[The history of observations and some methodological features of the studies on local sleep]. / K istorii nablyudeniya i nekotorym metodicheskim osobennostyam issledovaniya proyavlenii lokal'nogo sna.

The phenomenon of local sleep, a concept that has come into somnology relatively recently, has been attracting more and more attention of researchers. Under this name, two groups of phenomena are considered. The first is the appearance in different parts of the cerebral cortex of different EEG patterns during general sleep. The second is the disconnection of certain cortical areas from the processing of extero- or proprioceptive signals and their transition to spiking and slow wave electrical activity, which is typical for sleep, while awake. The authors believe that it is the second phenomenon that can be called real local sleep. The appearance of local cortical sleep is inseparably linked with the occurrence of local wakefulness. It can be expected that the occurrence of local sleep will have detrimental consequences for behavior in urgent and complicated situations, while local wakefulness can adversely affect the visceral health of the body. A possible way of early detection of the local sleep development is proposed. In conclusion, some methodological problems on the way of electrophysiological studies of the local aspects of sleep and wakefulness are considered.

[On the mechanism of therapeutic effects of electrostimulation. Interpretations and predictions based on the results of sleep studies]. / K mekhanizmu terapevticheskogo éffekta élektrostimuliatsii. Interpretatsii i predskazaniia, osnovannye na rezul'tatakh issledovanii sna.

Based on the studies of the transition from wakefulness to sleep, we propose that therapeutic effect of various types of electrical stimulations can be related to growing sleepiness promoted by the stimulation, and to the improvement of sleep quality resulted from this procedure. Namely, improved sleep but not the stimulation itself will cause the therapeutic effect. The authors also discuss the probable mechanisms of the anticonvulsive effects of the vagus nerve stimulation and suggest that this effect could be caused by the changes in rhythmical activity of the visceral organs as a result of stimulation. Changes in these frequencies will shift them out of the resonance range of the cortical neuronal circuits, towards which propagation of these visceral signals is opened during sleep.

[Progress of sleep studies in the age of electrophysiology. The visceral theory of sleep]. / Progress izucheniia sna v épokhu élektrofiziologii. Vistseral'naia teoriia sna.

Electrophysiological methods of studying the nervous system have opened up new opportunities for investigations of sleep. Striking changes in the pattern of EEG during the transition from wakefulness to sleep made it's recording a mandatory element of any somnological research. It was also found that the frequency of neuronal firing in the cerebral cortex during sleep does not decrease, but can significantly exceed the average level of the cortical activity during wakefulness. But it remained the main mystery of sleep, what was associated with this high activity of cortical neurons at a time when the thresholds of sensory perception raised and the propagation of signals from the outside world and from the own body towards the cerebral cortex were almost blocked. The resolution of this paradoxical situation was suggested by the visceral theory of sleep. This theory was based on the assumption that during sleep interoceptive afferentation from all visceral systems of the body arrives for analysis into the cerebral cortex. This article offers an overview of the studies performed for direct experimental verification of non-trivial predictions of this theory.

[Long and difficult way towards the understanding of sleep function. Period before the age of electrophysiology]. / Dolgii i trudnyi put' k ponimaniiu naznacheniia sna. Étap do épokhi poiavleniia élektrofiziologii.

It was proposed that historical analysis of ideas concerning the function of sleep will help to evaluate the tendencies in this field of science and will show the probable direction for further approach to understanding of this problem. We reviewed ideas of Ivan Pavlov and his Russian forerunners (Ivan Tarkhanoff and Maria Manaceine) and followers (Nikolay Rozjanskiy and Konstantin Bykov) on the functional role of sleep. This analysis led to the conclusion that state of sleep have been connected with realization of such functional operations, which have not been considered in the past and are not under consideration in the present neuroscience. Thus, one can expect that real understanding of sleep function will come only with new neurophysiologic paradigm.

[Sleep, emotions and the visceral control].

It is known that sleep is connected with sensory isolation of the brain, inactivation of the consciousness and reorganization of the electrical activity in all cerebral cortical areas. On the other hand, sleep deprivation leads to pathology in visceral organs and finally to the death of animals, while there are no obvious changes in the brain itself. It stays the opened question how the changes in the brain activity during sleep could be con- nected with the visceral health? We proposed that the same brain areas and the same neurons, which in wakefulness process the information coming from the distant and proprioreceptors, switch during sleep to the processing of the interoceptive information. Thus, central nervous system is involved into the regulation of the life support functions of the body during sleep. Results of our experiments supported this hypothesis, explained many observations obtained in somnology and offered the mechanisms of several pathological states connected with sleep. However, at the present level of the visceral sleep theory there were no understanding of the well known link between the emotional states of the organisms and transition from wakefulness to sleep, and sleep quality. In this study the attempt is undertaken to combine the visceral theory of sleep with the need- informational theory ofemotions, proposed by P. Simonov. The visceral theory of sleep proposes that in living organisms there is a constant monitoring of the correspondence of the visceral parameters to the genetically determined values. Mismatch signals evoke the feeling of tiredness and the need of sleep. This sleep need en- ters the competition with the other actual needs of the organism. In according with the theory of P. Simonov emotions connected with a particular need play important role in their ranking for satisfaction. We propose that emotional estimation of the sleep need, based on the visceral signals, is realized in the same brain structures which undertake this estimation for other behavioral needs in wakefulness. During sleep, the same brain structures, involved in estimation of emotions, continue to rank the visceral needs and to define their order for processing in the cortical areas and in the highest level of the visceral integration. In the context of the proposed hypothesis, we discuss the results of the studies devoted to investigation of the link between sleep and emotions.

[Sleep and pregnancy].

Sleep disturbances are frequent during pregnancy and are currently regarded as one of the most important factors determining pregnancy outcome. Detailed research of sleep features during pregnancy is obviously essential. In the present review recent data concerning changes in sleep structure and regulation in pregnant women and rats - main subjects of experimental sleep research, are given, including surmised mechanisms underlying such changes. The importance of women's sleep integrity preservation during pregnancy for the viability and normal development of the fetus is emphasized and possible ways of pathological influence of sleep disorders during this period are discussed.

[The features of sleep homeostasis in pregnant rats].

To investigate the effects of short-term sleep deprivation on the sleep pattern during pregnancy, cortical and hippocampal EEG and locomotor activity were recorded within 24-hours in a "disk-over-water" paradigm in 18 Wistar rats. Rats were adapted to experimental situation and were able to move across the rotating disk without falling in water. Then a polysomnogram was recorded for 3 sequential days in the control group 1 (n = 12) without disk rotation. On the next day non-pregnant rats (experimental group 1, n = 6) were subjected to the sleep deprivation procedure with a pre-set program of disk rotation from 11:00 to 14:00 during 3 sequential days. Other 6 rats (experimental group 2) were subjected to sleep deprivation on the 5-7th day of pregnancy. EEG and locomotor activity were also constantly recorded during the sleep deprivation procedure. In control group 2 (n = 6, without sleep deprivation), a polysomnogram was recorded on the 5-7th day of pregnancy. As compared to non-pregnant rats, sleep intensity of pregnant rats increased during the first hours after the deprivation, and a considerable rebound of REM sleep took place. Sleep pattern during the off-light 12 hours remained unchanged. The results suggest that homeostatic compensation of sleep deprivation effects in rats on the first week of pregnancy is more efficient than in control non-pregnant animals.

[The sleep and the visceral function control].

The review focuses on rapidly growing body of data indicating that disturbances of the natural sleep and sleep deprivation lead to various visceral disorders. The review mentions consequences of sleep disturbances on the gastro-intestinal system, cardio-vascular and respiratory, immune, endocrine and reproductive functions. In order to establish the functional link between the sleep and the visceral health it is proposed that during sleep the central nervous system including all cortical areas switches from the processing of the exteroceptive information to the processing of the interoceptive information. Review of the studies, which offer the direct confirmation of this hypothesis, is presented.

Visually triggered K-complexes: a study in New Zealand rabbits.

K-complexes are the EEG elements recorded during the state of developing sleep and during slow wave sleep. They are the only EEG components which can be elicited by sensory stimulation during sleep. The peculiarity of New Zealand rabbits to sleep with their eyes open allows the use of visual stimuli to elicit K-complexes. Experiments were performed with three rabbits. For visual stimulation, an elongated screen illuminated by LED flashes was attached to an implant on the animal's skull. The screen covered 20-120° of the visual field of one eye, and moved with the head during animal motion. One-millisecond flashes (15-s interval) were used during daytime in an illuminated room. Flashes elicited evoked responses, which, during the first stages of sleep, were often accompanied by K-complexes. The induced K-complexes were recorded from electrodes located both above visual and somatosensory areas. Evoked responses to visual stimuli were also recorded from both pairs of electrodes, although they were generated exclusively in the visual cortex. Correlation analysis showed that visual evoked responses and K-complexes induced by this stimulation were generated in visual cortex, and passively spread to the electrodes above the somatosensory area. Investigation of the latencies of induced K-complexes revealed two time windows when these complexes could be seen. Within each window there was no correlation between latency and amplitude of K-complexes. There was also no correlation between amplitudes of the visual evoked responses and K-complexes elicited by these responses. We propose that visual stimulation in light sleep temporarily opens a gate for some independent external signals, which evoke activation of the visual cortex, reflected in K-complexes.

[Efficiency of the "disk-over-water" method without feedback for sleep deprivation in rats].

The "disk-over-water" method, where animals are awakened by disk rotation triggered by sleep EEG signals, was efficiently used in many studies involving sleep deprivation. Recently, the modification of this method has been developed where, during the period of deprivation, the disk was rotated in accordance with a pre-set program (the "disk-over-water" method without feedback). We considered this modification as a potentially promising one for investigation of relationship between maternal sleep and litter development. However, none of these methods has been used in experiments on female rats, and efficiency of the method without feedback has never been tested using electrophysiological estimation of sleep-wake states either. Performing these tasks was the goal of the present study. Cortical EEG, hippocampal theta-activity and locomotor activity were recorded in 14 female Wistar rats underwent sleep deprivation in the "disk-over-water" setup without feedback. Three days long during the deprivation periods from 11:00 to 14:00 the disk was rotated for 8 s with 15 s intervals. REM sleep was totally eliminated during these periods, and amounts of slow wave sleep did not exceed 10% of 3 h. The results were identical both for pregnant and non-pregnant rats. The rate of sleep reduction during deprivation periods in our experimental conditions did not differ from that in the original system with the feedback. Thus the simplified "disk-over-water" method without feedback can be used in the studies involving relatively short sleep deprivation periods.

[Sleep patterns and the efficiency of the gentle methods of sleep deprivation in rats at different stages of pregnancy: behavioral study].

In Wistar rats, pregnant or not pregnant, sleep-wakefulness parameters were registered for 2 days from 10:00 till 14:00. Later, these rats were subjected to 3-hour (11:00-14:00) daily sleep deprivation (SD) during 3 consecutive days. To prevent sleep, the following manipulations were used: acoustic stimulation from moving of the food pellets, opening or horizontal rotation of the cage and gentle handling. Control pregnant or not pregnant rats were placed in individual cages in the same room, but their sleep was not disturbed. On average, not pregnant rats spent about 65% of the time in sleep. Sleep episodes were mostly short (less than 1 min) or medium (1-15 min). After the beginning and with advance of pregnancy, the amount, deepness and duration of sleep episodes increased. With the methods of SD used, not pregnant rats did not sleep almost at all during the SD session. In pregnant rats, the quantity and intensity of stimuli used for SD increased as compared to control, which was indicatives of the growth of "sleep pressure" during pregnancy.

[Prenatal experience and postnatal development of the rat hippocampus: sleep deprivation of pregnant rats].

The effects of sleep deprivation in pregnancy on the development of hippocampal function of the offspring have been investigated. For this purpose we compared electrophysiological characteristics in the hippocampal slices of 15-20-old-day rats of the control and two experimental groups. In the first experimental group the pups were taken from mother for weighting three times during the first postnatal week and then weekly. Another experimental group was brought up without handling. We found that CA1 population spikes developed to significantly less amplitude in experimental groups of rat pups. This phenomenon was observed at higher intensity of monosynaptic activation, although near-threshold stimuli didn't reveal any differences among groups. However, under paired-pulse stimulation (70 ms inter-pulse interval) small amplitudes in the hippocampal slices of experimental animals could facilitate up to control value, and second in pair responses didn't differ from corresponding control. Our data doesn't confirm the hypothesis about decreased connectivity in the hippocampus of experimental rats, but the efficacy of CA3-CA1 inputs seems to be lower. Besides excitatory transmission, the effectiveness of inhibition of paired-pulse facilitation at 15 ms inter-pulse interval was also significantly decreased. The observed effects of prenatal influences seem to develop under postnatal experience. We observed significant trend to more pronounced modifications upon age especially in the case of early handling and testing.

Sensory information--the major factor of ontogeny.

On the basis of their own data authors postulate that the increase in sensory input during early ontogeny results in a delay in the development of the sensory systems formed earlier. In connection with this, the sensory basis of behavioral patterns becomes ineffective, causing their reorganization and the appearance of new forms of behavior. Limitation of sensory input during during the critical periods of development stimulates the accelerated manifestation of behavioral patterns. However, this acceleration also has long-lasting negative effects - alterations in the process of learning and memory in adult animals.

[Sensory information--an important factor in ontogeny]. / Sensornaia informatsiia--vazhnyi faktor ontogeneza.

Ontogenetic process reveals a row of consecutive stages characterized by the gradual increase in complexity and by the changing specificity of sensory mechanisms basic for the adaptive behavior of the young. The study examines the mechanisms of interaction among different sensory systems during the formation of early behavioral patterns and analyzes why, at a certain stage of development, a particular sensory stimulus loses its efficacy in the organization of a given behavior and is substituted by another one, previously ineffective. A special attention is paid to formation of behavior based on sensory information within the limits of ontogenetically fixed developmental critical periods and to the role of the early sensory experience in learning in adult animals.

[The advanced display of behavioral reactions in sensory deprived rat pups]. / Operezhaiushchee proiavlenie povedencheskikh reaktsii u sensornodeprivirovannykh krysiat.

Bilateral section of nervus medianus was made in Wistar rat pups on 13, 14, 15 or 16-th days of life. Developmental analysis of motor abilities, locomotor and exploration activities during 10-30 days of life revealed three groups of facts. 1. Partial deafferentation of forelimbs don't influence on some types of behavior. 2. Some motor abilities hindered in rat pups with section of nervus medianus. 3. Partial deafferentation of forelimb gives rise to the faster appearance of the new types of behavior. The developmental analysis allowed to suggest that faster appearance of certain behavior reactions after deafferentation of the forelimbs is a result of actualization of latent sensory inputs including in the organization of these types of behavior but it is not connected with changing of velocity of morphological maturation.

[Changes in the galvanic skin reaction and speech parameters of 8- to 9-year-old children during play]. / Izmeneniia kozhno-gal'vanicheskoi reaktsii i parametrov rechi u detei 8--9 let vo vremia igry.

Changes of parameters of the speech signal (fundamental frequency, Ef, and evaluation of the frequency of the first formant, n(0)) were compared to the skin galvanic (SGR) reaction shifts in 8-9 years old children during playing computer games under different conditions: 1) playing using the child's own strategy; 2) that under the conditions of time deficits; 3) that with minimization of errors. In each playing situation a child had 3 trials. Parameter SGR-1 reflected SGR amplitude changes depending on a trial number, SGR-2 reflected those depending on the beginning, the middle, of the end of a battle with an enemy. At playing under the conditions of time deficits there was an increase of emotional stress and that of the number of negative emotional reactions of children being accompanied by worsening of playing activity parameters. Ef and SGR-2 were mostly expressed in comparison to other playing situations. The greatest changes of n(0) and SGR-1 were observed at playing with child's own strategy. Emotional stress in the latter situation was minimal, number of positive emotional reactions was comparable to that in the third playing situation, and negative emotional reactions were absent. The data obtained point to the structural change of motivation at complicating the situation (at playing with time deficits).

[The dependence of the emotional state of 8- to 9-year-old children on the conditions of play]. / Zavisimost' émotsional'nogo sostoianiia detei 8--9 let ot uslovii igry.

Dependence was studied of emotional state of children, aged 8-9, on the terms of computer play: without additional instruction (with a strategy typical of the child), at time deficiency and at demonstration of techniques of play without limitation in time. Prior to and during the play the following parameters were recorded: heart rate (HR); frequency of basis tone (Fb.t.) and evaluation of frequency of the first formant (n(0] of the vowel "a" in the word "da" pronounced by the child during the play in response to acoustic signal; reaction time (RT) to acoustic signal; parameters of playing activity and also spontaneous verbal expressions of children. Increase of emotional stress during the play at time deficiency was accompanied by the most expressed changes of HR, RT, Fb.t., worsening of playing activity and the increase of the number of negative emotional reactions. When playing without additional instruction, the children showed the best results of playing activity, accompanied by the least expressed changes of HR and Fb.t. in comparison with the background at the greatest expressiveness of the n(0) change, and predominantly positive emotional reactions. The analysis of the correlation of the motivational and informational characteristics of the studied playing activity allowed to make a conclusion about preferential connection of HR and Fb.t. with the motivational and n(0) with informational components of the playing activity.

Comparative psychological approach to the analysis of the functions of the hippocampus.

As compared with dogs, the development of conditioned reflex switching-over of heterogeneous conditioned reflexes in intact rats is often accompanied by the development of reactions of the neurotic type. Experiments involving injury of the hippocampus (in rats) and the recording of electrical activity (in dogs) showed that this structure participates in the formation of conditioned reflex switching-over of instrumental reflexes. Following the injury to the hippocampus, the rats successfully formed the switch-over. The switch-over signal altered the electrical activity of the hippocampus in the dogs. Consequently, the hippocampus in both species of animals belongs to the system of structures which participate in the formation of conditioned reflex switching-over. Hippocampectomized rats were not capable of developing an alimentary conditioned reflex at the 30% level of reinforcement. The highest values of the frequency of the hippocampal theta rhythm were obtained in the dogs at just this level of probability of reinforcement. These data indicate that the assurance of reactions to signals with a low probability of reinforcement is an important function of the hippocampus in various species of animals.

[The mental developmental level of 5- to 7-year-old children and the reflection of their emotional status in speech]. / Uroven' umstvennogo razvitiia detei 5--7 let i otrazhenie ikh émotsional'nogo sostoianiia v rechi.

In 22 children aged 5-7 during the play "make up a square" negative (1st step) and positive (2nd and 3rd steps) emotions were formed. General behaviour and speech expressions of children were recorded during the play. Before beginning of the play, intellectual development of children was tested, and two groups were singled out: with low (A) and high (B) levels of tasks solution. Changes of verbal values Fot and n(0) in children from two groups were compared during the play. Fot was most sensitive to the appearance of the emotional state. Emotional states were more expressed in children from group A: percentage of significant changes in Fot and n(0) values in comparison with the background was higher in the group A than in the group B. In children of the group A the negative emotion formed at the 1st step of the experiment caused a decrease of level of motivation to fulfillment of the task to make up a "difficult" square. In children of the group B the negative emotion did not cause any distinct decrease of motivation level. Fot reflects the change of motivational attitude to task) and n(0)--of informational (actualization of knowledge, reasoning etc.) components of the emotional reaction connected with the process of task solution.

[The influence of the emotional state of the child on the parameters of its verbal response]. / Vliianie émotsional'nogo sostoianiia rebenka na parametry rechevogo otveta.

The method of determination of human emotional state by speech was applied to the analysis of verbal expressions of 22 children during the play "make-up the square". Parameters of the verbal response--F0 (fundamental frequency) and n(0) (evaluation of the frequency of the first formant) changed to the greatest extent under the influence of emotional reactions which appeared in children during the play. Depending on the terms of the play different changes of these parameters took place in different children: in some cases significant increase of values was observed as compared with the background ones, in other cases--their significant decrease.