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Aim of the study. Clarification of the functional and diagnostic significance of topography, or the type of fMRI-response recorded during active and passive hand movements in patients after traumatic brain injury.Material and methods. fMRI-responses gained during active and passive hand movements were analyzed in 40 patients with posttraumatic motor function disturbances and compared with results gained from 17 healthy volunteers (control group ).Results. In analyzed patients the increase of percentage of diffuse fMRI-response has been shown along with the areas of activation not typical for movement activation pattern typical healthy volunteers. The fMRI response type being it local or multifocal does not clearly correlate with the presence of motor function impairment (hemiparesis). However, it was found that with greater severity of hemiparesis there is a larger percentage of multifocal fMRI-response.The transition from a multifocal form of a motor fMRI-response to a local one observed in a dynamic study is accompanied by an improvement of patient’s general condition, a shift towards normalization of a number of morphofunctional indicators of the central nervous system, the tendency of regression of motor disorders.Conclusion. The increase of multifocal fMRI-responses in patients after traumatic brain injury is one of the signs of cerebral dysfunction. Dynamically observed transformation from multifocal to local fMRI-responses is associated with current or long-term improvement in motor activity as well, wit the regression of other clinical impairments and can be considered as prognostically positive sign of the course of post-traumatic illness.

Motor fMRI responses analyzed in 10 patients with mild posttraumatic hemiparesis displayed high variability in deviations from normal on movement not only of the afflicted but also the intact hand. Changes in fMRI rearrangements, most marked on use of the afflicted hand, were apparent as weakening of the main components of the response and increases in activation of cortical and subcortical brain structures not specific for the movement. Comparison of fMRI responses on motor loading of the afflicted and intact hands showed that the clearest marker of mild hemiparesis was weakening of the cerebellar component of the response. Comparison with normative data (15 healthy subjects) showed more marked features in the reorganization of the sensorimotor motor fMRI response in patients with right-sided hemiparesis.

Analysis of fMRI in the resting state (RS) is a suitable methodological approach to studying basal levels of functional brain activity in humans in health and disease. The inadequate development of this direction in Russia is partly due to the small number of Russian publications describing approaches to data processing. This study uses an algorithm for analysis of fMRI signals in the RS based on independent components analysis (ICA) run in the FSL environment and used for studies of typical functional resting state networks (RSN) in health. Averaging observation data by group, which is applicable for studies of healthy people, is often not appropriate for studies of different forms of cerebral pathology, which are characterized by significantly greater levels of variation in hemodynamics. Thus, studies of 17 healthy subjects included comparative evaluation of the topography and a number of quantitative measures of typical RSN identified by group and individual analysis of fMRI signals. These networks were comparable with RSN described in the literature as main and were also reproducible in group and individual analysis, which confirms the suitability, reliability, and effectiveness of using this algorithm. Individual analysis of RSN identified variability linked with a number of psychophysiological characteristics of healthy subjects (sex, motor asymmetry profile, EEG pattern), partly explaining the different levels of compliance with the patterns of the group networks. Results obtained from individual fMRI and EEG comparisons showed the potential of analysis of the topography of the sources of individual rhythms as EEG markers for RSN. The lowest levels of variability of fMRI characteristics of resting networks in health (such as maximum network activation intensity, mean frequency of the active zone of the spectrum, frequency of dominant peak) may have diagnostic value for studies of RSN in pathology.

We have analyzed EEG alterations during a passive hand movement test in ten patients with varying degrees of hemiparesis caused by brain injury and compared them with normal data (17 healthy volunteers). The fMRI responses of the patients were normal. It was found that additional brain structures (that seem to be untypical of healthy people) are included in the reactive process in patients with brain injury. Additionally, we observed a widening of affected frequency bands. We observed the highest correlation with the degree of hemiparesis for the topographical parameters of changes in EEG coherence during the passive hand movement test with specific response features of the brain hemispheres contra- and ipsilateral to the movement. It is discussed whether there is any involvement of the tactile component in the passive motor EEG response. The data are considered in the context of the earlier hypothesis [1, 2] on the participation of the extrapyramidal system in the compensation of a post-traumatic motor defect.

fMRI data indicate that backward mental counting is accompanied by activation of structures in the left hemisphere: the supplementary motor area, the precentral gyrus, and the triangular part of the inferior frontal and inferior parietal gyrus, as well as the middle frontal gyrus on both sides. The literature indicates that each of these cortical activation zones is a component of the executive functions. The EEG response is highly diffuse. Its asymmetry and zonal concentration are apparent in the behavior of quantitative indicators of the individual frequency ranges. The greatest level of correspondence with the topography of fMRI responses is seen for increases in coherence in the EEG α2 and α3 ranges (9–12.5 Hz), especially in the prefrontal and anterotemporal areas of the left hemisphere. The aim of the present work was to analyze the cerebral structural-functional support of the “silent backward counting” task in healthy humans in the context of evaluating the state of executive functions. Complex EEG and fMRI investigations were conducted in eight healthy subjects aged 24 ± 3 years.

The results of the EEG study of patients with tumor lesion of diencephalic (29 subjects) and limbic (25 subjects) structures with the focus on the analysis of structural and functional organization of α activity have been summarized. It has been found that diencephalic structure dysfunction is accompanied by disorder of α-rhythm spatial organization in the form of generalization or translocation of its focus to the frontal regions of the cerebral cortex. Distinctive features of “diencephalic” type alteration of α rhythm are determined by predominant integration of the thalamic or hypothalamic structures into the pathological process. Involvement of the limbic structures, especially at early stages of the disease, induces increase in α-rhythm intensity in the temporal region of the affected hemisphere. The nature of the response of the EEG pattern to the functional stress allows identifying it as a “hippocampal α rhythm”. Implementation of the automatic methods of analyzing plays an important role in the identification of these specified pathologic forms of the α rhythm that are often invisible during visual assessment. Detected atypical forms of α rhythm facilitates the interpretation of hemispheric asymmetry of the EEG in patients with cerebral pathology.

The hemodynamic (magnetic resonance imaging, fMRI, 3T) brain responses were studied in 15 left-handed healthy subjects performing active and passive movements of the dominant and non-dominant hands. Group and individual fMRI responses to the motor load were analyzed. It was found that, during the active movements of dominant and non-dominant hands, the main activation cluster appeared in the preand postcentral gyrus of the contralateral hemisphere and which topographically similar during active and passive movements. The activation cluster of greater volume was identified in these areas; the response was more diffused during the non-dominant hand movements in comparison with the dominant hand. During passive movements, the cortical activation clusters of a smaller volume in comparison with the active movements were found, which was expressed most clearly during the performance of non-dominant hand movements and could reflect the weakening of the control from the cortical structures in these conditions.

Functional magnetic resonance imaging (fMRI) was used to study the variation of functional changes that arise in the brain in response to similar tests in healthy subjects. The approach was assumed to demonstrate diverse individual strategies of achieving the same external (behavioral) response via different brain mechanisms and to identify the factors responsible for the diversity. Hemodynamic (fMRI) responses to activation of attention while opening the eyes or performing motor (consecutively moving the fingers of the right and left hands) and speech (mentally repeating the months of the year or the days of the week in the backward order) tests were determined in 21 healthy subjects aged 21–30 years, including 14 males and 7 females. A variation in fMRI responses was observed, i.e., three or four types of reactive hemodynamic changes were seen in the same test in the group, the prevalence of each type varying from 40 to 10% in one test. The responses showed distinct gender differences, and their specifics depended on the nature of the functional test. In motor and speech tests performed with the eyes closed, the fMRI responses in the females were more specific and local than in the males. In motor tests, the fMRI responses of the males compared with the females were characterized by a greater involvement of the frontal regions, which are responsible for regulatory functions. In the activation test (eye opening), the fMRI responses were more diffuse in the females and more local in the males.

Bioelectrical (EEG) and hemodynamic (fMRI responses) reactions of the brain to motor tasks for the right and left hands and imaginary performance of those tasks were studied in 15 healthy right-handed subjects (21‐39 years old). In real movements, the main fMRI response was recorded in the central gyri of the contralateral (to the working hand) hemisphere. Activation zones were also seen in the supplementary motor area and the ipsilateral hemisphere of the cerebellum. The corresponding EEG showed increases in the coherence of the high-frequency alpha and beta frequencies in the activated hemisphere. Imagination of movements produced fMRI reactions which were highly variable in terms of extent and topography; weakening of responses was seen in the motor zone and cerebellum, with increased activation of subcortical structures in the parietal associative zones. Changes in the EEG in this situation were very variable; there were increases in the coherence of high-frequency alpha and beta oscillations, in the right hemisphere. Changes in spectral power were similar in real and imaginary movements and consisted of increases in the power and mean frequency of beta oscillations not confined to the activated hemisphere but also appearing in the left hemisphere. These reflected the nonspecific component of the responses.

Background Severe traumatic brain injury (STBI) is almost always accompanied by movement disorders. The use of electroencephalography (EEG), supplemented by mathematical analysis, in combination with functional magnetic resonance imaging (fMRI) expands the possibilities of studying brain neuroplasticity as a basis for compensation post-traumatic motor disorders. Material and methods Multichannel EEG and fMRI 3T during passive motor test (hand finger clenching by experimenter) were performed in 28 patients with STBI and 17 healthy subjects. The most detailed spectral-coherent analysis of spatial EEG changes was performed in 10 patients with varying degrees of hemiparesis, but similar to the norm fMRI response. Results It was revealed that individual EEG restructurings in a passive motor test in patients with STBI are characterized by significant variability and the inclusion of the brain regions not typical for the norm. Secondary statistical analysis showed that the topography of EEG coherence changes shows the greatest correlation with the degree of hemiparesis: increased reactivity of the frontal-central areas in the ipsilateral hemisphere relative movement with mild hemiparesis and the inclusion of both hemispheres as the motor disorders increase. Localization of these changes is similar to the topography of the fronto-pontine, parietotemporo-pontine and occipito-mesencephalic motor tracts cortical projections. Conclusions This results demonstrate a greater sensitivity of EEG responses to the degree of motor defect compared with hemodynamic (fMRI). They confirm our hypothesis put forward earlier on the possible participation of the extra-pyramidal system in compensating for the post-traumatic motor defect. Supported by RFFI 18-013-00355 .

Bioelectrical (EEG) and hemodynamic (fMRI-response) cerebral reactions to performance and imaginary motor tasks by right or left hand were analyzed in 15 right-handed healthy persons (21-39 years old). During actual movement the main fMRI-response was registered in the area of central gyrus of the hemisphere contralateral to the working hand. Areas of activation were also revealed in the supplemental motor area and the ipsilateral hemisphere of the cerebellum. EEG data showed coherence increase in high frequency alpha- and beta-bands in the activated hemisphere. In imaginary motor tasks the intensity and topography of fMRI-response became the more variable; response was decreased in the motor area and in cerebellum, they increased in the subcortical structures and in the parietal association zones. EEG changes were very variable in this situation also; it was observe an increase of EEG coherence in the right hemisphere for higher frequency of alpha and beta spectral bands. Changes of power spectrum parameters were similar to performance and imaginary motor tasks. Spectrum power and middle frequency of beta band were increased. Topographically these changes did not correspond to activated hemisphere and it was more in the left hemisphere. These changes were reflected nonspecific component of reaction.

Severe traumatic brain injury (STBI) is nearly always comes with movement disorders. Objectives Comparison of cerebral structural-functional control of movement’s opportunity and implementation in healthy volunteers and patients with various degrees of hemiparesis after STBI. Methods Observation groups: 28 patients with SOBI (main) and 17 healthy volunteers (control). 3T fMRI recorded at rest and passive right hand finger clenching (by experimenter). Individual and group analysis of Sensorimotor resting-state network and motor fMRI responses was carried out by FSL software (ICA algorithm), SPM8 and CONN. Topography and volume activated brain regions as well as brain connectivity between them were determined. Results At STBI in the majority cases without hemiparesis or with its mild degree, neuroanatomy of the rest-state sensorimotor network and “passive” motor fMRI response are close to normal. However with an increase of hemiparesis expression we have seen an asymmetric reduction of sensorimotor resting-state network and more diffuse “passive” fMRI response - with activation of nonspecific to movement brain structures: frontal and temporal cortex, cerebellar vermis and others. Discussion A comparison of the passive movement’s functional anatomy in STBI with motor system topographic anatomy indicates a variability in movement disorders compensation mechanisms based on the possible inclusion of different “functional doublers”, such as fronto-pontinus conduction tract as well as occipito–temporopontinus. This hypothesis confirmed by comparative analysis of brain connectivity within different neuroanatomical motor tracts in healthy volunteers and patients with STBI. Conclusions The retrieved data can be useful to develop individualized neurorehabilitation programs of post-traumatic motor disorders. Supported by RFFI 115-36-01038.

A comprehensive study with the assessment of reactive responses to motor tasks was performed in nine patients with a tumor localized in the frontal divisions of the brain using two methodological approaches: functional magnetic resonance imaging (fMRI) and EEG. The data obtained were compared to the results of a similar study on 12 healthy subjects. It was established that cerebral pathology was associated with disorders of functional specialization and an increase in the diffuse component of reactivity. The fMRI responses were characterized by greater intactness compared to the EEG parameters of reactive changes. These features are especially marked when an afferent stimulus is sent to the damaged hemisphere. The characteristics of the involvement of individual EEG bands in the formation of motor responses and changes in the fMRI response topography are determined by the degree of cerebral dysfunction reflected by the pattern of baseline EEG reorganization and the severity of the motor defect. The predominant increase in the coherence of slow rhythms in the damaged hemisphere irrespective of the target of the afferent stimulus in patients with severe cerebral dysfunction reflects the dominant formation of a pathological focus and is indicative of a greater, compared to healthy subjects, involvement of deep brain structures in the reactive process, which is confirmed by the fMRI data.

The functional magnetic resonance imaging (fMRI) and EEG responses to identical functional (visual and motor) loads have been compared in ten healthy subjects with the use of individual structural MRIs of the brain. It has been established that an increase in the coherence of the EEG α waves corresponds mostly to the zone of the fMRI response (as a +BOLD reaction). Reactive rearrangements, according to the data of fMRI and, particularly, EEG studies, are characterized by pronounced interindividual variation, which increases along with the functional test complexity. The fMRI responses have shown a greater locality and closer dependence on the modality of presented stimuli than EEG rearrangements, which underline the systemic character of brain response to functional loads. The −BOLD response accompanying the local +BOLD effect is more generalized, without distinct topographic referencing to the functional load modality; it conforms most of all to the decrease in the EEG’s coherence.

In order to determine more accurately the EEG markers of different types of attention (AT) of a healthy adult, 14 young healthy subjects (aged 18–30 years) were subjected to spectral coherent analysis of the electrical activity of the brain in the baseline state and during activation of different forms of AT (the orienting response to the sound tone and opening of the eyes, involuntary and voluntary visual AT). In the last two cases, specially developed computer-aided techniques were used. The quantitative differences in the states were assessed on the basis of nonparametric (the Mann-Whitney test) and parametric (Student’s t test) statistics. In three subjects, EEG and fMRI comparisons of the brain response to opening of the eyes were made. It was shown that the activation of different forms of AT in healthy subjects is accompanied by considerable diffuse nonspecific changes in the EEG spectral coherent characteristics (a decrease in the average spectral frequency and power, as well as in coherence) in combination with more local, more often oppositely directed shifts in the region of the cortical representation of the working analyzer. Complex systemic rearrangements of the brain activity involving all components of the activating system, as well as the specifics of different forms of AT connected with the rearrangement of activity between its divisions, are reflected in the diffuse changes of intercentral interaction. For example, marked reactivity of the symmetrical frontopolar (Fp1-Fp2) and the anterotemporal (F7-F8) cortical areas with unidirectional maximum shifts during voluntary AT is likely to reflect the responses of the frontothalamic component of the activating system. The reciprocity of the behavior of interhemispheric frontopolar and temporal relationships seems to be determined by the activity of its different components: frontothalamic and hippocampal. The local component of the EEG response to opening of the eyes in the form of increased α coherence in the occipital areas is coupled with increased oxygenation of blood in the cortical representation of the visual analyzer (the +BOLD effect of the fMRI response).

This paper analyzes the variation of the functional anatomy of the brain in healthy people performing identical activities on the basis of functional magneticresonance imaging (fMRI). According to the authors, this approach allows you to showcase a variety of individual strategies to achieve the same external (behavioral) result intracerebral different means, and to identify the factors that determine this diversity. Investigated hemodynamic (fMRT) brain reactions at activization of attention to opening of eyes, motor (search of the right and left hand fingers) and speech tests (mental transfer of months or days of the week upside-down) at 21 healthy subjects (21-30 years): 14 men, 7 women. Certain variety of fMRT answers is revealed: 3-4 jet types of hemodynamic changes were allocated for test in group, and the percent of supervision of each type fluctuated from 40 to 10%. Shown marked gender differences responses which specificity is determined by the nature of the functional load. In motor and speech tests, performed with his eyes closed, fMRI response in women is characterized by greater specificity and locality than in men. At motor tests fMRT answers of men are accompanied big, than at women, inclusion in reaction of frontal areas of the cortex, providing realization of regulatory functions. When opening of eyes the women's fMRT responses, on the contrary, become more diffusion, and men's--more local.

Computer-assisted superimposition of the equivalent dipole sources (EDSs) of the main pathological EEG patterns with the results of computer tomography and magnetic resonance imaging of the brain was performed for patients with organic CNS lesions. The greatest degree of structural determination was revealed for local and lateralized (in a traumatic injury) slow waves, whose EDSs mapped to the perifocal zone of the injury focus. The EDSs of epileptiform patterns could be located in the zone of damaged brain substance or in the intact hemisphere (when the limbic structures were damaged), reflecting the formation of secondary functional foci in the latter case. Bilateral paroxysmal patterns were more frequently determined by the functional state of the medial brain structures. The EDSs of pathological (diencephalic, hippocampal) α activity were closely associated with the corresponding anatomical brain structures, although without a strict dependence on the degree of their morphological intactness.

Bioelectrical (EEG) and hemodynamic (fMRI) responses of cerebral reactions to active and passive movements by the right hand were analyzed in 17 right-handed healthy persons. Individual and averaged fMRI and EEG data was analyzed. The main cortex fMRI responses (sensorimotor cortex of the contralateral, left hemisphere) were topographically similar during both active and passive movements. This fact allows us to recommend the usage of the passive movement paradigm for the mapping of the motor areas in patients with movement disorders. Including in reactive process of cerebellum and subcortical structures at passive movements was more variability than active ones. FMRI-reactions at passive movements were characterized more individual variability than during active ones at the expense of diversity of cerebellum and subcortical structures answers. The EEG analysis revealed that at both passive and active movements there is a coherence increase in the high-frequency alpha-ban in left central-frontal area of the left, activated hemisphere. The power-frequency changes of the EEG parameters during active and passive movements were primarily shown in a frequency increase and the desynchronization of the beta-band. Consistency with the topography of the fMRI response was not found.

This article generalizes the results of many years’ studies of the EEG of patients with tumorous lesions in the diencephalic, brainstem, and limbic structures, which fulfill the regulatory function in ensuring integral brain activity. The specific features of the inclusion of individual structures under investigation in the organization of the intra- and interhemispheric relations of cortical biopotentials were demonstrated against the background of diffuse changes in the biopotentials that reflect the systemic character of neurodynamic reorganizations when the regulatory brain structures are involved in the pathological process. This study expands the idea of the predominant functional connection of the diencephalic structures with the right hemisphere and brainstem structures with the left one with determination of the regional specific features of changes in the intrahemispheric EEG coherences. The distinguishing features of intercentral relations when the limbic structures are involved in the pathological process show similarity with the neurodynamic reorganizations in patients with lesions in both diencephalic and (even more so) brainstem structures. Universal elements were detected in the formation of integral adaptive reactions of the brain with lesions in its regulatory structures, which reflects their close functional interaction and makes it possible to consider them the individual links of an integral regulatory system. The study revealed reciprocal changes in various forms of electrical activity, which reflects reciprocation of interaction of individual regulatory structures. This is one of the EEG equivalents of the formation of adaptive-compensatory cerebral reactions. The specificity of influence of the studied regulatory structures are clearly seen in situations of their morphofunctional isolation observed during cerebral coma. In these conditions, when the cortex is functionally inactive, the authors demonstrated the dynamic character of changes in interhemispheric asymmetry, which reflects the dominance of individual links of the regulatory system playing the role of supreme regulator of life support of the body in critical states.

Paper describes a study of language lateralization of patients with brain tumors, measured by preoperative functional magnetic resonance imaging (fMRI) and comparison results with tumor histology and profile of functional asymmetry.During the study 21 patient underwent fMRI scan. 15 patients had a tumor in the left and 6 in the right hemisphere. Tumors were localized mainly in the frontal, temporal and fronto-temporal regions. Histological diagnosis in 8 cases was malignant Grade IV, in 13 cases--Grade I-III. fMRI study was perfomed on scanner "Signa Exite" with a field strength of 1.5 As speech test reciting the months of the year in reverse order was used. fMRI scan results were compared with the profile of functional asymmetry, which was received with the results of questionnaire Annette and dichotic listening test.Broca's area was found in 7 cases in the left hemisphere, 6 had a tumor Grade I-III. And one patient with glioblastoma had a tumor of the right hemisphere. Broca's area in the right hemisphere was found in 3 patients (2 patients with left sided tumor, and one with right-sided tumor). One patient with left-sided tumor had mild motor aphasia. Bilateral activation in both hemispheres of the brain was observed in 6 patients. All of them had tumor Grade II-III of the left hemisphere. Signs of left-handedness were revealed only in half of these patients. Broca's area was not found in 4 cases. All of them had large malignant tumors Grade IV. One patient couldn't handle program of the research.Results of fMRI scans, questionnaire Annette and dichotic listening test frequently were not the same, which is significant. Bilateral activation in speech-loads may be a reflection of brain plasticity in cases of long-growing tumors. Thus it's important to consider the full range of clinical data in studying the problem of the dominant hemisphere for language.

Bioelectrical (EEG) and hemodynamic (fMRI-response) cerebral reactions to performance and imaginary motor tasks by right or left hand were analyzed in 15 right-handed healthy persons (21-39 years old). During actual movement the main fMRI-response was registered in the area of central gyrus of the hemisphere contralateral to the working hand. Areas of activation were also revealed in the supplemental motor area and the ipsilateral hemisphere of the cerebellum. EEG data showed coherence increase in high frequency alpha- and beta-bands in the activated hemisphere. In imaginary motor tasks the intensity and topography of fMRI-response became the more variable; response was decreased in the motor area and in cerebellum, they increased in the subcortical structures and in the parietal association zones. EEG changes were very variable in this situation also; it was observe an increase of EEG coherence in the right hemisphere for higher frequency of alpha and beta spectral bands. Changes of power spectrum parameters were similar to performance and imaginary motor tasks. Spectrum power and middle frequency of beta band were increased. Topographically these changes did not correspond to activated hemisphere and it was more in the left hemisphere. These changes were reflected nonspecific component of reaction.

To gain a deeper insight into the relationship between the electrogenesis and oxygenation of the brain, fMRI and EEG reactions to identical functional loads (opening of the eyes and right- and left-hand fingering) were compared in 11 young right-handed healthy subjects with statistical techniques. Changes in power, frequency and coherent EEG parameters obtained by 18-channel monopolar recording were compared with values of + BOLD-fMRI response, calculated for 18 corresponding cortical areas on the basis of application of the "virtual cap" by the original algorithm. In reactive changes of both hemodynamic and bioelectrical parameters, sets of independent factors were identified, which were regarded on the basis of their topography as specific (localized in the cortical representation ofa relevant analyzer) and nonspecific (diffuse and similar under different functional loads). Specific component dominated in the fMRI response, whereas non-specific component was characteristic of the EEG reaction. The similar topography of reactive fMRI and EEG factors under normal conditions, confirmed by the correlation analysis, reflects the multilevel character of the systemic organization of the brain activity, visualized, in particular, in the sagittal projections of the individual fMRI images. Each of the reactive EEG factors included all of the EEG quantitative characteristics. EEG coherence, which dominated among other parameters (with a local increase in the cortical representation of a relevant analyzer and a diffuse decrease in the areas of the influence of the regulatory structures) displayed the highest correlation with hemodynamic responses of the brain.

fMRI (1.5 or 3 T) and EEG studies with estimation of reactive responses on motor task (by right or left hand) were performed in 9 patients with tumors localized in frontal lobe of the brain. Results of this investigation were compared with results of the similar study in 12 healthy persons. It was shown that in cases of the brain pathology disorders of functional specialization and increase of diffuse component of reactivity was observed, fMRI-responses had been characterized the more intact reactions than reactive changes of EEG parameters. This specificity was described in cases of afferent loads in damaged hemisphere. Peculiarity of including different spectral bands in forming of EEG responses on motor tasks and changes of fMRI-answer depend on degree of cerebral decompensation, reflected in the of baseline EEG reorganization and degree of motor defect. Predominantly an increase of EEG coherence in delta-band with the predominance of reaction in the damaged hemisphere in cases of addressing any afferent load was observed in patients with severe cerebral decompensation and reflect dominant character of pathological focus forming. This data indicate on the more including of the deep brain structures in process of reactivity in patients compared with healthy persons and confirmed by fMRI-data.

The authors summarized EEG findings and defined the nature of the intercentral EEG relationships in different functional states in healthy subjects and patients with organic cerebral pathology, based on a coherence analysis. Similar EEG characteristics in healthy individuals were identified: an anterior-posterior gradient of average coherence levels, the type of cortical-subcortical relationships in anterior cerebral structures. Right- and left-handed individuals showed frequent and regional differences in EEG coherence, which mainly reflected specificity of intracortical relationships. Development and regression of pathology in right-and left-handed individuals with organic brain lesions were thought to be caused by these differences. Lesions of regulatory structures (diencephalic, brain stem and limbic structures) provoked a more diffused kind of changes of intercentral relationships, in contrast to cortical pathology. These changes tended to reciprocate. The dynamic nature of intercentral relationships and their interhemispheric differences was revealed when changing functional states of the brain (increase and decrease of functional level) in healthy individuals and patients with organic cerebral pathology in the process of conscious and psychic activity restoration. Changing activity predominance of certain regulatory structures was considered one of the most important factors determining the dynamic nature of EEG coherence.

In order to reveal features of the brain reactions to external stimuli in the course of consciousness recovery after a severe craniocerebral injury, component P300 of acoustic evoked potential was analyzed in 9 patients with chronic and 32 patients with reversible unconsciousness. In patients with chronic unconsciousness, P300 parameters displayed a linear correlation with the current functional state. However, this component remained significantly different from its normal shape and varied only in a narrow range. In patients with reversible unconsciousness, time course of changes in amplitude and latency between recovery stages was of linear character with a tendency to normalization. The findings suggest that, in reversible unconsciousness states, processing of sensory information at different recovery stages may be performed with various functional systems that determine varying quality of processing, whereas changes in chronic unconsciousness are caused by a decrease in the number of active elements within the same functional system.

The authors summarized the EEG findings and defined the nature of intercentral EEG relationships in different functional states of healthy subjects and patients with organic cerebral pathology based on coherence analysis. The EEG features typical of healthy subjects were identified: an anterior-posterior gradient of the mean coherence and the character of cortical-subcortical relationships in the anterior cerebral structures. Right- and lefthanded subjects showed the frequency and regional differences in EEG coherence, which reflected, mainly, specific intracortical relationships. Development and regression of pathologic signs in right- and lefthanded patients with organic brain lesions are thought to be determined by these differences. As distinct from cortical pathology, lesions of regulatory structures (diencephalic, brainstem, and limbic) were shown to produce more diffuse changes in intercentral relationships with a tendency to reciprocity. Intercentral relations, including their interhemispheric differences, varied with changes in the functional state of healthy subjects (increase and decrease in the level of functioning). A certain time course of changes in intercentral relationships was also revealed in patients with organic brain lesions during recovery of their consciousness and mental activity. Changes in the dominance of activity of individual regulatory structures are considered to be one of the most important factors that determine the dynamic character of EEG coherence.

Dependence of manifestations of EEG pathological activity on the electrode montage was studied in cases of brain lesions involving limbic structures by means of the topographic mapping and 3-d dipole source localization. The original program DIPVIS on the basis of BRAINLOC software allowed us to reveal the stable sources of lateralized pathologic alpha activity and demonstrate the discrepancy between its localization and the localization of the normal human alpha rhythm. The sources of pathological activity in question were predominantly localized in the mediobasal structures of the affected hemisphere in contrast to the occipital region of a healthy human. It was established that the topography of the cortical pathological activity may be determined by peculiarities of localization and, especially, orientation of its dipole generators. Afferent stimulation produced an enhancement of the pathological alpha-activity and increase in dipole source concentration in the mediobasal portion of the temporal lobe. The findings suggest that the discovered from of the alpha-rhythm reflects the reaction of activation of the hippocampal structures involved in the pathological process.

In 50 patients with focal lesions of the brainstem was analysed the postsurgery dynamics of the interhemispheric interaction (by the characteristics of EEG coherence). Was shown a specific participation of the left and the right hemispheres in a realization of postoperative compensatory brain reactions. In survived patients in early terms after surgery the phase was revealed in which coherence in the left hemisphere exceeded that in the right one and the difference being significant for the frontal areas. This phenomenon reflected higher reactivity of the dominant hemisphere in a realization of the adaptive reactions of the CNS. Right hemispheric EEG coherence in general had lower values and was more inert. It dominated under the conditions when only vegetative regulation remained before the lethal exit.

Comparative EEG studies (with the normative data control) were carried out in patients with different anatomic-topographical variants of craniopharyngioma, effecting the hypothalamus (12 patients) and involving thalamo-subcortical structures in the pathological process (17 patients). Characteristics of EEG reorganization were found to be determined in the first instance by the stage of development of the focal process. Analysis of the regional characteristics and intercentral relations of the brain biopotentials revealed besides the common features, the differences in the effects of certain diencephalic structures on the spatial-temporal EEG organization. Hypothalamic areas exert mainly global influence on the EEG pattern formation. Thalamic structures influence genesis of the rhythmic activity forms and their intercentral relations more differentially and make more important contribution to the formation of the balanced (in norm) pattern of the brain electrical processes spatial-temporal organization.

In this work was studied a hemispheric specificity of the human brain in a realization of adaptive-compensatory reactions of the CNS. The interhemispheric correlation of EEG coherence functions of the left and the right hemispheres was computed in patients with brain focal lesions in early postsurgery period after an extraction of the medially-located tumor or in far-off time after a hard brain injury (i.e. at different stages of cerebral compensation). The observed peculiarities of changes of the interhemispheric biopotential relations revealed the dynamic character of preferable switching on the right or the left hemisphere in a formation of adaptive-compensatory brain reactions. The specificity of this switching depended on the stage of the pathologic process and reflected the degree of consciousness disturbance.

As many as 16 epileptic patients with the sings of sinistrality in the motor and sensory spheres were examined. The authors demonstrate the clinical characteristics of epilepsy in the left handed, that distinguish them from the right-handed; dissimilarity of each psychopathological symptom and syndrome to their analogs in the right-handed, the occurrence of unusual phenomena, impossible in the right-handed. Depict specific features of the EEG that distinguish the patients examined from healthy right- and left-handed. The data obtained are interpreted as evidence that the clinical characteristics and the EEG appearance of epilepsy are determined to a considerable measure by the profile of asymmetry of each patient as well as by the fact that the left-handed may demonstrate diverse varieties of functional brain asymmetry, differing from the type of asymmetry of cerebral hemisphere functions common to all the right-handed in the maintenance of integral neuropsychic activity.

On the basis of clinico-anatomo-electroencephalographic studies it was shown, that in early terms of cerebral trauma, at gross disturbances of the cortical functions and safety in some cases of only vital regulation, the parameters of the EEG stability or variability are of distinct information value for estimation of the functional state of patients. It was established, that changes of stability of the frequency, power, and coherent EEG characteristics correlate with different parameters of changes of the structural-functional brain organization. At this stage the greatest connection with the disease outcome reveals the EEG coherence parameters of the cortical symmetrical points reflecting the state of predominantly median formations and general brain reactions to traumatic action. In the process of restoration of disturbed neuromental functions priority prognostic significance is acquired by parameters of intrahemispheric coherence as well as by frequency-regional properties of interhemispheric asymmetry of coherence of the brain electrical processes, characterizing functional features of the lesion focus.

EEG coherence analysis was used to study aspects of the synchronisation of electrical processes in the left and right cerebral hemispheres of right-handed and left-handed healthy subjects in a state of calm wakefulness. Right-handed subjects showed a greater coherence in the left hemisphere and left-handed subjects in the right hemisphere. There were also differences between right-handed and left-handed subjects in the regional profiles of interhemispheric asymmetry and in the interhemispheric asymmetry of individual spectral bands. These differences may reflect variations in the involvement of cortical and subcortical cerebral structures in the formation of the hemispheric specificity. Changes in interhemispheric coherence with the onset of drowsiness were also observed. This suggests that changes in the interconnections of neural networks are also involved in changes in arousal. Certain characteristic regional interhemispheric asymmetry patterns and asymmetries in the spectral bands appear to be necessary for normal human brain function.