The distribution of lateral phenotypes in six- to seven-year-old children

An approach to the estimation of the lateral phenotype in children has been developed. During the study, more than 20 lateral phenotypes were identified in six-to seven-year-old children. The most frequent are the following lateral phenotypes: dextrality (motor and sensory), motor dextrality and sensory sinistrality, and motor dextrality and sensory ambidexterity (with a dominant left ear and right eye and with a dominant right ear and left eye). Unilateral left-handers accounted for 0.1% of all children studied; thus, the use of the laterality profile of motor functions as a “marker” of the brain functional asymmetry is rather questionable.     

Short-term adaptation of five- to seven-year-old children to mental load

Tetrapolar rheography according to Kubicek has been used to estimate the adaptive capacity of the cardiovascular system in 150 five- to seven-year-old children at rest and during mental load. Mental load evokes two variants of stroke volume (SV) responses, one of them characterized by an increase in the SV, and the other, by a decrease in the SV and an increase in the diastolic blood pressure (BP_d). Irrespective of the direction of the change in the SV, short-term adaptation to mental load in most five- to seven-year-old children does not stress the mechanisms of the cardiovascular system control and is generally favorable. In 13–15% of the children examined, short-term adaptation to mental load considerably stressed the cardiovascular system control. This is expressed in increased systolic blood pressure (BP_s), BP_d, and heart rate (HR); decreased CV and cardiac output (Q); and a prolonged restoration period for most central hemodynamic parameters.     

Metabolic characteristics of brain structures during conscious and unconscious anxiety

Metabolic processes accompanying conscious and unconscious anxiety states in patients with multiple sclerosis were studied. The correspondence between glucose metabolism rates (evaluated using positron emission tomography images) and indices of conscious and unconscious anxiety (according to the Taylor and Luscher test scores) was estimated. Data on the specific features of brain activity at various levels of conscious and unconscious anxiety were obtained. The elevation of conscious anxiety was accompanied by an increase in the metabolic activity of the left-hemisphere cortical and subcortical structures, as well as by a decrease in the glucose metabolism rate in the majority of right-hemisphere structures (except limbic and thalamic structures). The elevation of unconscious anxiety was accompanied by a decrease in the rate of glucose metabolism in the left frontal structures, whereas in the amygdala, as well as in the other limbic structures (gyrus temporalis inferior), its rate increased.     

Biomotor development in 1992 and 2002 samples of seven-year-old children

The aim of the study was to determine quantitative and qualitative differences in the morphological-motor status between elementary school first-graders of both sexes in 1992 and 2002. A standard set of 11 variables currently used in the Croatian school system to evaluate the morphological, motor and functional status of school children was employed at the beginning of academic years in a sample of 635 children (325 male and 310 female) in 1992 and a sample of 850 children (430 male and 420 female) in 2002. The mean age of study children was 7 years (+/- 2 months). Results of canonic discriminative analysis revealed the male children enrolled in elementary school first grade in 2002 to show better performance on the tests of aerobic endurance, static strength and explosive strength, and to have greater mass of muscle tissue and less adipose tissue, while achieving poorer results on the test of movement frequency than their 1992 counterparts. Female children tested in 2002 showed better results on the test of aerobic endurance and all tests of strength factors, with greater mass of muscle tissue and less adipose tissue, while yielding poorer results on the tests of flexibility, coordination and movement frequency as compared with their 1992 counterparts. Factor analysis in the morphological-motor system isolated three varimax factors each in children of both sexes tested in 1992 and 2002. First factor showed a pattern of a general morphological factor predominantly defined by body weight and volume in the children of both sexes from both study years. Second factor showed a pattern of a general motoricity factor predominantly defined by explosive strength, coordination and speed in children tested in 1992, whereas in their 2002 counterparts the general motoricity factor was predominantly defined by the factors of strength and endurance. Third factor was defined by flexibility in both 1992 and 2002 children. In female children tested in 1992, second factor mostly defined energy regulation with predominance of explosive and static strength, followed by coordination, whereas third factor was defined by movement frequency and aerobic endurance. In female children tested in 2002, second factor mostly defined energy regulation with predominance of explosive and repetitive strength, followed by aerobic endurance and coordination, whereas third factor was defined by movement frequency followed by muscle tone regulation.     

Characteristics of the development of visual perception in five- to seven-year-old children

The characteristic of visual perception (VP) were analyzed in five- to seven-year-old children according to a modified method of Frostig, which estimates the following VP components: visuospatial perception, figure-ground differentiation, and visuomotor integration. Age dependence of the development of VP components indicating the variation of the rates of their development was found. All VP components rapidly developed between five and six years of age; considerable changes in visuomotor integration and visuospatial perception were observed between six and seven years of age.     

Breakthrough to awareness: a preliminary neural network model of conscious and unconscious perception in word processing

 A neural network model is constructed to mimic the processing involved in semantic and working memory when subliminal effects are involved. These effects involve modifications of reaction time to later inputs, according to whether or not there has been conscious or unconscious processing of the earlier input. The model is constructed of two separate modules: one (a semantic memory module) allowing for processing at a semantic, but unconscious, level, and the other (a working memory module) for conscious experience. The latter module, although a replica of the earlier one, has different lateral connectivity and output function from the former. The model is shown to give a good fit to Marcel’s data on the processing of polysemous words. Further tests are suggested for the model, and a possible cortical implementation suggested. The relevance of the model to recent approaches to consciousness is also explored. Received: 7 February 1995/Accepted in revised form: 14 November 1995     

Activity-related changes of body fat and motor performance in obese seven-year-old boys

The effects of 35 weeks of extra-curricular, mainly aerobic, dynamic physical activity were analysed in overweight and obese 7-year-old boys contrasted with control groups. Body composition was estimated by using the body mass index (BMI) and skinfold thicknesses. Overweight or obesity was defined according to the suggestions of Cole and associates (2000). The activity program consisted of swimming and water games, folk dance, and soccer. Data were collected four times between September 2003 and October 2004. Thirty-one overnight or obese boys volunteered to participate in the activity program (weekly, to physical classes of 45 min. plus three extra-curricular activity sessions of 60 min. duration). The control subjects were 43 overweight or obese boys, and 75 non-overweight and non-obese ones. The controls had only two curricular physical education classes every week. Physical performance capacity was tested by 30 m dash, 400 m run, standing long jump, and fist-ball throw. Body fat content estimated by taking the sum of five skinfolds decreased significantly during the 35-week training program. However, body weight as well as skinfold thicknesses increased significantly during the four month non-active period that followed. Physical performance improved during the test period, but deteriorated between the third and fourth data collections. BMI, as well as the sum of five skinfolds increased in both control groups.Physical performance decreased in the overweight control subjects and increased moderately in the non obese ones. We inferred that more vigorous habitual exercise alone, i.e., without a program of dietary control, though effective, could not efficiently stabilise body fat, still less achieve a lasting reduction of it. Obese, but also overweight subjects need long term exercise programs of sufficient intensity, duration and frequency, plus dietary measures, to get rid of excess body fat.     

Psychophysiological study of the effects of adaptation to tactile interaction with dolphins in six- to seven-year-old children

The possibility of the use of an integrative psychophysiological approach to the investigation of the role of ultraslow information-controlling brain systems in the mechanisms regulating the wakefulness level and the actual development of cognitive functions in six- to seven-year-old children was estimated. For the studied children, with different types of psychological adaptation to an unfamiliar emotional situation (tactile interaction with dolphins), we found the features of the development of (a) corticosubcortical and limbic-reticular mechanisms of regulation of the wakefulness level and (b) suprasegmental mechanisms of autonomic, hemodynamic, and oxygen-dependent energy supply of the wakefulness level. The idea of a correlation between (1) the level of actual emotional and cognitive development and the type of adaptation to psychoemotional stress and (2) age-specific features of the formation of reflex and neurohumoral mechanisms of regulation of the wakefulness level in six- to seven-year-old children is substantiated.     

Correlation between different forms of trace phenomena in the activity of rabbit visual cortex neurons]

Plastic changes in the components of the unit responses in the rabbit visual cortex (VC) in the course of electrical stimulation (with different parameters) of the lateral geniculate body (LGB) were compared with the capacity of the same units for trace driving to the LGB preceding stimulation. Potentiation of inhibition (inhibitory pauses) in reponse to electrical LGB stimulation is the main plastic phenomenon in the activity of VC units. Trace driving is characteristic predominantly of units with enhanced plasticity of the excitatory sign, a tendency toward epileptiform activity after LGB tetanization. In most cases inhibitory reaction is expressed in weakening of the periodic component of neuronal activity corresponding to the frequency of stimulation. The level of trace suppression of periodicity positively correlates with potentiation of the inhibitory pause during prolonged LGB stimulation.     

Psychophysiological and neurophysiological features of the organization of visuo-spatial performance in right-handed and left-handed six- to seven-year-old children

The developmental features of individual components of the visual perception and brain functional organization during visuo-spatial activity of different complexity were studied in right-handed and left-handed 6–7-year-old children. The results of psychophysiological testing of their visual perception testify to the underdevelopment of the mechanisms of integrative brain activity. Some specific features of the brain functional organization were revealed in the left-handed children during visuo-spatial performance. More autonomous functioning of the cerebral hemispheres and the duplication of the activation processes in the right and left hemisphere during visuo-spaital performance of different complexity are characteristic of these children. This is probably associated with the involvement of compensatory mechanisms, which enable the performance reliability.