Sex differences in the relationship between creativity and hemispheric information selection at the global and local levels

Sex-related differences in creativity-related hemispheric selective processes at the global and local levels were studied using hierarchically presented letters under the conditions of their identification and comparison. The results showed that, irrespective of the sex and the type of creative thinking, its originality was associated with the acceleration of right-hemispheric processes of information selection at the global level and deceleration of interhemispheric communication. Relationships between the originality of ideas and hemispheric attentional characteristics were stronger in men during the solution of verbal creative problems and in women during figurative original thinking. The originality of verbal activity in men was more closely associated with the success of selective processes in the left hemisphere; in women, with the selective functions of both hemispheres. Figurative thinking in men was less related to hemispheric characteristics of attention compared to women. An increase in figurative originality in women was accompanied by the acceleration of information selection in the right hemisphere and a higher efficiency of local attention and speeds of global processing in the left hemisphere.     

Changes in the EEG power in male and female subjects during visual creative thinking

Gender-related differences in EEG patterns during creative visual thinking were investigated in 10 men and 10 women. The spectral power density was analyzed in the range of 4-30 Hz. Gender differences in the hemispheric asymmetry of theta1-rhythm desynchronization were found: females demonstrated greater desynchronization in the right hemisphere than in the left hemisphere, whereas no asymmetry was revealed in males. Only in women numerous negative correlations between creativity indices and task-induced theta1 desynchronization were found.     

Hemispheric interactions during a search of original verbal associations: EEG coherence in creative men and women

A hemispheric interaction during verbal creative thinking was studied by the analysis of EEG coherence in the band of 4-30 Hz. 18 males and 21 females (right-handed university students) participaited in the experiments. Independently of gender, the performance of Remote Associates Task was accompanied by an increase in coherence in the theta1 and beta2 frequency bands as compared to the states of rest and the letter-fluency and simple associate's tasks. Successful search for original word associates as compared to generation of standard words was accompanied by a local increase in the interhemispheric coherence of the beta2 rhythm mostly in the parietotemporal cortex. In creative men, the increase in the hemispheric interaction efficient for a search for original words was focused in the frontal and temporal loci of the right hemisphere and in the left occipital locus, whereas in creative women the increase in coherence was observed in the left frontal and temporal regions. Creative men differed from non-creative ones by higher inter- and intrahemispheric coherence and were similar to women in the level of hemispheric interaction. The cortical distribution of foci of interhemispheric coherence reactivity indicates that the cortical organization of verbal functions depends on both sex and creativity of men and women.     

Indices of Coherence of EEG Rhythms in the Course of Cognitive Activity as Markers of Creative Thinking: Gender Specificity

According to the results of psychological testing, persons aged 18 to 21 years were divided into four groups, women and men with low and high productivity of divergent (creative, nonroutine) thinking (n = = 18 to 23). Results of EEG recording (19 leads) were used for calculation of the coherence coefficients for oscillations of the delta, theta, alpha1, alpha2, alpha3, beta, and gamma frequencies in lead pairs and estimation of integral indices of coherence within the anterior and posterior cortical regions and between these zones (interaction coefficients, IC1-IC3, respectively). EEG was recorded in the resting state and in the course of resolving convergent- and divergent-type cognitive test tasks. It was found that, during the performance of tests of both types, men with a higher productivity of divergent thinking demonstrated significantly higher values of IC1 (that characterizes the coherence in associative linkages within the anterior cortex) for oscillations of all EEG frequency ranges compared with the respective estimates for “low-creative” men. Similar increments were typical of the IC2 values for low- and midfrequency EEG rhythms (delta, theta, and alpha). At the same time, values of the “interregional” IC3 for theta, beta, and gamma activity in “high-creativity” men were significantly lower. In women of both groups (low and high creativity), such specificity of the IC1-IC3 patterns was practically not observed, i.e., the respective aspect demonstrated clear gender specificity. The sex of the subjects and type of the performed cognitive tests could not be considered factors significantly affecting the calculated absolute IC values. The observed specificities of integral coherence indices are probably associated with different strategies of the performance of cognitive tasks in men and women. Our findings allow us to believe that the above interrelations between integrated coherence indices can be used as EEG markers of high productivity of divergent thinking in men. The more flexible strategies of thinking in women are probably related to more variable neurophysiological cortical mechanisms (compared with those in men), and this type of organization is not clearly reflected in the pattern of intracortical interactions estimated by coherence indices.     

Sex-Differences of Face Coding: Evidence from Larger Right Hemispheric M170 in Men and Dipole Source Modelling

The processing of faces relies on a specialized neural system comprising bilateral cortical structures with a dominance of the right hemisphere. However, due to inconsistencies of earlier findings as well as more recent results such functional lateralization has become a topic of discussion. In particular, studies employing behavioural tasks and electrophysiological methods indicate a dominance of the right hemisphere during face perception only in men whereas women exhibit symmetric and bilateral face processing. The aim of this study was to further investigate such sex differences in hemispheric processing of personally familiar and opposite-sex faces using whole-head magnetoencephalography (MEG). We found a right-lateralized M170-component in occipito-temporal sensor clusters in men as opposed to a bilateral response in women. Furthermore, the same pattern was obtained in performing dipole localization and determining dipole strength in the M170-timewindow. These results suggest asymmetric involvement of face-responsive neural structures in men and allow to ascribe this asymmetry to the fusiform gyrus. This specifies findings from previous investigations employing event-related potentials (ERP) and LORETA reconstruction methods yielding rather extended bilateral activations showing left asymmetry in women and right lateralization in men. We discuss our finding of an asymmetric fusiform activation pattern in men in terms of holistic face processing during face evaluation and sex differences with regard to visual strategies in general and interest for opposite faces in special. Taken together the pattern of hemispheric specialization observed here yields new insights into sex differences in face perception and entails further questions about interactions between biological sex, psychological gender and influences that might be stimulus-driven or task dependent.     

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.     

Lateral effects of emotional stimulation on verbal memory processes in men and women

Effects of short-term changes in emotional state of men and women on hemispheric organization of verbal memory processes were studied in the model of emotional electrodermal stimulation. Retrieval of dichotically presented lists of words was analyzed. The lists of words included pairs of emotionally neutral word and pairs combined of a neutral and emotional or both emotional words. There were no gender differences in the immediate retrieval of the words. Electrodermal stimulation prior to presentation of list of word resulted in a lateralized reduction of the immediate report of neutral words presented to the right ear and of emotional words presented to the left ear. Gender-related differences were shown in the delayed retrieval. In women, the stimulation applied before word presentation induced a decrease in delayed retrieval of left-ear emotional words. In men, the stimulation applied after the word presentation improved the retrieval of word lists independently of the side of presentation. Mechanisms of gender-related differences in interhemispheric interaction in verbal memory processes are discussed.     

Information processing specialization during interference between global and local aspects of visual hierarchical stimuli in men and women

Sex-related differences in global/local hemispheric selective processing were examined by hierarchically presented letters in conditions of their perception and comparison. Fifty-six right-handed men and 68 women (aged 17–22 years) participated in the experiment. During the interference between global and local aspects of stimuli, the mean reaction time for correct global responses was shorter than for local responses, and the right hemisphere dominated during global selective processing independently of sex. Sex-related differences in perception of visual hierarchical stimuli were more pronounced than during their comparison: men preferred the right-hemispheric global strategy of information processing, and women, the left-hemispheric local one. The dominance of the global strategy in men and local strategy in women during visual hierarchical stimuli perception, together with the absence of sex-related differences in correct responses indicates the possibility of obtaining the same efficiency of cognitive activity in different ways.     

Association Process and Functional Brain Asymmetry

Analysis is presented of word associations produced by subjects with left hemispheric (group 1), right hemispheric (group 2), and bilateral (group 3) speech representation. The strategy for producing extralinguistic responses was found to prevail over the strategy for producing linguistic associations in all subjects, irrespective of their type of speech representation. This strategy was more pronounced in subjects with right hemispheric speech laterality, suggesting a correlation between the generation of extralinguistic associations and functional brain asymmetry. Producing linguistic associations also depended on the type of cerebral organization of speech. The most important linguistic associations are syntagmatic. Syntagmatic associations were more closely related to the lateralization of speech to the left hemisphere. The data are compared to the results of studies of the ontogeny of associative processes.     

The hemispheric lateralization of the recognition of noisy visual stimuli in man

At tachistoscopic unilateral presentation of noisy visual stimuli and application of "yes-no" method in man predominance was found of the right hemisphere by the number and "yes" reaction time and of the left hemisphere by the number of responses "no". At verbal mnemic load preceding the presentation of visual patterns the left hemisphere asymmetry was observed by the number of "yes" responses and reactions time of both types. FMA was more clearly expressed in men in the first case and in women--in the second one. In more difficult conditions of recognition of several types of patterns, FMA was noticed mainly in women: initial left hemisphere advantage during the increase of the disturbance was changed to the right hemispheric one and appeared again. Preferential participation of the right hemisphere in singling out of the visual signal from noise is supposed. Possibility of the left hemispheric asymmetry manifestation was determined by the specificity and complexity of the visual task, by the level of the disturbance, presentation of competitive task and sexual composition of the group.     

The study of interhemispheric asymmetry in spatial-perceptive problem solving

Features of brain interhemispheric asymmetry during solving the spatial figurative task (maze model) were studied in men and women with different intelligence quotients (IQ). It was shown that during task solving the rate of information processing was higher in the right brain hemisphere, and amplitude characteristics of the event-related potentials were higher in the left hemisphere. No gender and IQ differences in the character of interhemispheric interaction were found during the realization of the maze-model task. The results testify that the character of hemispheric interaction depends om the task rype rather than gender and intelligence level.     

Selection of visual hierarchical stimuli between global and local aspects in men and women

Sex differences in global-local hemispheric selective processing were examined by hierarchical letter presenting in conditions of their perception and comparison. Fifty-six right-handed males and 68 females (aged 17-22 years) participated in the experiment. During interference between global and local aspects of stimuli the mean reaction times for correct global responses was quicker than local responses, and the right hemisphere has been dominated during global selective processing independently from the sex. Sex differences in perception of visual hierarchical stimuli were more pronounced than in comparison condition: men prefer mostly the right-hemispheric global strategy of information processing, but women--the left-hemispheric local one. Dominance of global strategy in men and local strategy in women during visual hierarchical stimuli perception together with no sex differences in correct responses indicates possibility of similar results in cognitive activity by different ways.     

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.     

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.     

Interhemisphere differences of extrastriate cortical activation during attention and selection of lateralized visual stimuli in humans

The cortical activation was estimated by event-related potentials (ERPs) methods during selection tasks of lateralized visual stimuli in right and left hemi-fields requiring different forms of attention: 1. Attention of a stimuli form, 2. Attention of a stimuli position, 3. Combined attention of form and position. ERPs were recorded in 15 young healthy adults in 6 leads: P3, P4, T3, T4, T5, T6 and endogenous ERPs components: CNV (contingent negative variation), N1, P3 and complex [N1--P3]. The differences between ERPs at contra- and ipsilateral stimuli in the right and left hemispheres were considered as indices of asymmetry. The asymmetry was revealed in right hemisphere in all kinds of attention forms. The level (amplitude) of right-side asymmetry was depended on the level of attention: The significant relation between the right-side asymmetry and subjects' reaction time was also revealed. It is proposed that such an asymmetry is the evidence of better spatial differentiation of visual stimuli in right hemisphere in humans.     

Sexual and interhemispheric differences in the involvement of serotonin from the hippocampus and amygdaloid body in the processing of new and repeatedly presented information in rats]

Effects of novel or relevant (a single exposure to experimental chamber) and irrelevant (20 exposures to experimental chamber) stimuli on the levels of serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the left and right hippocamp and amygdala were studied in male and female rats. It was found that hemispheric specificity of 5-HT metabolism in hippocampus and amygdala depended on sex and novelty of information. In male rats, the hippocampal level of 5-HT in response to the novel stimulus increased in the left hemisphere, and the 5-HIAA hippocampal level increased bilaterally in response to irrelevant stimulus. In females, an increase in 5-HT and/or 5-HIAA levels was observed only in the left hippocampus in response both to relevant and irrelevant stimuli. In the amygdala, a hemispheric asymmetry of the 5-HT involvement, due to right-hemispheric changes in 5-HT metabolism, was observed only in male rats. In females, an increase in 5-HT level was found in the left and right amygdalas in response to irrelevant stimulus. These data suggest that serotonergic neurotransmitter mechanisms are an important factor which determines hemispheric and sex differences in selective attention.     

Gender differences in hemispheric interaction during distributed and directed attention

Gender differences in the functional hemispheric organization during memorization of dichotically presented verbal information in the situation of focused or non-focused attention were studied. Analysis of EEG coherence reactivity in six frequency bands (4-30 Hz) showed that the focused attention to stimuli presented to one ear as compared to divided attention between both ears was accompanied by an increase in the interhemispheric interaction in the thetal frequency band between the frontal cortical areas in men and between the parietoccipital areas in women. In the betal band, the focused attention was associated with a contralateral increase in the intrahemispheric coherence in men, whereas no significant difference in the intrahemispheric coherence was found in women. On the basis of coherence changes in the thetal and betal bands depending on the attention conditions together with the obtained correlation between coherence reactivity and word-recall scores, it may be suggested that verbal memorization in men is associated, predominantly, with the regulation from the anterior system of attention and from the posterior system in women.     

Sex differences in EEG power changes in retention of dichotically and monaurally presented verbal stimuli

EEG power mapping was used to study gender differences in hemispheric functional organization during memorizing dichotically and monaurally presented verbal information. Right-handed students (12 men and 14 women) participated in experiments. The EEG was recorded from 16 electrodes placed at homologous sites of the left and right brain hemispheres. Task-related changes in the thetal power in men differentiated between monaural presentations to different ears, i.e., situations of oppositely directed attention. In women the thetal power reactivity (the difference between the band power logarithms under baseline conditions and in task interval) differentiated between dichotic and monaural presentations of words, i.e., situations with different memory loads. Gender differences were also found in the alpha frequency band. Power changes in the alpha 1 band in all memory tasks and power changes in the alpha 2 were more evident in the right hemisphere in men but in the left hemisphere in women. In contrast, in the posterior temporal lead the alpha 2 power reactivity in men was higher in the right hemisphere, whereas in women the lateral differences were absent. As compared to men, the alpha 2 desynchronization in women was also more pronounced in posterior regions of both hemispheres. There were no gender differences in efficacy of memorizing. It is suggested that different processing strategies rather than different behavioral performance may be responsible for the revealed specific spatiotemporal EEG patterns.     

Background activity of the brain in healthy mental aging

The EEG mapping study tested age-related changes in power of EEG rhythms from delta to gamma ranges under healthy cognitive aging associated with preserved cognitive abilities and involvement in complex professional activity. 32 subjects of higher age group (HAG, mean age 65.1 +/- 1.18, 14 men and 18 women) and 33 subjects of lower age group (LAG mean age 22.1 +/- 0.38, 18 men and 15 women) participated in the study. Mean power of slow (delta, theta and alpha2) activity decreased and of fast activity (beta, gamma) increased as subject age increased. Compared to subjects of LAG subjects of HAG displayed a reduction in heterogeneity of EEG activity across recording sites. Centro-temporal gradients of power for frequency ranges from delta to beta2 and frontoparietal gradients and hemispheric asymmetry for alpha and beta1 rhythms were smoothed in subjects of HAG. These results suggest that observed age-related changes in baseline EEG may be the prerequisite for compensatory neural recruitment that may be associated as with allocation of more resources in cognitive processes so with reorganization of cortical networks including areas susceptible to physiological changes with aging.     

The impact of experimental instruction on changes in EEG power during verbal creative thinking in men and women

Features of EEG pattern during verbal creative thinking depending on experimental instruction were studied in men and women. Spectral power density was analyzed in six frequency bands (4-30 Hz). Performance of a creative task produced an increase in the power of theta (4-6 Hz) and beta2 (20-40 Hz) components and decrease in the power of alpha (8-13 Hz) and betal (13-20 Hz). Changes in the alpha and betal bands were observed, predominantly, in the posterior areas, whereas power of the thetal and beta2 bands increased in the anterior areas. Independently of instruction, women demonstrated greater synchronization in the theta1 band than men, whereas in men the desynchronization in the alpha2 band (10-13 Hz) was more pronounced. When the subjects were instructed to create original sentences, a widespread decrease in the EEG power was observed in the band of 8-30 Hz as compared to instruction "to create sentences". Thus, the instruction-related changes in EEG power were not gender-specific. They may reflect neural activity mediating selective attention.