Event-related potentials elicited during a context-free homograph task in normal versus schizophrenic subjects

Thought disorder in schizophrenia may involve abnormal semantic activation ol faulty working memory maintenance. Event-related potentials (ERPs) were recorded while sentences reading "THE NOUN WAS ADJECTIVE/VERB" were present ed to 34 schizophrenic and 34 control subjects. Some nouns were homographs with dominant and subordinate meanings. Their sentence ending presented inf ormation crucial for interpretation (e.g., The ba,lk was [closed steep]). G reatest; N400 activity to subordinate homograph-meaning sentence endings in schizophrenia would reflect a semantic bias to strong associates. N400 to all endings would reflect faulty verbal working memory maintenance. Schizop hrenic subjects showed N400 activity to all endings, suggesting problems in contextual maintenance independent of content, hut slightly greater N400 a ctivity to subordinate endings that cor related with the severity of psycho sis. Future research,should help determine whether a semantic activation bi as in schizophrenia toward strong associates is reflected in ERP activity o r whether this effect is overshadowed by faulty verbal working memory maint enance of context.