EEG correlates of impaired anticipation processes in the early stages of schizophrenia

INTRODUCTION: An impairment of anticipation processes is considered as a common deficiency in schizophrenia (Kveraga et al., 2007), however its neural mechanisms remain poorly understood. OBJECTIVES: The aim of the study was to analyze CNV-like slow negative waves during the pre-target stimuli waiting period in patients with the first episode of the disease. METHODS: 32-channels EEGs during “Go / No go delay” saccadic paradigm have been recorded in 16 young male patients with illness duration less than 2 years and 18 age and sex matched healthy subjects. The delay period between fixation and target (“Go” or “No go”) visual stimulus was 2800-3000 ms. The early and late components of CNV - like slow negative waves (PMN1 and 2) have been studied in 1 sec pre-stimulus interval of delay period. RESULTS: As compared to norm, the patients showed significantly increased latencies of saccades to correctly discriminated stimuli and higher percent of “errors saccades”. The amplitudes of No go-PMN1 and Go-PMN2 waves were also increased in patients. The amplitude foci of these waves were diffusely distributed in patients and mostly localized in frontal leads in norm. CONCLUSIONS: The findings assume some violation of anticipation for action (motor or inhibitory response) processes as well as an increase of presumably cortical activation during stimulus anticipation in the “Go/No go delay” saccadic paradigm in the early stage of schizophrenia. DISCLOSURE: No significant relationships.