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.     

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.     

Changes in EEG rhythms during verbal and visual-image thinking

General and local characteristics of EEG activation were studied in frontal, central, temporal and occipital areas of the left and right cerebral hemispheres in 20 adult subjects during execution of various mental tasks. The analysis of the changes of five main EEG rhythms (delta, theta, alpha, beta-1 and beta-2) showed that EEG power decrease in alpha- and beta-frequency ranges is a reliable and sensitive index of brain activation at thinking. On this basis EEG activation mosaics are described at carrying out of each task and its systemic changes at transition from one type of task to another one, depending on their psychological structure--modality and complexity.     

Dynamics of interhemispheric asymmetry during perception of verbal information in men and women: EEG analysis

Neurophysiological basis of gender differences in the dynamics of asymmetry in retrieval of dychotically presented verbal information was studied by mapping of EEG power and coherence during a prolonged dychotical test. Right-handed students (20 men and 11 women) participated in the experiments. It was shown that gender differences in the EEG were absent at the initial stage of testing and appeared at the final stage. At this stage, the asymmetry of the theta 2 EEG power was lower in men than in women, while the interhemispheric coherence in the theta 2- and alpha 1-bands was more pronounced in women than in men, mainly, in the caudal cortical regions. Thus, different cortical electrophysiological processes underlie similar behavioral effects (the same values of asymmetry coefficients of retrieval of syllables at the final stage of dichotic testing) in men and women.     

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.     

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.     

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.     

Longitudinal changes in aerobic power in older men and women.

The purpose of this study was to describe the longitudinal (10 yr) decline in aerobic power [maximal O(2) uptake (Vo(2 max))] and anaerobic threshold [ventilatory threshold (T(Ve))] of older adults living independently in the community. Ten years after initial testing, 62 subjects (34 men, mean age 73.5 +/- 6.4 yr; 28 women, 72.1 +/- 5.3 yr) achieved Vo(2 max) criteria during treadmill walking tests to the limit of tolerance, with T(Ve) determined in a subset of 45. Vo(2 max) in men showed a rate of decline of -0.43 ml.kg(-1).min(-1).yr(-1), and the decline in Vo(2 max) was consequent to a lowered maximal heart rate with no change in the maximum O(2) pulse. The women showed a slower rate of decline of Vo(2 max) of -0.19.ml.kg(-1).min(-1).yr(-1) (P < 0.05), again with a lowered HR(max) and unchanged O(2) pulse. In this sample, lean body mass was not changed over the 10-yr period. Changes in Vo(2 max) were not significantly related to physical activity scores. T(Ve) showed a nonsignificant decline in both men and women. Groupings of young-old (65-72 yr at follow-up) vs. old-old (73-90 yr at follow-up) were examined. In men, there were no differences in the rate of Vo(2 max) decline. The young-old women showed a significant decline in Vo(2 max), whereas old-old women, initially at a Vo(2 max) of 19.4 +/- 3.1 ml.kg(-1).min(-1), showed no loss in Vo(2 max). The longitudinal data, vs. cross-sectional analysis, showed a greater decline for men but similar estimates of the rates of change in women. Thus the 10-yr longitudinal study of the cohort of community-dwelling older adults who remained healthy, ambulatory, and independent showed a 14% decline in Vo(2 max) in men, and a smaller decline of 7% in women, with the oldest women showing little change over the 10-yr period.     

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.     

Frequency-spatial organization of brain electrical activity in creative verbal thinking: role of the gender factor

Gender differences in EEG patterns associated with verbal creativity were studied by EEG mapping. The EEGs of 18 males and 21 females (right-handed university students) were recorded during a performance of Remote Associates Task (RAT) compared with the letter-fluency and simple associate's tasks. Gender differences were found in a factor structure of the indices of verbal thinking and a score of generating words was greater in women than men. No significant gender differences in originality of associations were revealed, however, gender-related differences in the EEG-patterns were found at the final and initial stages of RAT. In men, the beta2-power was increased in both hemispheres at the beginning of test. To the end of testing, the power of oscillations in the beta2 band increased only in the central part of the cortex. In women, the beta2-power was increased to a greater extent in the right than in the left hemisphere at the initial stage of task performance, whereas the final stage was characterized by a relative decrease in beta-activity in parietotemporal cortical regions and increase in the left prefrontal region. It is suggested that the verbal creative thinking in men is based mostly on "insight" strategy whereas women additionally involve the "intellectual" strategy.     

EEG power spectrum analysis for monitoring depth of anaesthesia during experimental surgery

The first attempts to introduce computerized power spectrum analysis of the electroencephalogram (EEG) as an intraoperative anaesthesia monitoring device started approximately 30 years ago. Since that time, the effects of various anaesthetic agents, sedative and analgesic drugs on the EEG pattern have been addressed in numerous studies in human patients and different animal species. These studies revealed dose-dependent changes in the EEG power spectrum for many intravenous and volatile anaesthetics. Moreover, EEG responses evoked by surgical stimuli during relative light levels of surgical anaesthesia have been classified as 'arousal' and 'paradoxical arousal' reaction, previously referred to as 'desynchronization' and 'synchronization', respectively. Contrasting reports on the correlation between quantitative EEG (QEEG) variables derived from power spectrum analysis (i.e. spectral edge frequency, median frequency) and simultaneously recorded clinical signs such as movement and haemodynamic responses, however, limited the routine use of intraoperative EEG monitoring. In addition, the appearance of EEG burst suppression pattern and isoelectricity at clinically relevant concentrations/doses of newer general anaesthetics (i.e. isoflurane, sevoflurane, propofol) may have weakened the dose-related EEG changes previously reported. Despite these findings, the EEG power spectrum analysis may still provide valuable information during intraoperative monitoring in the individual subject. The information obtained from EEG power spectrum analysis may be further supplemented by newer EEG indices such as bispectral index and approximate entropy or other neurophysiological monitors including auditory evoked potentials or somatosensory evoked potentials.     

Effect of verbal instruction on muscle activity during the bench press exercise

Recent research suggests that humans have some ability to selectively activate or relax some muscles during isometric or dynamic muscle actions without changing posture or position. This study sought to reveal whether trained athletes could isolate either the pectoral or triceps muscles, respectively, at different intensities when given verbal technique instruction. Eleven male Division III football players performed 3 sets of bench press at 50% 1-repetition max (1RM) and 80% 1RM while electromyographic (EMG) activity was recorded from the pectoralis major (PM), anterior deltoid (AD), and triceps brachii (TB). In the first set, the subjects performed the exercise without instruction. In the second set, the subjects were given verbal instructions to use only chest muscles. In the third set, the subjects were instructed to use only triceps muscles. Mean normalized root mean square EMG activity was calculated during 3 repetitions in each condition. Repeated-measures analysis of variance was used to detect differences from the preinstruction condition, with significance set to p ≤ 0.017 as indicated by a Bonferroni correction for multiple comparisons. During the 50% max lift with verbal instructions to focus on chest muscles, PM EMG activity increased by 22% over preinstruction activity (p = 0.005), whereas AD and TB activities were statistically unchanged. When the subjects were instructed to focus on only the triceps muscles, PM returned to baseline activity, whereas TB activity was increased by 26% (p = 0.005). When the lift was increased to 80% max, PM and AD activities were both increased with verbal instructions to use only chest muscles. The TB activity was unchanged during the 80% lifts, regardless of instructions. In conclusion, it is found that verbal technique instruction is effective in shifting muscle activity during a basic lift, but it may be less effective at higher intensities.     

The effect of unilateral training on contralateral limb power in young women and men

The purpose of this study was to determine the effect of training of one side of the body on the muscle torques and power output on the trained and untrained side. Seventeen female and twenty-two male students were subject to a four-week knee joint power training regimen on a specially designed stand. The subjects were divided into two groups: a training group (female – N = 11 and male – N = 16) and a control group (female – N = 6 and male – N = 6). Effectiveness of power training on the stand described previously was estimated based on bilateral knee torque and power under static and isokinetic conditions. The experiment lasted for 39 days and was preceded by preliminary studies (pre-training). Control measurements in training groups were made after four weeks of training (post-training) and after the next two weeks (de-training). Power training caused an insignificant increase in force and power in both groups for the untrained leg and a significant increase in RMS EMG. Therefore, the study confirmed the hypothesis that resistance training performed in dynamic conditions can affect the contralateral limb and may also trigger delayed adaptations to training conditions during the detraining phase. Sex differences in adaptation to power training are not clear; however, the differences in gains in contralateral effects between men and women were not confirmed.     

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.     

Circulatory and EEG changes during resuscitation in experiments

In anaesthetized dogs blood pressure (BP), carotid artery flow (CAF), oxygen tension of arterial blood (paO2) and brain surface (bs-pO2), ECG, frequency analyzed EEG were measured and/or recorded. The changes in these parameters were detected before and during ventricular fibrillation with external and direct heart massage as well as after defibrillation. Comparisons were made between the effect of oxygen and room air ventilation. The ratio of successful resuscitation was 88% with direct heart massage and O2 respiration, 76% with external thoracic massage and O2 ventilation, and 68% with external massage combined with room air respiration. The highest BP and CAF could be achieved with direct heart massage. The results suggest that the minimal requirement for success is to achieve a BP of 5 kPa (40 mmHg) and 13 ml/min CAF. In dogs with large and stiff thorax this minimal pressure and flow could not be attained. During effective massage with room air ventilation brain surface pO2 increases moderately, but with O2-respiration it returns to normal. Small or no changes in bs-pO2 indicates unfavourable prognosis. The start bs-pO2 elevation coincides with the reappearance of the first EEG waves, while pO2 increase on the brain surface precedes the normalization of EEG.