Lack of repetition priming effect on visual event-related potentials in schizophrenia

Background: The present study was designed to assess, using event-related potentials, whether aberrant semantic processing reported in schizophrenia results from primary semantic overactivation or contextual dysregulation. Methods: The visual event-related brain potentials were compared between 9 schizophrenic subjects and 16 normal control subjects performing two kinds of semantic categorization tasks with different nontarget stimuli: 1) nontargets comprising words, pseudowords, and unpronounceable foreign letters and 2) nontargets comprising initial presenting words, immediate repetition words, and delayed repetition words. Results: Schizophrenic subjects showed no evidence suggestive of a greater negative potential associated with words and pseudowords, but they did show a lack of amplitude change associated with immediately repeated words relative to that in control subjects. Conclusions: These results suggest that aberrant semantic activation in schizophrenia results mainly from a failure to utilize information from preceding words or context, and could explain the increased N400 to the congruent or related words recently reported in this disease. Copyright (C) 1999 Society of Biological Psychiatry.