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 understandingthe pathogenetic (including neurobiological) mechanisms of schizophreniais the study of patients with clinically high risk (CHR) for thedisease. The power and topography of the theta rhythm event-relatedsynchronization (ERS) related to peripheral stimulus that must beremembered (memory-guided saccades/antisaccades paradigm) have beenstudied in the groups of 20 mentally healthy subjects and 20 patientswith CHR. The analysis was carried out according to the Pfurtschellermethod. Based on the saccades latency value and the error numbers,the task performance was decreased in patients with CHR comparedto healthy subjects. Intergroup differences by theta rhythm ERSmagnitude and topography were found for three consecutive delayperiod intervals (900 ms each) before saccades to the right andantisaccades to the left. The findings are considered as being thereflection of violations of the spatial attention and working memory maintainingin CHR patients that has a certain interhemispheric asymmetry. Ithas been suggested an activation of the compensatory processes andthe cognitive control reorganization of the fronto-parietal networkswith predominantly right hemisphere preservation at the early stageof schizophrenia development.