[The variation of two types of spatiotemporal organization of brain potentials at different stages of a cognitive set based on illusory perception of length (Muller-Layer illusion)].

The spatiotemporal organization of brain potentials (STOP) under conditions of their multichannel recording was studied was studied in 35 young healthy subjects during formation, actualization, and extinction of the cognitive set on the basis of illusory perception of length (Müller-Layer illusion) by means of quantitative comparison of successive electroencephalotopograms (ET). The ET is an array of momentary values of potentials simultaneously recorded in all the derivations. An ET is characterized by a relief and mean level. Time changes in these characteristics determine a certain type of cortical STOP. Two main types of STOP were revealed. The interaction between these two types of STOP depended on the kind of performance of a subject and was ferlected in the coefficient of dynamic variation (CDV) of ETs. The CDVs were significantly different in subjects with stable and unstable forms of the cognitive set; in the latter this value was higher. The spectral characteristics of the EEG and STOP dynamics were compared. Analysis of power stectra revealed the significant intergroup differences in the alpha 1 frequency range both in the EEG and STOP; the power of this frequency range was higher in subjects with the stable set.