Amplitude Dependency of Synchrony Codes

Abstract

Event Abstract Back to Event Amplitude Dependency of Synchrony Codes Jan Grewe1*, Nahal Sharafi2, Henriette Walz1, Benjamin Lindner2, 3 and Jan Benda1, 4 1 Ludwig-Maximilians-Universität München, Department Biologie II, Germany 2 Max Planck Institut für Physik komplexer Systeme, Germany 3 Humboldt Universität zu Berlin, Theory of Complex Systems and Neurophysics, Germany 4 Eberhard Karls Universität Tübingen, Institut für Neurobiologie, Germany Synchronous activity among neurons in a population is usually associated with the occurrence of specific features in the common stimulus. We investigate the synchrony code in the context of the encoding of electrosensory information in the weakly electric fish Apteronotus leptorhynchus. Middleton et al., 2009 showed that the extraction of synchronous spikes from a population of input neurons shifts the range of encoded signals to higher frequencies and thus can be understood as a way to separarte coding channels. In the electrosensory world this separation roughly matches the frequency ranges used for the two purposes of active electrosensation, i.e. navigation and prey detection, in the lower range, and communication in the high frequency range. Here, we compare experimental results from in vivo recordings of p-unit electroreceptors with predictions from linear response theory in the limit of weak stimuli. Analytical expressions are derived for the coherence of both the synchronous spikes, as a coincidence detector would read them out, and the integrated spike trains. The theoretical results show how the synchrony code depends on stimulus amplitude and the power-spectrum of baseline firing. Theory predicts that any cell that has a regular baseline firing rate and contains a certain amount of intrinsic noise can employ a synchrony code and thus separate coding channels. Furthermore the separation of the frequency bands of integrated and synchronous responses dependes on the stimulus intensity. Weak stimuli lead to a clear separation that becomes weaker with increasing stimulus intensity. Our experimental results from the electrosensory systems of the weakly electric fish support these predictions. In irregular spiking P-units of the active electrosensory system the observed separation of the coding channels indeed shows the predicted stimulus dependency. On the other hand, ampullary receptors of the passive electrosensory system exhibit a much more regular baseline firing rate than those of the active system. Here the coding ranges of the synchronous and integrated responses are not shifted relative to each other. Thus, the receptors of the passive system do not have a sufficient level of intrinsic noise, although a distinction of synchronous and non-synchronous spikes is still possible. Again, these results are in line with the predictions of the theory. References Middleton, JW., Longtin, A., Benda, J., and Maler, L. (2009). Postsynaptic Receptive Field Size and Spike Threshold Determine Encoding of High-Frequency Information Via Sensitivity to Synchronous Presynaptic Activity. J. Neurophysiol., 101:(3) 1160-1170 Keywords: electrosensory system, population coding, synchrony code Conference: Bernstein Conference 2012, Munich, Germany, 12 Sep - 14 Sep, 2012. Presentation Type: Poster Topic: Sensory processing and perception Citation: Grewe J, Sharafi N, Walz H, Lindner B and Benda J (2012). Amplitude Dependency of Synchrony Codes. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference 2012. doi: 10.3389/conf.fncom.2012.55.00110 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: Dr. Jan Grewe, Ludwig-Maximilians-Universität München, Department Biologie II, Planegg-Martinsried, 82152, Germany, jan.grewe@uni-tuebingen.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 Jan Grewe Nahal Sharafi Henriette Walz Benjamin Lindner Jan Benda Google Jan Grewe Nahal Sharafi Henriette Walz Benjamin Lindner Jan Benda Google Scholar Jan Grewe Nahal Sharafi Henriette Walz Benjamin Lindner Jan Benda PubMed Jan Grewe Nahal Sharafi Henriette Walz Benjamin Lindner Jan Benda 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.