[EEG slow components during human mental activity].

A study was made on 13 subjects in a state of rest and mental stress, of interconnection between the level of distant biopotential synchronization of separate cortical zones (which is a criterion of the rate of brain activation) and the spectral power of EEG frequencies. There is a statistically significant positive correlation between the first parameter and the energy of low frequency activity band (delta-theta). At the same time similar dependences for the alpha- and beta-rhythms are negative and topographically less spread. The coherence function likewise increases during mental stress for the low-frequency band alone. The data obtained point to the special role of low-frequency rhythms in the transmission of excitation over the cortex and support the significance of the alpha-rhythm in providing for the mechanisms involved in the control of homeostasis.