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In order to examine the effect of dopamine on semantic processing, we performed a double-blind, placebo-controlled study. Healthy volunteers (n = 31) were tested in a lexical decision paradigm after ingestion of either L-dopa 100 mg with benserazide 25 mg or placebo. While direct semantic priming was influenced only marginally by L-dopa, the indirect(More)
This study of 70 schizophrenic patients used a lexical decision task involving the recognition of words that were preceded (primed) either by meaningfully or phonologically associated or by nonassociated words to study the intrusion of contextually inappropriate associations in thought disorder (TD). The patients were split into subgroups of TD and non-TD(More)
BACKGROUND In schizophrenia, disturbances in the development of physiological hemisphere asymmetry are assumed to play a pathogenetic role. The most striking difference between hemispheres is in language processing. The left hemisphere is superior in the use of syntactic or semantic information, whereas the right hemisphere uses contextual information more(More)
Healthy subjects performed a lexical decision task in a semantic priming paradigm while event-related potentials (ERPs) were recorded from 64 channels. Semantic distance between prime and target was varied by including directly, indirectly, and nonrelated word pairs. At centro-parietal electrodes an N400 to nonrelated pairs was elicited bilaterally which(More)
The characteristics of the spread of semantic activation in associative networks in normal subjects, thought-disordered (TD) and nonthought-disordered (NTD) schizophrenic patients with respect to time and semantic distance are examined. Direct and indirect semantic priming effects at two stimulus onset asynchronies (SOA) in a lexical decision task reveal(More)
Recent studies have demonstrated that positive and negative affective reactivity can be predicted by resting electroencephalographic (EEG) asymmetry in frontal brain regions. These studies used different methods to assess asymmetry and affectivity. The goal of the present study was a conceptual replication of these results and to investigate their(More)
Schizophrenic patients and normal controls performed a lexical decision task involving the recognition of words which were preceded (primed) by either associated, indirectly associated, or non-associated words. In contrast to normal control subjects who showed no indirect semantic priming effect at an inter-stimulus interval (ISI) of 0 ms, a trend towards(More)
The N400 component of event related potentials (ERP) was studied in 27 right-handed healthy subjects in a speeded lexical decision task. The semantic distance between primes (always words) and targets (50% words, 50% non-words) was systematically varied. Prime-target relations included directly related words (hen-egg), indirectly related words(More)
Schizophrenic patients (n = 44) and normal controls (n = 50) performed a computerized version of the Stroop color-word interference task. Schizophrenic patients generally showed more Stroop interference than normal subjects. The effect was neither related to demographic variables, nor to actual psychopathology. However, the course of the disorder was(More)
This study was designed to replicate recent findings suggesting that the P3 component of the event-related potential is dependent on the modality of the eliciting stimulus. When assessing this research hypothesis two methodological problems are of special interest: first, the amplitudes have to be normalized, due to problems with the model of the analysis(More)