The EEG spatial pattern and psychophysiological characteristics of divergent and convergent thinking in humans

The psychophysiological parameters of the spatial synchronization of bioelectric potentials during the nonverbal divergent, nonverbal convergent, verbal divergent and verbal convergent thinking have been analyzed. The relationships between the performances of tests for these thinking styles were different. The strongest significant correlation has been found between the productivities of the verbal divergent and verbal convergent thinking styles; the weakest correlation, between those of the nonverbal divergent and nonverbal convergent thinking styles. The thinking styles differ from one another in the topography of spatial synchronization of bioelectric potentials. They are the most pronounced during the two nonverbal tasks and the least pronounced during the two verbal tasks. The thinking styles also differ from one another in the degree of the enhancement of the coherence between bioelectric potentials during tasks compared to the baseline (with the eyes open). Some human psychophysiological characteristics facilitating the performance of divergent (creative) tasks have a negative effect on the performance of convergent (noncreative) tasks. The data are discussed in terms of the differences in the level of general activation and involvement of different types of information processing (simultaneous and successive).     

Comparative analysis of EEG spatial organization in the rats with different level of genetically determinated anxiety under ethanol

The pecularities of EEG changes in the rats with geneticaly different level of anxiety was studed after ethanol injection. The biopotentials spatial synchronization and entropy in the "high anxious" rats (strain MR) did not increase under low dose; on the contrary the above changes were characteristic for the rats without anxiety signs (strain MNRA). After injection of middle and high ethanol doses the "high anxious" rats as compared with "low anxious" ones had the "simplification" of reaction type--the increase of narrow frequency coherence (i.e. linear biopotentials relationship) and spectral power of theta-activity (5.75-7.25 Hz), which was combined with the decrease of nonlinear biopotential characteristics. This fact is interpreted as the predominance of subcortical mechanisms of the brain functional state regulation over cortical ones. The significant decrease of high frequency EEG components in "high anxious" rats takes place under more high ethanol doses, presumably reflecting the increase of the anxiolytic level of ethanol effect.     

Comparative analysis of spatial EEG organization on models of non-verbal divergent and convergent thinking

Features of neurophysiological organization of two main thinking types playing different roles in creative processes, i.e., divergent and convergent were studied with participation of 30 right-handed male subjects at the age from 30 to 50 years. Two tests were presented: (1) creation of many visual images on the basis of two simple geometrical figures (the model of divergent thinking) and (2) classification of a figure element with one of the offered standard samples (convergent thinking). The number of created images or correctly classified elements for five minutes served a criterion of performance productivity. It was found that performance of the divergent test with high productivity (as compared to low productivity) was characterized by a greater increase in non-linear interactions between the cortical potentials, especially in the axis right frontal--left occipital areas. At the same time, under conditions of high productivity, the number of active narrow-frequency spectral-coherent EEG bands increased. The data confirm the notion of neurophysiological organization of creative processes, according to which creative processes require the intensification of retrieval operations (both conscious and unconscious), based on extensive interhemispheric interaction and involvement of a system of EEG coherent structures oscillating with different frequencies.     

The functional significance of α<Subscript>2</Subscript> frequency range for convergent and divergent verbal thinking

Mapping of the power and coherence of α₂ bioelectric potentials was used to detect a common effect of rhythm desynchronization in two types of convergent verbal thinking (generation of any words beginning with the given letter or simple associations) with more pronounced left-hemispheric activation predominantly in the temporo-parieto-occipital cortical area. In addition, there were specific functional changes in α₂ bioelectric potentials depending on the subjects’ sex and verbal creativity level, which was estimated by the capacity for divergent thinking (finding associations for triads of semantically remote words). The dynamics of the regional activation of the cortex depending on the verbal operation type was more characteristic of men compared to women and of creative persons compared to noncreative ones. In creative persons of both sexes, more original associations were accompanied by a decreased α₂-rhythm coherence. In noncreative women, interhemispheric interaction was, conversely, increased.     

The influence of visual imagery experience on EEG spatial organization

The comparison of EEG spatial organization between groups of 23 students of graphic arts department ("professional" subjects) and 39 subjects of another specialization ("non-professional" subjects) was made in order to find EEG correlates of visual imagery experience. Changes in the spatial organization of biopotentials (spatial synchronization and spatial disorder, spectral power and coherence) were analyzed while subjects mentally composed visual images from two simple elements, right angle and oblique line. The total number of elements presented for the image composition increased with each subsequent task (in total, four tasks were presented) from the number adequate to simultaneous perception and conscious processing (less than 7 +/- 2) to a much higher number. Intergroup differences, especially, in the degree of the spatial disorder (non-linear processes), were most evident under conditions when the subjects operated with a greater number of elements (tasks 3 and 4). This parameter increased more rapidly in "professionals" than in "non-professionals". These changes were most pronounced in the right anterior cortex. In "non-professional" subjects, spatial synchronization (linear processes) increased in the right posterior area. In "professional" subjects, coherence and spectral power increased in a greater number of narrow EEG frequency subbands than in "non-professional" subjects. The findings suggest that the imagery performance in subjects with visual imagery experience involves complicated neurodynamic processes such as non-linear dynamics and numerous EEG spatial resonance systems.     

Features of the stress reaction in rats with genetically-determined emotionality (from EEG indicators)]

The features of the EEG spatial organization in two rat strains, i.e., with expressed emotional reactions (Maudsley reactive, MR) and less reactive (Maudsley nonreactive, MNR) were compared in two stress situations: during exposure to the action of pain (P) (i.p. injection of 0.9% NaCl solution) and during 24-hour water deprivation (D). Multichannel EEG recording (24 derivations) and their multiparametric estimation (840 signs) made it possible to differentiate characteristic features of the EEG spatial organization in rats with initially increased emotional reactions and passive behavioral strategy during exposure to stress. In both stress-inducing conditions, an increase in crosscorrelation and coherence between cortical potentials in parallel with rise of the spectral power in the range of high-frequency theta and its drop in the range of EEG high-frequency band was observed in the MR rats. The MNR rats showed the opposite changes. Different reactivity of the ratio between the coherence and spectral power of potentials was observed in two strains of rats. This index characterizes the level of the information-energy component of the spatial organization of cortical potentials. It is suggested that different character of the EEG changes reflects the features of interhemispheric relations, information-energy processes, and cortical regulation of autonomic processes in the system of adaptive stress reactions at different levels of emotionality and behavioral strategy.     

EEG spatial organization and activation of creative processes

Characteristic features of the spatino-temporal EEG organization of 24 right-handed children (aged from 8 to 13 years) were studied after stimulation of creative activity by the method of self-regulation of the brain functional state (Russian Inventor's Certificate no. 2157707, 01.06.1999). The multiparametric analysis of baseline recordings derived from 24 cortical points made it possible to find the most probable pattern of changes in the spatial synchronization of biopotentials, including increase in activity in the right anterior and left posterior cortical regions. These changes were accompanied by a rise in the information-energy parameter (the ratio between coherence and spectral power of potentials). This phenomenon may testify to a transition to the "economic" condition of information processing. Differences in EEG frequency characteristics corresponding to different levels of imagination and creative intuition were revealed.     

Motivation effect on power changes in the brain biopotentials in the figurative and verbal creativity tasks

Effect of extrinsic motivation stimulating the most original problem solving during verbal and figurative divergent thinking was studied by EEG mapping. The righthanded university students (27 males and 26 females) participated in the experiments. An instruction "to create the most original solution" as compared to condition with an instruction "to create any solution" induced an increase in the baseline power of the alpha 1 and alpha 2 rhythms most pronounced in the posterior cortex. Task-related desynchronization of the alpha rhythms was higher but the beta-2 synchronization was lower after the former than after the latter instruction. Differences in the asymmetry of the alpha 1 and alpha 2 rhythms in the parietal and temporal regions of hemispheres suggested the right hemisphere dominance in intrinsic alertness and evoked activation related to divergent thinking. The findings were common and gender-independent in both figurative and verbal tasks suggesting a generalized influence of extrinsic motivation on creative activity.     

Gender differences in chronic alcoholism: EEG analysis

Comparative analysis of spatial organization of cortical biopotentials of men (n = 120) and women (n = 75) suffering from alcoholism and persons without addiction to alcohol (control groups) was carried out. Gender differences in the EEG spatial parameters under study (linear spatial synchronization in the brain cortex, non-linear spatial disorder, EEG coherence, and spectral power) were shown to be markedly less pronounced between the control groups (68 women and 85 men) than between the alcohol addicts. The obtained data allow us to explain the known fact of more serious and "malignant" character of alcoholism in women than in men in terms of neurophysiology. In alcoholics, the synchronization of low-frequency oscillations (delta and theta) was higher, whereas the synchronization of the higher-frequency spectrum part (beta1 and beta2) was lower in women than in men. This fact can be a neurophysiological basis of more progredient inhibitory-degenerative processes in women.     

Electroencephalographic brain dynamics following manually responded visual targets

Scalp-recorded electroencephalographic (EEG) signals produced by partial synchronization of cortical field activity mix locally synchronous electrical activities of many cortical areas. Analysis of event-related EEG signals typically assumes that poststimulus potentials emerge out of a flat baseline. Signals associated with a particular type of cognitive event are then assessed by averaging data from each scalp channel across trials, producing averaged event-related potentials (ERPs). ERP averaging, however, filters out much of the information about cortical dynamics available in the unaveraged data trials. Here, we studied the dynamics of cortical electrical activity while subjects detected and manually responded to visual targets, viewing signals retained in ERP averages not as responses of an otherwise silent system but as resulting from event-related alterations in ongoing EEG processes. We applied infomax independent component analysis to parse the dynamics of the unaveraged 31-channel EEG signals into maximally independent processes, then clustered the resulting processes across subjects by similarities in their scalp maps and activity power spectra, identifying nine classes of EEG processes with distinct spatial distributions and event-related dynamics. Coupled two-cycle postmotor theta bursts followed button presses in frontal midline and somatomotor clusters, while the broad postmotor "P300" positivity summed distinct contributions from several classes of frontal, parietal, and occipital processes. The observed event-related changes in local field activities, within and between cortical areas, may serve to modulate the strength of spike-based communication between cortical areas to update attention, expectancy, memory, and motor preparation during and after target recognition and speeded responding.     

New aspects of the neurophysiological mechanism of the action of nootropic preparations

The influence of nootropic drugs on EEG spectral power of the cortex and hippocamp was studied in resting rats. All these drugs had a specific action on EEG spectral power, causing an increase and stabilization of maximum basic distribution peak of the EEG spectral power. Such action may be attributed to better organization of rhythmic activity in theta-range. The drugs also decreased interhemispheric asymmetry of the cortical and hippocampal EEG. The authors suggest that the increase and improvement of the basic rhythmic activity in the brain and an increased level of distant (spatial) synchronization form the basis for the nootropic drug effect.     

EEG spatial characteristics after intense exercises

Subjects performed intense exercises in a teadbahn under conditions of high ambient temperature and humidity. Spatial characteristics of the EEG were estimated. The information value of the time course of the combined index, characteristics of spatial synchronization and entropy of cortical biopotentials as a test for brain reaction to a load and recovery of its functional state was shown. The significance of non-linear relations between brain potentials in the activation of the adaptive and compensation processes was mentioned.     

Excitability of the sensomotor cortex and red nucleus of rabbits at different levels of spatial synchronization of cortical potentials

To determine the excitability of the rabbit sensomotor cortex and red nucleus the animal's motor response to electrical stimulation of these structures at threshold strength was investigated. In computerized experiments the excitability of these structures was compared in situations characterized by different degrees of correlation of cortical potentials. An increase in the level of spatial synchronization of cortical potentials was shown to be accompanied by an increase in the excitability of the sensomotor cortex and red nucleus. This increase in excitability is evidently a neurophysiological mechanism of the increase in probability of appearance of an effector response to sensory stimulation when the level of spatial synchronization of cortical potentials is raised.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 9, No. 1, pp. 19–24, January–February, 1977.     

EEG study of the anxiolytic effect of scopolamine

Effect of the central M-cholinolytic scopolamine on spatial organization of the rat brain electrical activity was studied under conditions of high and low emotional-stress responses. The EEG changes were estimated by 840 parameters. A possibility of the EEG discrimination by means of interstrain differences in responses to scopolamine, was shown. A more obvious decrease in spectral power and potentials coherence was revealed in Maudsley Reactive rats (MR) as compared with the Maudsley Nonreactive rats (MNRA), in parieto-temporal and occipital areas of the right hemisphere, and the reverse interrelationship occurred in the anterior parts of the right and posterior parts of the left hemisphere. These findings suggest some specifics in the spatial distribution of the maximum scopolamine action foci depending on the initial emotional level. Changes occurring under the scopolamine effect in different EEG frequency bands are different in the MR and the MNRA rats. The findings are discussed in respect to the EEG indices of anxiolytic component of cholinergic regulation of the brain activity.     

The phenomenon of spatial synchronization of the brain potentials in a broad frequency band 1-250 Hz

A review. The article dedicated to the centenary of academician Mikhail Nikolaevich Livanov briefly outlines the history of development of his original concept of the functional significance of the brain potential's spatial synchronization phenomenon as a possible way of studying systemic organization of the brain electrical activity. The new parameter of "space" introduced into neurophysiology by M. N. Livanov made it possible to research the earlier unknown aspect of the brain activity. Livanov's ideas have been developed in many studies of the late decades of the XX century. In the review, much attention is given to specific functional significance of this phenomenon in a broad frequency band 1-250 Hz, especially, during instrumental learning. Energy (power spectra) and coherent-phase characteristics of cortical potentials in traditional (1-30 Hz), gamma-(30-80 Hz) and high-frequency (80-250 Hz) bands are compared. The problem of linear and nonlinear processes in the organization of the brain potentials is mentioned.     

Shifts in spatial synchronization of rabbit cortical potentials evoked by applying acetylcholine and amizil to the visual area

Acetylcholine solution application to the visual cortex of walking unrestrained rabbit led approximately in 5 minutes to a certain increase of the spatial synchronization of the cortical potentials at the small conditions, the the cortex, 24 EEG channels being used. Under the same conditions, the application of muscarinic antagonist amizil had an opposite more distinct effect. Endogenous cholinergic input increasing the spatial synchronization is supposed to play an important role in the formation of the spatiotemporal cortical potentials' organization necessary for the occurrence of complex behavioural acts.     

Gender-Dependent Frequency-Spatial Organization of the Brain Cortex Activity during Convergent and Divergent Thinking: II. Analysis of the EEG Coherence

The gender dependence of inter- and intrahemispheric interactions of neuronal assemblies during convergent (CTh) and divergent (DTh) thinking was studied on the basis of analysis of coherence (Coh) of cortical potentials in a broad frequency band. CTh was studied with a model of mental arithmetic, and DTh, with a heuristic task. Right-handed subjects were examined. The distinctive feature of CTh was a functional change in the patterns of EEG Coh in the θ band. Men were characterized by an increase in interactions between the centro-parieto-occipital areas of both hemispheres and between the frontal and temporooccipital regions of the right hemisphere, whereas a similar pattern of coherent connections was shifted to the left temporal area in women, suggesting a predominant use of verbal calculation strategies by women and visuospatial strategies by men. Regardless of the gender, DTh was associated with an increase in interhemispheric Coh and an increase in Coh in the right hemisphere. However, the successful performance of a task in men and women was determined by different degrees of hemispheric interaction: men successfully solved the problem under conditions of a closer interaction of both hemispheres, whereas women efficient in their performance showed a weaker interaction of homologous cortical areas as compared to noncreative subjects.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 3, 2005, pp. 39–49.Original Russian Text Copyright © 2005 by Razoumnikova.     

Influence of informational oversaturation on the quality of creative activity and spatial organization of EEG

The features of the spatial organization of bioelectric potentials in the cases of successful and unsuccessful creative imagination (refusal or poor quality of the product) under conditions of informational oversaturation. Two groups of subjects were compared: professionals (23 healthy students of the Department of Graphic Arts) and non-professionals (34 persons whose specialties were not linked with systematic visual imagination). During the experiments, the subjects were asked to mentally create a visual image based on two simple graphic elements, a right angle and a diagonal; after recording the EEG, they had to draw the image on paper and give it a title. The total number of elements exceeded 7 ± 2; hence, information processing at the conscious level was impossible, which caused the necessity of involving the mechanisms of unconscious information processing. The quality of the created product was evaluated with regard to the degree of success of performing the task and the features of spatial EEG organization. The EEG was recorded from 24 scalp sites of a subject using a SIT-EEG portable telemetric device. In the case of the successful performance of the task by professionals, the parameters of spatial organization of bioelectric potentials, i.e., spatial synchronization (linear processes) and spatial disorder (non-linear process) were strengthened compared to the base-line level in the frontal temporal areas of the right hemisphere and parietal occipital areas of the left hemisphere. Conversely, in the nonprofessionals, these parameters increased in the frontal temporal areas of the left hemisphere and parietal occipital areas of the right hemisphere. In the case a task was not successfully performed by the professionals, the spatial disorder of bioelectric potentials increased in all the cortical areas; in the nonprofessionals, only weak changes were observed. In all situations, the groups differed also in the parameters of coherence (Coh), spectral power (Sp) of bioelectric potentials, and informational energy, which reflects the level of expenditure of the brain’s energy for information processing. The evidence obtained is interpreted in terms of electroencephalographic correlates of successful task performance by professionals and nonprofessionals, i.e., their creative imagination under the conditions of informational over-saturation.     

Effect of swinging on EEG of rats of juvenile age in the wakefulness state

Simultaneous recording of the EEG activity of superficial cortical and deep (caudate nucleus, dorsal hippocampus, anterior hypothalamus) brain parts has been performed for the first time after a 2-h swinging of frequency of 0.2 Hz in Wistar rats of juvenile age. Swinging was produced on a 4-bar parallel swing. Using a Neuron-Spectr electroencephalograph and a Diana program, normalized power spectra of wave EEG components, synchronization coefficients, and coefficients of cross-correlation between bioelectrical potentials of various brain structures were determined. After a 2-h swinging, the mean value of normalized power of slow waves of delta-diapason in hypothalamus and hippocampus was found to increase statistically significantly, while normalized power of fast waves of alpha- and beta1-diapasons in hippocampus decreased (p < 0.05). A statistically significant increase of synchronization coefficient was observed in hypothalamus and hippocampus. Changes of coefficients of cross-correlation between hypothalamus and hippocampus and other brain strictures were of the oppositely directed, individual character. In the parietal occipital brain cortex and in caudate nucleus, the changes of the EEG spectral composition also were of individual character. The obtained results on the whole correspond to data about an enhancement of the EEG low-frequency rhythms at swinging and agree with the resonance hypothesis of motion sickness.     

The effect of the level of consciousness on the spatial organization of cortical activity in mental processes

In the present study the influence of the level of consciousness on spatial organization of the cortical functional activity in human psychic processes was investigated. For regulation of the level of consciousness models were used of hypnotic analgesia, automatization of intellectual actions and mental activity in hypnotic state. Evaluation of the mosaic of the cortical activity was made by parameters of spatial synchronization of the potentials with topographic mapping of crosscorrelation, spectral and coherent-phasic EEG characteristics. The obtained data allow to conclude about special role of the frontal areas of the left hemisphere in the process of realization of information. It has been shown that one of the main functions in neurophysiological structure of consciousness is the selection of signals according to dominating motivation. The frontal areas of the left hemisphere control the degree of inclusion of foci of increased activity, specific and non-specific for each type of activity, and possibly, regulate the way of transformation of the information.