The within-pair similarity of the topographical maps of the spatial synchronization of the cerebral cortical potentials was studied in 11 pairs of monozygotic twins and 20 genetically unrelated subjects in the resting state and during four types of intellectual activity. It was demonstrated that the degree of similarity of the topographical maps is higher in the resting state in the monozygotic twins than in the genetically unrelated subjects. No frequency band of the EEG which exerts a special influence on the formation of the high degree of similarity of the spatial synchronization of the potentials was found. The maximal similarity in the topographical maps of the monozygotic twins is observed in the anterior regions of the left hemisphere and in the temporoparietal regions of the right. Differences between groups are recorded in both regions; however they are especially distinct in the right hemisphere. The data obtained make it possible to draw an inference regarding the influence of a genetic factor not only on individual components of the EEG (which had been previously demonstrated by a number of authors), but also on the systemic organization of the cortical processes. The right-hemispheric activity apparently relates to the most controllable genetic processes. The results of the analysis of the similarity of topographical maps during various types of activity confirm this: the coefficient of similarity reaches the level of significance in the majority of pairs of monozygotic twins only in a "right-hemispheric" test (simultaneous analysis of nonverbal material).

Theoretical questions of the spatial organization of electrical activity in the brain are discussed in terms of a multilevel realization of the synergetic principle for formation of functional systems underlying behavior and mental function. The role of the spatial-temporal superimposition of coherent structures of biopotentials in generating fields of increased activity in the cerebral cortex is discussed, these being responsible for integrative and associative functions. A hypothesis is proposed regarding the relationship between the energy and information factors of coherent structures as one of the important characteristics describing the efficiency of energy-informational processes. Emphasis is placed on the need for considering not only linear, but also nonlinear associations of biopotentials in considerations of the form and functional sense of their spatial organization.

The characteristics of the temporospatial organization of cerebral cortical potentials at different levels of genetically determined emotionality were analyzed by constructing topograms of instantaneous EEG levels in the inbred rat strains MR and MNRA. Two parameters were calculated for each topogram: the total level and the similarity coefficient. Power spectra were calculated for the values and these were found to change in an oscillatory manner. Interstrain differences were found in the correlated changes in total levels and similarity coefficients, in the durations of changes in the total level, which were more marked than those of similarity coefficients, and the nature of interhemisphere asymmetry. In MR rats, the power spectra of both measures showed significant peaks with modes at 2.0, 6.5, and 9.0 Hz. In MNRA rats, peaks in the spectra of these measures both coincided (2.0 Hz) and differed (7.0 Hz in the spectrum of the total level and 3.0, 4.5, and 6.0 Hz in the spectrum of the similarity coefficient). These data suggest different types of functioning of the reticulothalamocortical and hippocampocortical systems in rats of these strains.

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