Two distinct theta rhythms could underlie functional asymmetry of auditory cortices

Abstract

Event Abstract Back to Event Two distinct theta rhythms could underlie functional asymmetry of auditory cortices Benjamin Morillon1*, Catherine Liegeois-Chauvel2, Luc Arnal3 and Anne-Lise Giraud1 1 Ecole Normale Supérieure, France 2 Université de la Méditerranée, France 3 New York University, United States Poeppel (2003) proposed that left hemispheric dominance in speech processing relies on asymmetric sampling of auditory information. Cortical oscillations in the gamma (~40Hz) and low-theta (~5 Hz) range could be instrumental to this purpose, underpinning phonemic and supra-segmental parsing in left and right auditory cortices, respectively. Yet, whether and how left-hemispheric information sampled at phonemic timescale is re-concatenated into syllabic frames is unaddressed by the theory. Here we present evidence from local field potentials data from an epileptic patient implanted bilaterally in primary (PAC) and secondary (SAC) auditory cortices that two distinct theta ranges operate in right and left auditory cortices. During periods of silence, we observed a peak of energy at 5 Hz in the right auditory cortex and at 8 Hz in the left one. These effects were maximal in SAC. This asymmetric background low and high theta activity was boosted by the presentation of transient tones and syllables. The 8 Hz response in left auditory cortex was accompanied with a low-gamma transient response. Finally, sentences elicited sustained responses in the theta range, with the same 5/8 Hz asymmetrical pattern. We thus confirm that low-theta rhythm (5 Hz) is right-dominant both at rest (Giraud et al., 2007) and during speech processing (Abrams et al., 2008), but additionally show the presence of a parallel high-theta rhythm (8 Hz) in left auditory cortex. Its predominance in left SAC relative to PAC, where gamma rhythm is more strongly expressed (Morillon et al., 2010; Giraud et al., 2007) could reflect that it integrates information from the latter into syllabic frames to guide further processing stages. The role of this specific rhythm (Mo et al., 2011) needs to be further explored. Keywords: cortical oscillations, Intra-cranial Electrophysiology Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Abstracts Citation: Morillon B, Liegeois-Chauvel C, Arnal L and Giraud A (2011). Two distinct theta rhythms could underlie functional asymmetry of auditory cortices. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00063 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: 15 Nov 2011; Published Online: 25 Nov 2011. * Correspondence: Dr. Benjamin Morillon, Ecole Normale Supérieure, Paris, France, bnmorillon@gmail.com 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 Benjamin Morillon Catherine Liegeois-Chauvel Luc Arnal Anne-Lise Giraud Google Benjamin Morillon Catherine Liegeois-Chauvel Luc Arnal Anne-Lise Giraud Google Scholar Benjamin Morillon Catherine Liegeois-Chauvel Luc Arnal Anne-Lise Giraud PubMed Benjamin Morillon Catherine Liegeois-Chauvel Luc Arnal Anne-Lise Giraud 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.