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Abstract:
Abstract: A syntactic and a semantic task was performed by
healthy German-speaking subjects and aphasics with lesions in the
dominant left hemisphere. In both tasks, depicted objects were
presented and participants had to classify these objects by
pressing buttons. The classification was about grammatical gender
in the syntactic task (masculine or feminine gender?) and about the
semantic category in the semantic task (man- or nature-made?).
Behavioral data revealed a significant Group by Task interaction
with aphasics showing most pronounced problems with syntax. Brain
potentials showed different task-dependent laterality patterns in
both subject groups. In normal controls, the syntax task led to
strongly left-lateralized responses, whereas the semantic task
produced more symmetric responses over the hemisphere. The opposite
was the case in the patients, where, paradoxically, stronger
laterality of physiological brain responses emerged in the semantic
task compared to the syntactic task. Statistical analysis of
event-related brain potentials recorded from the left and right
hemispheres confirmed a significant interaction of the Group factor
with both Task and Hemisphere. We interpret these data based on
neuro-psycholinguistic models of word processing and current
theories about the hemispheres roles in language recovery.
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