title: Conservation law for self-paced movements.
abstract: Optimal control models of biological movements introduce external task factors to specify the pace of movements. Here, we present the dual to the principle of optimality based on a conserved quantity, called "drive," that represents the influence of internal motivation level on movement pace. Optimal control and drive conservation provide equivalent descriptions for the regularities observed within individual movements. For regularities across movements, drive conservation predicts a previously unidentified scaling law between the overall size and speed of various self-paced hand movements in the absence of any external tasks, which we confirmed with psychophysical experiments. Drive can be interpreted as a high-level control variable that sets the overall pace of movements and may be represented in the brain as the tonic levels of neuromodulators that control the level of internal motivation, thus providing insights into how internal states affect biological motor control.
authors.affiliation: Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037; Gatsby Computational Neuroscience Unit, University College London, London W1T 4JG, United Kingdom; huh@salk.edu terry@salk.edu.
authors.forename: Dongsung
authors.initials: D
authors.lastname: Huh
authors.affiliation: Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037; Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92161 huh@salk.edu terry@salk.edu.
authors.forename: Terrence J
authors.initials: TJ
authors.lastname: Sejnowski
mesh_terms: D000465:Algorithms; D001921:Brain / Q000502:physiology*; D006225:Hand / Q000502:physiology; D006801:Humans; D008959:Models, Neurological; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*
keywords: conservation law; internal motivation; motor system; optimal control; scaling law in movements