In this study, we were interested in how humans plan and execute trajectories during spatially oriented locomotion. In particular, we tested the effects of vision and locomotor mode (forward vs backward walking) on the geometric and dynamic attributes of the locomotor trajectories.
We hypothetized, according to our previous works (Hicheur et al. 2007, Pham et al. 2007), that human locomotor trajectories should exhibit invariants consistently across subjects and conditions, reflecting optimal processes through which locomotor trajectories are planned and executed. To test this hypothesis, we recorded the whole-body movements of 16 subjects during a goal-oriented locomotor task consisting of walking (backward or forward, blindfolded or with vision) towards targets defined in both position and orientation. When examining the variability pattern throughout task execution, for both curved and straight trajectories, we were also able to distinguish the respective contributions of planning- and implementation-level mechanisms to the formation of locomotor trajectories.
H. Hicheur, Q. C. Pham, G. Arechavaleta, J. P. Laumond, A. Berthoz. The Formation of Trajectories during Goal-Oriented Locomotion in Humans. I. A Stereotyped Behavior. European Journal of Neuroscience, vol. 26, pp. 2376-2390, 2007.
Q. C. Pham, H. Hicheur, G. Arechavaleta, J. P. Laumond, A. Berthoz. The Formation of Trajectories during Goal-Oriented Locomotion in Humans. II. A Maximum Smoothness Model. European Journal of Neuroscience, vol. 26, pp. 2391-2403, 2007.