[Gamma-rhythm, positive, negative symptoms and cognitive dysfunction in schizophrenia].

We studied characteristics of gamma-band (30-40 Hz) EEG in dependence on the prevalence of positive or negative symptoms of schizophrenia, taking into account the state of cognitive functions. Twenty patients with ICD-10 diagnosis of schizophrenia, with different disease duration (first episode and duration of more than two years) and 38 healthy people were studied. The presence and intensity of positive and negative symptoms were measured by the PANSS scale and cognitive functions were assessed using neuropsychological tests. Compared to the controls, the gamma-rhythm power was higher in patients with the prevalence of positive symptoms and lower in patients with negative symptoms. The reduced number of coherent relations, in particular, interhemispheric ones, and the absence of gamma-band synchronization in different brain areas were found in patients as well.

[Psychophysiologic parameters of reproducing emotions in healthy subjects and patients during the first episode of depression]. / Psikhofiziologicheskie pokazateli myslennogo vosproizvedeniia émotsional'nykh sostoianii v norme i u bol'nykh pri pervom pristupe depressii.

We analyzed the spectral power of EEG rhythms and some psychological features in patients with depression (first episode) and in healthy subjects. In the control group, the distributions of the spectral power of the alpha3 and gamma rhythms was symmetrical. In reproducing joy, the power of the alpha3 rhythm increased in the occipital and that of the gamma rhythm increased in the temporal areas of the left hemisphere. In depressive patients, predominant activation of the left posterior cortical quadrant in the alpha3 band was observed both in the baseline activity and during reproducing emotions of both valences. In these patients, the gamma rhythm predominated in the anterior regions of the right hemisphere during rest. The mental reproduction of joy and grief in depressive patients shifted the maximal gamma rhythm spectral power to the occipital cortical regions. Thus, in depressive patients, any emotional load, regardless of its valence, results in a decrease in the pathologic gamma activity and makes the distribution of cortical electric activity more close to that of healthy subjects.