[Adaptive function of the brain and problems of hypoxia].

Based on the findings of various authors and own experimental data it was concluded that adaptive behaviour is regulated by changing in the level of spontaneous neuronal activity. Spontaneous firing is monitored by brain metabolic M-cholinergic reaction which increased the efficacy of dendritic propagation by mechanism of K+ membrane channels blockade. High energy demands of cholinergic process creates a threat to nerve cells survival in hypoxic conditions.

[Emotionality and spatio-temporal organization of momentary EEG potentials].

With the aim to reveal features of the neocortical spatiotemporal organization of potentials characteristic of different genetically predetermined emotional levels, momentary values of EEG potentials were analyzed in inbred rats of MR and MNRA strains. A topogram was described by a basic parameter such as its general level (the mean of momentary values of potentials derived from 24 symmetrical electrodes bilaterally implanted into the brain cortex) and a similarity coefficient (correlation between the set of its momentary values and that of a standard topogram). The general level and similarity coefficient values were calculated for a series of successive topograms individually for the right and left hemisphere. Also, right- and left-side power spectra of these series were calculated. In rats of MR strain, significant (p < 0.05) peaks in the general level and similarity coefficient spectra were observed in the delta (2.0 Hz), teta (6.5 Hz) and alpha (9 Hz) frequency bands. In this strain, the general level power was higher at the right side, and the similarity coefficient power displayed the left-side dominance. In rats of MNRA strain, peaks in the delta(2.0 Hz) band coinsided in the general level and similarity coefficient spectra, whereas, independently, the general level spectra had peaks in the theta band (7.0 Hz), and similarity coefficient had peaks at frequencies 3.0, 4.5, and 6.0 Hz. The left-side general level spectral power was higher than the right-side general level spectral power in the delta and lower in the high-frequency theta bands. The similarity coefficient power displayed the left-side dominance for the peaks in the delta (2.0 Hz) and theta (3.0 Hz) bands, and it displayed the right-side dominance for the peaks in the theta (4.5 Hz) band. The specific features of the cortical spatiotemporal organization of potentials revealed in rats of MR and MNRA strains suggest different modes of functioning of at least two systems, reticulo-thalamo-corticaland hippocampo-cortical.

[Influence of chronic melipramine administration abolition on locomotion and defensive conditioned reflexes in passive and active avoidance in rats].

The chronic (21 days duration) administration of tricyclic antidepressant melipramine of Wistar rats strain (15 mg/kg daily, intraperitoneally) evoked weight loss of animals. The 7 days after melipramine abolition its sedative effect was observed in the "open field" test by decrease of locomotion and the number of boles. The 7 and 14 days after melipramine abolition the difference between control and melipramine treated animals in passive and active avoidance learning and memory not found. The experimental results comparison with the literature data show, that chronic melipramine administration of intact animals evokes a sedative state. This conclusion does not contradict to idea of punishment function of brain serotoninergic system.

[Multiparametric analysis of the effect of ethanol in various doses on EEG in rats]. / Vliianie étanola vrazlichykh dozakh na éég krys. Mnogoparametricheskii analiz.

Multiparametric EEG analysis (840 parameters) was performed for 24 points over the entire dorsal cerebral cortex in outbred rats intraperitoneally injected with ethanol in low (0.75 g/kg), medium (2.0 g/kg), and high subnarcotic (4.5 g/kg) doses. Acute intoxication with low ethanol doses led to an increase in the spectral power and coherence in the frequency band of the dominating theta-rhythm peak (5.75-7.25 Hz), which was indicative of activation of the septo-hippocampal system (with improvement of the related functions such as attention, memory, and exploratory activity). The coherence was also increased in several high-frequency bands of the EEG alpha- and beta-rhythm. Ethanol administered in medium and high doses produced a shift of the dominating theta-rhythm peak to lower frequencies (4.50-5.75 Hz), which was evidence of reduced activity of the septo-hippocampal system and the related CNS functions. These doses of ethanol significantly decreased the spectral power and coherence in most of the high-frequency bands of the EEG alpha- and beta-rhythm, which can be explained by reduced energy and synaptic activity of the cortex leading to impaired high brain functions and the development of somnolent and narcotic effects. Using special sets of reliably modified parameters and a special algorithm, it is possible to solve the inverse problem of identifying experiments (EEG fragments) corresponding to low, medium, and high doses of ethanol.

[Comparative analysis of EEG spatial organization in the rats with different level of genetically determinated anxiety under ethanol]. / Sravnitel'nyi analiz prostranstvennoi oprganizatsii EEG u krys s raznym urovnem geneticheski determinirovannoi trevozhnosti pri vozdeistvii étanola.

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.

[Effect of novel anxiolytic agent aphobazole on coherence of the brain biopotentials in MR and MNRA rats]. / Vliianie novogo anksiolitika afobazola na kogerentnost' biopotentsialov kory golovnogo mozga krys linii MR i NMRA.

Effect of the anxiolytic drugs afobazole, diazepam, and chlordiazepoxide on the cortical biopotential coherency was studied in MR and MNRA rats with increased and decreased level of emotionality, respectively. Afobazole increased a difference in the biopotential coherency between rats of the two lines in the range of EEG theta, alpha, and beta rhythms. In the subrange of dominating theta activity (6.00-7.25 Hz), this effect took place at the expense of reduced coherency in MNRA rats in the absence of changes in the MR line. Afobazole decreased the biopotential coherency in the alpha activity band (7.5-8.25 Hz) in the rats of both lines. This is indicative of the presence of a CNS-stimulating component in the pharmacological activity spectrum of afobazole. The expediency of using afobazole in patients with different levels of anxiety is discussed.

[Effect of a novel antimigraine preparation tropoxin on EEG of MR and MNRA rats]. / Vliianie novogo protivomigrenevogo preparata tropoksina na EEG krys linii MR i MNRA.

Effect of the new antimigraine drug tropoxin on the EEG profile was studied in MR and MNRA rats with genetically determined high and low levels of emotionality, respectively. In MR rats, tropoxin decreased the number of the bioelectric activity parameters changed by the stressor action (0.9% NaCl, i.p.). The drug reduced the spectral power in the EEG delta band, and increased that in the theta, beta-1, and beta-2 bands. This was evidence of the central stimulating action and the possible enhancement of the exploratory activity. In MNRA rats no changes in bioelectric activity were observed in the low-frequency delta and theta bands, while the spectral power in the beta-1, and beta-2 bands showed a decrease. It was concluded that a neural component is present in the mechanism of the tropoxin action, which may play an important part in the therapeutic effect of the new drug.

[Features of the stress reaction in rats with genetically-determined emotionality (from EEG indicators)]. / Osobennosti stress-reaktsii u krys s geneticheski determinirovannoi émotsional'nost'iu (po pokazateliam EEG).

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.

[Spatial organization of EEG in rats with genetically determined emotionality]. / Prostranstvennaia organizatsiia EEG pri geneticheski determinirovannoi émotsional'nosti u krys.

In order to study the possibility of EEG discrimination of genetically determined emotionality (increased propensity to emotional and stress reactions and anxiety) brain electrical activity was recorded in rats of two strains: Maudsley Reactive and Maudsley Nonreactive (24 derivations from the convexital skull surface were used). The program package "Synchro-EEG" was used for EEG processing. It was demonstrated that the two rat strains were significantly different in 120 EEG parameters of 840 ones analyzed. On the basis of 37 parameters, each rat was correctly recognized as belonging to the respective group with the error of 4.89%. The analysis of the detected signs allowed their classification to be performed in accordance with the peculiarities of the emotional and cognitive processes and the level of nonspecific activation. Specific forms of interaction between these components in the system of emotional reactions were revealed.

[EEG study of the anxiolytic effect of scopolamine]. / EEG-issledovanie anksioliticheskogo éffekta skopolamina.

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 effect of scopolamine on the spatial organization of rat cortical potentials]. / Vliianie skopolamina na prostranstvennuiu organizatsiiu potenstialov kory golovnogo mozga krys.

The influence of scopolamine (1 mg/kg, i.p.) on the spatial organization of the neocortical electrical activity was studied in rats. A decrease in the spectral power and coherence of brain potentials in the range of the dominant theta-rhythm peak (6.00-7.25 Hz) and their increase in the adjacent low-frequency band were observed. Both indices were decreased in the wide beta band (19.00-30.00 Hz). The described changes took place over the whole areas of the right hemisphere and parieto-temporal region of the left hemisphere. The obtained results are discussed with respect to the role of the cholinergic brain system in the higher nervous activity.

[The effect of opioid neuropeptides on the cholino- and adrenoreactivity of the sensorimotor cortex cells in rats]. / Vliianie opioidnykh neiropeptidov na kholino- i adrenoreaktivnost' kletok sensomotornoi kory krys.

The effect of two neuropeptides, dalargine and betaendorphine, on cholino- and adrenoreactivity of sensorimotor cortex cells has been studied in immobilized rats in acute experiments. Subcutaneous administration of the peptides led to redistribution of cells according to the type of their reaction and to changes in intensity of neuronal reactions to the applied neurotransmitters. The observed changes in chemoreactive properties of cortical neurons under the influence of the neuropeptides may play a certain part in the processes of learning and memory.

[Decreased chemoreactivity of neurons of the sensorimotor cortex during adaptation to stress and its role in the prevention of heart fibrillation in acute ischemia]. / Snizhenie khemoreaktivnosti neironov sensomotornoi kory pri adaptatsii k stressovym vozdeistviiam i rol' étogo iavleniia v preduprezhdenii fibrilliatsii serdtsa pri ostroi ishemii.

The effect of the adaptation to repeated short-term stress on the bioelectrical responses of neurons in the IV layer of the sensorimotor cortex developed under the action of acetylcholine and norepinephrine was studied in rats along with the effects on the development of arrhythmias, fibrillation and mortality in conscious animals with cardiac ischemia. It has been established that the preliminary adaptation reduced considerably the chemoreactivity and especially adrenoreactivity of the neurons and at the same time decreased fibrillation and mortality in acute ischemia.

[Participation of beta-endorphin in the regulation of the membrane chemoreactive properties of the cortical neurons in rats]. / Uchastie beta-éndofina v reguliatsii khemoreaktivnykh svoistv membran kortikal'nykh neironov krys.

The subcutaneous administration of beta-endorphin and its endogenic accumulation in the process of elaboration of adaptation to the short-term stress influences is accompanied by the change of chemoreactive properties of rat sensorimotor cortex neurons expressed in increasing of the share of areactive cells and lowering of the share of cells reacting by the response activational form to acetylcholine and noradrenaline led to them microiontophoretically. The reaction intensity of cells, both activational and inhibitory forms to the led neurotransmitters in both experimental groups is significantly lower than in control. The revealed changes of chemoreactive properties of neurons, arising under the influence of the increase of beta-endorphin amount in brain may be one of the mechanisms of its participation in the processes of learning and memory.

[Effect of vasopressin and enkephalin analogs on the chemoreactive properties of the sensorimotor cortex neurons in rats]. / Vliianie analogov vazopressina i énkefalina na khemoreaktivnye svoistva neironov sensomotornoi kory krys.

On immobile rats it has been shown that subcuteneous injection of two different neuropeptides causes different distribution of activating, inhibiting and areactive cells resulting from microionoforetically administrated acetylcholine and noradrenaline without altering the mean frequency of the background unit activity sensorimotor cortical neurons. At the same time the alteration in the pattern of neurons impulse activity has been revealed, which acquires the character of packet activity with a specific packet length of 2-3, 4-6, 7-10 impulses. Depending on the injected neuropeptide reliable but almost contrary effects of the packet activity alterations have been observed. These effects have been suggested to result from the alteration of the chemoreactive properties of the neuron membranes and the corresponding reorganisations of interneuron attitudes.

[Effect of a vasopressin analog on the chemoreactive properties of sensorimotor cortex neurons]. / Vliianie analoga vazopressina na khemoreaktivnye svoistva neironov sensomotornoi kory.

Subcutaneous injection of 10 micrograms desglycilargininvasopressin (DG-AVP) does not alter the mean frequency of background unit activity of sensorimotor cortical neurons. However, the pattern of impulse activity is essentially changed. At the same time the reactions of sensorimotor cortical neurons to microiontophoretic administration of acetylcholine and noradrenaline experience definite changes. It is suggested that the DG-AVP-induced changes in chemoreactive properties of neurons underlie the effect of this peptide on the learning and memory.