Zh. V. Nagornova

Comparison of the effects of the subjective complexity and verbal creativity on EEG spectral power parameters

The EEG recording was made when the subjects performed tasks that involved overcoming the stereotype (creative) and retrieving information from memory (noncreative) with the usual and complicated presentation of the initial material (incomplete proverbs and sayings without concluding words). The subjective complexity of the task performance under different conditions was assessed. The EEG power from 19 EEG derivations was compared in the β2 and γ frequency bands. The creative task performance was associated with a marked increase in the EEG power; significantly more complicated noncreative tasks were not accompanied by marked changes in the EEG power in these bands.

Changes in the power and coherence spectra of the EEG rhythmic components during solution of a verbal creative task of overcoming a stereotype

Changes in EEG power and coherence were analyzed in 117 subjects during the performance of the creative task of finishing well-known proverbs in a new way, so as to change, if possible, their meaning, and the noncreative task of recalling the original (well-known) version of the end of each proverb. A characteristic feature of the creative task was that proverbs and sayings are stereotypes fixed in a memory matrix. During the task performance, the EEG was recorded in 19 derivations according to the international 10–20 system. Performance of the creative task was accompanied by a highly significant and reproducible increase in the power of the γ and β2 EEG frequency bands, as well as a less pronounced decrease in the power of the ϑ band in the central and parietoccipital cortical areas. In addition, the performance of the creative task was also characterized by an increase in the EEG coherence in the α2, β2, and γ bands. No gender-related differences were found in the patterns of EEG changes.

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.

Changes in the EEG power during tests for nonverbal (figurative) creativity

The EEG was recorded in 19 standard derivations according to the international 10–20 system in 30 subjects during a test for figurative creativity. To involve subjects in the creative process, they were presented with the following creative tasks: (Cr1) 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 spectral power for the frequency bands α1, α2, β1, β2, and γ showed that the creative task performance was characterized by an increase in the EEG power in the β2 and γ bands and single differently directed power changes in the α1, α2, and β1 bands. The findings were compared to previous results of EEG studies on creative activity.

EEG pattern decoding of rhythmic individual finger imaginary movements of one hand

The results of four-class classification of the motor imagery EEG patterns corresponding to the right hand finger movements (little finger, thumb, index and middle fingers) of eight healthy subjects are presented in this study. The motor imagery of individual right-hand finger movements was executed by the subjects in a prescribed rhythm and the trials contained no external stimuli. Classification was performed by means of a specially developed two-level committee of classifiers on the basis of support vector machine and artificial neural networks at the first level and by generalizing an artificial neural network at the second level. The area under the EEG signal curve and the curve length calculated in a sliding time window for sites F3, C3, and Cz of the International 10?20 System were selected as the key features of signals from the sensorimotor and adjoining frontal cortical areas contralateral to the movements. The average accuracy of four-class singletrial classification for all subjects was 50 ± 7 [SD] (maximum, 58%) for the pair of sites F3–C3 and 46 ± 11% [SD] (maximum 62%) for the pair of sites C3–Cz with a theoretical guessing level 25%.

Passive perception of auditory stimuli in healthy and mild mentally retarded adolescents from Northern Russia

Event-related potentials (ERPs) during passive perception of auditory stimuli were studied using the oddball paradigm in healthy and mild mentally retarded adolescents. The study involved 25 subjects aged 11–15 (13.1 ± 1.4) years from Northern Russia, including Arctic regions. The peak latency of the difference wave for deviant and standard stimuli in frontal central derivation was 129 ± 21 ms in the healthy children, and the mean amplitude was–2.6 ± 1.3 μV. In the mentally retarded group, a negative peak of the difference wave was observed only in 9 out of 13 adolescents, its latency was more than in the healthy adolescents (156 ± 29 ms), and the mean amplitude was–2.1 ± 1.4 μV. Differences in perception of deviant and standard stimuli were observed in the healthy adolescents, in particular, along the central line. In the adolescents with mental disorders, there was no significant difference in the fronto-central and central derivations. A discriminant analysis of the amplitudes of ERP components observed in the fronto-central derivations in response to deviant stimuli and the difference in amplitude between ERPs evoked in the fronto-central derivation by standard and deviant stimuli differentiated the adolescents with and without mental disorders. Based on the findings, ERP components in the oddball paradigm were assumed to provide potential markers of disorders in mental development.

Assessment of the Parameters of Cognitive Potentials in Adolescent Northerners in Health and Developmental Delays

Components of event-related potentials (ERP) were studied using an active sound signal discrimination task in northern schoolchildren aged 12–18 years with impaired mental development and learning difficulties (IQ 65 ± 4) and without mental developmental impairments (IQ 90 ± 10). The peak latency of the P300 component in the central and parietal areas of the cortex on perception and discrimination of target sound stimuli was greater in northern children with impaired mental development (Cz 370 ± 36 msec, 8.8 ± 4.1 μV; Pz 375 ± 39 msec, 10.2 ± 3.3 μV) as compared with their normally developing peers (339 ± 28 msec, 10.4 ± 3.0 μV; 340 ± 35 msec, 12.2 ± 2.2 μV, respectively). Negative correlations were found between cognitive abilities, the accuracy and speed of information processing in an attention task, and the latency of the P300 component, with positive correlations with the amplitude of the P3 component for measures of attention. The spatial, temporal, and amplitude characteristics of ERP in adolescents with impaired mental development reflect the functional incompetence or immaturity of the hierarchical organization of the system processing and discriminating information arriving in the brain and requiring concentration of attention and decision-taking.

Analysis of Age-Related Dynamics and Gender-Specific Characteristics of Spontaneous Bioelectrical Activity and Components of Auditory Evoked Potentials in Junior School Students Living in the Arctic Region of the Russian Federation

We studied neurophysiological characteristics of the age-related development in junior school students (7–8 and 10–11 years of age) living in the Arctic region of the Russian Federation. The background electroencephalograms (EEGs) were recorded during quiet wakefulness with the eyes closed and open, and event related potentials (ERP) were recorded during the passive perception of sound stimuli within the oddball paradigm in the group of children (33 subjects, 18 boys and 15 girls). A decrease of the latency period and the spatial rearrangement of mismatch negativity with an increase in the amplitude in the centrofrontal cortex have been revealed in the groups of children aged 10–11 years during the perception of a rare stimulus and a decrease of the latency period of the Р300 component in the central and parietal areas associated with the maturation of mechanisms for involuntary auditory attention. Age-specific differences in the components of auditory ERP (N1 and N2) have been shown during passive perception of rare and frequent sounds, which reflect the processes of the morphofunctional maturation of the brain cortex in healthy Arctic school students (an increase of the N1 component amplitude, a decrese of the amplitude and the latency period of the N2 component). The analysis of the background EEG characteristics has shown both the common features, such as a decrease with age of the EEG power in the Δ and θ bands in the eyes-open state, and the different direction and topographic specificities in the age-dependent reorganization of bioelectrical activity in boys and girls in the α1 and α2 EEG bands.

Mechanisms of Reading in Persons with Different Levels of Written Text Comprehension

The aim of the present study was to investigate the reading mechanisms in adults (27 subjects; mean age, 19.5 ± 0.8 [SD] years) with different levels of written text comprehension using fMRI. The main objective was to analyze the basic brain mechanisms of verbal stimuli perception with and without semantic component during reading discrimination tasks. The BOLD signal changes during WORD and PSEUDOWORD reading comparing to GAZE FIXATION state were estimated using both analysis of whole brain activation and ROIs (structures connected with the brain system providing reading) in two groups of subjects, “good” and “poor” readers. It was revealed that activations were higher in “poor” readers in lingual gyrus, SMG, STG compared to “good” readers during PSEUDOWORD reading. It was supposed, that the strategies of words and pseudowords recognition differed in two groups of readers: “good” readers identified words or pseudowords already at the stage of visual analysis of “word” structure and demonstrated attempts to decode pseudowords (i.e., language lexical zones were not activated); “poor” readers, apparently, tried to read pseudowords using the same strategy as for the words reading referring to the lexicon, and after failure identified pseudowords as meaningless concepts. In that case, activations of both lexical “language” zones and visual word form area (VWFA) were observed.

Age-specific characteristics of EEG coherence in children and adolescents living in the European North of Russia

The article, based on the investigations carried out in 91 school students aged 7–18 years who were exposed to severe weather conditions as residents of the European North of Russia, analyzes the processes underlying the development of structures for providing the spatial synchronization of cerebral bioelectric potentials. The coherence values were evaluated for 19 channels (171 pairs of leads) in five basic EEG frequency bands (Δ, θ, α1, α2, and β). The article describes the age-related dynamics, gender-specific features, and topical specificity in the development of coherent connections in the left and right cerebral hemispheres, as well as in the formation of interhemispheric and interregional connections. We used a computerized evaluation technique for distinguishing between three school age groups of northerners using the frequency structure of EEG coherence with the purpose of elaborating some criteria for diagnosing school students with a developmental delay in the formation of spatial organization for the interaction of local EEG processes. The recorded age-related changes in the EEG-pattern structure reflect the pattern of morphofunctional brain development in children and adolescents exposed to the severe conditions of the North at different stages of their postnatal ontogenesis.