[Early electrophysiological consequences of dosed traumatic-brain injury in rats]. / Rannie élektrofiziologicheskie posledstviia dozirovannoi cherepno-mozgovoi travmy u krys.

AIM: To analyze the pathological electrical activity during the acute period after traumatic brain injury (TBI) and to search for potential morphological correlates of this activity in the neocortex and hippocampus. MATERIAL AND METHODS: The study was performed on male Sprague Dawley rats. TBI was modeled using a lateral hydrodynamic impact in the sensorimotor cortex area. ECoG was continuously recorded one week before and one week after TBI. A histological analysis was performed one week after TBI. Brain slices were Nissl stained as well as immunohistochemically stained for astrocytes (GFAP) and microglia (Isolectin B4). The damage to the neocortex and hippocampus was evaluated. RESULTS AND CONCLUSION: The slowdown of the background activity one and six hours after TBI and appearance of epileptiform activity in a half of animals one week after TBI were shown. The number of discharges was correlated with the area of astrocyte gliosis in the neocortex and with the number of dark (ischemic-like) neurons in the hippocampus. Microglial activation did not correlate with the epileptiform activity. These data are important to understanding early mechanisms of post-trauma epileptogenesis.

[The Effects of Chronic Combined Stress: Changes in Behavior of Rats with Various Responses to Novelty].

We studied the effect of chronic combined stress (model of experimental neurosis) on behavior of rats with different basal strategies of behavior in novelty conditions. Chronic stress resulted in decreases in the body weight and testosterone contents in the blood and neocortex in all animals. Animals with initially low orient- ing-exploratory response in the "open field" test did not exhibit substantial alterations of behavior during repeated testing in this test of the "dark-light chamber" test; however, the depression-like behavior was more expressed in the second forced swim test. Chronic combined stress did not significantly affect the behavior of this group of rats. Animals with initially high orienting-exploratory response in the "open field" test exhibited decreased locomotor and exploratory activity in the repeated "open field" tests. The decreases in the locomotor and exploratory activity were substantially less expressed in the repeated tests in these rats after chronic combined stress. The indices of depression-like behavior increased one month after the end of exposure to chronic combined stress. Our data demonstrate that different responses to novelty in the "open field" test do not allow predict with reasonable certainty the development of depression-like behavior after exposure to chronic combined stress.

[Behavior of rats after immobilization and structural reorganization in the motor cortex and hippocampus].

Behavioral changes and accompanying morphological neuron-glia reorganization in the rat brain were analyzed after long-term immobilization. Wistar rats (n = 23) were stressed by interruptive immobilization, which was carried out within three week daily for 7-8 h. Behavioral immobilization of rats was accompanied by a decrease in the locomotor and exploratory activity in "open field" test and increase in the number and duration of freezing episodes. The morphometric studies revealed a statistically significant threefold increase in the density of hypoxic neurons in the motor neocortex of both hemispheres and CA3 field of the hippocampus in the experimental animals as compared to control. The number of glia cells in the motor cortex did not change. The increase in the density ofglial cells and multi-nucleolar neurons in CA3 region of the hippocampus are indicative of the compensatory processes in the brain. The hypoxic changes in neurons were of the functional character.

Comparison of the behavior of rats after immobilization with structural changes in the motor cortex.

Behavioral and neuronal-glial changes after emotional stress induced by discontinuous (7-8 h per day for one week) immobilization were compared in Wistar rats (n = 20). Immobilization led to increases in horizontal and vertical activity and the duration of "comfort" grooming in the open field test. Morphometric measurements demonstrated significant increases in the density of hypoxic neurons in the motor area of the right hemisphere of experimental animals as compared with measures in controls. Hypoxic changes in neurons were functional in nature. Experimental rats can be regarded as a model of the redistribution of brain functional activity with a preferential increase in the role of the left hemisphere.

[Interaction of immobilization stress and food-getting learning].

The behavioral effects of emotional negative stress (immobilization) were studied in Wistar rats intact and those that had previous positive emotion experience. The food-getting learning has been chosen as positive emotion experience. Animals were trained in food pellet-reaching task by their preferred paw. It was shown that immobilization of intact rats leads to suppression of motor activity and increasing the duration of grooming. These effects indicate enhancement of passive-avoidance reactions. It was also shown that motor learning in group of rats with food reinforcement before immobilisation significantly reduces appearance of passive-avoidance reactions. It was found that immobilization stress does not inverse the initial direction of limb preference in majority of rats.

[On a possibility of understanding over the limits of imagination].

Intellectual abilities of mathematicians led them to the creation of some number systems, among which the set of real numbers occupies a special place. A visual representation which would distinguish between the rational number system and the real number system was not found. Nevertheless, the set theory of real numbers was understood and accepted by mathematicians.

[Correlation of the rat behavior after immobilization with structural reorganization in the motor cortex].

Behavioral changes and accompanying morphological neuron-glia reorganization in the rat brain were compared after emotional stress. Wistar rats (n = 20) were stressed by the interrupted immobilization, which was carried out during one week 7-8 h daily. Behavioral immobilization of rats was accompanied by an increase in horizontal and vertical locomotors activity and in duration of the III and IV phases of grooming ("comfortable" grooming) in the "open field" test. The morphometric studies showed a statistically significant increase in the density of hypoxic neurons in the right neocortex of the experimental animals as compared with control. Hypoxic changes in neurons were of functional character. Experimental rats can be considered as a model of redistribution of functional brain activity with preferential intensification of the left brain hemisphere.

Behavior and measures of respiration in rabbits differing in terms of movement activity in an open field.

Analysis of the behavior of 19 Chinchilla rabbits the first time they were placed in an open field allowed them to be divided into three groups differing in terms of investigative movement activity (passive rabbits accounted for 37%, active for 21%, and intermediate for 42%). On repeat placing in the open field, passive rabbits increased and active rabbits decreased their levels of activity. Correlations were found between the rabbits' behavior in the open field and the nature of their external respiration in the absence of movements in the comfort situation. Passive rabbits, as compared with intermediate and active animals, showed longer respiratory cycles, expirations, and breath holds in expiration. Animals with a predominance of right-hand turns in the open field showed shorter respiratory cycles and expirations than animals with a predominance of left-hand turns. These studies led to the conclusion that the characteristics of external respiration can serve as a predictive factor for the passive-defensive strategy of behavior in rabbits in emotionally negative situations.

[Temporal sequence of SWD emergence and spontaneous jerks in WAG/Rij rats with absence epilepsy].

In rat model of absence epilepsy, abnormal complex movements of cervicothorathic part (jerks) were observed in the state of passive wakefulness. When a desynchronized low-amplitude electrical activity was recorded in the parietal and visual cortex, either SWD or jerks were observed. The SWD appearance prevented a jerk. If the discharge appeared between jerks, the interval between jerks increased. Particularly important is the fact that after subtraction of the discharge duration, the distribution of intervals between jerks became the same as in the absence of the SWD. This finding shows that an SWD just interrupts the development of a jerk. That is, when the discharge is over, the jerk develops from the level at which it was stopped by the discharge rather than from the initial level of excitation.

Acquisition of a conditioned avoidance reflex and morphometric characteristics of the sensorimotor cortex in rats subjected to social deprivation in early ontogenesis.

Male Wistar rats were subjected to social deprivation from day 22 to day 70 of postnatal development to form a group of isolants. Measures of learning of a passive avoidance and the results of training to active avoidance of painful electrical stimulation in these rats were significantly lower at age 110-120 days than in control rats. The characteristics of movement activity in isolants during training and testing, as well as in the open field test, probably resulted from their high levels of anxiety. Morphometric measurements of the numbers of neurons, satellite glial cells, and free glial cells in the sensorimotor area of the neocortex showed that isolants had a significantly lower density of neural elements per unit area, which resulted from a decrease in the afferent flow due to social isolation.

[Influence of emotional stimuli on behavior and respiration of rabbits with various locomotor activity in the "open field"].

Different behavioral reactivity of rabbit groups differentiated by locomotor activity in the "open field" was revealed during exposure to emotional stimuli (rustle, loud sound, pressuring on back of the neck, vibroacoustic tactile stimulation of an ear). In passive rabbits, the active locomotor reactions were induced harder and freezing was obtained easier than in active animals. During exposure to sound stimuli, passive rabbits increased their locomotion more rarely than active animals, pressing on back of the neck produced longer freezing, a threshold of defensive ear shaking in response to a vibroacoustic stimulus in passive animals was highest. Training to mild immobilization increased the threshold of defensive responses in active rabbits and animals of the intermediate type. Changes in respiratory parameters were correlated with behavioral reactions to emotional stimuli. The duration of exhalation and respiratory cycle increased during freezing and increased during enhanced locomotion. The duration of inhalation decreased in response to emotional stimuli irrespective of a behavioral reaction. The respiratory reactions to emotional stimuli differed in rabbits of different groups. The respiratory rate more frequently changed in passive rabbits than in animals of other groups. Passive animals reacted mainly by exhalation, active rabbits and animals from the intermediate group predominantly responded by inhalation.

[The behaviour and respiration features in rabbits with different pattern of their open field locomotor activity].

Behavior of 19 Chinchilla rabbits was tested in the open field. By the results of the first trial, animals were divided into three groups by the type of the exploratory locomotor activity (passive--37%; active--21; and medium--42%). During the repeated open field trials, the passive rabbits increased their activity and the active ones decreased it. Correlations were found between the open field behavior and patterns of the external respiration in the absence of movements. The longest respiratory cycles, expirations and respiratory breath holdings were observed in passive rabbits. Animals with prevailing right turnings in the open field displayed longer respiratory cycles and expirations than those with prevailing left turnings. It seems that the pattern of external respiration can predict the passive defensive strategy of rabbits in negative emotional situations.

[Avoidance conditioning and morphometric characteristics of the sensorimotor cortex of rats exposed to social deprivation in early ontogeny].

Male Wistar rats were exposed to social deprivation in the period from the 22nd to 70th days of postnatal development. The characteristics of the learning of these rats at the age 110-120 days in the passive avoidance box and during training for active avoidance of electroshock were significant lower than those of control animals. Features of motor activities of the "isolants" in learning and testing, and in the "open field" may be related to their higher anxiety level. Morfometric studies of neurons and glial cells and neocortex thickness showed that significantly lower density of neural elements may be the result of the afferent sensory input limitation produced by the social deprivation.

[Breathing patterns peculiarities as the index of the "animal hypnosis" state in the rabbit]. / Osobennosti vneshnego dykhaniia kak pokazatel' sostoianiia "zhivotnogo gipnoza" krolika.

Breathing patterns were recorded during "animal hypnosis" in seven Chinchilla rabbits. The state of "animal hypnosis" was evoked by the hand pressure on the thorax and the waist of a rabbit. Breathing pattern was recorded by means of an elastic coal-powder element that was set round the rabbit's thorax. Distortions of the breathing patterns in the active state and in the course of hypnosis development were marked by numbers 0, 1, 2. In all rabbits, modifications of the breathing patterns depended on the features of the animal state: quiet state, tension, and "animal hypnosis".

Characteristics of behavior associated with alternative choice in a Y maze in rats and their interpretation in terms of complex probability amplitudes.

This report demonstrates the possibility of interpreting rat behavior in situations associated with the choice between "safe" locations in a Y maze using pain reinforcement on the basis of summation rules for complex amplitude probabilities characterizing the prognostic assessment by the rat that it will achieve relative safety. Functionally incomplete actions in rat behavior were analyzed in the experimental situation. When the rat needed to avoid pain reinforcement and both pathways to avoid painful stimulation were equally suitable, interference could appear in the animal's assessment of the suitability of the two paths, this preventing decision-making. When this occurred, there was a delay in the executive action. After rats left one of the "safe" arms, they could move into the other "safe" arm, and vice versa. These transfers were completed in a quasi-periodic fashion, as predicted by a formal description of transfers between coincident (or sufficiently similar) states.

[Features of rat behavior associated with alternative choice in Y-maze and their interpretation in terms of complex probability amplitudes]. / Osobennosti povedeniia krys v Y-labirinte, sviazannye s al'ternativnym vyborom i ikh interpretatsiia v terminakh kompleksnykh amplitud veroiatnostei.

The two-way alternative avoidance of a weak electric shock by male Wistar rats in Y-maze was studied. The following behavioral characteristics of a rat were determined in each test series: total time of an arm choice (going away into one of two safe maze arms), number and sequence of alternate turnings to the outlets in the process of choice, time of immobility in the Y-maze center, and "freezing" reaction. Rat behavior of choice of safe arms in Y-maze be interpreted on the basis of the rules of summation of complex probability amplitudes, which characterize a predictive estimation of achievement by a rat of its relative safety. With the need to avoid an electric shock, rat's estimations of suitabilities of two different avoidance ways can interfere. This makes it difficult for an animal to take a choice decision (if both pathways are equally acceptable for a rat). After entering a safe arm, sometimes a rat can leave it for another arm, such passages occur quasiperiodically.

[Rat behavior in a light/dark chamber: place preference task]. / Povedenie krys v temno-svetloi kamere: zadacha vybora mesta.

After a 6-week social isolation (from 22nd to 70th day from birth) male Wistar rats (a sibship, 10 animals), were tested for 20 min in a light/dark box in order to reveal behavioral features of choice of their spatial localization in unknown conditions. Socially deprived rats significantly differed from control animals in longer time of the room choice, higher number of entries of the light section, and higher number of rearings, which was probably explained by their higher anxiety and lack of experience to estimate unexpected stimuli and select a response. The mean level of behavioral activity during exploration of the box defined by the number of elementary operations per minute remained constant and was significantly higher in the socially deprived rats than in the control animals.

[Peculiarities of exploration behavior of socially deprived rats in stress situation]. / Osobennosti issledovatel'skogo povedeniia sotsial'no deprivirovannykh krys v stressovoi situatsii.

Male Wistar rats (n = 18) were studied at the age of 120 days after social deprivation in the period from the 22nd to 70th days of postnatal development. They displayed significant lower activity in the open field, elevated plus-maze, and Porsolt test than control animals (n = 19). Decreased exploratory activity was found to be related with higher level of anxiety. This was confirmed by their avoidance of open arms of the elevated plusmaze and reactions to approaching hand. These animals had problems in the maze arm choice. They showed low time variability of choice-related actions (waiting in the center of the open field or elevated plus-maze and change in the movement direction along an open-field wall, including the movement per se, and arm choice and changing, i.e., alternative choice). Shorter time of choice-related actions was observed in situations of unequal alternatives.

[Correction by succinic acid of behavioral and physiological parameters of neurosis-like condition in white rats]. / Korrektsiia povedencheskikh i fiziologicheskikh pokazatelei nevrozopodobnogo sostoianiia belykh krys vvedeniem iantarnoi kisloty.

The neurosis-like state of white rats is accompanied by development of cerebral hypoxia. Negative symptoms of the neurosis-like state (behavioral, anatomic and energy) were decreased by per os administration of succinate (30 mg/kg) during the second half of the neurotization process. Succinate provided chiefly the delayed action on the system arterial tension, on the succinate dehydrogenase and NADH dehydrogenase activity. The effects depended on the propensity of a rat to the catatonic "freezing". The "freezing" was detected by a specific breathing pattern: a short inhale and a long pause. In "freezing" rats succinate corrected the system tension to a greater extent, while in "non-freezing" animals it corrected to a greater extent the succinate and NADH dehydrogenase activities. The positive effect of succinate administration is probably associated with its antihypoxic properties.