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Abstract:
Abstract: We report time course and topography of brain
magnetic (MEG) activity related to the processing of ungrammatical
active and passive sentences involving illicit case assignments
(*...daß der/die Frau eine Probefahrt untersagt hat/wurde.)
as well as their grammatical counterparts. Previous reaction time
studies established that the ungrammaticality of actives can be
reliably detected whereas ungrammatical passives are frequently
judged as grammatical. This leads to the hypothesis that the
processing mechanisms involved in coping with an illicit case
assignment in ungrammatical actives and passives are partially
distinct. The particular goal of this study was to investigate
whether this processing distinction induces differences in
electromagnetic brain activity. MEG (148-sensor-magnetometer, BTI)
was recorded while subjects (n=8) performed a speeded
grammaticality judgement task. Magnetic source reconstruction was
based on a minimum norm least square approach constrained by a
realistic head model. The comparison of magnetic source
distribution in ungrammatical actives and passives revealed
distinct patterns between 350-800 ms. While both conditions give
rise to a sequence of sources in left inferior temporal (plus right
inferior temporal in actives) and supramarginal regions,
ungrammatical passives show an additional early source in the left
inferior frontal cortex. Magnetic activity triggered by
ungrammatical passives that were judged as grammatical shows a
delayed left inferior temporal but no left inferior frontal or
supramarginal source. The results suggest that illicit case
assignment in ungrammatical passives triggers additional decision
processes specifically related to a sequence of activations in
inferior frontal and supramarginal regions of the left
hemisphere.
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