Аннотация:Parkinson's disease (PD) is a chronic progressive neurodegenerative disorder resulting from the preferential alterations in dopaminergic neurons of nigrostriatal system, which lead to deficiency ofdopamine and imbalance of other monoamine neurotransmitters. The most common neurophysological alteration in PD is generalized slowing of the EEG which is considered to be associated with progression of cognitive impairment. The objective of this study was to evaluate relationships between alpha narrow-band (1 Hz) spectral power, its asymmetry and cognitive functions. Resting EEG was studied in a group of 25 Parkinson's disease patients with varying disease duration and severity. Extensive clinical and neuropsychological testing was performed in all subjects to assess cogntive function (verbal fluency, verbal and visual memory tests, counting attention task). Association was found between the increase of slow-alpha activity and cognitive decline. The results show different role of left and right hemispheres in the mechanisms of attention and verbal memory.