Motor equivalence reveals coarticulation in arm movement sequences involving obstacle avoidance

Abstract

Event Abstract Back to Event Motor equivalence reveals coarticulation in arm movement sequences involving obstacle avoidance Eva Nowak1*, Britta Grimme1, Hendrik Reimann1 and Gregor Schöner1 1 Ruhr-Universität Bochum, Institut für Neuroinformatik, Germany We study movement sequences involving obstacle avoidance in naturalistic 3D arm movements in humans looking for coarticulation. We use the concept of the uncontrolled manifold (Scholz & Schoener, 1999) to uncover motor equivalent solutions when movements in one segment are preceded by different movements in the preceding segment. In the experiment, participants moved an object with their hand along a horizontal path from one target to the next while avoiding obstacles placed between the targets. Each of four segments began with tapping the object on a target, then moving over an obstacle and tapping on the next target, which started the following segment. The obstacles varied in height, higher obstacles being placed in the second and third segments of the movement. We looked for coarticulation, that is, for influences of these higher obstacles on the first and last segments. Avoiding lower obstacles immediately after avoiding higher obstacles resulted in adaption of the spatial path of the transported object (post-coarticulation). This adaption increased with increasing height of the preceding obstacle. At the joint level we decomposed the variance of joint configurations into components that leave the spatial position of the transported object invariant (UCM) and the orthogonal complement (ORT). We found higher variance within the UCM than within ORT across the entire movement sequence. Coarticulation was addressed at the joint level by decomposing the difference between joint configurations in different conditions into a UCM and an ORT component. The UCM component is motor equivalent because it leaves the task variable invariant. The difference between joint configurations in a given segment, when different obstacle conditions were experienced in the preceding segment, lay largely in the UCM. Such motor equivalence is evidence for coarticulation at the level of the joint angles. Anticipatory coarticulation was not found consistently across all participants. Acknowledgements The authors acknowledge support from the German Federal Ministry of Education and Research within the National Network Computational Neuroscience - Bernstein Fokus: "Learning behavioral models: From human experiment to technical assistance", grant FKZ 01GQ0951. References Scholz JP, Schoner G. (1999) The uncontrolled manifold concept: identifying control variables for a functional task. Exp Brain Res 126: 289–306 Keywords: arm movement, coarticulation, motor equivalence, obstacle avoidance, Uncontrolled Manifold Conference: Bernstein Conference 2012, Munich, Germany, 12 Sep - 14 Sep, 2012. Presentation Type: Poster Topic: Motor control, movement, navigation Citation: Nowak E, Grimme B, Reimann H and Schöner G (2012). Motor equivalence reveals coarticulation in arm movement sequences involving obstacle avoidance. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference 2012. doi: 10.3389/conf.fncom.2012.55.00232 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 11 May 2012; Published Online: 12 Sep 2012. * Correspondence: Mrs. Eva Nowak, Ruhr-Universität Bochum, Institut für Neuroinformatik, Bochum, 44780, Germany, eva.nowak@ini.rub.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Eva Nowak Britta Grimme Hendrik Reimann Gregor Schöner Google Eva Nowak Britta Grimme Hendrik Reimann Gregor Schöner Google Scholar Eva Nowak Britta Grimme Hendrik Reimann Gregor Schöner PubMed Eva Nowak Britta Grimme Hendrik Reimann Gregor Schöner Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.