Event Abstract Back to Event Signal dependent noise- and time-minimization determine head-free gaze shifts Murat Saglam1, 2*, Nadine Lehnen3, Ulrich Büttner1, 4 and Stefan Glasauer1, 2, 4 1 Ludwig-Maximilians-Universität, Institute for Clinical Neurosciences, Germany 2 Ludwig-Maximilians-Universität München, Bernstein Center for Computational Neuroscience Munich, Germany 3 Ludwig-Maximilians-Universität, Dept. of Neurology, Germany 4 Ludwig Maximilians Universität München, Integrated Center for Research and Treatment of Vertigo, Germany To foveate a distally located visual target, we need to perform coordinated eye and head movements. Experimental studies show that these movements have stereotypical behavior although a gaze shift can be an arbitrary combination of eye and head movements. The motor system is hypothesized to eliminate this redundancy by optimizing certain features of the movement. One possible strategy is to move the gaze as fast as possible, which would result in a “bang-bang” control switching the control signal from one extreme to the other and would give unrealistic velocity profiles. On the other hand, the final gaze position needs to reach the desired target and remain there with minimum positional variance (MV) in the presence of signal dependent noise (SDN). It has been previously shown that the MV model penalizes the SDN, namely the control signal, with a time-varying function depending on the plant dynamics. The MV strategy results in a smooth control signal which gives experimentally consistent velocity profiles, but does not specify movement time. The cost of SDN is a decreasing function of movement time and therefore imposes a trade-off between SDN and time. In this study, we minimized the weighted sum of SDN and time costs to compute the eye and head control signals for head-unrestrained large gaze shifts. Eye and head dynamics were modeled by third order linear plants. The model successfully reproduced the observed velocity profiles and contributions of eye and head to the desired gaze shift. To test our proposed optimality criterion, we investigated the dependence of the control signal on plant dynamics. In order to do that, we empirically increased the head moment of inertia in healthy subjects, changed the head plant in the model accordingly, and kept other parameters constant. The model successfully predicted slower head dynamics, increased peak eye velocity and increased skewness of the gaze velocity profile under increased inertia condition (see Fig. 1). These results indicate that optimizing the trade-off between minimizing the impact of SDN and movement duration may determine the properties of head-free gaze shifts. Figure 1 Comparison of empirical (left, mean of trials from a single subject) and predicted (right) velocity profiles of head (black), eye (red) and gaze (blue) for a gaze shift of 70 degrees (-35 to 35). The data with increased head moment of inertia is shown by dashed lines. Figure 1 Acknowledgements Funded by BMBF (BCCN 01GQ0440, IFB 01EO0901). Keywords: computational neuroscience Conference: Bernstein Conference on Computational Neuroscience, Berlin, Germany, 27 Sep - 1 Oct, 2010. Presentation Type: Presentation Topic: Bernstein Conference on Computational Neuroscience Citation: Saglam M, Lehnen N, Büttner U and Glasauer S (2010). Signal dependent noise- and time-minimization determine head-free gaze shifts. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference on Computational Neuroscience. doi: 10.3389/conf.fncom.2010.51.00106 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: 09 Sep 2010; Published Online: 23 Sep 2010. * Correspondence: Dr. Murat Saglam, Ludwig-Maximilians-Universität, Institute for Clinical Neurosciences, Munich, Germany, murat.saglam@lrz.uni-muenchen.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 Murat Saglam Nadine Lehnen Ulrich Büttner Stefan Glasauer Google Murat Saglam Nadine Lehnen Ulrich Büttner Stefan Glasauer Google Scholar Murat Saglam Nadine Lehnen Ulrich Büttner Stefan Glasauer PubMed Murat Saglam Nadine Lehnen Ulrich Büttner Stefan Glasauer 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.