
number = "1",

}

Bilateral synergies in foot force production tasks. / Sarabon, Nejc; Markovic, Goran; Mikulic, Pavle; Latash, Mark.

In: Experimental Brain Research, Vol. 227, No. 1, 01.05.2013, p. 121-130.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Bilateral synergies in foot force production tasks

AU - Sarabon, Nejc

AU - Markovic, Goran

AU - Mikulic, Pavle

AU - Latash, Mark

PY - 2013/5/1

Y1 - 2013/5/1

N2 - We analysed the effects of task symmetry during bilateral accurate force production tasks performed by the two feet. In particular, we tested a hypothesis that bilateral deficit would lead to higher indices of synergies defined as co-varied adjustments in the two forces across trials that reduced total force variability. The subjects produced steady-state force followed by a quick force pulse into the target. The two feet could be acting both into plantar flexion and into dorsiflexion (symmetrical tasks), or in opposite directions (asymmetrical task). We used the framework of the uncontrolled manifold hypothesis to quantify two variance components, one of which did not change total force (V UCM), while the other did (V ORT). Synergy indices during the asymmetrical task were higher than in either symmetrical task. The difference was due to higher V UCM (compared to the symmetrical plantar flexion task) or lower V ORT (compared to the symmetrical dorsiflexion task). The synergy index showed a drop (anticipatory synergy adjustment, ASA) starting 100-150 ms prior to the force pulse initiation. The ASA tended to be shorter and of a smaller magnitude for the asymmetrical task. This is the first demonstration of bilateral synergies during accurate force production by the legs. We conclude that bilateral deficit has no or weak effects on two-leg synergies. The results fit the earlier introduced scheme with two groups of neural variables defining average performance of a redundant system and patterns of co-variation among its elemental variables, respectively.

AB - We analysed the effects of task symmetry during bilateral accurate force production tasks performed by the two feet. In particular, we tested a hypothesis that bilateral deficit would lead to higher indices of synergies defined as co-varied adjustments in the two forces across trials that reduced total force variability. The subjects produced steady-state force followed by a quick force pulse into the target. The two feet could be acting both into plantar flexion and into dorsiflexion (symmetrical tasks), or in opposite directions (asymmetrical task). We used the framework of the uncontrolled manifold hypothesis to quantify two variance components, one of which did not change total force (V UCM), while the other did (V ORT). Synergy indices during the asymmetrical task were higher than in either symmetrical task. The difference was due to higher V UCM (compared to the symmetrical plantar flexion task) or lower V ORT (compared to the symmetrical dorsiflexion task). The synergy index showed a drop (anticipatory synergy adjustment, ASA) starting 100-150 ms prior to the force pulse initiation. The ASA tended to be shorter and of a smaller magnitude for the asymmetrical task. This is the first demonstration of bilateral synergies during accurate force production by the legs. We conclude that bilateral deficit has no or weak effects on two-leg synergies. The results fit the earlier introduced scheme with two groups of neural variables defining average performance of a redundant system and patterns of co-variation among its elemental variables, respectively.

UR - http://www.scopus.com/inward/record.url?scp=84877574830&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84877574830&partnerID=8YFLogxK

U2 - 10.1007/s00221-013-3494-4

DO - 10.1007/s00221-013-3494-4

M3 - Article

C2 - 23568657

AN - SCOPUS:84877574830

VL - 227

SP - 121

EP - 130

JO - Experimental Brain Research

JF - Experimental Brain Research

SN - 0014-4819

IS - 1

ER -