Features of the organization of the default system of the brain in connection with the severity of delusions and hallucinations in schizophrenia

Objective. The main objective of the study was to identify the extent to which symptoms such as hallucinations and delusions, the severity of which was assessed quantitatively using the corresponding PANSS scales, are interconnected both in their manifestations and in terms of the corresponding brain processes. Methods and materials. The article presents the materials of an empirical study of women (N = 22) who were treated at the Mental-Health Clinic № 1 named after N.A. Alexeev with a diagnosis of schizophrenia (including 17 cases of F20.0, 3 cases of F23), undergoing similar drug therapy at the age of 23 to 65 years (M = 41.8, SD = 10.4). The 19-channel EEG was recorded for 1–3 minutes in a state of calm wakefulness. Results. The use of a new method for localizing brain activity, the “virtual implanted electrode”, allowed us to reconstruct electrical signals at 41 points selected from the MNI152 atlas. As a result, for each subject separately (1) the activity level of each of the structures was assessed, as well as (2) the functional connectivity of these structures by calculating the correlation coefficients between all pairs of these structures. This in turn made it possible to find correlations between the severity of delusions and hallucinations and changes in the functional connections of the brain. Conclusions. The results indicate that the qualities under study, delusions and hallucinations, are largely independent of each other, and their severity is associated with various systemic changes in functional connections.