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Abstract:
Abstract: Syntactically as well as semantically incongruent
sentences elicit a special pattern of event related brain
potentials (ERP). Sentences whose terminal verb was incongruent
with preceding context produce a N400, whereas syntactic violations
elicit a late positivity (P600). In various psychiatric diseases
patients suffer from language / formal thought disorder. Matching
these psychopathological findings, studies with schizophrenic
patients showed differences in the N400 compared to healthy
controls.18 depressed patients, 13 schizophrenic patients and 9
healthy controls were investigated. Stimulus material consisted of
192 sentences. They included three different conditions: correct,
semantic mismatch, and syntactic mismatch condition. Subject`s task
was to simply read the sentences while EEG was recorded. In line
with previous studies, semantic violations elicited a N400 in both
depressed patients and in controls. Depressed patients show smaller
amplitudes and a more frontally distributed N400 than controls.
Schizophrenic patients on the other hand had the smallest N400
amplitudes. Concerning the syntax-condition there are no
significant differences between the three groups in latency and
amplitude of the P600. There is a difference in the topography of
the P600. Depressed patients show a frontally distributed P600
compared to the other two groups. The differences in amplitude and
topography of both the N400 and the P600 between the three groups
suggest that syntactic as well as semantic processing seem to be
affected in depression and schizophrenia.
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