[Biomechanical properties of the human cranium: aging aspects].

Biomechanical properties of the human skull affect its dynamic tensility (pliability, compliance) by changes of intracranial volume and pressure (deltaV/deltaP). The goal of this study is to substantiate a possibility of noninvasive and dynamic evaluation of cranial compliance. The transcranial dopplerogram of middle cerebral artery and hemispheric bioimpedance were synchronously recorded, which represent information about pulsative changes of intracranial pressure and volume, respectively. The parameters were recorded at rest and during adequate hemo- and liquorodynamic tests in different age groups--20-30, 40-50, and 70-85 years. As compared with the young group, a decrease of the cranial compliance in the intermediate age group was revealed due to an observed increase if rigidity of skull bones and ligaments, which indicates a decrease of stability of the intracranial circulatory system. However, in the group of 70-85 years the compliance rose again due to an enlargement of intracranial liquor spaces and facilitation of liquor circulation inside the intracranial cavity; this can be suggested to be a compensatory mechanism for supporting the adequate brain circulatory-metabolic state.

[A correlation between the efficiency of probabilistic prediction and characteristics of left and right interhemispheric activation]. / Vzaimosviaz' éffektivnosti veroiatnostno-prognosticheskoi deiatel'nosti cheloveka s osobennostiami aktivatsii levogo i pravogo polusharii.

The interhemispheric difference in the level of EEG activation was studied as a correlate of the efficiency of human probabilistic activity. The interhemispheric asymmetry of the arousal duration in the projection (occipital) and associative (central) areas was assessed in two tested groups of subjects: with an adequate prediction and difficulties in predictive activity under conditions of different information significance of a stimulus. Under conditions of relevant stimulation, the asymmetry coefficient was higher, and the desynchronization reaction in the central areas of the left hemisphere was considerably shorter in bad predictors than in good ones. It is suggested that the asymmetry observed in bad predictors is determined by a nonspecific activation of subcortical structures, and in good predictors the asymmetry is related with the local neocortical activation.

[The characteristics of probabilistic prognosis and of the orienting reaction in children with learning difficulties]. / Osobennosti veroiatnostnogo prognozirovaniia i orientirovochnoi reaktsii u detei s trudnostiami obucheniia.

Middle-aged school-children were examined with learning disabilities, differentiated by the parameters of probabilistic prognosis in two subgroups: with disturbances of attention (1) and memory (2). The first subgroup differed from the norm by intensified reaction of desynchronization of the projection areas of the cortex to irrelevant stimuli. Relevant information evoked an increase of activation of the associative zones, less expressed than in the norm. In the second subgroup a weak involvement of associative cortical areas in the reaction of desynchronization to relevant stimuli correlated with insufficient formation of alpha 2-rhythm and high frequency of meeting the signs of dysfunction of mesodiencephalic brain structure. The results are discussed in the aspect of the role of neurophysiological mechanisms of regulation and trace fixation for the formation of the integrative brain activity in the ontogenesis.

[Neurophysiologic mechanisms of attention disorder in children with learning difficulties]. / O neirofiziologicheskikh mekhanizmakh narusheniia vnimaniia u detei s trudnostiami obucheniia.

In order to study neurophysiological mechanisms of the disturbance of voluntary attention in children of 6.5-9 years old, which had difficulties in learning caused by a delay of psychic development (DPD), characteristics were studied of electrocortical and vegetative components of orienting reaction (OR) to indifferent and relevant stimuli and also of background EEG. A decrease of OR components revealed in situation of involuntary attention against the background of insufficiently formed cortical rhythm of alpha-range, as compared with the norm, is compensated at the increase of stimuli significance by verbal instruction. These facts confirm the supposition about deficit of regulating influences of the frontal cortical areas on the ascending activating system in children with difficulties in learning. Deficiency of the involvement of the central cortical areas in OR realization, typical of the children with DPD in a situation of voluntary directed attention, can be considered as reflection of disturbances of integrative brain activity.

[Psychophysiological features of test subjects with different effectiveness of probabilistic-predictive activity]. / Psikhofiziologicheskie osobennosti ispytuemykh s raznoi éffektivnost'iu veroiatnostno-prognosicheskoi deiatel'nosti.

A correlation between behavioral characteristics of predictive activity and EEG and autonomic indices of the orienting reacting reaction was revealed. A relationship between the personality traits and characteristics of attention, memory, and generalization process was described.

[The role of interhemispheric neurodynamics in the process of probability predicting]. / Rol' mezhpolusharnoi neirodinamikiv protsesse veroiatnogo prognozirovaniia.

The interhemispheric asymmetry of electrocortical components of the orienting reaction (the amplitude and latency of P300) were studied in the projection (occipital) and associative (central) areas in 8 subjects who were capable for adequate prediction under conditions of different information significance and 6 subjects with prediction problems. Under conditions of relevant stimulation, the amplitude asymmetry was more expressed and the latency of P300 in the central areas of both hemispheres was considerably shorter in good predictors than in bad ones. The rostrocaudal activation gradient was more expressed in good than in bad predictors, especially, under conditions of high information importance. It is suggested that the observed asymmetry in persons with prediction problems is related with nonspecific activation of subcortical structures and in good predictors it is caused by the local neocortical activation.

[Changes in the complex conditioned reflex activity of rat pups under the influence of penta-peptide]. / Izmenenie slozhnoi uslovnoreflektornoi deiatel'nosti krysiat pod vliianiem penta-peptida.

Influence of YFRKD, modified fragment of interferon-alpha, on the formation of two-links system of feed-procuring conditioned reflexes was studied in rats in ontogenesis. The experiments have shown that YFRKD impedes both current learning and use of previous experience. The process of synthesis of two reflexes in united complicated functional complex is disturbed.

[Effect of piracetam on the conditional reflex memory under probable reinforcement conditions]. / Vliianie piratsetama na uslovnoreflektornuiu pamiat' krys v usloviiakh veroiatnostnogo podkrepleniia.

The effect of piracetam on the development of a two-link system of feed-procuring conditioned reflexes was studied in rats with probability reinforcement. The experiments showed that piracetam improves both the current learning process and the memory track (previous experience) reproduction. In addition, the drug decreases the role of the probabilic character of reinforcement, thus facilitating the synthesis of two reflexes in a united functional complex.

[Interhemisphere asymmetry of the CSF dynamics and biomechanical properties of the skull].

This investigation shows that both intracranial liquor circulation and skull biomechanical properties evaluated by its pliability (compliance) to intracranial pressure are characterised by marked interhemisphere asymmetry. The interhemisphere differences of cerebrospinal fluid mobility were evaluated by means of asymmetry coefficient (right/left ratio of liquor mobility) which was found to be 1.25-1.45 in healthy middle-age persons. For the skull pliability (compliance) the coefficient of hemispheric asymmetry was 0.75-0.95. These two hemisphere asymmetry coefficients are characterized by reciprocal relationships. These coefficients demonstrated no dominancy related to right/left hemisphere as well as no correlation with neurophysiological parameter. Functional tests (apnoea, hyperventilation, Stookey test) gave rise to significant changes of these coefficient values. At ageing, the magnitudes of these coefficients decreased. The spectral analysis of pulse waves of dopplerogram and rheoencephalogram reveals hemisphere asymmetry, too. It should be suggested that the interhemisphere asymmetry of the CSF dynamics and skull biomechanical properties is a special mechanism which contributes in the process of circulatory-metabolic support of brain activity.

[Age-related characteristics of relationships between brain blood flow, liquor dynamics and biomechanical properties of human cranium].

The peculiarities of relationships between changes of cerebral blood flow, intracranial liquor dynamics and skull biomechanics in humans were studied in an age aspect. For this aim, a non-invasive method was proposed based on concomitant registration of rheoencephalogram and transcranial dopplerogram and evaluation of relationships between intracranial volume and pulse pressure changes (P-V index). The data obtained were analyzed by pattern-phase computer processing and compared with the blood flow parameters. The investigation was carried out on healthy volunteers of 18-25, 40-50 and 65-75 years of age. It was shown that circulatory-metabolic supplying of human brain was supported by such factors as volume brain blood flow, intracranial liquor dynamics in cooperation with skull biomechanics. The cerebral blood flow decrease at aging could be compensated by increase of the reserve-compensatory abilities of the system of cranial-spinal liquor dynamics.

[Characteristics of learning in ontogeny]. / Osobennosti obucheniia v ontogeneze.

The rate of learning in young animals and in adults is different, it is higher in ontogenesis. The mechanism of learning in young animals is also different. In the ontogenesis it is similar to imprinting. Probably the mechanisms of the infantile amnesia develops according to the model of dissociated when the association is a certain chemical composition of brain which is typical of this age level. The information more important from the biological point of view is less dissipated and better restored that testifies the low effectiveness of reproductive system and not low memory trace consolidation. The difficulties in extinction and differentiation in experiments with rats are connected with reflex automatisation but not with the deficit in inhibition.

[Penta-peptide (YFRKD) suppression of complex conditioned-reflex activities in the ontogeny of white rats]. / Podavlenie penta-peptidom (YFRKD) slozhnoi uslovnoreflektornoi deiatel'nosti v ontogeneze belykh krys.

Influence of YFRKD, modified fragment of interferon-alpha, on the formation of two-links system of feed-procuring conditioned reflexes was studied in rats in ontogenesis. The experiments have shown that YFRKD impedes both current learning and use of previous experience. The process of synthesis of two reflexes in united complicated functional complex is disturbed.