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Front. Physiol. | doi: 10.3389/fphys.2018.00131

Grip force adjustments reflect prediction of dynamic consequences in varying gravitoinertial fields

  • 1INSERM U1093 Université de Bourgogne Franche Comté, France
  • 2Institute of Neuroscience, Université Catholique de Louvain, Belgium
  • 3Physical and Rehabilitation Medicine Department, Université Catholique de Louvain, Belgium
  • 4Institute of Information and Communication Technologies, Electronics and Applied Mathematics, Université Catholique de Louvain, Belgium
  • 5Department of Sport and Health Sciences, Technische Universität München, Germany

Humans have a remarkable ability to adjust the way they manipulate tools through a genuine regulation of grip force according to the task. However, rapid changes in the dynamical context may challenge this skill, as shown in many experimental approaches. Most experiments adopt perturbation paradigms that affect only one sensory modality. We hypothesize that very fast adaptation can occur if coherent information from multiple sensory modalities is provided to the central nervous system. Here, we test whether participants can switch between different and never experienced dynamical environments induced by centrifugation of the body. Seven participants lifted an object four times in a row successively in 1, 1.5, 2, 2.5, 2, 1.5 and 1g. We continuously measured grip force, load force and the gravitoinertial acceleration that was aligned with body axis (perceived gravity). Participants adopted stereotyped grasping movements immediately upon entry in a new environment and needed only one trial to adapt grip forces to a stable performance in each new gravity environment. This result was underlined by good correlations between grip and load forces in the first trial. Participants predictively applied larger grip forces when they expected increasing gravity steps. They also decreased grip force when they expected decreasing gravity steps, but not as much as they could, indicating imperfect anticipation in that condition. The participants’ performance could rather be explained by a combination of successful scaling of grip force according to gravity changes and a separate safety factor. The data suggest that in highly unfamiliar dynamic environments, grip force regulation is characterized by a combination of a successful anticipation of the experienced environmental condition, a safety factor reflecting strategic response to uncertainties about the environment and rapid feedback mechanisms to optimize performance under constant conditions.

Keywords: motor control, grip force, switching, Gravity Sensing, uncertainty, Hypergravity

Received: 27 Oct 2017; Accepted: 08 Feb 2018.

Edited by:

Yury Ivanenko, Fondazione Santa Lucia (IRCCS), Italy

Reviewed by:

Alessandro Moscatelli, Università degli Studi di Roma Tor Vergata, Italy
Ke Li, Shandong University, China
Bing Chen, University of Miami, United States  

Copyright: © 2018 White, Thonnard, Lefèvre and Hermsdörfer. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Olivier White, INSERM U1093 Université de Bourgogne Franche Comté, Dijon, France, olivier.white@u-bourgogne.fr