[Features of the spatial organization of EEG manifestations in different variants of anxiety symptoms in patients with depression].

Investigations were carried out on 36 patients with reactive depressive states and repeating depressive episodes with severe manifestation of anxiety syndrome. The spatial organization of brain activity by cross-correlation analysis was studied. Shown, that clinical depression and anxiety syndrome is reflected in the structure of the spatial organization of EEG depending on options manifestation of anxiety disorder.

[Features of the organization of biopotentials of a cerebral cortex and visceral status at the person at neurotic depression].

Researches are spent on 20 patients with various clinical variants of neurotic depression. The regional organization of bioelectric activity of a brain by a method cross-correlation and coherent analysises was studied. Vegetovisceral status was studied by auricular criotest (measuring of cold sensibility of auricular points). It is shown, that the clinical picture of neurotic depression finds reflectance in frame of regional organization EEG. Regional organization EEG is modified depending on a degree of manifestation of the most neurotic depression and concomitant syndromes of alarm and an asthenia. In bunch with a depressive syndrome without concomitant asthenic and disturbing exhibitings the maximum changes are taped in the right frontotemporal range--left posttemporal ranges. In bunch where along with depression the alarm--depression cross-correlation and coherent communications frontotemporal ranges of both hemispheres was taped, strongly pronounced rising cross-correlation attitudes in right occipital ranges. In bunch where depressive and disturbing syndromes were combined with the expressed asthenic exhibitings, depression cross-correlation and coherent communications in frontotemporal ranges of both hemispheres was observed. The clinic of neurotic infringements finds reflection in a specific picture of variations of the spatial organization of electric activity of a brain and in variations of parameters of the vegetovisceral status. Realization of negative emotional conditions at the person is accompanied by variations visceral functions. Thus variations in the central brain structures cover zones of representation of emotional reactions and the zones connected with cortical representation visceral functions. The minimal central regulation, even insignificant central variations can cause vegetovisceral dysfunctions.

[Modification of evoked potentials by increasing visual search difficulty in humans].

Monopolar evoked potentials on increasing difficulty of the task of visual search in frontal, parietal, temporal and occipital regions was studied in 16 young healthy subjects. Search complication and adding noise in the form of visual stimulus hindered recognition of images that affected search time and errors amount. Correlation between evoked potential magnitude and parameters of the search generally observed in frontal region: a significant positive one between N2, P4 components; between SN-SP difference waves and task difficulty: a negative one between P3 and N2 components. Amplitudes of N2 and P4 components were mostly expressed in frontal lobe. It was supposed that the data obtained indicated dominance of the frontal structures in the attention system during increasing the difficulty of the task.

[Characteristics of the EEG spatial organization of the brain neocortex biopotentials in various clinical neurotic depression].

In 20 patients with various clinical variants of neurotic depression, regional organization of the brain bioelectric activity was studied with the aid of cross-correlation, factorial and coherent analyses. Clinical picture of neurotic depression was reflected within the frame of regional organization of the EEG. Regional organization EEG is modified depending on the degree of neurotic depression manifestation and concomitant syndromes of alarm and asthenia. In depressive syndrome without concomitant asthenic and disturbing, the maximum changes are registered in the right fronto-temporal range--left post-temporal areas. In depression and the alarm, depression cross-correlation and coherent communications in fronto-temporal areas of both hemispheres were recorded. In depressive and disturbing syndromes with the asthenic manifestations, depression cross-correlation and coherent communications in fronto-temporal areas of both hemispheres were observed.

[On using EEG autointerval-grams for analysing reactions to periodical light stimulation].

We have analyzed autointerval-grams of the extremums of human electroencephalograms, registered during periodical light stimulation. We have compared them with the visual analysis of EEG and EEG's testing by sinusoids. We have shown that in most cases building interval-grams is as good or even better than two other methods, as it allows us to discover reactions and obtain additional information.

Interhemisphere differences during tasks involving attention and selection of lateralized stimuli.

The state of cortical activation in the parietal and temporal areas of the right and left hemispheres was evaluated using evoked potentials (EP) during tasks consisting of selection of visual stimuli lateralized in the right and left visual fields and needing three different types of attention: to stimulus shape, to stimulus position, and simultaneously to stimulus shape and position. EP were recorded in 15 young healthy experimental subjects using six cortical leads: P3, P4, T3, T4, T5, and T6; the following endogenous EP components (in standard terminology) were analyzed: contingent negative variation (CNV), N1, P3, and the N1-P3 complex. Asymmetry in evoked potentials was assessed in terms of differences to contra-and ipsilateral stimuli in the right and left hemispheres. EP asymmetry was detected in the right hemisphere in all types of selection of lateralized stimuli. The magnitude of asymmetry in the right hemisphere depended on the level (or intensity) of attention: the degree of asymmetry increased with increases in the need for attention to analyze the stimuli. There was a significant relationship between the magnitude of asymmetry and the latent periods of the subjects' responses. The functional significance of these data demonstrating asymmetry may be that it provides better spatial differentiation of visual signals in the right hemisphere, along with dominance of the right hemisphere in attention tasks.

Characteristics of activation in the parietal areas of the cortex in humans in different types of visual attention.

The state of cortical activation in the parietal and temporal areas was assessed using evoked potentials (EP) during the tasks of selection of lateralized visual stimuli requiring three different types of attention: to stimulus shape, to stimulus position, and to both. Studies in 15 young, healthy subjects involved recording of EP in six cortical leads: P3, P4, T3, T4, T5, and T6, with analysis of the endogenous EP components CNV, N1, P3, and the EP complex [N1-P3] (according to standard terminology). Changes in EP components in response to the attended and non-attended stimulus features were compared. Differences between them were assessed using the index of selectivity of attention to one or another feature of the visual stimuli. In the parietal area, selectivity was seen in conditions of attention to stimulus position and attention to stimulus shape. In conditions of simultaneous attention, the indexes of selectivity were essentially equal to the sum of the indexes of selectivity of attention to shape and position. The most marked endogenous EP components (CNV, N1, and P3) in visual selection were seen in the parietal areas, with a greater gradient of increased activation of the parietal areas of the cortex as the need for attention increased, along with a lower threshold for the action of attention, and anticipatory development of the P3 wave in the parietal area as compared with the temporal area. These results suggest that the parietal cortex has priority in the visual attention system and that the magnocellular (M) pathway forms the most important visual input to the dorsal parietal area of the neocortex.

Cross-interval histograms for analysis of brain electrical activity.

A method for constructing cross-interval histograms for time-localized EEG fragments of particular types is described. The basic principles of the method are presented. Examples of cross-interval histograms constructed for EEG extrema and their derivatives are presented. Cross-interval histograms were shown to include peaks, troughs, and other features. Cross-interval histogram and cross-correlation histograms are compared. The method yields qualitatively new data on interactions between changes in biopotentials in different areas of the brain and allows rapid processes to be studied.

[Interhemisphere differences of extrastriate cortical activation during attention and selection of lateralized visual stimuli in humans].

The cortical activation was estimated by event-related potentials (ERPs) methods during selection tasks of lateralized visual stimuli in right and left hemi-fields requiring different forms of attention: 1. Attention of a stimuli form, 2. Attention of a stimuli position, 3. Combined attention of form and position. ERPs were recorded in 15 young healthy adults in 6 leads: P3, P4, T3, T4, T5, T6 and endogenous ERPs components: CNV (contingent negative variation), N1, P3 and complex [N1--P3]. The differences between ERPs at contra- and ipsilateral stimuli in the right and left hemispheres were considered as indices of asymmetry. The asymmetry was revealed in right hemisphere in all kinds of attention forms. The level (amplitude) of right-side asymmetry was depended on the level of attention: The significant relation between the right-side asymmetry and subjects' reaction time was also revealed. It is proposed that such an asymmetry is the evidence of better spatial differentiation of visual stimuli in right hemisphere in humans.

[Characteristics of the parietal cortex activation in humans during different attention tasks].

The cortical activation was estimated by the event-related potential (ERPs) methods during selection tasks of lateralized visual stimuli requiring different forms of attention: 1) form of stimuli, 2) stimuli position, 3) combined attention of form and position. The ERPs were recorded in 15 young healthy adults in 6 leads P3, P4, T3, T4, T5, T6, and endogenous ERPs components: CNV (contingent negative variation), N1, P3 and the complex [N1-P3]. Differences between the ERPs at "attended" and "non-attended" stimuli were considered as indices of selection attention of particular feature of visual stimuli. Such indices of form and position were revealed selectivity in parietal leads. The most eminent ERPs components, the pronounced activation gradient during increase of attention demands were revealed in parietal regions (vs. temporal ones). In our opinion, parietal cortex has a high priority in selection attention system.

[Crossintervalograms for analysis of electrical activity of the brain].

A method of construction of crossintervalograms for electroencephalograms is proposed. Particular points or EEG fragments of particular shape are used as time-locked events, and the intervals between these reference points are analyzed. The method is theoretically substantiated. Examples of crossintervalograms constructed for EEG extrema and derivative EEGextrema are given. The information validity of these crossintervalograms is demonstrated and their features are indicated. Comparison crossintervalograms with crosscorrelograms is performed. The possibilities of further development and applications of a method are specified. It is suggested that the method will be useful for investigation of operative interaction of brain subsystems.

Effects of selective visual attention in the parietal and temporal areas of the human cortex using evoked potential data.

Studies of 11 young subjects addressed the analysis of evoked potentials in the parietal and temporal areas to sequential presentation of visual symbols on the left and right sides; symbols were squares and circles and were observed passively and in conditions of selective attention to target stimuli presented to the subjects in random order and requiring rapid and precise motor responses. Comparison of monopolar evoked potentials in leads P3, P4, T3, T4, T5, and T6 with bipolar potentials in leads P3-T3, P3-T5, P4-T4, and P4-T6 in conditions of passive and selective attention showed that voluntary attention was accompanied by significant rearrangements in evoked activity in the parietal and temporal areas. This was evident as: 1) an increase in correlations between evoked potentials in the parietal and temporal areas; 2) stabilization of monopolar evoked potentials over time, i.e., increases in the correlations of sequential evoked potentials, in both associative visual areas; 3) stabilization of bipolar parietal-temporal evoked potentials in terms of increases in their sequential correlations. It is suggested that selective attention facilitates linked activity of the two associative areas, which is needed for performance of visual selection.

[Construction in chimpanzees]. / Konstruirovanie u shimpanze.

Chimpanzees with the help of reconstruction and the "step-by-step" analysis of a figure--sample can plan a circuit of actions, forming an image of an end result. Ability to such actions proves at them an opportunity of cogitative operations, allowing to collect multielement figures on a sample. Generalization of concrete operations with concrete elements creates the precondition for the generalized understanding of a principle of actions--knowledge--in general to collect separate elements in complex designs. In it the powerful conceptual potential chimpanzees is covered. It allows to use chimpanzees as model preverbal a level of thinking.

Genetic determination of neurophysiological mechanisms of cortical-subcortical integration of bioelectrical brain activity.

The contribution of genetic factors to the formation of the neurophysiological mechanisms of cortical-subcortical integration was studied in 12 pairs of monozygotic and five pairs of dizygotic twins (aged 18-25 years). Intrapair similarity of the nature of spatial interactions between bioelectrical activity in the cerebral cortex, assessed from different combinations of statistical interactions of EEG from 16 monopolar recordings, was assessed in each pair of twins (and among 544 non-related pairs of subjects in both groups). The results suggest a high level of general population invariance and relatively small inherited and phenotypic variability in the morphofunctional systems making up the major neurophysiological mechanisms of brain integration as a whole. The ontogenetic formation of stem and subcortical regulatory structures, which have a leading role in the systems combination of different parts of the brain into a single formation, appears to occur in all individuals by the same principle, as disturbance can apparently affect the fundamental monomorphic features of the species. In turn, we might expect to find large interindividual variability in the establishment of interregional connections of the neocortex, the role of inherited and environmental factors being different in the processes forming long and relatively short intercortical interactions.

Assessment of the state of activation of the cortical zones in humans during visual attention and selection.

The state of cortical activation during visual symbol shape and position selection tasks was assessed in humans in terms of the magnitude of prestimulus negativity (contingent negative variation, CNV) and the amplitude of the N1-P3 complex in evoked potentials (EP). Evoked potentials in the frontal parietal, occipital, and temporal leads were recorded in 18 young healthy subjects in two sets of experimental conditions: in a screened chamber and in an "open field" beside the experimenter, who communicated the results to the subjects and guided them towards quicker and more precise responses to the target stimuli. The maximum magnitudes of CNV and evoked potentials during selective attention were seen in the parietal areas, and additional increases of activation indexes were observed in the "open field," where subjects' motivation was enhanced. The state of readiness (CNV) was an informative measure of cortical activation, as it determined the parameters of subsequent evoked potentials; the more marked the readiness, themore marked and stable were EP. Comparison of the situations of passive observation and selective reactions to stimuli revealed a reciprocal relationship between CNV in these conditions: the greater the magnitude of CNV in "passive" conditions, the smaller the difference between CNV in "passive" conditions and during selective attention and vice versa. We termed this "additivity of involuntary and voluntary attention." The fact that activation indexes were greatest in the parietal areas suggests that the occipital-parietal system is dominant in visual selection tasks in humans.

[Manifestations of selective visual attention in human parietal and temporal cortex according to evoked potentials]. / Effekty selektivnogo zritel'nogo vnimaniia v temennykh i visochnykh otdelakh kory u cheloveka po dannym vuzvannykh potentsialov.

The event-related potentials (ERPs) in visual discrimination task in parietal and temporal cortical areas were recorded in 11 young adults during passive observation (involuntary attention) and target selection (voluntary attention). The voluntary selective attention resulted in: 1) increased ERP correlation between the parietal; and temporal cortical areas; 2) increased correlation of sequential ERPs in monopolar leads (P3, P4, T3, T4, T5, T6); and 3) increased correlation of sequential ERPs in bipolar leads (P3-T3, P3-T5, P4-T4, P4-T6). The findings suggest that voluntary attention maintains a concordant activity of the parietal and temporal cortical areas in execution of visual selection tasks.