Direction-dependent arm kinematics reveal optimal integration of gravity cues.
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.
Université Bourgogne Franche-Comté, INSERM CAPS UMR 1093, Dijon, France.
Jeremie
0000-0001-8827-1486
J
Gaveau
CIAMS, Université Paris-Sud, Université Paris Saclay, Orsay, France.|CIAMS, Université d'Orléans, Orléans, France.
Bastien
B
Berret
Department of Neuroscience, Baylor College of Medicine, Houston, United States.
Dora E
0000-0002-9650-8962
DE
Angelaki
Université Bourgogne Franche-Comté, INSERM CAPS UMR 1093, Dijon, France.
Charalambos
C
Papaxanthis
D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena; D001921:Brain / Q000502:physiology*; D006112:Gravitation; D006801:Humans; D011597:Psychomotor Performance / Q000502:physiology*
computational biology; gravity; human; kinematics; motor planning; neuroscience; optimal control; sensorimotor adaptation; systems biology