The formation of trajectories during goal-oriented locomotion in humans. I. A stereotyped behaviour

Authors

  • Halim Hicheur,

    1. Laboratoire de Physiologie de la Perception et de l'Action, Collège de France CNRS UMR7152, 11 place Marcelin Berthelot, 75005 Paris, France
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  • Quang-Cuong Pham,

    1. Laboratoire de Physiologie de la Perception et de l'Action, Collège de France CNRS UMR7152, 11 place Marcelin Berthelot, 75005 Paris, France
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  • Gustavo Arechavaleta,

    1. LAAS-CNRS, 7 avenue du Colonel Roche, 31077 Toulouse, France, LPPA, Collège de France-CNRS, 11 place Marcelin Berthelot 75005 Paris, France
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  • Jean-Paul Laumond,

    1. LAAS-CNRS, 7 avenue du Colonel Roche, 31077 Toulouse, France, LPPA, Collège de France-CNRS, 11 place Marcelin Berthelot 75005 Paris, France
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  • Alain Berthoz

    1. Laboratoire de Physiologie de la Perception et de l'Action, Collège de France CNRS UMR7152, 11 place Marcelin Berthelot, 75005 Paris, France
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Dr Halim Hicheur, as above.
E-mail: halim.hicheur@college-de-france.fr

Abstract

Human locomotion was investigated in a goal-oriented task where subjects had to walk to and through a doorway starting from a fixed position and orientation in space. The door was located at different positions and orientations in space, resulting in a total of 40 targets. While no specific constraint was provided to subjects in terms of the path they were to follow or the expected walking speeds, all of them generated very similar trajectories in terms of both path geometry and velocity profiles. These results are reminiscent of the stereotyped properties of the hand trajectories observed in arm reaching movements in studies over the last 20 years. This observation supports the hypothesis that common constraining mechanisms govern the generation of segmental and whole-body trajectories. In contrast, we observed that the subjects placed their feet at different spatial positions across repetitions, making unlikely the hypothesis that goal-oriented locomotion is planned as a succession of steps. Rather, our results suggest that common planning and/or control strategies underlie the formation of the whole locomotor trajectory during a spatially oriented task.

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