[Dipole models of alpha-rhythm generators]. / Dipol'nye modeli generatorov al'fa-ritma.

Different hypothesis of the alpha rhythm origin were tested by dipole simulation of the alpha rhythm sources. EEG was recorded during driving photic stimulation in order to increase the signal-to-noise ratio. Models with fixed and moving dipoles were analyzed. Dipole sources were compared with magnetic resonance imaging (MRI) scans to find the exact location of oscillations in brain anatomical structures. A two-level multiple dipole model was found to fit the EEG most adequately. The first level was represented by two oscillators localized in the thalamic reticular nuclei, and the second level is associated with two modality-specific oscillators localized in the respective cortical areas.

Rhythmic alpha-activity generators in the human EEG.

This study was designed to locate the neuronal mechanisms of rhythmic activity in the human brain in the alpha-rhythm range using an equivalent dipole model. The experiments approach used here is based on using the "imposed rhythm" phenomenon, whereby a light stimulus flashing with a frequency close to the frequency of the individual alpha rhythm increases its power in the EEG spectrum. The results obtained showed that the activity of the structures generating the alpha rhythm could be differentiated by using a specific photostimulation frequency and were located by constructing a dipole model. Two sources of alpha-rhythm generation were found, located in the thalamic structures of the brain and operating over a narrow-band frequency range with maximum response resonance frequencies of 10.1 and 10.5 Hz.

[Generators of the rhythmic alpha activity in the human EEG]. / Generatory ritmicheskoi al'fa-aktivnosti EEG cheloveka.

An attempt to localize brain mechanisms of the rhythmic activity in the alpha-rhythm range was made using the equivalent dipole model. It is known that light flickering stimuli with the frequency close to that of the individual alpha rhythm induce an increase in its spectral power ("photic-driving" phenomenon). It was shown that the activity of the neuronal structures generating the alpha rhythm can be identified by specific frequency of the light stimulation and localized by means of construction of dipole models. Two sources of the alpha rhythm in the narrow-frequency bands with the maximal resonance responses in the frequencies of 10.1 and 10.5 Hz were localized in the thalamic structures.

[The specific nature of the color and brightness components of the human visual evoked potential]. / Spetsifihatsiia tsvetovogo i iakostnogo komponentov zritel'nogo vyzvannogo potentsiala u cheloveka.

In order to gain an insight into the electrophysiological cortical mechanisms of color discrimination and to compare the results with psychophysiological data summarized in the previous publications as the spherical model of color discrimination a problem was specified to identify color and brightness components of human evoked potentials. The experiments were carried out with alternating pairs of light flashes constituted of five colors (white and four main colors; red, blue, yellow, and green). Each of the light stimuli varied by seven brightness levels. Color and brightness components (N87 and P120, respectively) were reasonably reliably detected in all cases of substitution of stimuli with identical or different spectra. However, the latency and amplitude analysis of N87 and P120 components in these cases showed that N87 reflects not only color but also brightness information. It makes it possible to draw on the analogy between the N87 as one of the earliest components and N1 in primate cortical evoked potential and suggest that these components reflect the activity of cells receiving information directly from the lateral geniculate body. This process can be considered as the first stage of cortical analysis of chromatic and achromatic light characteristics. The brightness component P120, probably, represents the activity of cortical cells related to the analysis of nonchromatic stimuli characteristics, such as form, movement, orientation, etc. These characteristics are also based on luminance gradients and contrasts, however, in contrast to N87, these characteristics are not directly related with brightness of light.

Population-genetics approach to the genetics of human behaviour.

Invariant values of inheritance factors within and between different populations can show the existence of and measure the degree of genetic determination of behavioural characters. The absence of inbred depression of quantitative behavioural characters in isolated populations of highland inhabitants of Daghestan is demonstrated by means of comparative analysis of the mean population values of psychophysiological characters in outbred, moderately isolated, and extremely isolated (and inbred) populations. The absence of pronounced adverse effects of inbred marriages, known as the 'Daghestan phenomenon', is explained by the antiquity of the native populations and the severe ecological conditions under which these populations live which have led to elimination of carriers of hereditary diseases and other detrimental phenotypes.

[Phenotypic and genetic differentiation of human populations with respect to morphologic and psychophysiological traits]. / Fenotipicheskaia i geneticheskaia differentsiatsiia populiatsii cheloveka po morfologicheskim i pscikhofiziologicheskim priznakam.

Four groups of human characters (mendelian markers, anthropometry, neurodynamics and psychodynamics) were studied in eight human populations characterized by different degrees of isolation and different ethnic backgrounds, and located in different ecological conditions. The populations examined were proved to display phenotypic and genetic differentiation for the studied groups of characters which were compared with linguistic and geographical distances. The role of genetic factors and that of environmental factors was shown to diminish and to increase, respectively, as the degree of complexity of expression of the group of characters under study (from anthropometry to psychodynamics) goes up.

[Integral evaluation of phenotypic and genotypic variability of morphologic and psychophysiologic human traits]. / Integral'nye otsenki fenotipicheskoi i genotipicheskoi izmenchivosti morfologicheskikh i psikhofiziologicheskikh priznakov cheloveka.

The paper demonstrates the expedience of the developed populational-genetic approach to studying the genetic bases of a complex of quantitative characters pertaining to different levels of human organization: anthropometry, neurodynamics and psychodynamics. The studies were carried out in eight human populations of different degree of isolation and ethnical background. It is shown that correlation phenotypic variability is higher for these characters, as compared to genotypic variability, the number of general genes responsible for this variability being decreased, respectively.

[Phenotypical and genetic differentiation of human populations for morphological and psychophysiological traits. Factor analysis]. / Fenotipicheskaia i geneticheskaia differentsiiatsiia populiatsii cheloveka po morfologicheskim i psikhofizicheskim priznakam. Faktornyi analiz.

The multivariate genetic factor analysis is used, as first attempt, to study genetic bases of correlation variability of neurodynamic and psychodynamic levels of individual organization among isolates of Daghestan. Closer similarity between factors described in templates of phenotypic correlations is explained by lower heritability of the parameters under study. Interpopulation differences revealed by the multivariate genetic analysis are the result of differences in the genetic structure of the populations.

[Heritability of neurodynamics and psychodynamics in human populations]. / Nasleduemost' neirodinamiki i psikhodinamiki v populiatsiiakh cheloveka.

A component analysis of human neurodynamic and psychodynamic characters in the norm was carried out in 8 human populations characterized by different degrees of isolation and ethnic origin. An increase in phenotypic variability and a decrease in heritability with increasing complexity of organization of the characters under study were demonstrated for all these populations. The additive effect plays the major role in genetic determination of neurodynamic and psychodynamic characters studied. For a number of neurodynamic parameters the effect of intralocus dominance indicative of the oligogenic determination system was observed. Data in favour of real contribution of the factors linked to X-chromosome were obtained for simple sensomotor reactions.

[Population genetics of Dagestan highlanders]. / Populiatsionnaia genetika gortsev Dagestana.

Subdivision of some isolates and heterogenic populations in Daghestan is analysed by human gene and phen frequencies. Comparative population study of phenotypic variability of quantitative characters (anthropometric, neurodynamic and psychodynamic) is carried out. Common hierarchy of variability for all populations as well as an effect of inbreeding and panmixis on variability of the above-mentioned quantitative characters in different populations is demonstrated.

[Population genetics analysis of the association of sensitivity to phenylthiocarbamide and nervous system strength]. / Populiatsionno-geneticheskii analiz assotsiatsii chuvstvitel'nosti k feniltiokarbamidu i sily nervnoi sistemy.

The results of gene pool analysis of three Daghestan isolates for mendelian markers and multifactorial characters are presented. The neurodynamic status of persons with tt and T-phenotypes for sensitivity to phenylthiocarbamide is characterized.