Intrinsically generated phase precession of grid cells in a network model

Abstract

Event Abstract Back to Event Intrinsically generated phase precession of grid cells in a network model Kay Thurley1, 2*, Franziska Hellmundt1 and Christian Leibold1, 2 1 Ludwig-Maximilians-University, Munich, Department Biology II, Germany 2 Bernstein Center for Computational Neuroscience Munich, Germany Stellate cells in layer II of the medial entorhinal cortex exhibit place-specific firing in-vivo. Their firing fields are arranged on a spatial hexagonal lattice, generally referred to as grid. Grid-field activity is accompanied by oscillations of the local field potential (LFP) in the theta band (4-12 Hz). The theta phase of single spikes thereby decreases with the distance traveled in the field, a phenomenon called phase precession. Stellate cells have been characterized as type II oscillators with a subthreshold resonance in the theta range. As such they are considered to be pacemakers. It is unclear how spiking of such putative pacemaker neurons would be able to precess in phase relative to a self-generated oscillation. Based on a recent model of phase precession in the hippocampus (Geisler et al. 2010 Proc. Natl. Acad. Sci, U.S.A. 107: 7957), we developed a theory on how this paradox can be resolved. For the original hippocampus model, the core idea is that a population oscillation, i.e. LFP, is a little slower than the individual neuronal oscillators, when the latter have firing fields of limited spatial extent and are sequentially activated. The individual neurons hence phase precess with respect to the LFP. Extending the original model to grid fields is not straightforward since the periodicity of the grid fields generally destroys the phase coordination. Moreover, the original model strongly relies on a compression parameter that governs the transformation of the rate place code to spike timing. The compression parameter, however, has an entirely unclear mechanistic origin. Our simulations show that the type II property of stellate cells is instrumental in synchronizing small cell groups and thereby accounts for theta oscillations and phase precession. Direct excitatory coupling between the stellate cells, indirect inhibitory coupling via a gamma-oscillating network of interneurons, or both could mediate this phase coordination. The compression of the place code from rates to spike timing follows as a natural consequence of the self organization of firing phases. The model also explains phase precession for changes in the running speed of the animal and variable grid-spacing. Keywords: Entorhinal Cortex, stellate cells, Theta Rhythm Conference: Bernstein Conference 2012, Munich, Germany, 12 Sep - 14 Sep, 2012. Presentation Type: Poster Topic: Other Citation: Thurley K, Hellmundt F and Leibold C (2012). Intrinsically generated phase precession of grid cells in a network model. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference 2012. doi: 10.3389/conf.fncom.2012.55.00161 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: 18 Sep 2012; Published Online: 12 Sep 2012. * Correspondence: Dr. Kay Thurley, Ludwig-Maximilians-University, Munich, Department Biology II, Munich, Germany, thurley@bio.lmu.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 Kay Thurley Franziska Hellmundt Christian Leibold Google Kay Thurley Franziska Hellmundt Christian Leibold Google Scholar Kay Thurley Franziska Hellmundt Christian Leibold PubMed Kay Thurley Franziska Hellmundt Christian Leibold 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.