Hyper-coherence and increased energy of gamma oscillations in patient with first onset schizophrenia and cerebral white matter damage

Abstract

Background: According to current knowledge, gamma frequency is closely related to the functioning of neural networks underlying the basic activity of the brain and mind. Disorders in mechanisms synchronizing brain activity observed in patients diagnosed with schizophrenia are at the roots of neurocognitive disorders and psychopathological symptoms of the disease. Synchronization mechanisms are also related to the structure and functional effectiveness of the white matter. So far, not many analysis has been conducted concerning changes in the image of high frequency in patients with comorbid schizophrenia and white matter damage. The aim of this research was to present specific features of gamma waves in subjects with different psychiatric diagnoses and condition of brain structure. Methods: Quantitative analysis of an EEG record registered from a patient diagnosed with schizophrenia and comorbid white matter hyperintensities (SCH+WM), a patient with an identical diagnosis but without structural brain changes present in the MRI (SCH-WM) of a healthy control (HC). The range of gamma waves has been obtained by using analogue filters. In order to obtain precise analysis, gamma frequencies have been divided into three bands: 30-50Hz, 50-70Hz, 70-100Hz. Matching Pursuit algorithm has been used for signal analysis enabling assessing the changes in signal energy. Synchronization effectiveness of particular areas of the brain was measured with the aid of coherence value for selected pairs of electrodes. Results: The electrophysiological signals recorded for the SCH+WM patient showed the highest signal energy level identified for all the analyzed bands compared to the results obtained for the same pairs of electrodes of the other subjects. Coherence results revealed hipercompensation for the SCH+WM patient and her level differed substantially compared to the results of the other subjects. Conclusions: The coexistence of schizophrenia with white matter damage can significantly disturb parameters of neural activity with high frequencies. The paper discusses possible explanations for the obtained results.