title: Context-dependent impact of presuppositions on early magnetic brain responses during speech perception.
abstract: Discourse structure enables us to generate expectations based upon linguistic material that has already been introduced. The present magnetoencephalography (MEG) study addresses auditory perception of test sentences in which discourse coherence was manipulated by using presuppositions (PSP) that either correspond or fail to correspond to items in preceding context sentences with respect to uniqueness and existence. Context violations yielded delayed auditory M50 and enhanced auditory M200 cross-correlation responses to syllable onsets within an analysis window of 1.5s following the PSP trigger words. Furthermore, discourse incoherence yielded suppression of spectral power within an expanded alpha band ranging from 6 to 16Hz. This effect showed a bimodal temporal distribution, being significant in an early time window of 0.0-0.5s following the PSP trigger and a late interval of 2.0-2.5s. These findings indicate anticipatory top-down mechanisms interacting with various aspects of bottom-up processing during speech perception.
authors.affiliation: Center for Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Germany. Electronic address: ingo.hertrich@uni-tuebingen.de.
authors.forename: Ingo
authors.initials: I
authors.lastname: Hertrich
authors.affiliation: Evolutionary Cognition, Department of Psychology, University of Tübingen, Germany.
authors.forename: Mareike
authors.initials: M
authors.lastname: Kirsten
authors.affiliation: Descriptive and Theoretical Linguistics, Department of English, University of Tübingen, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Tiemann
authors.affiliation: Descriptive and Theoretical Linguistics, Department of English, University of Tübingen, Germany.
authors.forename: Sigrid
authors.initials: S
authors.lastname: Beck
authors.affiliation: Center for Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Wühle
authors.affiliation: Center for Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Germany.
authors.forename: Hermann
authors.initials: H
authors.lastname: Ackermann
authors.affiliation: Evolutionary Cognition, Department of Psychology, University of Tübingen, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Rolke
mesh_terms: D000161:Acoustic Stimulation; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D006801:Humans; D007802:Language; D008037:Linguistics; D015225:Magnetoencephalography; D013060:Speech; D013067:Speech Perception / Q000502:physiology*; D013997:Time Factors
keywords: Alpha suppression; Auditory processing; Magnetoencephalography; Phase locking; Semantics in context; Speech perception