[Event-related potentials in semantic speech processing by schizophrenic patients]

Event-related potentials (ERPs) can be used for high-resolution mental chronometry. For about 15 years, this method has been applied to the study of linguistic phenomena. Semantic incongruency produces a negative component at about 400 ms after stimulus onset, the N400. We measured the N400 component in 20 schizophrenic patients and 20 normal control subjects performing a lexical decision task in which semantic distance between prime and target was varied. The results provide evidence of dysfunctional semantic information processing in schizophrenic patients, and reaction time data from previous studies can be interpreted within an electrophysiological framework. The N400 amplitude and latency data support recent spreading activation models of schizophrenic language dysfunction.