The effect of 40 mcg/kg i. p. injections of ACTH4-10 were investigated in C57BL/6J mice. Peptide injections caused a significant (p less than 0,05) decrease in rearing activity frequencies as well as a decrease in defecation and grooming levels. ACTH4-10 accelerated the acquisition of conditioned food-motivated running reaction and also induced significant resistance against extinction of this habit. The ability of mice to solve the task of extrapolating the direction of stimulus movement was nonsignificantly reduced at the first task presentation and in the total experiment. The ACTH4-10 ability to facititate stereotype reactions is one of possible mechanisms of behaviour changes in the present experiments.

Adrenocorticotropic Hormone↗

PubMedDate not supplied

[Cytoarchitectonics of the cerebral cortex in mice selected for high and low brain weight].

The cortex cytoarchitectonics was studied in mice, which had been genetically selected for high (H-line) and low (L-line) brain weight and manifested some differences in their behaviour. Microscopic brain sections were analysed to estimate the areas of the neocortex, archicortex and paleocortex and to investigate quantitatively the microstructure in different zones of the neocortex. In the H-line, absolute value of total cortical area is, on the average, by 18% higher than that in the L-line--mainly owing to the larger area of neocortex, while the mean values of neurone volume fraction and profile field reveal no significant difference between the H- and L-line. Hence, the total number of neurones in the neocortex of mice from H-line should be greater, as compared with the L-line. Besides, within the framework of the same cerebral organization in general, the obtained data are indicative of a somewhat higher spatial differentiation of the neocortex in mice from the H-line.

Animals↗

PubMedDate not supplied

[Ability to solve extrapolation problems in mice selected for different brain weights].

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Animals↗

PubMedDate not supplied

[Features of higher nervous activity in mice with Robertsonian chromosomal translocations].

The ability of laboratory mice to learn to solve a simple food searching task, and their ability to extrapolate the direction of stimulus movement, were investigated in animals of CBA inbred strain (64 mice) and in mice with Robertsonian fusion of 8 and 17 chromosomes -- Rb (8, 17) 1 IEM possessing different genetic background (122 mice). As the ability for extrapolation is tested while the animal has no previous experience of such task solving, this form of behaviour seems to be different from conditioning. Mice with Rb (8, 17) 1 IEM but not CBA mice proved to be capable to solve the extrapolatory task at its first presentation. Their learning ability was found to be also superior to that of CBA mice. The present data proved that mice with Rb (8, 17) 1 IEM translocation may serve as a very promising model for investigation of complex behaviour patterns.

Adaptation, Psychological↗

PubMedDate not supplied

[Physiological and genetic ways of studying the extrapolation capability of mice].

Elementary reasoning--the ability of mice to extrapolate the direction of alimentary stimulus movement--was investigated in gentically different groups of animals. It was shown that mice possessing. Robertsonian translocation Rb(8,17) 11EM were superior in the extrapolation task solving than mice with normal kariotype, or mice with Robertsonian translocations of other types (RB(5, 19)1Wh, Rb(6, 15)1ALD, Rb(9, 14)6Bnr, Rb(16, 17)7bnr). Mice selected for low brain weight were superior in the extrapolation task solving than mice with high brain weight in 3--11 generations of selection. In F12--F14 this difference was absent. Mice with Robertsonian translocations and mice selected for brain weight are perspective models for physiological and genetic study of elementary reasoning.

Animals↗

PubMedDate not supplied

[Capacity for learning and extrapolation of mice selected for having different brain weights].

Ability for learning a simple food-searching reaction, and for extrapolation of a food stimulus movement has been studied in two lines of laboratory mice selected throughout 15 generations for high (H-line) and low (L-line) brain weight. It has been found that the mice from H-line learn the food-searching reaction more rapidly than those from L-line. In first presentation of the extrapolation task, the percentage of right solvings by mice from H- and L-lines does not differ from the 50%, expected for the random alternative choice. In subsequent presentations, the percentage of right solvings steadily increases in both lines, and taken over all presentations significantly exceeds the 50% random level, while the mean time of performance gradually grows shorter. Thus, no difference is observed between H- and L-lines either in solving the extrapolation task or in learning this practice, in contrast to a noticeable superiority of H-line in learning a simple motor reaction.

Animals↗

PubMedDate not supplied

[Functional interhemispheric asymmetry in rats during analysis of the geometric shape of visual stimuli].

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Animals↗

PubMedDate not supplied

[Interstrain differences in extrapolation capacity and exploration of a cruciform maze correlate with various indices of monoamine metabolism in the brain].

C57BL/6J (B6) and CBA mice with normal karyotype and respective substrains carrying robertsonian translocation (fusion) of chromosomes 8 and 17 (Rb) were compared in their ability to extrapolate the direction of stimulus movement disappearing from the field of vision, rearings and hole-poke responses, and exploration strategies in a plus-maze. Rb mice were shown to be superior to normal karyotype groups in extrapolation behaviour. The pattern of interstrain differences in noradrenaline level in the cortex and serotonin turnover indices in the hippocampus correlated with differences in extrapolation ability, while exploration strategies in the plus-maze correlated with differences in dopamine level and its turnover rate in the neocortex and striatum. The data demonstrated that chromosomal rearrangement inducing behavioural differences was accompanied also by discrete neurochemical changes, and that spatial exploration strategies (being probably the constituent of general spatial abilities of mice) were to a large extent independent from extrapolation ability which was regarded as the index of animal reasoning capacity.

Animals↗

PubMedDate not supplied

[Audiogenic epilepsy in 101/HY mice at different periods of postnatal development].

It has been established that mice of strain 101/HY suffer from audiogenic epilepsy seizures, the frequency and severity of which depend on animal sex and age. Mice were subjected to high intensity sound (about 100 dB) at the age of 14-16, 30, 60, and 190-270 days (Groups I, II, III, and IV, respectively). The testing was done three times. Mice of Group I were tested twice. The duration of sound stimulus was 20 s. Mice of both sexes from Group I were most sensitive. During the first test, the so-called "wild-run" behavior developed in 90% of animals and 60% showed tonoclonic seizure. Lethal outcomes in animals of this group (26.7% of the males and 23.5% of the females) were observed mainly during the second test, conducted one day after the first one. Only 6.7% of the males died during the first test in Group I. Severity of audiogenic seizure in males decreased with age, whereas among females there was a decrease in the number of animals with sensitivity to the sound stimulus. Among females of Groups III and IV, we did not detect any animals responding to the audiogenic stimulus by seizure and there were no deaths. Mechanisms underlying the audiogenic sensitivity of 101/HY mice are reviewed in the light of other information about the development of this genetic trait in rodents and in connection with other biological characteristics of these animals.

Acoustic Stimulation↗

PubMedDate not supplied

[An aversive olfactory signal during the Y-maze learning of mice selected for greater or lesser brain weight].

Learning abilities of mice selected by the small and large brain weights were studied in Y-maze. Thirsty mice were trained to find water in one of the maze arms. The minimal latency of this reaction reached in the process of learning was shorter in the mice selected by the heavy brain. Benzaldehyde which is commonly supposed to be an aversive olfactory stimulus being presented before drinking sharply increased the latency, nevertheless, it remained shorter in mice with heavy brain. The response to the aversive stimulus varied between the individuals, especially in mice selected by the small brain weight.

Animals↗

PubMedDate not supplied

[The action of ACTH 4-10 on the behavior of mice from different inbred strains].

We found that the administration of ACTH4-10 fragment to newborn mice of several strains (DBA/2, CBA, C57BL/6J, CBARb, and BLRb) for 5 days from the second day of life led to changes of several behavioral characteristics of adult animals. The effect of peptide administration on exploratory behavior of mice and on following the direction of stimulus movement are opposite to those induced by pain stimulation, i.e., administration of a solvent. The results are interpreted as a possible antistress effect of the peptide, which is realized during the period of neurodifferentiation. These data are discussed in terms of a possible effect of the used peptide on differentiation of the nervous system.

Adaptation, Physiological↗

PubMedDate not supplied

[Audiogenic seizures in mice selected for larger and smaller brain mass].

Mice selected for large and small brain weights (LB and SB strains, respectively) were tested for audiogenic seizure sensitivity. We have examined 150 LB and 120 SB mice of the 13th and 14th generations. In mice of the 12th generation brain and body weight values were 498.6 +/- +/- 2.1 mg and 26.2 +/- 0.4 g, respectively, for the LB and 415.35 +/- 1.9 mg and 23.8 +/- 0.3 g for the SB, the difference being significant for both values (p < 0.001). The SB mice revealed higher audiogenic sensitivity (larger proportion of seizures and deaths) at the age of 22-27 days. Adult LB mice were more sensitive than SB of the same age (irrespective of whether they received priming stimulation or not). The obtained evidence is discussed in the context of differences between audiogenic fits and other seizure states.

Acoustic Stimulation↗