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 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.     

The reflection of different aspects of brain activation in the electroencephalogram: Quantitative electroencephalography of the states of rest with the eyes open and closed

The rest states with the eyes open (RSEO) and closed (RSEC) were subjected to quantitative EEG study as states similar in the pattern of mental activity and subjective assessments but different in the EEG pattern. The mean values of the spectral power and EEG coherence function were compared in 74 subjects for the following bands: Δ, ?, α₁, α₂, β₁, β₂, and γ. Upon the transition from the RSEC to the RSEO, the EEG local power significantly decreased over the whole cortex for the α, ?, and β bands. A simultaneous decrease in the EEG power in all the bands (including β and γ) was most pronounced (as judged by relative changes and tests of significance of difference) in the parietooccipital derivations immediately related to the cortical zones where an increase in the neuronal activity upon opening the eyes is most probable. A significant increase in the EEG power was observed only for the γ band in frontal derivations F ₃ and F ₄. Significant differences in the mean EEG coherence in the RSEO-RSEC comparison were present in many derivation pairs, especially in the α₂, β₁, β₂, and γ bands. For each of these bands, the number of differences determined on the basis of Fisher test was more than 70% of the maximum possible number. In the overwhelming majority of cases, the coherence was lower in the RSEO; however, in the caudal cortical zones, a higher coherence in the α₁, ?, and Δ bands in the RSEO was rather typical. The results confirmed that the two states under study differ in a number of averaged EEG parameters with high statistical significance and may be used as reference states during performance of tasks with the eyes open and closed, respectively. The differences between the RSEC and the RSEO may be caused by the fact that the RSEC is a functional state oriented predominantly to the analysis of internal information (internally oriented), and the RSEO, predominantly to the analysis of information coming from the outside (externally oriented). The pattern of the observed EEG differences points to a combination of effects both localized in the visual zone and reflecting changes in the network cortical activity, i.e., simultaneous, although nonuniform, changes over all the main zones of the cortex. Comparison of the results with published estimations of differences in the local cerebral blood flow (ICBF) between the RSEO and the RSEC shows that increase in the ICBF may be associated with a local decrease in the EEG spectral power in any frequency band, including the high-frequency β and γ bands, or several frequency bands simultaneously.     

Changes in the power and coherence of the β<Subscript>2</Subscript> EEG band in subjects performing creative tasks using emotionally significant and emotionally neutral words

Changes in the power and coherence of the β₂ EEG band (18.5–30 Hz) were studied in subjects performing creative tasks under the conditions of emotional induction of different valence and without it. EEGs were recorded in subjects instructed to think up, within a limited time, the largest possible number of original definitions, differing in meaning, of emotionally positive, negative, and neutral nouns using additional words that were selected for them from another or the same semantic field. Significant changes in EEG power and coherence were found in the β₂ band. The performance of the creative task without emotional induction led to a local decrease in β₂ EEG power in the left frontotemporal area and a diffuse decrease in the coherence of the same band in most cortical zones. Emotional induction had a considerably stronger effect on the state of the cortex than the creative tasks used in the study: positive emotional induction caused a generalized increase in the power and coherence of the β₂ EEG band, while negative emotional induction caused a diffuse decrease in the power of this band over the parietal, central, and temporal cortical areas.     

Electroencephalographic characteristics of cognitive-specific alerting attention in verbal learning: I. Characteristics of EEG local synchronization

The EEG was recorded in 19 standard derivations in 88 students in the following states: rest with the eyes open, memorization (learning) of bilingual verbal semantic pairs (Latin and Russian), and retrieval (check) of the learned information. In order to calculate the mean heart rate (HR) in each state, the electrocardiogram was recorded. The subjective difficulty of task performance was assessed. Statistical comparison of the spectral power estimates in these states for frequency bands θ (4–7 Hz), α₁ (7–10 Hz), α₂ (10–13 Hz), β₁ (13–18 Hz), β₂ (18–30 Hz), and γ (30–40 Hz) demonstrated a number of significant differences in the EEG absolute power (local synchronization) between the states reproducible in subgroups. Comparison of the states of memorization and retrieval showed that, in the state of memorization, the EEG power in the γ, β₂, and θ bands was significantly lower throughout the cortical surface. Comparison of the active states with the reference state of rest showed that, in both active states, changes in the EEG power were of the same direction in the majority of the frequency bands (an increase in the θ, β₂, and γ bands and a decrease in the α₂ band) except α₁, in which memorization was predominantly accompanied by a decrease in the power, whereas retrieval was associated with an increase. No significant differences were found between the states of memorization and retrieval in the HR or the subjective estimate of task difficulty. The results can be interpreted as a reflection of cognitive-specific forms of general preparatory attention.     

Electroencephalographic Correlates of Brain States during Verbal Learning: I. Characteristics of EEG Local Synchronization

Electroencephalograms (EEGs) were recorded by 19 standard derivations in 57 subjects in a resting state with the eyes opened, during memorization of verbal bilingual semantic pairs (Latin and Russian), and during retrieval (monitoring) of the learned information. Statistical comparison of the EEG spectral power in the frequency bands θ, α₁, α₂, β₁, β₂, and γ showed that induction of the states of memorization (encoding) and retrieval of the verbal information led to multiple significant changes in the EEG absolute power (local synchronization) as compared to the state of rest. Such changes took place simultaneously in different frequency bands over the entire cortex. The relative values and significance of changes in different cortical regions varied. The main features of the EEG power-difference patterns were an increase in the power of the γ band over the entire cortex, a bilateral increase in the power of the β₂ band in the temporal areas, and a decrease in the power of the α₂ and α₁ bands over a large part of the cortical surface. In the state of retrieval, synchronization in the γ- and β₂ bands and desynchronization in the α₂ band were significantly stronger than in the state of encoding. In the α₁ band, desynchronization was more pronounced in the state of encoding than in the state of retrieval. The results are discussed in combination with the available data of the EEG studies of different types of memory.     

Electroencephalographic Correlates of Brain States during Verbal Learning: II. Characteristics of EEG Spatial Synchronization

Spatial EEG synchronization was studied using mean EEG coherences in 57 subjects in a resting state with the eyes open, during memorization of verbal bilingual semantic pairs (Latin and Russian), and during retrieval (monitoring) of the learned information. Statistical comparison of the EEG spectral power in the frequency bands θ, α ₁, α₂, β₁, β₂, and γ showed that induction of the states of memorization and retrieval of the verbal information resulted in multiple significant increases in the mean coherence (spatial synchronization) as compared to the state of rest. These increases were significantly higher in the state of retrieval than in the state of memorization. Such changes simultaneously occurred in different frequency bands and over the entire cortex. The highest relative augmentations of coherence with the highest significance estimates were observed in long-distance derivation pairs involving the temporal areas or combining the anterofrontal and frontal derivations with the parietal and occipital ones. The results are discussed in combination with data obtained in the same study for changes in EEG local synchronization and reported earlier. The intense rearrangements of the bioelectrical activity of the cortex may be determined both by the effect of cognitively specific mechanisms of encoding-decoding of information in the memory system and by a cognitively nonspecific modulating system of the brain.     

EEG spectral power of young schoolchildren with perinatal pathology of the CNS

The influence of perinatal risk factors (prematurity and hypoxia) on the spectral power values of individual EEG frequency bands (θ₁, θ₂, α₁, α₂, β₁, β₂, and γ) in the state of quiet wakefulness in young schoolchildren with educational problems was studied. The results of statistical analysis showed a significant predominance of the power in the θ₁ (especially in the anterior and posterior associative areas), β, and γ (on the whole surface of the cortex, with a predominance of differences in the anterior associative areas) bands in children with a gestational age (GA) less than 38 weeks at birth compared to that in the control group (a GA of 38 weeks). The intergroup differences in the power of most frequency bands were most pronounced in the left temporal area. A relationship between the consequences of perinatal hypoxia and the GA, namely, an increase in the power (especially in the left-hemispheric areas) of all the EEG frequency components (except α₂) in the group with a GA less than 38 weeks, in contrast to its slight inhibition in the control group (except the γ band), was found. The genesis of the specific features of the pattern of local EEG synchronization, as well as their functional significance in the formation of different structures of cognitive disorders in children with perinatal dysontogenesis, is discussed.     

EEG beta and gamma powers when comparing certain psychophysiological states with normal and weakened electromyogram of facial muscles

With the advancement of contemporary techniques for studies of high-frequency electroencephalograms (EEGs), possible contamination of the EEG with the electromyogram (EMG) of pericranial muscles has raised more and more concern. The aim of the present study was to demonstrate if certain EEG correlates of mental activities can be revealed in a high-frequency scalp EEG in spite of EMG contamination. Nineteen healthy women who performed similar test tasks before and after cosmetic injections of Dysport in various facial regions for reduction of the activity of facial muscles took part in the study. Inductions of emotional states with different valences, memory storing, and extraction of verbal information were used in the test tasks. The default state of rest was examined as well. During performance of the tasks, parallel registrations of the EEG from the scalp surface (19 channels) and EMG from several facial muscles (6 channels) were carried out. Changes in the spectral power in β₂ and low γ frequency bands (18–40 Hz) in EEG- and EMG-derivations after Dysport injections were analyzed. Changes in the spectral power in the same bands in pairwise comparisons for the test tasks before and after Dysport injections were also analyzed separately. It was demonstrated that Dysport injections lead to reduction of the EMG power in areas of the injections and to reduction of EEG power in the frontal and temporal derivations. However, the EEG-correlates revealed when comparing different test tasks remained qualitatively invariable as for after and before Disport injections. These facts confirm that EMG makes a noticeable contribution to the electric activity registered from the scalp in the frequency ranges greater than 18 Hz. At the same time, one can see that at least in certain experimental situations the influence of EMG does not make impossible identification of EEG-correlates of mental activity with EEG registration from the head surface at least in the β₂ and low γ frequency bands (18–40 Hz).     

EEG differences between resting states with eyes open and closed in darkness

Transition from a resting state with eyes closed (REC) to a resting state with eyes open (REO) is associated with visible changes in EEG, which are traditionally considered to be a sign of reorganization of the brain’s activity in response to visual stimuli. The EEGs recorded in the REC and REO states in complete darkness, when the stimulatory effect of light to the eye’s retina was absent, were compared. Thirty healthy subjects participated in the study. EEG in the range of 1.5–50 Hz was recorded from nineteen zones of the head monopolarly. It was found that, under conditions of complete darkness, the REC and REO states significantly differed in their EEG spectral power and coherence in the Δ, θ, α₁, α₂, β₁, β₂ and γ frequency bands. Under experimental conditions, these changes in the EEG could not be induced by external influence to the visual system. Therefore, we suppose that they are correlates of the switching of involuntary preliminary attention from internally directed attention specific for the REC state to externally directed attention specific for the REO state.     

Relationships between the EEG θ- and β-parameters and heart rate variability during human cognitive performance

We studied the dynamics of spectral coherence characteristics of the EEG θ-, β₁-, and β₂-activity and the heart rate variability (HRV) in subjects performing cognitive tests. We found an association between the HRV parameters in the process of cognitive activity and the coherence of potentials in the EEG θ-, β₁-, and β₂-bands. The heart rate parameters in the baseline state and during the test performance best correlated with the levels of the right-hemispheric coherence of potentials in the θ-, β₁-, and β₂-bands of the baseline EEG (eyes closed). The higher coherence levels corresponded to lower values of the mean time of RR intervals (RRNN), coefficient of variation (CV), total power (TP), the power of the high-frequency (HF) and low-frequency (LF) components in the HRV spectrum. During the performance of the test, higher coherence values in the EEG θ-bands with the focus in the right temporal lead corresponded to higher LF/HF values reflecting the predominance of sympathetic effects on heart rate.     

The influence of reward on the performance of verbal creative tasks: Behavioral and EEG effects

The goal of this study was to compare the effects of the verbal instruction (IN1) that stimulated originality and of monetary reward (IN2) on the efficiency of performing a verbal creative task. The EEG patterns were also compared on the basis of mapping the bioelectric potential power within the frequency range of 4 to 30 Hz. Right-handed students (10 men and 10 women) participated in the experiment. The originality of the solution improves if a monetary reward is expected. In contrast to IN1, the promise of a monetary reward caused a global increase in task-related synchronization of bioelectric potentials in the θ₂ band. Hemispheric asymmetry of the power of the θ₁, θ₂, and α₂ rhythm grows with higher values in the right hemisphere. These changes in response to IN2 were in the background EEG, which testifies that an overall increase in hemispheric asymmetry induces a preparatory state after the promise of monetary reward. Specific changes in regional brain activity were at the β₂-rhythm frequency. In all posterior derivation, except for the frontotemporal ones, the power of the β2 rhythm decreased in response to IN2 in contrast to IN1. The rewardinduced changes in EEG were characteristic of men to a greater extent. An increase in the θ₂-rhythm asymmetry and the power of the α rhythm was observed only in men in response to a monetary reward. Our results suggest that the promise of monetary reward is favorable for creative thinking and original solutions. Gender differences of changes in the power of bioelectric potentials suggest that the neurophysiological mechanisms of creativity are different in men and women.     

Characteristics of EEG reactivity changes during the performance of dual tasks in healthy subjects (voluntary postural control and calculation)

Comprehensive EEG and stabilography investigation with separate and simultaneous performance of motor (voluntary postural control) and cognitive (calculation) tasks has been performed in 20 healthy subjects (22 ± 0.7 years). Specific spatial and frequency reactive changes have been found during motor task performance. These included an increase in coherence in the EEG α band for distant derivation pairs in the right hemisphere, as well as in symmetric parietal-occipital areas in both hemispheres. Cognitive task performance was accompanied by an increase in coherence for the slow bands (δ and θ) with a higher activation in the left hemisphere and frontal cortex areas. In performing the dual task, one could observe activation of spatial and frequency changes including both motor and cognitive tasks. In the dual tasks where both components were performed worse as compared to the control, reactive reorganization of EEG coherence was less pronounced than during the performance of separate tasks. A decrease in the coherence of the α₁ band in the frontal areas appeared as a zone of “conflict of interest” or interference. In dual tasks with better performance of each component as compared to the control, EEG coherence increased in each specific area, as well as in the areas of “conflict of interests.”     

Electroencephalographic characteristics of cognitive-specific attention in verbal learning—II: General characteristics of EEG spatial synchronization

Electroencephalograms (EEGs) were recorded in 19 standard derivations in 88 subjects (students) in states of: rest with the eyes open; memorization (learning) of verbal bilingual semantic pairs (Latin and Russian); and recollection (control) of the memorized information. Estimates of EEG coherence in these states were compared using statistical methods for the frequency bands θ, α₁, α₂, β₁, β₂, and γ. The results of this comparison showed that transition from the state of rest to those of memorization and recollection was accompanied by numerous changes in coherence in all the frequency bands. These changes varied in intensity and embrace practically the entire convexital cerebral cortex. Decrease in EEG coherence was predominant during the transition to the memorization state in various frequency bands, whereas during the transition from the rest state to that of recollection, EEG coherence increased in most of the frequency bands except for the band α₂. The reproducibility of this pattern of changes in EEG coherence is confirmed by the results in the subgroups formed by randomly subdividing the subjects into two groups. We think that the observed intense rearrangement of the spatial synchronization of the cortex electrical activity reflects the reorganization of the functional systems of neuronal ensembles to provide efficient memorization and recollection, respectively.     

Electrophysiological Correlates of Major Depression Disorder with Anxious Distress in Patients of Different Age Groups

The electrophysiological correlates of major depression disorder with anxious distress in patients of different age groups have been investigated. The spectral characteristics of 19-channel background EEG were analyzed and the power spectra recorded with the eyes closed vs. eyes open in 64 patients with anxiety–depressive disorder and in 194 healthy subjects were compared. The subjects were divided into the two age groups: 18–39 and 40–76 years old. The spectral parameters were calculated for 5 main EEG frequency bands: θ (4–8 Hz), α (8–12 Hz), β₁ (12–20 Hz), β₂ (20–30 Hz), and γ (30–40 Hz). The most statistically significant differences between the groups were found in the α, β, and γ bands. Lower values of spectral power of the α rhythm in occipital areas and the higher values of spectral power of the β and γ rhythms in the frontocentral region were recorded in the group of 18-to-39-year-old patients with the eyes closed. Higher values of spectral power of the β rhythm in the fronto-central region and in the left temporal lobe were recorded in the group of 40-to-76-year-old patients with both the eyes closed and the eyes open. The higher β-activity in the fronto-central regions in both groups of patients may be caused by increased excitability of the cerebral cortex and decreased activity of inhibitory processes. Increased activation of the left temporal lobe in older subjects is probably associated with the severity of anxiety symptoms and may be a distinctive marker of mixed anxiety and depressive disorder. The lower values of α-power revealed only in the group of younger subjects are probably associated with age-related reorganization of EEG in older subjects.     

Strategy and results: Sex differences in electrographic correlates of verbal and figural creativity

Sex differences in electroencephalographic (EEG) correlates of creativity were studied using verbal and figural divergent tasks to be performed in accordance with the instructions to “give any solution” or “give an original solution.” The common effect was a greater activity of the right hemisphere, which did not depend on the sex, task type, or instructions for performance of the tasks. The α₂ and β₂ rhythms were the main EEG frequency correlates of creative thinking; the degree and sign of their reactivity depended on the aforementioned factors. Although the creative abilities in men and women were similar under test conditions, the EEG correlates of both figural and verbal tasks were sex-dependent. A high reactivity of the α₂ rhythm was more marked during verbal creative thinking in women; and that of the β₂ rhythm, during figural creative thinking in men. The instruction-related improvement of the critical selection of solutions was to a greater extent reflected by changes in the cortical activity, more pronounced in the frontal cortex in the women. Thus, the same creative productivity in men and women was mediated by different strategies of performance of both figural and verbal tasks, and the sex-related differences in these strategies remained even when the motivation for creativity was changed.     

Parameters of cortical interactions in subjects with high and low levels of verbal creativity

Parameters of cortical interactions depending on the level of creative achievements were studied in 40 right-handed subjects (22 men and 18 women). EEG was recorded at rest and during performance of a verbal creativity task (the Cognitive Synthesis test). The subjects were divided (by the median split) into groups with high and low originality scores (OSs). EEG coherence was computed within a range of frequencies from 4 to 30 Hz. The total values of coherence were determined separately for intra- and interhemispheric coherent connections using each of 16 electrode sites. Unlike subjects with a low OS, those with a high OS values were characterized by a decrease in the interhemispheric coherence of the θ_1,2-rhythm bioelectric potentials, which was especially pronounced in frontal cortical regions, and by an increased β₁-rhythm interhemispheric coherence in the occipital and temporal-parietal brain regions. The results are discussed in the context of right- and left-hemisphere contributions into the top-down and bottom-up regulation mechanisms during creative thinking.     

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.     

Reflection of the Intelligence Structure in the Spatiotemporal Features of the Baseline EEG

The EEG correlates of the verbal, numerical, and figural IQ components according to the power and coherence characteristics of the baseline EEG in six frequency bands were studied taking into account personality traits of subjects (extroversion, neuroticism, psychoticism, and anxiety). Analysis of variance and correlation showed that a decreased power of the low-frequency _{1, 2}and ₁ rhythms and increased EEG power in the ₂ band with the right-hemispheric dominance were characteristic of persons with higher intelligence. These EEG characteristics were associated with increased interhemispheric interaction according to the coherence indices and increased coherence within the right hemisphere. Each of the intelligence components (verbal, numerical, and figural) was characterized by a specific baseline frequency–spatial EEG pattern distinguished by specific interactions, predominantly, between the frontal and caudal cortical regions in the and/or ₂ frequency bands.