Features of temporal dynamics of oscillatory brain activity during creative problem solving in young and elderly adults

Considering evidence from psychological research, successful aging is accompanied by long-term preservation of creative potential despite slowing of mental processes; however, the neurophysiological mechanisms that ensure the maintenance of those abilities are unclear. In this study, we compared temporal dynamics of changes induced by divergent task electrical activity (event-related spectral perturbations, ERSP) in a wide range of EEG frequencies in the younger (YA, N = 80, 22.6 ± 3 years) and older (OA, N = 80, 63.4 ± 6.7 years) age groups. The groups were sex-matched. EEG was recorded while participants performed the “alternate uses task”. The time ranges 200–400, 400–600 and 600–800 ms after stimulus presentation were analyzed. It was found that task performance was associated with distinct patterns of ERSP changes in the θ and α₃ rhythms in young and elderly subjects. The elderly subjects exhibited smaller θ-desyn-chronization of anterior brain areas at the initial stage of creative thinking as compared to young participants. The gradient of fronto-parietal activation was unchanged during the entire interval of analysis in the elderly subjects, whereas it was observed in young adults in the interval 200–400 ms only. Decrease in desynchronization of the parieto-occipital area in the α₃ rhythm in the interval 600–800 ms in elderly subjects was revealed, and it resulted in disappearance of differences between parietal and fronto-temporal areas, while they were preserved in the young group. Significant correlations between ERSP in the α₃ band and originality, in the β₁ band and solution rate were obtained in old adults exclusively. Identified age-related changes in oscillatory activity may be the basis of different strategies in solving creative task in young and elderly adults.     

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 ? 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.     

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.     

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.     

Background cerebral electrical activity in healthy mental aging

EEG power mapping in the frequency bands from Δ to γ₂ was used to study the changes in the background cerebral activity during “successful” cognitive aging, with the cognitive ability preserved, in subjects engaged in complex occupational activities. The sample consisted of an older age group (OAG) of 32 subjects (14 men and 18 women with a mean age of 65.1 ± 1.18 years) and a younger age group (YAG) of 33 subjects (18 men and 15 women with a mean age of 22.1 ± 0.38 years). The mean power of the slow (Δ, θ, and α₂) rhythms decrease with age, and that of the fast (β and γ) rhythms increase with age. The heterogeneity of the power parameters recorded at different sites was decreased in the OAG compared to the YAG. The centro-lateral power gradient was smoothed in the frequency bands from Δ- to β₂-, and both the centro-lateral and fronto-parietal power gradients and interhemispheric differences, in the α- and β₁ bands in the OAG. The results suggest that the observed age-related changes are prerequisites for the involvement of compensatory mechanisms, which may be related to both mobilization of larger resources ensuring cognitive activity and reorganization of cortical networks in the areas prone to age-related physiological changes.     

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.     

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.     

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.     

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.     

Cognitive Reserve in Young and Old Healthy Subjects: Differences and Similarities in a Testing-the-Limits Paradigm with DSST

Cognitive reserve (CR) is understood as capacity to cope with challenging conditions, e.g. after brain injury or in states of brain dysfunction, or age-related cognitive decline. CR in elderly subjects has attracted much research interest, but differences between healthy older and younger subjects have not been addressed in detail hitherto. Usually, one-time standard individual assessments are used to characterise CR. Here we observe CR as individual improvement in cognitive performance (gain) in a complex testing-the-limits paradigm, the digit symbol substitution test (DSST), with 10 repeated measurements, in 140 younger (20–30 yrs) and 140 older (57–74 yrs) healthy subjects. In addition, we assessed attention, memory and executive function, and mood and personality traits as potential influence factors for CR. We found that both, younger and older subjects showed significant gains, which were significantly correlated with speed of information processing, verbal short-term memory and visual problem solving in the older group only. Gender, personality traits and mood did not significantly influence gains in either group. Surprisingly about half of the older subjects performed at the level of the younger group, suggesting that interindividual differences in CR are possibly age-independent. We propose that these findings may also be understood as indication that one-time standard individual measurements do not allow assessment of CR, and that the use of DSST in a testing-the-limits paradigm is a valuable assessment method for CR in young and elderly subjects.     

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.     

The effect of age on the recognition thresholds of three sweeteners: sucrose,saccharin and aspartame

It iS believed that people's sensitivity to taste declines with age but the evidence is inconclusive. This study was designed to test the hypothesis that taste recognition thresholds (TRTs) for sweetness are higher in older than in younger individuals, using groups of 16 younger subjects (18–30) and 16 older subjects (60–85). Three test substances were used: sucrose, aspartame and saccharin. A questionnaire recorded variables which might have affected TRTs, but data failed to show any trend that might have biased the principle variate-age. There was a significant alteration with age of recognition thresholds, at least for sucrose and saccharin. The differences between the groups for the three sweeteners were due to the fact that all the very sensitive subjects were young. None of the older subjects had particularly poor discrimination: all but one had TRTs within the range of younger subjects. Although there are age-related taste changes, they are much less dramatic than commonly occurs with other senses, such as sight and hearing. The findings of this study have implications for institutional catering and the dietary management of older people using non-sugar sweeteners.     

Turner's syndrome: a qualitative and quantitative analysis of EEG background activity

Summary A qualitative and quantitative analysis was performed on the EEG background activity in 62 Danish girls and women with Turner's syndrome (30 with karyotype 45,X and 32 with other karyotypes) whose ages ranged from 6 to 47 years (87% were aged 15 years or more) and age-matched controls. The pooled data and a case-control study showed characteristic features in Turner subjects, including: (1) more rapid frequency, larger amplitude and lower amount of alpha waves, (2) higher amount of theta waves, (3) larger amplitude and higher amount of delta waves and (4) larger amplitude and higher amount of beta waves than in controls. These findings in Turner subjects were more pronounced in the left hemisphere, and more typical, except for the amplitude in alpha waves, in Turner subjects with 45,X than in those with other karyotypes. The effects of advancing age on the EEG background activity observed in controls — including more rapid frequency, decreased amplitude and amount of alpha waves, increased amount of theta and delta waves, and increased amount of beta waves, particularly after 35 years of age — were found in some Turner subjects. Hemispheric differences with higher activity (i.e. more rapid frequency, larger amplitude and higher amount of alpha waves, particularly at Fp₁ and F₃, and, inversely, lower amount of theta or delta waves) at P₃, T₃, T₅ and O₂ than at the opposite side were found in many Turner subjects. However, these findings were not specific for Turner subiects, since the same hemispheric differences were also observed much more markedly in controls. These topographic distributions with hemispheric differences did not provide evidence for hypofunction in the temporo-parieto-occipital tertiary area of the right hemisphere in Turner subjects, though this had been expected on the basis of neuropsychological examinations. Our findings, including transiently appearing brain hypofunction at the parietal, temporal and occipital areas, most often in the right hemisphere, indicate a relationship between the chromosomal constitution 45,X and EEG background activity. They suggest the presence of functional brain disturbance in the thalamus and in the ascending reticular activating system, which tends to disturb the thalamo-cortical circuit. Further studies, including topographic and sequential power spectrum analysis of EEG background activity, 24-h continuous EEG recording, blood flow studies (positron computerized tomography) and neuropathological examination, may be needed.Tables I-VI are available on request     

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.     

Frontal bilateral synchronous theta waves and the resting EEG coherence in children aged 7–8 and 9–10 with learning difficulties

The resting state cortical functional connectivity was studied in children of 7–8 (N = 29) and 9–10 (N = 23) years with learning difficulties whose EEG showed the frontal bilateral synchronous theta waves (FTW) and in the control children of 7–8 (N = 32) and 9–10 (N = 16) years who did not experience school difficulties and whose EEG did not show signs of abnormality. The functional connectivity was estimated in the θ, α₁, α₂, and β₁ frequency bands via measuring the coherence for the resting EEG that was free from any abnormal patterns. Compared to control children, there was a reduction in the strength of the functional coupling between the frontal and anterior temporal cortices found predominantly in the left hemisphere of FTW children. The relative weakness of the coupling between the frontal cortex and the other cortical areas was more pronounced in children of 7–8 than in children of 9–10 years. These between-group differences were unaffected by the frequency band or gender factors.     

Frequency shift in topography of spontaneous brain rhythms from childhood to adulthood

It has been described that the frequency ranges at which theta, mu and alpha rhythms oscillate is increasing with age. The present report, by analyzing the spontaneous EEG, tries to demonstrate whether there is an increase with age in the frequency at which the cortical structures oscillate. A topographical approach was followed. The spontaneous EEG of one hundredand seventy subjects was recorded. The spectral power (from 0.5 to 45.5 Hz) was obtained by means of the Fast Fourier Transform. Correlations of spatial topographies among the different age groups showed that older groups presented the same topographical maps as younger groups, but oscillating at higher frequencies. The results suggest that the same brain areas oscillate at lower frequencies in children than in older groups, for a broad frequency range. This shift to a higher frequency with age would be a trend in spontaneous brain rhythm development.     

Age-related changes in the circadian and homeostatic regulation of human sleep

The reduction of electroencephalographic (EEG) slow-wave activity (SWA) (EEG power density between 0.75-4.5 Hz) and spindle frequency activity, together with an increase in involuntary awakenings during sleep, represent the hallmarks of human sleep alterations with age. It has been assumed that this decrease in non-rapid eye movement (NREM) sleep consolidation reflects an age-related attenuation of the sleep homeostatic drive. To test this hypothesis, we measured sleep EEG characteristics (i.e., SWA, sleep spindles) in healthy older volunteers in response to high (sleep deprivation protocol) and low sleep pressure (nap protocol) conditions. Despite the fact that the older volunteers had impaired sleep consolidation and reduced SWA levels, their relative SWA response to both high and low sleep pressure conditions was similar to that of younger persons. Only in frontal brain regions did we find an age-related diminished SWA response to high sleep pressure. On the other hand, we have clear evidence that the circadian regulation of sleep during the 40 h nap protocol was changed such that the circadian arousal signal in the evening was weaker in the older study participants. More sleep occurred during the wake maintenance zone, and subjective sleepiness ratings in the late afternoon and evening were higher than in younger participants. In addition, we found a diminished melatonin secretion and a reduced circadian modulation of REM sleep and spindle frequency-the latter was phase-advanced relative to the circadian melatonin profile. Therefore, we favor the hypothesis that age-related changes in sleep are due to weaker circadian regulation of sleep and wakefulness. Our data suggest that manipulations of the circadian timing system, rather than the sleep homeostat, may offer a potential strategy to alleviate age-related decrements in sleep and daytime alertness levels.     

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.     

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.     

Age-related differences in the serum prolactin response during standardized surgery

The aim with the present study was to assess possible age-related differences in the serum prolactin, cortisol and blood glucose responses to standardized surgical stress in humans. Relatively healthy men suffering from inguinal hernias were selected. The subjects were divided into a group of younger people (M=36.4 years, r=13–45, n=7) and one of older people (M=66.5 years, r=56–75, n=9). Surgery was carried out under general anesthesia. Blood was drawn before, during and following the operation. Blood pressure and pulse rate were also monitored. No differences were noticed in plasma prolactin, cortisol, and blood glucose during basal conditions. Even though plasma prolactin increased significantly in both groups during surgery, it was higher in the younger group (M= 56.2 μg/1) as compared with 28.7 μg/1 for the older group, p<.01. Plasma prolactin during surgery, but not under basal conditions, correlated inversely with age. No differences between groups were found during surgery in blood glucose and serum cortisol. This study indicates a diminished stress response in older subjects, possibly due to age-related neuroendocrine changes.