D. S. Sakharov

Intercentral relations of the human EEG during listening to music

Different musical styles and intensities produce characteristic patterns of changes in the correlation of neocortical biopotentials. Classical music of three intensities and rock music of medium and high intensities were shown to produce asymmetry in the pattern of coherence (Coh) of the cortical activity of listeners: intrahemispheric Coh in the right hemisphere increased, while a decrease in the EEG synchronization prevailed in the left hemisphere. A focus of Coh integration, most pronounced for the γ frequencies, was formed during listening to both classical and rock music (except rock music of a low intensity). Listening to rock music of a low intensity substantially increased the probability of a decrease in intra- and interhemispheric Coh in both hemispheres, which was pronounced in all frequency bands. Listening to rock music changed interhemispheric Coh in a greater percent of cases than listening to classical music.

Spectral analysis of the human EEG during listening to musical compositions

A reorganization of the spectral power (SP) of the human brain potentials takes place during listening to music. The characteristic features of the reorganization depend on the type of the musical composition. Listening to classical music (of low and moderate intensity) produces an increase in the SP of the high-frequency EEG (α2, β1, β2, and γ bands) widely generalized over the brain cortex. Listening to rock music (of moderate and high intensity) produces an increase in the SP predominantly in the θ and α1 frequency bands. There were variations within each EEG pattern caused by different intensity of the music listened to.

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, ϑ, 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.

Influence of music with different volumes and styles on recognition activity in humans.

The efficiency of the recognition of masked visual images (Arabic numerals) increased when accompanied by classical (62 dB) and rock music (25 dB). These changes were accompanied by increases in the coherence of potentials in the frontal areas seen on recognition without music. Changes in intercenter EEG relationships correlated with the formation a dominant at the behavioral level. When loud music (85 dB) and music of other styles was used, these changes in behavior and the EEG were not seen; however, the coherence of potentials in the temporal and motor cortex of the right hemisphere increased and the latent periods of motor reactions of the hands decreased. These results provide evidence that the “recognition” dominant is formed when there are particular ratios of the levels of excitation in the corresponding centers, which should be considered when there is a need to increase the efficiency of recognition activity in humans.

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.

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 T4 and T6. 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 T6 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 O1-P4 and O2-F7, 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.

Solution of Mathematical Logical Problems in a Sensory Enriched Environment (classical music)

Accompaniment of the solution of mathematical logical problems with classical music at levels of 35 and 65 dB led to decreases in problem solution times. Louder music (85 dB) had no significant influence on the problem solution process. Solution of mathematical logical problems without musical accompaniment led to increases in the coherence of potentials in the beta1, beta2, and gamma frequency bands in the occipital areas of the cortex, with a predominance in the left hemisphere. EEG coherence decreased in the frontal area of the cortex. Music decreasing problem solution time induced increases in left-sided EEG asymmetry. Accompaniment of problem solution by classical music increased both intrahemisphere and interhemisphere coherence of potentials in the frontal areas of the cortex. Use of louder music (85 dB) to accompany problem solution induced right-sided EEG asymmetry, and foci of coherence links also often appeared on the EEG of the temporal area of the right hemisphere.

The EEG during Solution of Mathematical Logical Tasks

A model creating a dominant focus in the CNS arising on solution of specially constructed mathematical logical tasks was developed. The dominant state was accompanied by increases in coherence in the delta range. The low-frequency ranges (dealt, theta, alpha) showed increases in combinations of potentials in the frontal cortex. In the high-frequency ranges (beta1, beta2, gamma), coherence decreased in the frontal areas of the cortex, while increases were seen in the central, parietal, temporal, and occipital areas, with a predominance in the left hemisphere. Significant changes in the numbers of connections (increases) were seen in diagonal coherence values. Analysis of EEG spectral power showed that solution of tasks was associated with generalized increases in values in the delta range across the cortex. Theta activity increased in the frontal cortex and gamma activity increased in the occipital areas. Spectral power in the alpha range mainly decreased.

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 β1, β2, and γ 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.

Changes in the latencies of motor responses to visual stimuli presented with musical accompaniment

The effects of music with specific intensity on the latencies of the left or right hand motor responses to visual stimuli have been studied. When the latency of the initial motor response is more than 400 ms, the music accompaniment decreases the latency of the motor response of the left hand. It is supposed that the decrease in the mean latency of the left hand response in subjects who are not professional musicians is related to the activation effect of music on the right hemisphere. Music has no effect when the initial motor responses have shorter latencies.