[A comparative study of the P300 wave and evoked theta-rhythm in schizophrenia and personality disorders]. / Sravnitel'noe issledovanie kharakteristik volny R300 i vyzvannogo teta-ritma pri shizofrenii i rasstroistvakh lichnosti.

OBJECTIVE: Amplitude and latency of evoked potential P300 are considered as major correlates of cognitive functions. At the same time the changes in the theta-band event-related oscillations that appears at the same time window as P300 wave are less studied. The purpose of this study was to provide the complex assessment and comparison of neurophysiological indices of cognitive processes in healthy people and patients with personality disorder, schizotypal disorder and schizophrenia with different levels of cognitive dysfunction. MATERIAL AND METHODS: The total number of participants was 124, including 44 healthy volunteers, 40 schizophrenic patients, 22 patients with personality disorder, 18 patients with schizotypal disorder. Patients were examined in standard two-stimulus oddball paradigm. The P300 amplitude and latency, and evoked theta-band power and coherence were identified for target and non-target stimuli. RESULTS AND CONCLUSION: The decrease in P300 amplitude, prolongation of P300 latency, and reduction in the evoked theta-band power and coherence were revealed in all groups of patients compared to healthy subjects. These changes were spatially generalized and the most pronounced in schizophrenic patients. In patients with personality and schizotypal disorders, the changes had a local character, and didn't differ significantly when the groups were compared. The results show the gradual cognitive decline as follows: healthy patients, patients with schizotypal disorder, patients with personality disorder, and patients with schizophrenia. Such cognitive decline might be in line with the reduction of critical and prognostic abilities.

[Specificity of spatial organization of evoked EEG rhythms in patients with paranoid schizophrenia]. / Osobennosti prostranstvennoi organizatsii vyzvannykh ritmov ÉÉG u bol'nykh paranoidnoi shizofreniei.

AIM: The study aimed at analyzing the spatial patterns of evoked event-related oscillations in patients with paranoid schizophrenia and their relationship with clinical symptoms of disease. MATERIAL AND METHODS: Evoked delta, theta, alpha, beta, and gamma rhythms in response to target auditory stimulus in an oddball paradigm were studied in 21 schizophrenic patients and 22 healthy subjects. The independent spatial patterns were revealed within each of the frequency range using the principal component analysis. Each spatial pattern was characterized by the specificity of intra- and inter-hemispheric relations. RESULTS AND CONCLUSION: The schizophrenic patients were characterized by a decrease in the evoked activity in the theta range with the most pronounced changes in the frontal-central areas of the right hemisphere and parietal-occipital areas bilaterally. Associations of the evoked rhythms with PANSS positive and negative symptoms were identified. The study demonstrated the high functional significance of evoked EEG rhythms changes for neurophysiological characteristics of patients with paranoid schizophrenia.