Spectral analysis of the human EEG while listening to music

EEG was recorded from 16 electrodes (International 10-20 System) in 14 healthy volunteers aged from 18 to 45 in the state of rest and during listening to music (popular classical symphonic pieces). The EEG spectral analysis was carried out. Presentation of musical pieces increased the EEG spectral power in the alpha-range in the parietal and occipital areas of both hemispheres. During repeated listening of the same musical fragment there was a tendency for attenuation of these changes. A significant decrease in the peak frequency of the alpha-band was found in the process of listening. The spectral values did not significantly differ between the left and right hemispheres. The findings suggest a decrease in the level of CNS activation under the influence of music.     

On the informative value of coherence analysis in clinical EEG studies

Within the framework of discussion about the informative value of the method of coherent analysis, results of successful clinical application of this method of EEG processing in different morbid conditions are reviewed. Not denying the theses proposed by the opponent about the imperfection of methodological maintenance of the EEG coherent analysis and incompatibility of the results received with different software, the ways of overcoming these difficulties are specified. First of all, it is offered to unify procedural conditions of the technique. The thesis of the opponent that calculation errors are influenced by hypothetical "noise" (all signals of the environment) is regarded skeptically, as it could not be found in patients with "zero" coherence with the diagnosis of brain death. Some doubts are cast upon the prospect of replacement of the coherent analysis with an artificial envelope of the modulated groups of waves in assessment of synchronous processes of the brain. It is concluded that all technological and methodological problems of application of the EEG coherent analysis existing now can be overcome.     

Universality in the brain while listening to music.

The human brain, which is one of the most complex organic systems, involves billions of interacting physiological and chemical processes that give rise to experimentally observed neuroelectrical activity, which is called an electroencephalogram (EEG). The presence of non-stationarity and intermittency render standard available methods unsuitable for detecting hidden dynamical patterns in the EEG. In this paper, a method that is suitable for non-stationary signals and preserving the phase characteristics and that combines wavelet and Hilbert transforms was applied to multivariate EEG signals from human subjects at rest as well as in different cognitive states: listening to music, listening to text and performing spatial imagination. It was found that, if suitably rescaled, the gamma band EEG over distributed brain areas while listening to music can be described by a universal and homogeneous scaling, whereas this homogeneity in scale is reduced at resting conditions and also during listening to text and performing spatial imagination. The degree of universality is characterized by a Kullback-Leibler divergence measure. By statistical surrogate analysis, nonlinear phase interaction was found to play an important role in exhibiting universality among multiple cortical regions.     

Gender-related differences in EEG coherence in Stroop task

Gender-related differences in EEE coherence were studied in young male and female university students during performance of Stroop task, in which color and word could be congruent or incongruent and spatially integrated or separated. The most clear-cut gender-related differences in the EEG coherence were revealed in the alpha2 and beta frequency bands. In the alpha2 band, gender-related differences in the interhemispheric coherence were associated with spatial characteristics of stimuli: left or right presentation and features of mutual localization of relevant and irrelevant stimuli. These differences were observed when information was addressed to the left hemisphere. Gender-related differences associated with spatial organization of stimuli were also observed for intrahemispheric beta1 coherence. Under conditions of the spatial separation of relevant and irrelevant stimuli, only females demonstrated enhancement of coherence in response to the right-side stimulus presentation as compared to the left-side presentation. It was shown that, during the differentiation of the semantic meaning of verbal stimuli, gender-related differences were caused by the features of integration of beta2 oscillators in the posterior cortical regions. The results are indicative of qualitative gender-related differences in organization of both frontoparietal and lateral attention systems in actualization of selective processes.     

Congenital amusia persists in the developing brain after daily music listening

Congenital amusia is a neurodevelopmental disorder that affects about 3% of the adult population. Adults experiencing this musical disorder in the absence of macroscopically visible brain injury are described as cases of congenital amusia under the assumption that the musical deficits have been present from birth. Here, we show that this disorder can be expressed in the developing brain. We found that (10-13 year-old) children exhibit a marked deficit in the detection of fine-grained pitch differences in both musical and acoustical context in comparison to their normally developing peers comparable in age and general intelligence. This behavioral deficit could be traced down to their abnormal P300 brain responses to the detection of subtle pitch changes. The altered pattern of electrical activity does not seem to arise from an anomalous functioning of the auditory cortex, because all early components of the brain potentials, the N100, the MMN, and the P200 appear normal. Rather, the brain and behavioral measures point to disrupted information propagation from the auditory cortex to other cortical regions. Furthermore, the behavioral and neural manifestations of the disorder remained unchanged after 4 weeks of daily musical listening. These results show that congenital amusia can be detected in childhood despite regular musical exposure and normal intellectual functioning.     

Spectral and coherence EEG analysis of rats differing in the level of seizure readiness

The resting EEGs of several brain structures (motor and visual cortex, caudate nucleus and intralaminar thalamic nuclei) were submitted to spectral and coherence computer analyses in two rat strains. Genetically predisposed to convulsive state KM rats were shown to differ from nonpredisposed Wistar rats in EEG spectral properties. KM rats EEG pattern was characterized by increase of low frequencies (1-2 Hz) power and decrease of faster activity (5-12 Hz) power in cortical spectrograms as well as by decrease of caudate nucleus EEG absolute power. The coherence value between cortical or subcortical structures at below 4 Hz was intensified in KM rats. Reinforcement of cortical auto-oscillating properties manifested by ECoG synchronization in cortical-thalamic resonance interaction as well as weakening of striatal inhibitory system may constitute neurophysiological mechanisms of enhanced convulsive readiness. The probable role of mediator imbalance in these mechanisms is discussed.     

Correlation between the EEG coherence and recognition of emotions in speech

Analysis of the EEG in 2 extreme groups: subjects with high and low indexes of identification of emotional intonation, was carried out. The number of pairs of electrode sites with significant differences in coherence was compared at rest and during the emotion identification task in 6 standard frequency bands. The data revealed that, in general, coherence is higher in the group with low identification rates.     

Neurodynamic evaluation of hearing aid features using EEG correlates of listening effort

In this study, we propose a novel estimate of listening effort using electroencephalographic data. This method is a translation of our past findings, gained from the evoked electroencephalographic activity, to the oscillatory EEG activity. To test this technique, electroencephalographic data from experienced hearing aid users with moderate hearing loss were recorded, wearing hearing aids. The investigated hearing aid settings were: a directional microphone combined with a noise reduction algorithm in a medium and a strong setting, the noise reduction setting turned off, and a setting using omnidirectional microphones without any noise reduction. The results suggest that the electroencephalographic estimate of listening effort seems to be a useful tool to map the exerted effort of the participants. In addition, the results indicate that a directional processing mode can reduce the listening effort in multitalker listening situations.     

Interhemispheric EEG interrelations in recognition of masked visual images accompanied by music

Changes in the EEG depend on the style of accompanying music. Classical music produces more patterns with increased diagonal coherences in the γ frequency band, where two foci of integration are formed at points T ₄ and T ₆. During listening to rock music, a larger proportion of all changes occurred in the θ-and α₁ frequency bands; an integration focus was formed at point T ₆ in the α₁ and γ frequency bands. An increase in diagonal coherences that was observed during the recognition was especially pronounced in the Δ-, θ-and α₁ frequency bands. In addition, there was an increase in the coherence between the potentials recorded at points O ₁-P ₄ and O ₂-F ₇, and it was observed in all the frequency bands. During the recognition of masked visual images accompanied by classical or rock music, there were more patterns with an increased diagonal coherence of the currently dominant activity. Before erroneous recognition, a widely generalized increase in coherence over the brain cortex was observed in the Δ, θ, and α₁ bands, which was an informative indicator of the subsequent erroneous recognition. In tests with recognition unaccompanied by music, as well as with music, the main change in symmetrical coherences was either a decrease in or an absence of changes in this indicator versus the background value.     

The human EEG in recognition of noisy visual images accompanied by music

The recognition of noisy visual images (Arabic numerals) carried out under the conditions of recognition accompanied by classical or rock music of a specified power improves the recognition. When music-accompanied recognition of visual images is carried out, the structure of coherent relations (their number and significance level) observed during recognition without musical accompaniment is activated and the left-sided asymmetry of the coherence values is also retained (instead of the right-sided asymmetry, which appears in response to music alone). In other words, when the recognition dominant is formed at the behavioral level, changes in the spatial organization of the neocortical electrical processes also seem to follow the dominant principle.     

Changes in EEG coherence during tests for nonverbal (Figurative) creativity

Brain neurodynamics was studied by the EEG method during the performance of a task for figurative (or imaginative) creativity. The EEG was recorded in 19 standard derivations according to the international 10–20 system in 30 subjects. The following creative tasks were presented to subjects to involve them in the creative process: (Crl) thinking up and drawing an original picture; (Cr2) drawing a face, a house, and a clown in an original manner; (C1) drawing a picture from memory; and (C2) drawing geometric figures without any system. All the tasks had to be performed using a given set of geometric figures (a circle, semicircle, triangle, and rectangle). Statistical analysis of the EEG coherence function in these states for the frequency bands Δ, θ, α₁, α₂, β₁, β₂, and γ showed that the performance of creative and control tasks was associated with significant coherence changes in all the EEG frequency bands. As compared to the control tasks, performance of creative tasks caused an increase in the coherence of the α₁-and α₂ bands, more pronounced when creative tasks were compared with the second control task. In addition, the performance of the creative tasks (as compared to the control tasks) was accompanied by a decrease in the interhemispheric coherence of high-frequency rhythms (β₂ and γ) and an increase in the intrahemispheric coherence of these rhythms. The findings are compared to the results of previous EEG studies on creative activity.     

Interhemispheric interactions in right- and left-handed individuals based on EEG coherence data

The functions of interhemispheric EEG coherence were analyzed in 12 healthy subjects with the right individual profile of motor and sensor asymmetry and 7 subjects with the left profile in 2 experimental conditions: the state of rest and photostimulation of the central visual field. It was shown that in the rest condition the right-handed subjects have the higher values of EEG coherence in the thetal band in symmetrical frontal and central areas than the left-handed. These differences decreased for the frontal and central areas during activation caused by photostimulation but increased in the theta 2 and betal bands in symmetrical temporal areas (the coherence in the left-handed being higher). The difference in the EEG coherence between conditions was greater for the frontal and central areas in the right-handed than in the left-handed, especially, for the theta 1 and theta 2 bands. These findings suggest that the left-handed subjects have a less developed hierarchy of subcortical control of the functional state shifts than the right-handed.     

Functional regional asymmetry of the EEG intrahemispheric coherence in dogs during conditioning

Individual features of the regional interhemispheric relations in the brain were studied in dogs during alimentary conditioning. The electrical activity was recorded from symmetrical anterior (frontal and motor cortices) and posterior (visual and auditory cortices) areas of the neocortex. Comparison between the averaged left and right intrahemispheric EEG coherences revealed a dynamic character of interhemispheric relations dependent on the stage of conditioning. Individual features were shown. In a dog with strong type of the nervous system, in the anterior brain regions, the EEG coherence was higher in the left hemisphere than in the right one, whereas, on the contrary, in the posterior regions, the values were higher in the right than in the left hemisphere. In dogs with weak type of the nervous system, there was an inverse relationship. Thus, the spatial organization of the cortical electrical activity in the associative and projection brain areas was different.