Classification of the adolescent EEG by the spectral and segmental characteristics for normals

The 16-channel EEG records of 45 adolescents with schizophrenia and 39 healthy adolescents were subjected to statistical combinatorial analysis of 160 elementary EEG characteristics (6 spectral and 4 segmental EEG characteristics for a channel). Employing pattern recognition algorithm "Kora-n", a list of 37 combined EEG patterns was compiled. This list characterized with a minimal error the EEG of healthy adolescents in such a way that none of these characters featured the EEG of adolescents with schizophrenia. Analysis of this list of EEG characteristics suggests that the contrast between EEG of healthy and ill adolescents is the sharpest in the F4, Cz, T3 and O1 derivations. Compared to EEG samples of schizophrenic subjects, EEGs of healthy subjects exhibit lower levels of delta and theta activity mainly in the frontal and temporal regions of the cortex and higher level of alpha activity predominantly in the occipital region. Applicability of the list of EEG patterns for diagnostics of schizophrenia-type disorders of adolescents is discussed.     

Effect of inhalation therapy on the dynamics of electroencephalographic and rheoencephalographic indices in patients with vasomotor dystonia and with pathology of respiratory organs]

Dynamics of electro- and rheoencephalographic (EEG and REG) indices in patients with some forms of cephalgia (vegetovascular dystonia--VVD) as well as with chronic nonspecific pulmonary diseases has been studied under the effect of artificial mountain climate therapy conducted using a special chamber "Orotron" created by a collective of researchers from Academy of Sciences of Ukraine. The results of EEG and REG analysis reflect a general tendency to improvement of the bioelectrical brain activity and cerebral hemodynamics.     

Spectral analysis of the effects of nomifensine on bioelectric activity of the rat brain]

The influence of nomifensine on bioelectrical activity of sensorimotor cortex, dorsal hippocamp and lateral hypothalamus in conscious rats in free behavior was studied. The pharmacological and EEG analysis of nomifensine action on EEG power spectra by Fourier technique was measured. It was established that nomifensine evoked an increase and stabilization of the dominant peak in EEG spectra in the left and right cortex and in the left hippocamp, while in the other ranges of frequency a decrease was observed. The effects on hypothalamus was opposite--EEG power spectra decreased in all the ranges. The authors conclude that nomifensine evokes higher level of wakefulness, vigilance of the animals. This is likely to underlie neurophysiological mechanisms of optimal behavior due to stimulants of CNS, including nomifensine.     

Peculiarities of disorders of brain bioelectrical activity spatial-time organization in patients with different consciousness depression after severe head injury

Specific changes of bioelectrical brain activity was found in 27 patients with different level of posttraumatic consciousness depression by the methods of crosscorrelation, coherence and factor analysis of EEG. The changes of activity of morphofunctional systems of intracerebral integrations were revealed partially by decreasing of unspecific activity from brainstem structures reflected with increasing of slow wave activity and decreasing of EEG coherence in alpha- and beta-range. Depression of system organization of interconnections of bioelectrical brain activity in frontal and occipital regions of both hemispheres was also detected, and testified about decreasing of intercortical and thalamocortical brain system action under brain dislocation. The changes of integrative brain system activity, provides interhemispheric interaction, had the specific characted. Our results propose a "facilitation" of activity of system, providing "direct" interhemispheric connections through corpus callosum and other commissural tracts of telencephalon as a sequel of mesodiencephalon structures depression with steady reciprocal, antiphase relations of slow weve activity in symmetrical areas of hemispheres in coma II patients. The data of our research had shown no complete disintegration of system brain activity in coma II patients in spite of consciousness and brainstem reflexes depression.     

Concerning the amplitude modulation of the human EEG

Amplitude-modulated processes can be formally presented as a product of two or more sinusoids. This makes it possible to study them by means of analysis of multiplicative phenomena using the Fast Fourier Transform (FFT). To assess the contribution of amplitude EEG modulation to the dynamic of electrical activity of the human brain, the results of the FFT of simulated signals obtained by multiplication of oscillatory processes with different parameters were compared with the results of the FFT of a single EEG recording from a subject at rest. We studied the temporal dynamics of spectral components calculated with different spectral resolution under similar conditions for real and simulated signals. An attempt was made to analyze and interpret the amplitude-modulated EEG processes using the additive properties of the FTT. It was shown that processes of amplitude modulation are present in electrical brain activity and determine the synchronism of changes in time in the majority of frequency components of the EEG spectrum. The presence of the amplitude modulation in bioelectrical processes is of a fundamental nature, since it is a direct reflection of the control, synchronization, regulation, and intersystem interaction in the nervous and other body systems. The study of this modulation gives a clue to the mechanisms of these processes.     

Brain bioelectrical activity at a high anxiety level in humans

Brain bioelectrical activity was studied in 38 and 34 subjects with high and low levels of anxiety, respectively, by means of toposelective mapping of EEG spectral power and recording of P300 endogenous event-related auditory evoked potentials (EPs). Analysis of EEG spectra demonstrated, in the subjects with a high level of trait anxiety, a higher power of β₁ oscillations in the central-parietal areas of both hemispheres and the occipital area of the right hemisphere, as well as a higher power of θ and α oscillations in the frontal areas of both hemispheres and the central-parietal area of the left hemisphere. The occipital-frontal gradient of the spectral power of these rhythmic EEG components was altered in subjects with a high level of trait anxiety. Comparison of P300 cognitive auditory EPs in the subjects with high anxiety and in the control group showed that, in the former, the P300 EP amplitude and the habituation distortion (dishabituation) of the P300 EP amplitude were significantly higher in both hemispheres. This indicates that, at a high level of anxiety, the active directed attention was disturbed, which is confirmed by the results of neuropsychological examination, demonstrating reduced selectivity, concentration, and stability of attention in the Münsterberg test and Schulte’s test. The results of electrophysiological examination suggest that the malfunction of regulatory brain modulating systems is an important neurophysiological mechanism of attention pathology and disturbed adaptation in subjects with a high level of trait anxiety.     

EEG characteristics of bioelectrical activity of the brain in women with normal and complicated pregnancy

Spectrum and coherent EEG analysis has been made at 109 pregnant women during 35-36 weeks of gestation. It has been shown, that functional interhemispherical asymmetry of the brain is the sensible parameter of normal and complicated gestation. It has been found out that as for normal pregnancy prevailing activation in central and temple areas of the brain contralateral to the side of placenta placement in uterus is characteristic. The development of gestation complications accompanied by the inversion of interhemispherical asymmetry of EEG activation. It was pointed out that correlative relations of bioelectrical activity of the brain in women with normal gestation are the indicator of dominating of nervous centers of left hemisphere in the integrational process.     

Mechanism of low-level microwave radiation effect on nervous system

The aim of this study is to explain the mechanism of the effect of low-level modulated microwave radiation on brain bioelectrical oscillations. The proposed model of excitation by low-level microwave radiation bases on the influence of water polarization on hydrogen bonding forces between water molecules, caused by this the enhancement of diffusion and consequences on neurotransmitters transit time and neuron resting potential. Modulated microwave radiation causes periodic alteration of the neurophysiologic parameters and parametric excitation of brain bioelectric oscillations. The experiments to detect logical outcome of the mechanism on physiological level were carried out on 15 human volunteers. The 450-MHz microwave radiation modulated at 7, 40 and 1000 Hz frequencies was applied at the field power density of 0.16 mW/cm². A relative change in the EEG power with and without radiation during 10 cycles was used as a quantitative measure. Experimental data demonstrated that modulated at 40 Hz microwave radiation enhanced EEG power in EEG alpha and beta frequency bands. No significant alterations were detected at 7 and 1000 Hz modulation frequencies. These results are in good agreement with the theory of parametric excitation of the brain bioelectric oscillations caused by the periodic alteration of neurophysiologic parameters and support the proposed mechanism. The proposed theoretical framework has been shown to predict the results of experimental study. The suggested mechanism, free of the restrictions related to field strength or time constant, is the first one providing explanation of low-level microwave radiation effects.     

Effect of cholinolytics on the functional lability of the visual analyzer in cats

The effect of aminoethers of derivates of glycolic acid (glipine and amizil) in doses of 0.1--5 mg/kg and of derivates of acetic acid (diphacyl and thropacin) in doses of 10--40 mg/kg on bioelectrical activity of the retina was studied in experiments on 10 intact cats. To control the effect of cholinolytics, electrodes were chronically implanted in the visual cortex and EEG ws recorded. It was noted that the frequency of white, yellow, green and blue photic stimuli is reproduced on ERG within the range from 1 to 23 c/s both before the administration of cholinolytics and during their action in all of the used doses. Flash rhythm reproduction was not disturbed (in spite of an increase in the waves' amplitudes in the retinal background bioelectrical activity) following administration of cholinolytic substances. All cholinolytics in all of the studied doses caused in the EEG of the visual cortex an increase in waves' amplitude, i. e. a synchronization.     

The role of damage to the cerebral subcortical divisions in the formation of alalia

The role of the cerebral subcortical structures in speech formation was studied by analyzing the data on the comprehensive examination of children with alalia. Alalia is a systemic underdevelopment of speech in which all the speech components are disordered. The assessment of the functional state of the brain structures by means of EEG allowed us to identify two groups differing in the pattern of changes in bioelectrical activity (BEA): group 1 with α rhythm changes and/or local BEA changes, predominantly in the left hemisphere, and group 2 with predominantly generalized EEG changes of brainstem origin. Integrated analysis of clinical data allowed us to suggest that a lesion of the left hemisphere subcortical structures and the brainstem divisions underlies the formation of alalia. The analysis of the perinatal risk factors allowed us to advance the hypothesis that damage to the subcortical structures was linked to antenatal complications in the first half of pregnancy.     

Comparison of reactive EEG changes and fMRI characteristics of brain health based on multivariate statistics

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.     

Disorders of the spatiotemporal organization of the brain’s bioelectrical activity in patients with different depressions of consciousness after severe head injury

Specific changes in the bioelectrical activity of the brain have been found in 27 patients with different levels of posttraumatic consciousness depression (stupor, spoor-coma I, coma II) by the methods of cross correlation, and coherence and factor EEG analysis. The changes in activity of the morphofunctional systems of intracerebral integrations were expressed partly in a decrease in the nonspecific activating effects from brainstem structures, which was reflected in an increase in the slow wave activity along with a considerable decrease in the level of EEG coherence in the α and β ranges. The observed depression of the system’s organization of the interrelations of the bioelectrical brain activity in the frontal and occipital regions of both hemispheres could be due to a decreased activity of the associative systems of intercortical and thalamocortical integration. The results suggest a certain facilitation of the activity of the system providing direct interhemispheric connections through the corpus calossum and other commissural tracts of the telencephalon as a consequence of the depression of the mesodiencephalon structures (which normally largely contribute to the synergistic interhemispheric interaction via synchronous ascending effects on the cortex of both hemispheres). This results in steady, reciprocal, and almost antiphase relations of slow wave activity in symmetrical areas of the hemispheres.     

Features of the dynamics of the forebrain EEG of Emys orbicularis during the solving of an extrapolation problem

Sharp EEG changes are recorded in bioelectrical activity of the dorsal cortex and dorsal ventricular edge in marsh tortoises in conditions of free movement during solving of an extrapolation task (a test of elementary reasoning ability). These changes of a pathological character, accompanied by neurotic states, were observed in some animals having correctly solved the task several times in succession (2-5), beginning with the first presentation. Such changes of EEG and behaviour were not found in tortoises that committed errors at first presentations of the task and only gradually learned correct solving. Formation of the adequate behaviour can proceed by two means: on the basis of elementary reasoning ability and learning. Disturbance of adequate behaviour in the experiment with characteristic changes of EEG testifies to a difficult state of the animal during solving of the extrapolation task.     

Electroencephalogram changes in animals with neurosis as a correlate of metabolic brain disorders

Experiments were made to correlate changes in bioelectrical activity of the brain of different animals (rats, cats, monkeys) with neurosis and its treatment to the time course of the activity of ATPase, one of the most important enzymes of energy metabolism. It was demonstrated that the electroencephalogram (EEG) taken during neurosis is marked by an increase in the total energy of quick-wave components and reduction in the total energy of slow-wave ones in all the structures under study, by the deterioration of the rhythm change response. These changes corresponded with the inhibited activity of brain Na, K-ATPase, particularly of Mg-ATPase. The EEG returned to normal and ATPases were activated after nikogamol injections.     

The intercentral relations of the frontal cortex and limbic structures of the brain in dogs]

In 3 dogs with implanted electrodes, in conditioned experiments correlation of the bioelectrical processes was studied by coherence function calculation of the hippocampus, hypothalamus, amygdala and frontal cortex biopotentials. It was shown, that the level of maximum values of coherence function of bioelectrical oscillations, led from various pairs of the studied brain structures significantly differed both in magnitude and frequency at which the greatest synchronization of biopotentials was noticed. In one dog with a high degree of connection between the hippocampus and hypothalamus biopotentials oscillations, a low synchronization of the frontal cortex and amygdala oscillations was found; in two other animals with a higher level of coherence between the oscillations of the frontal cortex and amygdala biopotentials, a lower degree of connection between the oscillations led from the hippocampus and hypothalamus was revealed. Synchronization of the biopotentials of the hippocampus and frontal cortex and also of the hippocampus and amygdala biopotentials proved to be low in all experimental dogs, what additionally testifies to different role of these structures in organization of the behaviour.     

Effect of learning on EEG characteristics of children during the third year

Characteristics were studied of frequency spectrum and spatial-temporal organization of bioelectrical cerebral activity and also of heart rate dynamics in children of the third year of life in the state of quiet wakefulness and during orienting reaction. Changes were recorded in the parameters of the cerebral activity under the influence of developing learning and in particular of formation of symbolic thinking function. It has been established that the involvement of the child in the process of learning leads to definite shifts of the EEG of quiet wakefulness testifying to acceleration of the process of the CNS functional maturation. Mastering of a high degree of play symbolization causes not only changes in the EEG but also an increase of the child orientating-investigatory activity.     

Neurophysiological analysis of the correction by nootropic substances of disorders in the bioelectric activity of the brain in animals during chronic administration of ethanol

The influence of some drugs (piracetam and 3-oxypyridine derivative) having a nootropic effect on ethanol-induced changes of bioelectrical activity was studied in experiments on freely moving rats. Discontinuation of ethanol administration (1, 2 g/kg, i.p. for 40 days) has been found to provoke destructuring of Fourier's spectral power of sensorimotor cortex and dorsal hippocamp on the EEG. Long-term administration of piracetam or 3-oxypyridine derivative (300 and 50 mg/kg, respectively, i.p. for 40 days) with ethanol has a protective effect and normalizes EEG at the cortical level. The authors discuss possible neurophysiological mechanisms of nootropic drug action in ethanol-induced pathology.     

Relation of the individual specificity of emotional autoregulation controlled by EEG feedback to the influence of a genetic factor as revealed by a twin study

On the model of biofeedback connection by the given parameters of the EEG alpha-rhythm the dynamics of bioelectrical and vegetative characteristics and correlative connections between them were compared in the pairs of mono- and dizygotic twins. More likeness in the dynamics of the studied parameters was found in the pairs of genetically identical monozygotic twins. There was a maximum increase of the objective similarity characteristics in the moment of activity realization, judging by the change of alpha-rhythm parameters. The obtained results testify to genetic determination of individual specific styles in organization of complex integrative processes of the higher nervous activity.     

Synchronized oscillations at alpha and theta frequencies in the lateral geniculate nucleus

In relaxed wakefulness, the EEG exhibits robust rhythms in the alpha band (8-13 Hz), which decelerate to theta (approximately 2-7 Hz) frequencies during early sleep. In animal models, these rhythms occur coherently with synchronized activity in the thalamus. However, the mechanisms of this thalamic activity are unknown. Here we show that, in slices of the lateral geniculate nucleus maintained in vitro, activation of the metabotropic glutamate receptor (mGluR) mGluR1a induces synchronized oscillations at alpha and theta frequencies that share similarities with thalamic alpha and theta rhythms recorded in vivo. These in vitro oscillations are driven by an unusual form of burst firing that is present in a subset of thalamocortical neurons and are synchronized by gap junctions. We propose that mGluR1a-induced oscillations are a potential mechanism whereby the thalamus promotes EEG alpha and theta rhythms in the intact brain.     

Electrophysiological and neuropsychological studies of the functional maturity of the brain cortex in first-graders with different levels of memory development

Visual analysis of the resting EEG revealed features of functional immaturity of cortical rhythmogenesis in a group of children with low parameters of memory. The closest correlations were observed between the neuropsychological parameters of memory and the character of the α rhythm, which confirmed the involvement of α oscillations in neurophysiological mechanisms of mnestic activity.