Stimulus-specific adaptation in subcortical regions of the central auditory system

Abstract

Event Abstract Back to Event Stimulus-specific adaptation in subcortical regions of the central auditory system Manuel S. Malmierca1*, F M Antunes1, D. Pérez-González1, 2 and E. Covey1, 2 1 Institute for Neuroscience of Castilla y Leon, University of Salamanca, Spain 2 Department of Psychology, University of Washington, United States Mismatch negativity (MMN) studies have undeniably had a profound impact on our understanding of many cognitive phenomena and are a powerful tool when dealing with various clinical populations. However, because these studies rely on scalp-recorded gross potentials they do not reveal much about processing at subcortical levels. This has led to the assumption that adaptation to common sounds and detection of novel sounds is a function of the cortex with little or no contribution of subcortical processing. The pioneering electrophysiological studies in cat by Ulanovsky and colleagues (2004) came to the same conclusion. These authors used an oddball stimulus paradigm similar to that used in MMN studies, to demonstrate that neurons in the auditory cortex (AC) show a reduced response to a repeated stimulus, but briefly resume firing if a novel stimulus is presented. This phenomenon is called stimulus-specific adaptation (SSA) This same study failed to demonstrate SSA in the medial geniculate body (MGB). More recently, however, SSA has been observed in the inferior colliculus (IC) of the rat (Perez-Gonzalez et al., 2005; Malmierca et al. 2009) indicating that SSA is not an exclusive feature of the cortex. Since the MGB receives its main inputs from the IC and AC, both of which show SSA, we reexamined the issue of whether neurons in the rat MGB show SSA. Our data demonstrate that SSA is indeed present throughout the MGB, being more prominent in the dorsal and medial subdivisions. This finding raises the question of whether SSA in the IC is created there of whether it is inherited from the cortex via descending projections. To address the issue of whether synaptic inhibition is involved in creating SSA in the IC, we recorded responses of rat IC neurons using an oddball stimulation protocol similar to that of Ulanovsky et al. (2004). while applying microiontophoretic injections of bicuculline, a GABAA receptor blocker. Our preliminary results indicate that SSA is at least partially created in the IC through the action of GABAergic inhibition. These results taken together indicate that SSA and enhanced responses to novel stimuli are present at every level from the IC on, and that SSA is not simply a property inherited through excitatory descending projections from the AC. Acknowledgments: Supported by Spanish MEC (BFU2006-00572) and JCYL (GR221) to MSM, NSF grant (IOS-0719295) to EC and MEC fellowship (BES-2007-15642) to FMA. S. Cristaudo participated on the preliminary microiontophoretic experiments. Conference: MMN 09 Fifth Conference on Mismatch Negativity (MMN) and its Clinical and Scientific Applications, Budapest, Hungary, 4 Apr - 7 Apr, 2009. Presentation Type: Oral Presentation Topic: Abstracts Citation: Malmierca MS, Antunes F, Pérez-González D and Covey E (2009). Stimulus-specific adaptation in subcortical regions of the central auditory system. Conference Abstract: MMN 09 Fifth Conference on Mismatch Negativity (MMN) and its Clinical and Scientific Applications. doi: 10.3389/conf.neuro.09.2009.05.042 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: 23 Mar 2009; Published Online: 23 Mar 2009. * Correspondence: Manuel S Malmierca, Institute for Neuroscience of Castilla y Leon, University of Salamanca, Salamanca, Spain, msm@usal.es 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 Manuel S Malmierca F M Antunes D. Pérez-González E. Covey Google Manuel S Malmierca F M Antunes D. Pérez-González E. Covey Google Scholar Manuel S Malmierca F M Antunes D. Pérez-González E. 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