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Abstract:
Abstract: The observation of language impairments in brain
damaged patients has led to the conclusion that language is
localised in certain areas of the left hemisphere. Nevertheless,
psychophysiological studies applying language tasks often report
activation beyond these classical areas. A model of cortical
function based on the approach of Hebb's cell assemblies offers an
integration of these findings. Electrophysiological studies could
show the usefulness of this model in the investigation of different
word-classes. This study was conducted to find further evidence by
investigating EEG responses to different kinds of action related
verbs. Subjects had to perform a lexical decision task in which
they had to decide by button press whether visually presented
stimuli were words or pseudowords. The words consisted of 3 classes
of verbs: face-related, arm-related and leg-related verbs of German
language. They were matched for word length and word frequency. A
60-channel-EEG-montage was used. Topographical differences between
the verb-classes were found at electrode sites over motor and
premotor areas. Statistical analysis revealed a verb-class x
topography interaction around 250 ms after stimulus onset.
Leg-related verbs led to most pronounced ingoing activity at
central sites, while more lateral activity signs were seen for
face-related words. This systematic relationship between semantics
and the topography of word-evoked potentials is support for the
Hebbian language model (Pulvermueller, BBS, 1999, (22) 253-331).
These results cannot be explained by the idea that the lexical
categories of words are responsible for their electrocortical
correlates. Semantic aspects are crucial.
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