Direction-dependent arm kinematics reveal optimal integration of gravity cues
Abstract
The brain has evolved an internal model of gravity to cope with life in the Earth's gravitational environment. How this internal model benefits the implementation of skilled movement has remained unsolved. One prevailing theory has assumed that this internal model is used to compensate for gravity's mechanical effects on the body, such as to maintain invariant motor trajectories. Alternatively, gravity force could be used purposely and efficiently for the planning and execution of voluntary movements, thereby resulting in direction-depending kinematics. Here we experimentally interrogate these two hypotheses by measuring arm kinematics while varying movement direction in normal and zero-G gravity conditions. By comparing experimental results with model predictions, we show that the brain uses the internal model to implement control policies that take advantage of gravity to minimize movement effort.
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Author details
Funding
Institut National de la Santé et de la Recherche Médicale
- Jeremie Gaveau
- Charalambos Papaxanthis
Agence Nationale de la Recherche (projet MOTION, 14-CE30-007-01)
- Charalambos Papaxanthis
National Institute of Neurological Disorders and Stroke (R21-NS-075944-02)
- Jeremie Gaveau
- Dora E Angelaki
- Charalambos Papaxanthis
Centre National d'Etudes Spatiales
- Jeremie Gaveau
- Bastien Berret
- Charalambos Papaxanthis
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Human subjects: Informed consent, and consent to publish, was obtained from all participants. The regional ethics committee of Burgundy (C.E.R) and the ethics committee of INSERM (Institut National de la Santé et de la Recherche Médicale) approved experimental protocols. All procedures were carried out in agreement with local requirements and international norms (Declaration of Helsinki, 1964).
Copyright
© 2016, Gaveau et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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