title: Optimality of Upper-Arm Reaching Trajectories Based on the Expected Value of the Metabolic Energy Cost.
abstract: When we move our body to perform a movement task, our central nervous system selects a movement trajectory from an infinite number of possible trajectories under constraints that have been acquired through evolution and learning. Minimization of the energy cost has been suggested as a potential candidate for a constraint determining locomotor parameters, such as stride frequency and stride length; however, other constraints have been proposed for a human upper-arm reaching task. In this study, we examined whether the minimum metabolic energy cost model can also explain the characteristics of the upper-arm reaching trajectories. Our results show that the optimal trajectory that minimizes the expected value of energy cost under the effect of signal-dependent noise on motor commands expresses not only the characteristics of reaching movements of typical speed but also those of slower movements. These results suggest that minimization of the energy cost would be a basic constraint not only in locomotion but also in upper-arm reaching.
authors.affiliation: Graduate School of Engineering, University of Fukui, 910-8507 Fukui, Japan taniai@rbt.his.u-fukui.ac.jp.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Taniai
authors.affiliation: Graduate School of Science and Engineering, Yamaguchi University, 753-8512 Yamaguchi, Japan nishii@sci.yamaguchi-u.ac.jp.
authors.forename: Jun
authors.initials: J
authors.lastname: Nishii
mesh_terms: D000465:Algorithms; D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena; D004734:Energy Metabolism / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D013997:Time Factors