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.     

Lateralization of perception of short time intervals and cortical evoked activity in man

Recognition of short time intervals (10, 60, and 180 ms) between visual stimuli presented to the left or right hemisphere was studied in adult healthy people. The interval of 180 ms is recognized better than that of 10 or 60 ms. Learning with repeated tests with 180 ms intervals proceeds better than that with short intervals. The predominance of the left hemisphere has been revealed only for perception of 10 ms interval. The other time intervals asymmetry is not observed. It is suggested that the left hemisphere is predominant in estimation of short (less than 60 ms) time intervals. In formation of time nervous model a significant role is played by local activation of the cortical zone where the standard stimulus is addressed.     

Effects of monochromatic light on time sense for short intervals

We examined the effects of monochromatic light on the time sense and the central nervous system. Nine young adult volunteers participated in this study. They were exposed to red-light and blue-light environments (illuminance was kept at 310 lx). We evaluated the time sense by time-production tests of 90 s and 180 s and measured the P300 event-related potentials during an auditory oddball task. The 90-s time intervals produced by subjects in the two monochromatic light conditions were not significantly different. However, the 180-s time interval produced in the red-light condition (163.2+/-50.4 s) was significantly (p<0.05) shorter than that in the blue-light condition (199.0+/-54.4 s). The peak latency of P300 in the red light (322.2+/-26.6 ms) was found to be significantly (p<0.05) shorter also than that in the blue light (332.6+/-20.2 ms). The feelings measured by the visual analogue scales in the two light conditions were not significantly different. These results indicate that the time sense ran faster in the red-light than in the blue-light condition. We suggest that the higher activity in the central nervous system that is accounted for by the shorter latency of P300 is related to the acceleration of the time sense.     

Observation time and sampling intervals for measuring behavior and interactions of chimpanzees in the wild

This study examined two problems in the measurement of chimpanzee behavior: (1) comparability among data sets varying in length of total observation time; and (2) the longest interval for scoring reliable numbers of sample points with instantaneous sampling (this required procedures for evaluating the chi-square statistics of the sampled data). During a 4.5-month field study conducted at the Mahale Mountains National Park, Tanzania, one adult male was observed as a focal animal for about 300 hr with continuous recording. His behavior was classified into five categories. Data sets varying in total time were prepared by extraction from the raw data. Comparability among the data sets was evaluated using Pearson's correlation coefficients and Kendall's coefficients of concordance calculated from two kinds of measures obtained from the raw and simulated data sets: (a) the percentages of time spent by the focal animal in each behavior category; and (b) those of the time spent by adult males in his proximity. The results revealed that observation time of 25 hr was the critical length for scoring the above measures reliably. Sample points for the focal animal's behavior categories and for adult males in his proximity were simulated with intervals of various lengths for data sets differing in total time. The longest interval was measured by comparing the simulated scores with confidence limits calculated for the number of sample points to be scored with the respective intervals. It was found that the interval for sampling should be set at 3 min or shorter, and that chi-square statistics calculated from the data sampled with such an interval should be evaluated after their modification into the values to be obtained from the data sampled with a 5-min interval. These results may not be directly applicable to studies dealing with other behavior categories, other age/sex classes of focal animals, etc. However, the above problems should be examined widely in studies attempting to measure animal behavior, and the methods employed in this study are applicable to such studies.     

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.     

Estimation of time intervals during exposure to a static load

Ten healthy subjects from 17 to 23 years old participated in the study. The subjects had to hold the ergograph load with their right hand thus fulfilling a static work. The effort magnitude was 50 per cent of maximal value of voluntary strength. The subjects pressed the button on the ergograph handle with their thumb depending on the experimental conditions and held it for 0.8 or 2.5 s. The work with each interval included three conditions: interval estimation without static load (SL), the same with the SL and after SL. At the end of experiment the subjects worked with the interval of 2.5 s under the conditions of maximally long SL holding as far as it would go. An increase of reaction time (RT) was observed at the transition from simple button pressing to interval estimation. RT tended to increase with prolongation of a standard interval. SL did not influence significantly the RT value if it did not cause the general fatigue. A gradual increase of interval estimations was observed under the influence of SL the interval of 0.8 s being estimated more accurately. Estimation of various intervals was supposed to reflect different mechanisms of their perception. Estimation of the interval of 0.8 s was based on the memory trace processes and that of 2.5 s interval was connected with conditioned reflex activity. Apparently SL did not influence interval estimation directly but by changing the functional state of the subject's organism it predetermined a prolongation of the interval estimations.     

A search for specificity in DNA-drug interactions

The GRID force field and a principal component analysis have been used in order to predict the interactions of small chemical groups with all 64 different triplet sequences of B-DNA. Factors that favor binding to guanine-cytosine base pairs have been identified, and a dictionary of ligand groups and their locations is presented as a guide to the design of specific DNA ligands.     

Human cortical mechanisms of visual attention during orienting and search.

Functional anatomical studies indicate that a set of neural signals in parietal and frontal cortex mediates the covert allocation of attention to visual locations across a wide variety of visual tasks. This frontoparietal network includes areas, such as the frontal eye field and supplementary eye field. This anatomical overlap suggests that shifts of attention to visual locations of objects recruit areas involved in oculomotor programming and execution. Finally, the fronto-parietal network may be the source of spatial attentional modulations in the ventral visual system during object recognition or discrimination.     

Systolic time intervals in burn injury

Systolic time intervals were studied in 28 young, previously healthy burn patients (TBS 10-90%) on 145 occasions. A NEK 116 type 3 channel recorder of 100 mm/sec paper speed was used. Synchronous ECG recordings in lead II, PCG in the m "1" frequency band, and external carotid pulse tracings were recorded. RR, QS2, S1S2, LVET, PEP, PEP/LVET and QT, QTc, QS2-QT intervals were measured in 5-10 cardiac cycles in each of the examinations. Calculation of the additional parameters ICT, LVET/ICT, DT, EVR, PRP, EF and SV values were correlated to the extent of, and the time elapsed since, burn injury. The derivated parameters and statistical analysis were performed on a Commodore 64 type computer based on a software program. Elongation of QTc (greater than 440 msec) and frequent electrodynamic failure (QT-QS2 greater than 40 msec) especially during the first postinjury week were found characteristic in severe injury. In 53% the PEP/LVET ratio was less than 0.31, mean 0.32 +/- 0.093. In 21 cases of severe hypovolaemia the increase of PEP raised this value beyond 0.41. With the exception of 3 examinations, QS2I was normal or shortened. Calculated EF were normal or increased, SV reduced being interdependent with burn extent and shortening of DT. In patients with severe burns, oxygenization was inadequate (EVR less than 0.8); it showed an inverse correlation to HR. The simultaneously high LVET/ICT ratio and shortened ICT values pointed to an increase in contractility.