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

Abstract

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.

Keywords

• go/no-go delay paradigm
• anticipation
• saccade
• slow waves