Some features of spatiotemporal organization of brain biopotentials in persons with different levels of anxiety and other personality traits

Anxiety and other personality traits were scored in 55 practically healthy subjects with the aid of 16-PF Cattell questionnaire. EEG was analysed by the mapping method after N.E. Sviderskaya. It was shown that two groups with equally high anxiety scores had different spatiotemporal organizations of brain biopotentials. The most "unfavorable" EEG characteristics were found in the group of "anxious conformists": poorly pronounced alpha rhythm with a low level of coherence in the alpha band was concomitant with the theta and beta rhythms with high levels of coherence and power density.     

Pharmacological action of phenazepam and caffeine on emotional sphere changes ethanol preference in Wistar male rats

Earlier we showed that direction of changes in the initial anxiety level during compulsory alcoholization was more essential for development of alcohol preference than the initial anxiety level per se. The goal of this work was to study effect of the anxiety level changes on development of ethanol preference in Wistar male rats pharmacologically affected by phenazepam and caffeine. Out of four groups (60 rats) over the period of 4 months, group I had access to 10% ethanol, group II-to 10% ethanol with 0.4 g/l caffeine, group III-to 10% ethanol with 0.5 mg/l phenazepam, and group IV (control)—to water only. The anxiety level and behavioral parameters were evaluated before the onset of the experiment and every 5 weeks thereafter by using the open field test. The ethanol preference was determined by the 2-glass test before the onset of the experiment and every 4 weeks thereafter. In the experimental groups, the long-term consumption of ethanol, ethanol with caffeine, and ethanol with phenazepam led to an increase in alcohol preference as compared with control. A decrease in motor activity under compulsory alcoholization was found to correlate positively with the low level of alcohol preference. Rats that consumed ethanol with caffeine sensitive to this anxiety-enhancing psychostimulant developed ethanol preference faster. The rats insensitive to caffeine developed no alcohol preference. The rats sensitive to the sedative effect of phenazepam were less anxious and did not prefer alcohol subsequently. In rats insensitive to phenazepam, anxiety increased and alcohol preference developed.     

Spatial organization of EEG activity during active hyperventilation (cyclic breath) I. general patterns of changes in brain functional state and the effect of paroxysmal activity

Changes in spatial organization of EEG activity were analyzed in 44 humans during active 1-h hyperventilation using cyclic or circular breath (CB) technique similar to rebirthing breath technique. The dynamics of different indices was recorded each 5 min (using 12 time slots). A double-humped pattern of changes in spatial organization indices (linear processes) and spatial disorder (nonlinear processes) of biopotentials: an initial decrease within 1 to 20–30 min and a second one from 35–40 min to the end of session. A complex dynamics of spatial frequency processes (coherence and spectral power of biopotentials) with different pattern of changes within narrow frequency EEG bands. The dynamics of the spatial organization of EEG indices proved to depend on the intensity of hyperventilation-induced paroxysmal activity. The indices of spatial synchronization and disorder of biopotentials as well as low frequency β-activity (16.00–22.50 Hz) decreased more at the background of high rather than low paroxysmal activity, while the low frequency components (Δ and Θ) and high frequency α-activity (11.25–12.50 Hz) increased more. The obtained data are considered in terms of specific consciousness state induced by CB.     

The influence of intracysternal insulin administration on the rat temporal behaviour dynamics

Rat behaviour in the open field and elevated plus-maze was analyzed in rats after intracysternal administration of 2.5, 25, 50 and 200 ng of insulin in 45 min, 24 hrs and on the 9th day after single injection. Dose-dependent changes in 45 min occurred in both behavioural tests: insulin in low doses (2.5 and 25 ng) increased probability of locomotion and investigative activity in open field, while insulin in high doses (50 and 200 ng) did not alter locomotor activity and showed tendency to weakening of the investigative behavior (especially in the dose of 50 ng). Tendency was found in 24 hrs to increase probability of investigative behavior in open field after injection of 25 ng of insulin, although on the 9th day after insulin administration this behaviour increased in all experimental groups for all used doses. Insulin in the doses 2.5 and 200 ng decreased anxiety in elevated plus-maze in 45 min during the first five min; the doses 2.5 and 25 ng at the second five min exerted the same effect. In 24 hrs, the anxiety level increased for the doses 50 and 200 ng, and there was a tendency for an increase in the doses 2.5 and 25 ng; anxiety was decreased on the 9th day for all used doses of insulin. Thus, single insulin administration induced weakness of non-associative memory in open field on the day 2 and day 9 as well as increase of anxiety level on the day 2 and decrease of anxiety level on the day 9 in elevated plus-maze.     

The ECoG of rats with genetic catalepsy]

Electrographic study was carried out in Wistar rats and the rats of genetical catalepsy (GC) strain. In contrast to Wistar rats epileptiform activity was observed in ECoG of GC rats being enhanced at the transition to a cataleptic state. Analysis of spectra and coherence of EEG revealed the presence of interhemispheric brain asymmetry in all the rats. In some frequency bands in GC rats inversion of interhemispheric asymmetry was found, which had been characteristic for Wistar strain. The highest interhemispheric synchronization of biopotentials was observed in the frontal cortical areas in GC rats and in the occipital areas in those of Wistar strain.     

Changes in the behavior and EEG of rats administered penicillin and a physiological solution into the amygdalar basal nuclei]

Three weeks after implantation of the electrodes for EEG recording, hyperactivation of the basal nucleus of rat's amygdala was produced by a local injection of penicillin (0.5 mcl, 1% solution). Saline injection of the same volume served as control. The hyperactivation of the amygdala resulted in a long-lasting (at least for 3 weeks) increase in the locomotor activity against the background and deficit in exploratory behavior and rise of the level of anxiety and fear. The behavioral changes were accompanied by a long-term disruption of the hippocampal theta rhythm, appearance and slowing of the immobility-related high-voltage spindles, and increase in the EEG dominant frequency in the state of emotional tension. Saline injection led to a short-time (up to 1 week) decrease in locomotor and exploratory activity and increase in anxiety. These phenomena were accompanied by a short-time disruption of the theta rhythm and appearance of the 10-13-Hz oscillations characteristic for the state of emotional tension.     

Psychophysiological indices in six-to eight-year-old children under information load depending on anxiety as a stable individual characteristic

The study of psychophysiological indices in children aged six to eight years under information loads of various complexity showed that anxious subjects were characterized by a high level of nonspecific activation at rest and a shift of the autonomic balance towards a relative domination of the tone of the sympathetic division of the autonomic nervous system (ANS). The information load in the “auto-rate” mode caused in children aged six to eight years an increase in the level of nonspecific activation and the activity of sympathetic regulation and an inhibition of parasympathetic regulation. An information load in the “maximum rate of work” mode caused a decrease in the quantitative and qualitative indices of mental activity in comparison with that under comfortable conditions and a subsequent increase in autonomic shifts and the level of situational anxiety. The decrease in the efficiency of intellectual work performed at a maximum rate against the background of a high level of nonspecific activation and an increase in situational anxiety in both groups apparently reflected an increase in the activity of the modulating cerebral system due to the domination of the nonproductive activation system related to defensive behavior. At the same time, in children with a high personal anxiety, autonomic manifestations of activation and situational anxiety in both modes of work were more distinct and the efficiency of work lower than in subjects with a low anxiety. This indicates that, in anxious children, due to the excess activation of the sympathetic division of the ANS, the information load has a higher physiological cost. Thus, children with a high level of personal anxiety under intense information loads are characterized by a larger increase in the activity of the sympathetic division of the ANS and the attenuation of the effect of the parasympathetic division; a considerable increase in situational anxiety; low efficiency of activity; and, hence, its high physiological cost.     

Selective influence of dehydroepiandrosterone-sulphate on anxiety induced by corticotropin-releasing hormone injection

The objective of this study was to ascertain the effect of dehydroepiandrosterone-sulphate (DHEA-S) on changes of anxiety level, induced by corticotropin-releasing hormone (CRH) injection. Active and passive rats were selected from Wistar rats on the basis of T-maze testing. Active rats were then divided into the groups with high (HA) and low anxiety (LA) level after testing in elevated-plus maze. Intranasal injection of CRH induced increase of anxiety level in the LA rats, while in HA rats it remained unchanged. DHEA-S exerted a moderate anxiolytic effect on the LA rats and sedative effect--on the HA rats. DHEA-S injection had no effect on anxiety level in passive rats that typically demonstrate high level of trait-anxiety and resistance to CRH. These results suggest that DHEA-S effect depends on the individual psycho-emotional status and responsiveness to CRH.     

Chronic low dose ethanol intake: biochemical characterization of liver mitochondria in rats

Liver mitochondria were isolated from male rats exposed for 2 months to low doses of ethanol (3% v/v in drinking water), a condition not associated with tolerance or dependence. The results show no significant changes in the content of reduced or oxidized glutathione in the liver mitochondria of ethanol treated rats with respect to controls. However, a slight but significant increase in lipid peroxidation, accompanied by an increased content of oxidized proteins, was found in ethanol exposed animals. Mitochondrial content of cytochrome complexes was not significantly affected by ethanol intake. The specific enzymatic activity of cytochrome oxidase showed, however, a significant decrease in ethanol-treated rats. The slight mitochondrial alterations found in the liver of rats exposed chronically to low doses of ethanol might represent the beginning of a more extensive damage previously observed in rats exposed to high doses of this substance.     

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.     

A correlation of EEG characteristics of pregnant women with the level of their anxiety

It has been shown that the EEG of pregnant women with high anxiety level is characterized by a lower occipital alpha and theta rhythm spectral power if compared to the EEG of women with low anxiety level. The frequency of the alpha rhythm of their EEG was reliably higher. Pregnant women with high anxiety level with a pregnancy interruption threat diagnosis have an essentially lower occipital alpha rhythm spectral power than women of this group without such a diagnosis. And vice versa, the occipital alpha rhythm spectral power in the EEG of pregnant women with low anxiety level with a pregnancy interruption threat diagnosis is essentially higher and its frequency essentially lower than the EEG of women without that diagnosis. The data received are interpreted as a change in hormone regulation during the pregnancy period, as well as psychogenic influence on the pregnancy.     

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.     

Possible correlations between the level of alcoholic motivation and the electrophysiological structure of sleep in the rat

Using modified Porsolt's method, the electrophysiological sleep pattern was studied in normal conditions and after a single intraperitoneal ethanol injection to noninbred male albino rats divided into 2 groups ("high activity" and "low activity" rats). Voluntary alcohol intake in these rats was measured during free choice between 10% ethanol and water for 20 days. "Low activity" rats were characterized by a statistically significant 3.4-fold higher level of ethanol consumption and 2.7-fold longer REM-sleep stage, as compared to "high activity" animals. In "low activity" animals ethanol (1 g/k, 10% solution, i. p.) inhibits and in "high activity" rats it increases REM-sleep stage, thus removing differences in the sleep pattern in the two groups of rats. The data obtained suggest a possible role of REM-sleep in the development of alcohol motivation.     

Epileptogenic activity of tripeptide corticotropin-releasing factor fragment (CRF(4-6))

The effects of centrally administered tripeptide fragment CRF(4-6) of corticotropin-releasing factor on convulsive activity in outbred albino rats were investigated. The peptide CRF(4-6) (icv; 6, 30, 150 nmol/head) causes dose-dependent increase in total EEG power in 1-40 Hz frequency range as a reflection of tripeptide-induced various epileptiform EEG signs such as single peaks and spike trains without external convulsion. Higher doses of CRF(4-6) (icv; 150, 225, 300 nmol per animal) induce tonicoclonic seizures. Switching to convulsive activity occurs at CRF(4-6) dose of 150 nmol per animal: injection of this dose leads only to EEG paroxysmal activity under habitual conditions and induces pathological locomotor activation under stressing conditions. Thus, CRF(4-6) similarly to full-length corticotropin-releasing factor induces epileptiform activity in rats.     

A differential action for ethanol on baroreceptor reflex control of heart rate and sympathetic efferent discharge in rats

The acute effects of ethanol (0.33, 0.66, or 1 g/kg) on baroreflex control of heart rate (HR) and sympathetic efferent discharge (SED) were investigated in chloralose-anesthetized rats. The two higher doses of ethanol caused a progressive and significant increase in baseline SED and a slight increase in HR. That these effects were ethanol mediated is suggested by the absence of any change in blood pressure following ethanol injection in any amount used and the finding that equivolume saline had no effect on any of the tested parameters. On the other hand, the baroreflex slope of the MAP-SED relationship after ethanol was similar to the control (preethanol) value in contrast to a significant decrease in the baroreflex slope of MAP-HR under the same conditions. These findings suggest that the sensitivity of the reflex control of SED was preserved whereas that of HR was impaired after acute ethanol administration. Since these findings were obtained in the same animals, our data suggest that acute ethanol has a differential action on reflex control of SED and HR. Further, the significant increase in SED after moderate and high doses of ethanol suggests an increased central sympathetic tone as recordings were made from preganglionic nerve fibers (splanchnic nerve). The absence of an increase in baseline MAP, in spite of a significant increase in baseline SED following acute ethanol injection, could be explained, at least in part, by an ethanol-evoked reduction in pressor responsiveness to phenylephrine, an alpha-adrenergic agonist.     

Effect of chronic ethanol consumption on emotional stress in the white rat

Chronic pain emotional stress (PES), paired action of the white noise and electric skin stimulation and chronic (during 7 months) ethanol consumption in white rats were shown to act in the same direction. Hypertension, decrease of respiratory rate and increase of Hildebrandt index were observed as a result of PES, ethanol consumption, and especially under PES during ethanol consumption. Ethanol consumption by the animals led to their growth retardation and increase of the spleen and heart mass. Accidental thymus involution was noted both under ethanol consumption and PES. Activation of lipid peroxidation and decrease of superoxide dismutase activity (of its mitochondrial form especially) as well as of Na+,K+-ATP-ase activity were observed in brain homogenates of the rats after PES, while the general ATP-ase activity remained unchanged. An increase of triiodothyronine level and the tendency to thyroxine level increase as well as a decrease of superoxide dismutase activity were observed in the blood serum of these animals. A tendency towards lipid peroxidation level decrease and to brain superoxide dismutase activity increase, as well as blood antioxidation activity increase (evaluated by transferrin and coeruloplasmin contents and by serum superoxide dismutase activity) and a decrease of thyroxine level were observed as a result of ethanol consumption. The mechanisms are discussed of the "anti-stress" action of short-term ethanol consumption and of the action of its chronic consumption, additive to PES.     

Effect of serotonin on the electrical activity of the cerebral cortex in the rabbit

Application of serotonin on the rabbit cerebral cortex produced prolonged (minutes) periodical oscillations of the activation level and the level of spatial synchronization of neocortical biopotentials. Periodical changes of biopotentials correlation were due above all to a significant reorganization of phasic correlation of the EEG theta-components of remote neocortex points. The changes may be explained by the appearance, due to serotonin, of slow oscillations of the excitation level of the cortical neurones, as a systemic transitional reaction to the change in the balance of excitatory and inhibitory processes. The ability of serotonin to influence phasic relationships of the distantly-synchronous cortical theta-rhythm is of considerable significance for conditioned activity.     

Organization of the spatial-temporal relationships of cerebral electrical processes in children during exposure to verbel commands]

An EEG cross-correlation analysis has shown that in children aged four to five years higher sensory analysis of verbal commands and their meaning was reflected in the nature of synchronous interactions between oscillatory processes and their spatial-temporal patterns. At the moment of perception of the command "listen" highly synchronous synphasic relations were recorded between biopotentials in the associative infero-parietal cortex and projection temporal centres of the left hemisphere. Oscillations of the parietal areas preceded the rhythms of the occipital, motor and frontal lobes in the left hemisphere; slow oscillations with a 3 osc/sec frequency predominated, and the intensity of the periodic processes increased. The command "look" evoked a high degree of synchronous synphasic relations of biopotentials in the parietal-occipital cortical parts of both hemispheres; oscillations with 6 osc/sec frequency predominated; their intensity rose; synphasic relations of oscillations in parietal and motor and temporal centres grew more manifest, while the rhythmic activity in the parietal zones preceded the potentials in the frontal lobes of both hemispheres.     

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.     

The intercentral relations of the frontal cortex and limbic structures of the brain in dogs]

In 3 dogs with implanted electrodes, in conditioned experiments correlation of the bioelectrical processes was studied by coherence function calculation of the hippocampus, hypothalamus, amygdala and frontal cortex biopotentials. It was shown, that the level of maximum values of coherence function of bioelectrical oscillations, led from various pairs of the studied brain structures significantly differed both in magnitude and frequency at which the greatest synchronization of biopotentials was noticed. In one dog with a high degree of connection between the hippocampus and hypothalamus biopotentials oscillations, a low synchronization of the frontal cortex and amygdala oscillations was found; in two other animals with a higher level of coherence between the oscillations of the frontal cortex and amygdala biopotentials, a lower degree of connection between the oscillations led from the hippocampus and hypothalamus was revealed. Synchronization of the biopotentials of the hippocampus and frontal cortex and also of the hippocampus and amygdala biopotentials proved to be low in all experimental dogs, what additionally testifies to different role of these structures in organization of the behaviour.