Symposium: Fast dynamic encoding of the sound landscape: regularities, deviance and categories
Thursday, Sep 10, 2015
Functional dissociation between regularity encoding and deviance detection along the auditory hierarchy
1Cognitive Neuroscience Research Group, Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Spain
2Institute for Brain, Cognition and Behavior (IR3C), University of Barcelona, Spain
3Department of Audiology, Faculty of Rehabilitation Sciences, Tehran University of Medical Sciences (TUMS), Tehran, Iran
4Institute of Psychology, University of Leipzig, Leipzig, Germany
It is well known that human auditory brain can extract acoustic regularities and detect any deviation from those regularities in the dynamically changing acoustic environment. The mechanism under which the brain can detect deviating stimuli has been a matter of research since the discovery of the Mismatch Negativity (MMN) component of the event-related potential (ERP), peaking at about 100-250 ms from an acoustic change onset. However, recent studies have identified correlates of auditory deviance detection already at about 20ms after the deviant stimulus onset, both in animal models and at the level of the Middle-Latency Responses (MLR) of auditory evoked potentials (AEPs). These findings have demonstrated that deviance detection is a basic property of the auditory system that extends from lower to higher levels of the auditory hierarchy. Yet, the functional relationship between regularity encoding and deviance detection at different levels of the auditory hierarchy has not been addressed so far. In this talk, we will present a recent study where the magnitude of deviance processing at different levels of the auditory deviance detection system was examined. MLR and MMN responses were recorded to auditory stimuli presented randomly from 5 loudspeakers at azimuthal angles of 0°, 12°, 24°, 36° and 48° during oddball and reversed-oddball conditions. Our results showed that MMN amplitude increased as a function of the separation between the standard and deviant locations, whereas MLR deviance-related enhancements did not. These data support the differential role of these two levels of the auditory hierarchy in deviance processing.