[Sensory analysis of the words with different occurrence frequency in the norm and in patients with schizophrenia and schizophrenic spectrum disorders].

The paper introduces the study of the early stages of verbal information processing in the brain during the passive reading of single words with different occurrence frequency in Russian and of pseudo-words in healthy subjects and in patients with schizophrenia and schizophrenic spectrum disorders using evoked potentials method. It is shown that the latency of P100 and N170 in healthy subjects increased during visual perception of rare words compared to frequent ones and pseudo-words that apparently reflected the necessity to involve large quantity of brain resources during sensory stages of the processing of the verbal stimulus with intricate semantic. In patients with schizophrenia and schizophrenic spectrum disorders more complicate pattern was observed during the perception of verbal stimuli of various categories. P100 latency was the largest during pseudo-words reading, and P100 amplitude--during frequent words reading in this group. N170 atency in the patients' group was maximal during frequent words reading. Abnormality of evoked potentials polarity in anterior cortical areas most evident during visual perception of meaningful verbal information was also found in these subjects. The obtained results may point to the dysfunction ofprefrontal cortex top-down influence in schizophrenia and schizophrenic spectrum disorders, which is manifested in the disturbed sensory processing ofvarious categories verbal stimuli.