Influence of music on the solution of mathematical logical tasks

Musical accompaniment (of different styles and intensities) of the solution of mathematical logical tasks influenced the time required for their solution. Classical music 35 and 65 dB and rock music 65 and 85 dB in terms of loudness decreased the time of the solution. Louder classical music (85 dB) did not have this effect. Solution of tasks without musical accompaniment led to an increase in coherent values, especially in ??₁, ??₂, and ?? the frequency bands in the EEG of the occipital cortex. The intrahemispheric and interhemispheric coherences of frontal EEG increased and EEG asymmetry (in the number of Coh connections in the left and right hemispheres) arose during the solution of the tasks accompanied by music. Classical music (35 and 65 dB) caused left-side asymmetry in the EEG. The use of more powerful classical or rock music led to a prevalence of the number of Coh connections in the right hemisphere.     

EEG dynamics during conditioning in symmetrical neocortical regions in dogs

Changes in the frequency of the EEG recorded in symmetrical areas of the frontal and auditory cortices were studied during food conditioning in four dogs. Spectral-correlation analysis was applied. EEG frequency changes depended on individual features of the animals, frequency band, and stage of conditioning. In the beta-2-range, the EEG frequency increased in comparison to the initial values in all the dogs. In three dogs, the EEG frequency in the beta range decreased in the frontal and increased in the auditory cortex. Heterodirectional frequency changes led to the development of the functional interhemispheric EEG asymmetry that was partial and dynamic. At the initial stages of conditioning higher activity was in the left hemisphere, later on asymmetry was absent (or activity of the right hemisphere predominated).     

EEG in mathematical logical problem solving

The model of mathematical logic tasks was developed at which decision there was a value coherence in delta-range raised. In low-frequency ranges (delta, theta, and alpha) a coherence of potentials of frontal cortex were increased. In high-frequency ranges (beta1, beta2, gamma) in frontal cortex coherence was decreased, and its increasing in central, parietal, temporal, and occipital areas with prevalence in the left hemisphere. Most changes of quantity of positive connections observed in value diagonal coherence. Analysis of spectral power EEG has shown, that at the decision of tasks there is a generalised raising on a cortex in delta-range. Theta-activity increased in a frontal cortex, and gamma band was raised in occipital areas. A spectral power in an alpha range mainly decreased.     

The locked-in patient and the characteristics of the electrical activity of his brain

"Locked-in" state differs from the known states characterized by the motor activity blockade, preservation of conscience of speech contact, despite the fact that connection with outer world during this state is limited only by vertical movements of eyes and eyelids in response to speech signals. Three "locked-in" men were studied at different stages of development of this state. Spectral-coherent analysis of the EEG was conducted. The most typical for the developed state of the "locked-in" man is a uniform change of the intercentral EEG relations. In the motor areas of the cortex alpha-activity and its links are not formed (coherence in alpha-range is zero) while high and low frequencies are coherent. In the visual areas, in contrast, the alpha-rhythm is coherent. Distinct interhemispheric asymmetry of coherent connections appears. In the right hemisphere a decrease of coherence level is sharp and even, in the left one--in occipito-temporal parts the level remains close to norm, while in the frontal parts of the cortex it decreases.     

Functional asymmetry of electric processes in the rabbit brain cortex at formation of the hunger dominant

The motivational condition of hunger and formation of the hunger dominant after daily food deprivation was studied in the conditions of chronic experiments on rabbits. It was shown, that the hunger condition was accompanied by left sided interhemispher asymmetry on indicators of spectral capacity of EEG frontal and right-hand asymmetry sensorimotor areas of the cortex. A hunger dominant was accompanied by falling of spectral capacity of EEG of areas of both hemispheres. The condition of hunger and a hunger dominant were characterized by right-hand asymmetry on average level of EEG coherence of frontal and sensorimotor areas. At transition of a condition of hunger in a hunger dominant there was an average level of EEG coherence decrease in areas of the right hemisphere. Electric processes of the cortex of the brain at a motivational condition of hunger and a hunger dominant were different.     

EEG characteristics determining the quality of subsequent recognition of visual images

Recognition of noisy pictures of Arabic numerals was accompanied by an increase in EEG coherence in the frontal cortical regions, especially in the left hemisphere, and between the frontal and occipital areas in both left and right hemispheres. Coherence values decreased in the temporo-centro-occipital areas of both hemispheres. A correlation was found between the coherence pattern in the prestimulus period and the quality of subsequent activity. Correct recognition was preceded by left-side asymmetry of the EEG coherence. Before erroneous recognition, EEG coherence levels were higher than before a correct response, and the increase in coherence was widely generalized over the cortex (especially in the Δ, ?, and α₁ frequency bands). The frequency of expression of an increased integral EEG coherence was higher before erroneous recognition than before a correct response. These changes in coherence were symmetrical.     

Gender differences in EEG coherent activity before and after training navigation skills in virtual environments

Gender differences in electroencephalographic activity (EEG) changes during navigation task performance after training were assessed in young adults. Female and male subjects were matched on initial navigation performance. EEG recordings were obtained while subjects navigated in an immersive virtual environment without visual cues, before and after a navigational skills training (9 sessions). In spite of task performance was similar in both groups, females showed higher theta band coherent activity between frontal and parietal and frontal and central regions than males before training. Correlation in theta band between fronto-central, fronto-parietal, and centro-parietal regions was enhanced in the left hemisphere for females but in the right hemisphere for males after training. Females also demonstrated a decreased in correlation in theta band over the right hemisphere between centro-parietal regions, whereas males demonstrated a similar effect over the left hemisphere. Navigation training seems to promote fronto-central-parietal synchronization in both genders but in different hemisphere. These results are interpreted as reflecting verbal-analytical working memory functions in females and global-spatial working memory mode in males.     

Change in parameters of interhemispheric asymmetry during simulation of a destructive action

Interhemispheric EEG asymmetry was studied in 26 male subjects aged 8-23 with different behavioral destructiveness levels. Subjects with higher destructiveness level in the state of rest had the focus of interhemispheric asymmetry in the temporal and frontal areas of the left hemisphere, whereas in subjects with lower destructiveness level the asymmetry focus was found in the same areas of the right hemisphere. Simulation of aggressive activity led to displacement of the asymmetry focus to the right hemisphere in both groups. However, in the group with higher destructiveness the changes in the focus were observed in the EEG theta band, which suggested the involvement of mainly stem oscillators of EEG activity in the destructive behavior. In the group with lower destructiveness changes were observed mainly in the alpha3 and beta1 bands, which indicated that cortical oscillators of EEG activity were involved in the control of the destructive behavior. The results suggest better perception and assessment of stimuli by subjects with lower aggressiveness and their choice of more adequate models of behavior.     

Effect of music on the latency recognition of even and odd numbers

Studied influence of music of certain intensity on latency recognition of even and odd numbers with participation of the left and right hand accordingly. Music accompaniment decreased the latency recognition more pronounced with participation of the left hand that, apparently, is connected with activated influence of music on the right hemisphere at the people who are not professional musicians. Increase of efficiency of recognition in music accompaniment is considered as realisation of a principle of a dominant.     

Characteristics of disturbances of intercortical and cortical-subcortical integration in various clinical forms of neurotic depression

Cross-correlation, coherent, and factor analyses of the EEG were used to detect disturbances of spatial organization of brain bioelectric activity, with certain specific features determined by concomitant anxiety and asthenia syndromes in 20 patients with various clinical forms of neurotic depression. In the group of patients with dominance of the depressive syndrome without marked symptoms of asthenia or anxiety, opposite changes in the anterior areas of the right and left hemispheres were found; the interregional relationships of the EEG of anterior areas of the right hemisphere were decreased as compared to the norm, while the normal level of systemic interaction of bioelectric potentials of the cortex of the left hemisphere was increased. In patients with the depressive syndrome combined with increased anxiety, as well as in patients with distinct asthenic symptoms, a considerable decrease in the level of interregional interactions of bioelectric potentials in frontal regions of the cortex of both hemispheres was detected. This was accompanied by an increase, as compared to the norm, of the level of distant relationships of the EEG in posterotemporal, parietal, and occipital regions. The data indicate that, in the case of neurotic depression, irrespective of concomitant anxiety and asthenia syndromes, there is transient inhibition of the functional activity of frontal regions along with an increased rigidity of systemic interactions of the posterior regions of the cortex of both hemispheres. This suggests that neurotic depression is accompanied by dysfunction of intercortical and cortical-subcortical integration, which causes a disturbance of the systemic organization of ordered interactions of the activity of the anterior and posterior regions of both hemispheres, with certain specific features in patients of each group.     

Interhemispheric EEG asymmetries during unilateral bright-light exposure and subsequent sleep in humans

We tested whether evening exposure to unilateral photic stimulation has repercussions on interhemispheric EEG asymmetries during wakefulness and later sleep. Because light exerts an alerting response in humans, which correlates with a decrease in waking EEG theta/alpha-activity and a reduction in sleep EEG delta activity, we hypothesized that EEG activity in these frequency bands show interhemispheric asymmetries after unilateral bright light (1,500 lux) exposure. A 2-h hemi-field light exposure acutely suppressed occipital EEG alpha activity in the ipsilateral hemisphere activated by light. Subjects felt more alert during bright light than dim light, an effect that was significantly more pronounced during activation of the right than the left visual cortex. During subsequent sleep, occipital EEG activity in the delta and theta range was significantly reduced after activation of the right visual cortex but not after stimulation of the left visual cortex. Furthermore, hemivisual field light exposure was able to shift the left predominance in occipital spindle EEG activity toward the stimulated hemisphere. Time course analysis revealed that this spindle shift remained significant during the first two sleep cycles. Our results reflect rather a hemispheric asymmetry in the alerting action of light than a use-dependent recovery function of sleep in response to the visual stimulation during prior waking. However, the observed shift in the spindle hemispheric dominance in the occipital cortex may still represent subtle local use-dependent recovery functions during sleep in a frequency range different from the delta range.     

Gender differences in resting EEG related to Eysenk's Personality Traits

EEG mapping was used to study gender differences in hemispheric organization related to personality (40 male and 42 female subjects, the students 17-20 ages). The results showed, that each clearly defined personality trait (neuroticism, extraversion, psychoticizm and social conformity) characterized by special EEG pattern differenced on men and women groups. At the same time, more close interaction of gender and neuroticism was observed, but gender and extraversion were less connected. Neuroticism related patterns of coherence in the alpha2- and beta2-bands were associated with an activity changes in anterior cortex in men but posterior--in women, at that the positive correlations were observed in the beta2-band in the former case and negative ones in the second. There are two opposing tendencies of the interaction between extraversion and gender in a modulation of the resting theta-rhythm: an increase of cortex connections in men and decrease ones in women. The specificity of spatial-temporal EEG patterns in men associated mostly with a psychoticizm value but in women--with a social conformism. In either case these personality traits related to activity of frontal cortex in the left hemisphere.     

Functional asymmetry of the neocortex electrical activity during food conditioning in dogs

Four dogs were trained to perform a conditioned alimentary response to a sound stimulus. The EEG was recorded from six pairs of chronically implanted neocortical electrodes. The EEG spectra and coherence functions between the neighboring derivations of each of the hemispheres were analyzed in the theta, alpha, beta 1 and beta 2 frequency ranges. At the first stages of conditioning, the percent of cases increased when the highest mean values of EEG frequency were localized in the left hemisphere. Later on the percent of cases, when the mean coherence values in the left hemisphere were higher than in the right hemisphere, also increased. At the stage of conditioned response stabilization, this asymmetry either disappeared or the right hemisphere became more active than the left one. The spatial localization of the maximal values of the EEG frequency was different for different frequency ranges. The highest values in the beta 1 range were more frequently registered in the posterior cortical regions and in the beta 2 range they were revealed, predominantly, in the anterior areas. The maximal values of coherence dominated in the anterior regions and their spatial distribution was similar for different frequencies. Thus, the initial stages of conditioning are accompanied by activation of the left hemisphere.     

EEG coherence analysis in music listening

Changes in EEG coherence were studied in subjects without special musical education when they were listening to low classic music (below 30 dB). The numbers of significant changes in coherence function in the left and right hemispheres were different. Predominant increase in coherence in the alpha 2, beta 1, and beta 2 frequency ranges was observed in the right temporal-central and parietal-occipital cortical areas. The left-hemispheric coherence was predominantly, decreased on the account of its decrease in the alpha range.     

Asymmetry of the bioelectrical activity of the human brain at different levels of consciousness

Asymmetry of different human EEG indices was studied at different levels of consciousness. Subjects' self-reported changes in the content of consciousness: the intensity and quality of involuntary mental processes served as indicator of the level of consciousness. It was shown that a certain profile of EEG asymmetry corresponded to each the observed level of consciousness. In active state of consciousness, the connections in the high-frequency bands: beta-2 and gamma, were more pronounced in the left hemisphere of the brain. At the same time, transition of the focus of coherent connections to the right hemisphere was characteristic of the state of inhibition of "internal speech". The interhemisphere dynamics of autospectra amplitude and foci of coherent connections supports the notion that the character of interhemisphere asymmetry of the brain bioelectrical activity depends on its functional state.     

Hemispheric asymmetry of visual evoked potentials during human recognition of facial emotional expressions

Visual evoked potentials (VEP) in standard 16 EEG derivations were recorded in 26 young men and 20 women during recognition of facial emotional expressions and geometric figures. The stimuli were presented on a computer screen in the center of the visual field or randomly in the right or left vision hemifields. Peak VEP latency and mean amplitude in 50-ms epochs were measured; spatiotemporal VEP dynamics was analyzed in a series of topographic maps. The right hemisphere was shown to be more important in processing emotional faces. The character of the asymmetry was dynamic: at earlier stages of emotion processing the electrical activity was higher in the right inferior temporal region compared to the left symmetrical site. Later on the activity was higher in the right frontal and central areas. The dynamic mapping of "face-selective" component N180 of VEPs revealed the onset of activation over the right frontal areas that was followed by the fast activation of symmetrical left zones. Notably, this dynamics didn't correlate with the hemifield of stimuli exposition. The degree of asymmetry was lower during presentation of figures, especially in the inferior temporal and frontal regions. The prominent asymmetry of information processes in the inferior temporal and frontal areas was suggested to be specific for recognition of facial expression.     

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.     

Changes in spectral coherent characteristics of EEG in the early postpartum period in mothers with anxious and depressed mood

Postpartum EEG spectral and coherence characteristics were estimated in mothers with or without postpartum depressions. In mothers without affective disorders the power of oscillations in the delta, theta, and alpha 1 frequency bands was increased as compared to controls. Intrahemispheric EEG coherence between the left frontal and adjacent derivations in the delta and theta bands and interhemispheric coherence in the central areas was increased and decreased over the remaining cortical surface. These changes led to a significant decrease in EEG asymmetry. It is suggested that during normal postpartum the influence of the limbicodiencephalic and lower brainstem structures on the cortex is augmented and a certain kind of dominanta is formed. In mothers with postpartum depressions the EEG alpha-band power was lower than in the control and normal groups, coherence changes in the delta and theta bands diminished the EEG asymmetry. The insufficiency of limbicodiencephalic influence and impairment of adaptive brainstem reactions are suggested to be responsible for problems in the formation of maternal dominanta, which results in the development of postpartum depressions.     

The influence of eye dominance on saccade characteristics and slow presaccadic potentials

Characteristics of saccades and presaccadic slow potentials were studied in 36 right-handed men with right (the RE group) and left (the LE group) eye dominance. Three light-emitting diodes located in the center of the visual field (the central fixation stimulus, CFS) and 10 deg to the left and to the right of the center (peripheral stimuli, PSs) were used for stimulation. The subjects performed a task with simple saccades to a PS and a task with antisaccades to the horizontal mirror position of the PS. Monopolar EEGs at 19 derivations and electrooculograms (EOGs) were recorded. Back averaging of the EEG time-locked to the PS onset or the saccade onset was used to obtain slow presaccadic potentials. The saccade characteristics in the RE and LE groups were similar. Differences between them were found only in the antisaccade task. The amplitude of negative presaccadic potentials (NPPs) time-locked to the PS in the frontal cortex was lower in the LE group compared to the RE group. Analysis of potentials time-locked to the saccade onset showed that changes in the slow potentials during the last 50 s before the saccade depended on the saccade direction and reflected the activation of the hemisphere opposite to the saccade direction. The activation of the right hemisphere before left-side saccades was higher in the LE than the RE group. In addition, the amplitude of NPPs was decreased in the frontal area and increased in the left posterior temporal area in the LE group compared to the RE group. The obtained results indicate that the involvement of the frontal cortex in cognitive and motor processes is decreased in subjects with the left eye dominance.     

Spectral-correlation characteristics of the electrical activity of the brain of the rabbit in a state of calm wakefulness

Inter- and intrahemispheric relations of electrical activity of the pre-motor, sensorimotor (representation of forelimb and blinking) and visual zones of rabbit's cerebral cortex in calm alertness was studied by method of spectral-correlative analysis. Mean coherence levels of the EEG of tested hemispheric symmetric points and symmetric pairs of leads in the left and right hemispheres were characterized by a high temporal stability in the state of calm alertness and during sensory stimulation. A comparison of mean coherence values of EEG in symmetric leads, revealed a tendency to left-side dominance of statistical bonds of electrical processes. A tendency was shown towards interhemispheric asymmetry by mean parameters of EEG power spectra: the left hemisphere of the rabbit is characterized by a lower mean frequency of electrical activity and a more narrow effective frequency of the spectrum.