Peculiarities of formation of the cognitive functions in junior school children with different maturity of regulatory brain systems

To reveal the specific role of maturation of modulating, regulatory brain systems in formation of cognitive processes at the junior school age, was performed a complex electroencephalographic and neuropsychological examination of the 7–8-year-old children with different degrees of functional maturity of the regulatory systems. It has been shown that an essential factor determining formation of the higher psychic functions (HPF) at the junior school age is maturation of the fronto-thalamic system. Immaturity of this system in the 7–8-year-old children leads to a deficiency of functions of programming, regulation, and control of the activity. The most substantial changes were revealed for the components of the voluntary organization of the activity, which are connected with its selectivity both in realization of current tasks and in creation of the activity strategy. The deficiency of processes of voluntary regulation in the 7–8-year-old children with immaturity of the fronto-thalamic system is combined with a delay of development of the meaning-forming speech function. Comparison of data of the neuropsychological and electroencephalographic examination has permitted suggesting that the basis of the revealed changes in the HPF formation in the 7–8-year-old children is immaturity of the main neurophysiological mechanisms that provide a selective involvement of different cortical regions in providing their activity both in the course of its realization and during preparation to it as well as an under-development of differentiated intracortical connections in the left hemisphere.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 427–435.Original Russian Text Copyright © 2004 by Machinskaya, Semenova.To the 100-Anniversary of N. N. Traugott     

Influence of moderate physical exercise on the cardiac rhythm parameters of elementary and junior high school children

To reveal the specific features of the influence of moderate exercise (running) on the autonomic regulation of the cardiac rhythm, changes in the heart rate variability (HRV) parameters have been analyzed during three months in 292 children aged 9–14, as dependent on the sex and the baseline autonomic tone estimated by means of cluster analysis. It has been shown that, in schoolchildren engaged in running for health, HRV changes give evidence for the optimization of the mechanisms of autonomic regulation. The HRV parameters in the girls were more resistant to muscular activity compared to boys. The data obtained indicate that running for health requires a differential approach to dosing of the exercise, taking into account the sex and the baseline autonomic tone.     

Prevalence of zinc deficiency in junior high school students of Tehran City

Zinc deficiency is a health problem in many communities especially among adolescents because of pubertal growth sprout. This investigation was carried out to determine the epidemiology of zinc deficiency in junior high school students in Tehran City in 1997. This cross-sectional study was performed on 881 students (452 males and 429 females) with the mean age of 13.2±1.0 yr, who were selected by multistage random sampling method. Plasma, erythrocyte, and hair zinc levels were assayed by flame atomic absorption spectrophotometry. Anthropometric and demographic characteristics were measured and recorded on a questionnaire. Dietary intakes were evaluated by a 24-h recall method. Zinc deficiency was defined as having at least two indices from indices of erythrocyte, plasma, and hair zinc below 10 μg/mL, 100 μg/dL, and 125 μg/g of hair, respectively. The results showed that zinc deficiency prevalence was 31.1% (confidence interval: 28–34.4%). Zinc deficiency was 65%, 49%, and 1.3% based on plasma, erythrocyte, and hair zinc levels, respectively. The mean ± SD for plasma, erythrocyte, and hair zinc concentration, height-for-age, as well as weight-for-age Z scores were 95.2±17.7 μg/dL, 10.3±2.3 μg/mL, 239.4±54.4 μg/g, −0.40±0.92, and 0.12±0.91, respectively. As for dietary intake compared with the RDA, 50% of the subjects consumed less than 50% of their requirement for zinc RDA based on a 24-h dietary recall. Zinc intake in subjects was 7.5±3.7 μg, that in boys was higher than in girls. Correlation coefficients between zinc status indices were very weak. There was neither a linear nor nonlinear relationship between biochemical parameters and nutritional zinc intake. It is concluded that almost one-third to one-half of the subjects would be considered zinc deficient.     

Spatial organization of the cortical electrical activity at different stages of visual set in children of preschool and junior school age

Set-forming and set-shifting were studied in children of three age groups: five to six-, six to seven- and nine to ten-year-old. Set effect displayed itself in contrast illusions in most of the subjects (69 of 73). Age differences in set plasticity and in reaction time to a probe stimulus were revealed. Five to six-year-old children formed a more rigid set than older ones. According to EEG coherence function in theta- and alpha-bands and behavioral data, a hypothesis of two systems being involved in set-forming and set-shifting is proposed. These systems are: a fronto-talamic system of selective attention, and a system of cortico-hippocampal connections that are involved in cortical processing of novel visual information and in episodic memory. The age of 6-7 years is shown to be critical in forming a plastic type of cognitive set.     

Dynamics of pattern formation

Experiments were designed to test the validity ofTuring's suggested pattern-forming mechanisms, which are initially capable of giving rise to only five to seven uniform structures.TheOregon-R (wild-type), mass-cultured strain ofDrosophila melanogaster was employed. Selection for the regular arrangement of microchaetac on the margin of the fourth abdominal sternite was practiced for twenty generations. In the L line, individuals with six uniformly spaced bristles were selected as parents of every generation. Due to the absence of nine bristles dividing the sternal margin uniformly, the progeny was raised in each generation in the H line from males and females with nine as equidistant bristles as possible. The whole experiment was performed at 25±0.50°C.Selection was effective in increasing the frequency of six regular bristles in the L line. But no progress in the desired direction was obtained in the H line, although the proportion of sternites with nine irregular structures was found to increase. The experimental results supportTuring's diffusion-reaction scheme of pattern formation in morphogenesis.Supported by grants GB-1388 and GB-3219 from the National Science Foundation.     

Dynamics of soleplate formation

Immunohistochemical techniques with anti-desmin, anti-acetylcholine receptor and anti-fibronectin antisera and autohistoradiography were used to determine the dynamics of neuromuscular synaptogenesis. Fast twitching muscles were taken from chick embryos at 5 to 14 days of incubation. "Primitive eminences" at terminal arborizations of motor neurons were composed of Karnowsky positive, anti-desmin and anti-acetylcholine receptor positive cells which contained sites bound to alpha-bungarotoxin. These cells, characterized as myoblasts, fused with the myotubes during formation of neuromuscular junctions in the sites of contact with terminal arborizations of motor neurons. Their nuclei and cytoplasmic organelles become the nuclei and organelles in the soleplate.     

Dynamics of pattern formation in biomimetic systems

This paper is an attempt to conceptualize pattern formation in self-organizing systems and, in particular, to understand how structures, oscillations or waves arise in a steady and homogenous environment, a phenomenon called symmetry breaking. The route followed to develop these ideas was to couple chemical oscillations produced by Belousov-Zhabotinsky reaction with confined reaction environments, the latter being an essential requirement for any process of Life. Special focus was placed on systems showing organic or lipidic compartments, which represent more reliable biomimetic matrices.     

Dynamics of sheet nacre formation in bivalves

Formation of nacre (mother-of-pearl) is a biomineralization process of fundamental scientific as well as industrial importance. However, the dynamics of the formation process is still not understood. Here, we use scanning electron microscopy and high spatial resolution ion microprobe depth-profiling to image the full three-dimensional distribution of organic materials around individual tablets in the top-most layer of forming nacre in bivalves. Nacre formation proceeds by lateral, symmetric growth of individual tablets mediated by a growth-ring rich in organics, in which aragonite crystallizes from amorphous precursors. The pivotal role in nacre formation played by the growth-ring structure documented in this study adds further complexity to a highly dynamical biomineralization process.     

Dynamics of plaque formation in Alzheimer's disease

Plaques that form in the brains of Alzheimer patients are made of deposits of the amyloid-beta peptide. We analyze the time evolution of amyloid-beta deposition in immunostained brain slices from transgenic mice. We find that amyloid-beta deposits appear in clusters whose characteristic size increases from 14 microm in 8-month-old mice to 22 microm in 12-month-old mice. We show that the clustering has implications for the biological growth of amyloid-beta by presenting a growth model that accounts for the experimentally observed structure of individual deposits and predicts the formation of clusters of deposits and their time evolution.     

Influence of maturation on anthropometry and body composition in Japanese junior high school students

Background

The purpose of this study was to examine maturity-related differences in anthropometry and body composition in Japanese youth within a single year.

Methods

Two hundred and ten Japanese youth aged from 13 to 13.99 years participated in this study. Their maturity status was assessed using a self-assessment of stage of pubic hair development. Bioelectrical impedance analysis was used to estimate percent body fat and lean body mass (LBM). Muscle thickness of the anterior thigh, posterior lower leg and rectus abdominis muscles were measured by ultrasound.

Results

For boys, height, body weight, and LBM in less mature groups were lower than that in more mature groups. The maturity-related differences were still significant after adjusting for chronological age. On the other hand, muscle thickness values in the lower extremity and abdomen differed among the groups at different stages of pubic hair development, whereas there was no maturity-related difference in the relative values corrected by LBM, except for those thickness values measured at the abdomen. For girls, only the muscle thickness at the anterior thigh and muscle thickness relative to LBM^1/3 at the posterior lower leg was significantly affected by maturity status, but significant maturity-related difference was not found after adjusting for chronological age.

Conclusions

At least for Japanese boys and girls aged 13 years, maturity status affected body size in boys, but not in girls, and the influence of maturation on the muscularity of the lower extremity and trunk muscles is less in both sexes.     

Models for tuna school formation

Schooling behavior is a challenging topic in the context of animal aggregation. It is also of economic importance for the estimation and conservation of stock sizes. An individual based movement model will be developed, taking into account energetic advantages of schooling. This model is a cellular automaton with a hexagonal grid. The latter considers the geometry of a school, where fish swim in a diamond-shape configuration in order to take advantage of the velocity, induced by the tail strokes of preceding fish. Furthermore, knowing the induced velocity field makes it possible to consider the energetic needs of fish swimming in that school and to describe the break up of schools due to oxygen depletion. This allows us to estimate maximum school sizes.     

初中生生物学前科学概念来源的研究

在文献分析的基础上,分析了初中生生物学前科学概念的来源。其主要来源有:1)个体的日常生活经验;2)自己的判断、推理;3)生物学概念的术语;4)教学资料;5)教师的前科学概念;6)同学、朋友;7)学生遗忘了;8)相近概念的混淆;9)社会媒体;10)家人。这些来源依内-外部的维度,可分为内部因素和外部因素;依人-物的维度,可分为人的因素和物的因素;依教育领域的维度,可分为学校教育因素、社会教育因素和家庭教育因素。     

Dynamics of visual association formation in man]

The subjects were asked to memorize four combinations of paired visual stimuli on an illuminated tableau. The test-signal, a single flash on the tableau, was presented after the signal pair and could coincide either with the second component of the association or with the elements not involved in this particular association. After presentation of the test signal, the subject had to press the key as quickly as possible and then point to the pair on the tableau, associated with the signal pair (the second component of the association). The changes occuring in the structure of the association were evaluated by the changes of reaction time (rt) to the test-signal and the RT variability. Differences have been revealed between the RT dynamics and variabilities, which characterize the functional state of the elements activated during the achievement of the association and those not participating in the given association. During stabilization of the visual association, oppositely directed tendencies of RT changes and variabilities were observed.