Evoked synchronization of theta EEG rhythm during preparation of memory-guided saccades and antisaccaded in normals and in patients with clinically high risk for schizophrenia

One of the informative and widely used approaches to understanding the pathogenetic (including neurobiological) mechanisms of schizophrenia is the study of patients with clinically high risk (CHR) for the disease. The power and topography of the theta rhythm event-related synchronization (ERS) related to peripheral stimulus that must be remembered (memory-guided saccades/antisaccades paradigm) have been studied in the groups of 20 mentally healthy subjects and 20 patients with CHR. The analysis was carried out according to the Pfurtscheller method. Based on the saccades latency value and the error numbers, the task performance was decreased in patients with CHR compared to healthy subjects. Intergroup differences by theta rhythm ERS magnitude and topography were found for three consecutive delay period intervals (900 ms each) before saccades to the right and antisaccades to the left. The findings are considered as being the reflection of violations of the spatial attention and working memory maintaining in CHR patients that has a certain interhemispheric asymmetry. It has been suggested an activation of the compensatory processes and the cognitive control reorganization of the fronto-parietal networks with predominantly right hemisphere preservation at the early stage of schizophrenia development.