S. V. Afanas’ev

Shape memory effect in Mn-V-C austenitic steels involving deformation reorientation of ɛ-martensite

The shape memory effect with a reversible deformation of 1.6–1.7% in the metastable steels like 20G20S2F with the ɛ-martensitic original structure is obtained as a result of the shear repeated twinning of ɛ-martensite during cold deformation and the subsequent ɛ → γ transformation during heating.

The influence of social conditions on the development of ethanol preference in rats

23 The study of alcoholism as an addictive behavior requires the study of zoosocial relationships. Model experiments with animals showed that dominant rela tionships in communities of alcoholized animals are disturbed [1, 2]. It was found that, when housed in groups, the subdominant animals more readily become ethanol dependent than the dominant ani mals: the former consume more ethanol and earlier become alcohol addicts [1]. In addition, an increase in the physical aggression as a result of alcoholization was demonstrated [3, 4]. It was assumed that ethanol, in general, stimulates social activity [5]. It is known that, in animal colonies, alcohol dependence develops at different rates in different animals depending on their social status [6]. In isolation, conversely, alcohol preference is observed in the dominant animals [7, 8]. The question as to how group or individual ethanol consumption under conditions of group housing affects the development of alcohol addiction in ani mals remains to be answered. The goal of this work was to study the pattern of development of alcohol depen dence during individual alcohol consumption in ani mals housed in the groups where other members were not alcoholized in comparison to the development of alcohol dependence in the groups of animals where all members were alcoholized. Experiments were performed with 48 male Wistar rats weighing 250–300 g. To increase the intensity of aggressive interactions, adult males were isolated from the other animals for two weeks. The separated ani mals were kept in individual metal cages (200 × 150 mm) and received water and food ad libitum. After 14 days of isolation, rats were placed in cages 570 × 350 mm; (three animals in each cage) with fresh litter. To determine the hierarchical relationships between the rats, the interactions between them were observed for the first 15 min after placing them into one cage. To analyze the social interactions, four parameters were determined: the number of attacks, the number of defensive and submissive postures, and interactions expressed in grooming and sniffing of partner’s body. Then, the rats were housed in this cage in the same composition. After three days of housing in groups, the interactions between animals were studied again using the resident–intruder test: a foreign male was placed into the cage and the social behavior of rats was recorded for the first 15 min. Then, at the 15th minute, a female was placed into the cage and the behavior of rats, including the copulative acts, was recorded. On the basis of the interactions between animals recorded in all tests, the rank of animals (dominant, subdomi nant, and subordinate) was determined. Studies were performed in experimental groups of three types. In one type of groups, only one rat of each group was given alcohol, whereas the other members received water. Such individual alcoholization was studied in animals of different hierarchical levels. In the second type of groups, alcohol solution was given to all animals living together. In the third type of groups (control), all rats received water. In the constant housing cages, waterers were absent. For drinking, each rat was placed daily for 1 h in an individual cage, where it had access to liquid. In our experiments, we used the forced alcoholization model. For two months, all the rats subjected to alco holization had no access to any liquid except for 10% ethanol. All other rats received water. The level of alcohol preference was assessed in the “two bottle test.” A rat was placed in an individual cage with two waterers, one of which was filled with water and the other one contained 10% alcohol. The volume of liq uid consumed from each waterer determined and the number of approaches to each waterer were counted for 15 min. During the experiment, this test was per formed three times—before as well as 27 and 54 days after the beginning of forced alcoholization. The dynamics of different parameters was moni tored in the “Suok test” [9]. In this test, a rat was placed on a 5 cm wide rod, which was divided into PHYSIOLOGY

Encoding of Conditioned Reflex Activity in Different Directions by Neurons in the Monkey Striatum

Two types of neuron spike activity were detected in the striatum (putamen) of moneys: patterns with low and high activity. Low-activity patterns were no more than twice the level of baseline activity, while high-activity patterns had larger factors. An individual neuron could generate different patterns during different actions. On performance of tasks requiring movement in different directions, the greatest differences in the sets of neurons with high-activity patterns were seen during preparation and onset of the movement in the chosen direction and on completion of the movement. Differences between the sets of neurons with low-activity patterns, conversely, decreased at these behavior stages. They were maximal before presentation of the conditioned signal, when the animal was still unaware of the task, and at the end of the program, when the alternative choice task had been completed. These data provide evidence that the encoding of signals reflecting the involvement of the striatum in solving the alternative choice task occurs by means of multilevel addressed signal encoding. The main role in this is played by changes in the set of neurons generating patterns of different levels of activity.

Database SPBLAKES for Natural Lakes in Leningrad Oblast, Russian Federation: The Structure, Composition, and the Results of First Data Analyses

Database SPBLAKES was developed, containing vast authors’ and literary geographic, morphological, climatological, limnological, and other data on 1268 natural lakes in the territory of Leningrad oblast (LO), Russian Federation. The structure, format, and the current state of the database SPBLAKES are discussed. The geographic (coordinates, elevation above sea level, and administrative position) and statistical distributions of some lacustrine dimensional (area, volume, mean and maximal depths, etc.) and dimensionless (coastline indentation, specific drainage area, etc.) morphometric and hydrochemical (water salinity, pH) characteristics are evaluated, and the distribution of lakes by bed genesis is determined. The total areas (1.291 × 103 km2) and water volumes (4.44 × 103 km3) of lakes are evaluated, and the lake area share in the total area is calculated (0.016 or 1.6%). The database SPBLAKES can be expected to help solving various theoretical and applied limnological problems.

Producing a gradient-composition nanocrystalline structure on nitrided surfaces of invar-type Fe-Ni alloys using megaplastic deformation

A nanocrystalline Fe-Ni matrix strengthened by dispersed CrN and TiN nitrides has been produced on the ion-plasma-nitrided surfaces of the austenitic Fe-Ni38-Cr15 and Fe-Ni36-Ti4 alloys using cyclic “nitride dissolution-nitride precipitation” phase transformations induced by megaplastic deformation. The high-pressure torsion of the nitrided alloys has led to the dissolution of the CrN nitrides and Ni3Ti intermetallic compounds, which appeared in the matrix, in the surface layer and to the mechanical alloying of the nitrided subsurface layer and the unnitriderd bulk of the specimens. Subsequent annealing has resulted in the formation of secondary nitrides, which propagated to a depth substantially exceeding the thickness of the original nitrided layer.

The Relationship between Prefrontal Cortex Neuron Activity in the Two Hemispheres on Performance of a Choice Task in a Two-Ring Maze

Neuron activity in two symmetrical areas of the prefrontal cortex in the left and right hemispheres of the rat brain (55 and 47 neurons, respectively) was recorded as the animals performed a behavioral choice task in a two-ring maze. Experiments were performed in two sets of conditions – i) working with a conditioned signal, when excursions to the side indicated by the signal were reinforced, and ii) without a signal, when any excursion was reinforced. The levels of involvement of a neuron in different steps of the behavioral program were evaluated in terms of the level of differential activity, i.e., differences in neuron activity in right- and left-sided performances. In conditions in which the animal took the decision without orienting itself to external signals (in two behavioral situations: working without signals and erroneous performance of the program), there was a predominance of differential activity in the left hemisphere. In correct performances of the program, activity dominated in the right hemisphere. This appears to be evidence of a consistent dynamic in the interaction between the hemispheres depending on external and internal conditions and the special role of the right hemisphere in learning mechanisms and inclusion of the external determinant in the adaptive response system.

A Two-Ring Maze for Studies of the Behavior of Laboratory Animals

The behavior of rats was studied in a two-ring maze in which the animal could make its own choice of one of two trajectories of the same length, independently returning to the start point. All maze sectors – starting chamber, signal sector, arm, and feeding sector – were separated by one-way doors. The time structure of passage through the maze sectors reflected both the level of the animal’s motivation and fully defined aspects of behavior, i.e., attention, short-term memory, and long-term memory, as well as the cognitive aspect, i.e., taking movement trajectory decisions on the basis of the conditioned signal presented, and the emotional aspect, i.e., assessment of the result of the action. Analysis of the time parameters of the activity allowed changes in various behavioral components to be evaluated in relation to treatment applied to the animals and ongoing status. We suggest that this behavioral model will be useful in different types of neuropharmacological, electrophysiological, and behavioral experiments.

Combinations of active striatal neurons connected selectively with certain behavioral actions of the monkey Macaca mulatta

At present there is widely spread concept of populational coding of information by brain neurons; it is based first of all on results of comparison of neuronal activity with parameters of the used stimulus. Relation between the neuronal activity coding and the observed behavioral actions has been practically not studied. In the present work, neuronal impulse activity has been studied in groups of 6 neurons recorded in parallel. Distribution of frequencies of the presence of cases of excitation of one or several cells has been established to differ statistically significantly from the theoretical distribution of the same values; this indicates that under real conditions, the appearance of individual combinations of active neurons is not random, but is connected to a certain degree with conditions of experiment. The selective combinations of neuronal activity have been revealed to be different at stages of program. This indicates that organization of different behavioral actions is associated with activities of certain combinations of neurons.

Sex-and age-related differences between healthy children in solving syllogisms

278 The modern human science holds that child’s thinking qualitatively differs from adult’s. Vygotskii’s [1] typology is mainly based on thinking in sets or “complexes” within which elements are linked with one another by concrete and factual, empirically learned connections revealed through direct experience of a child. Conversely, in theoretical thinking by “scientific concepts,” the relationship between elements is abstract and logical; this thinking is based on uniform connections logically identical to one another, systematically understood and mastered in the course of education. In contrast to the “complex” thinking, the “scientific” (abstract) one occurs consciously; moreover, a person can comprehend concepts themselves. Abstract forms of thinking are studied with the use of solution of syllogisms [2].

Gender Differences in Verbal Learning of 5- to 15-Year-Old Children and Adolescents

It is known that boys are behind girls in speech development as early as at an age of four years, when the dominance of the left hemisphere with respect to speech is also manifest in girls (see [1] for review). Neuropsychological studies [2] have demonstrated that the mental development of healthy children is heterogeneous. For example, the parameters of aural/verbal memory are improved in girls at an age of nine years (earlier than in boys); however, they were substantially regressed after 11 years of age. However, the use of a single parameter, namely, the memory volume does not allow answering questions as to whether a child can study in a secondary school, whether the child uses mechanical or semantic memory, and how interfering factors affect verbal learning. In addition, the pattern of changes in verbal learning in the course of growth and development remains unknown. These data would permit the estimation of age-related changes in the formation of rightand left-hemispheric cerebral functions involved in verbal learning of healthy children.