Modelling of cortical and thalamic 600Hz activity by means of oscillatory networks

Abstract

Event Abstract Back to Event Modelling of cortical and thalamic 600Hz activity by means of oscillatory networks Thomas Milde1, 2, Jens Haueisen2, 3, Herbert Witte1, 2 and Lutz Leistritz1, 2* 1 Friedrich Schiller University Jena, Germany 2 Albert-Ludwigs-University, Germany 3 Technical University Ilmenau, Germany The purpose of this study is to investigate information processing in the primary somatosensory system with the help of oscillatory network modelling. Specifically, we consider directed interactions in the oscillatory 600 Hz activity between the thalamus and the cortical Brodmann areas 3b and 1. Electrical stimulation of peripheral somatosensory nerves evokes two types of early brain activity in two distinct frequency ranges that can be detected with electroencephalography (EEG) or magnetoencephalography (MEG). An oscillatory brain activity with a mean frequency at about 650 Hz overlays the initial low-frequency (up to 250 Hz) cortical responses at latencies of 18 to 30 ms after stimulus. Although the origin of the fast oscillatory activity at about 650 Hz is not yet completely clear, this activity will provide a new non-invasive window to the brain, since it is most likely not caused by the excitatory postsynaptic potentials as the common low frequency activity. Our measurements consist of simultaneous 31-channel MEG and 32-channel EEG recordings and individual 3D MRI data. We perform source localization by means of a multi-dipole model. The dipole activation time courses are then modelled by three coupled oscillators, described by linear second-order ordinary delay differential equations (DDEs) with several parameters. The three nodes of the network symbolize the thalamus and the cortical Brodmann areas 3b and 1. The resulting network model may be used to analyze directed information transfer within the somatosensory system. The parameters of the DDE system are successfully fitted to the data of 12 volunteers by an evolutionary optimization method. The pre-stimulus state of the network is defined by zero, which is a fixed point of the DDE. To activate the oscillatory network, an individual input function is used, based on measurements of the propagated stimulation signal measured at the biceps. In accordance with physiological assumptions, the system returns to the pre-stimulus state not later than 35 ms after the stimulus. A significant feedback from the cortex to the thalamus could be detected by comparing the network modelling with and without feedback connections. Our finding in humans is supported by earlier animal studies. We conclude that this type of rhythmic brain activity can be modelled by oscillatory networks in order to disentangle feed forward and feedback information transfer. Conference: Bernstein Symposium 2008, Munich, Germany, 8 Oct - 10 Oct, 2008. Presentation Type: Oral Presentation Topic: All Abstracts Citation: Milde T, Haueisen J, Witte H and Leistritz L (2008). Modelling of cortical and thalamic 600Hz activity by means of oscillatory networks. Front. Comput. Neurosci. Conference Abstract: Bernstein Symposium 2008. doi: 10.3389/conf.neuro.10.2008.01.087 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: 17 Nov 2008; Published Online: 17 Nov 2008. * Correspondence: Lutz Leistritz, Friedrich Schiller University Jena, Jena, Germany, Lutz.Leistritz@mti.uni-jena.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 Thomas Milde Jens Haueisen Herbert Witte Lutz Leistritz Google Thomas Milde Jens Haueisen Herbert Witte Lutz Leistritz Google Scholar Thomas Milde Jens Haueisen Herbert Witte Lutz Leistritz PubMed Thomas Milde Jens Haueisen Herbert Witte Lutz Leistritz 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.