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The dynamics of direct current potentials of the brain was studied in 10-11-year-old children during sustained attention to successive presentation of series of Shulte tables. Children were examined twice: before and after the series of training to fast reading. A gradual increase in the level of direct current potentials during sustained attention was observed. The increase was more pronounced in children with excessive than in children with moderate reactions to the loading. After the series of training to fast reading, the increase in the level of direct current potentials was reduced in both groups. This aftertraining neurophysiological phenomenon was combined with a transformation of psychophysiological characteristics: a decrease in the time of viewing of Shulte tables and increase in the speed of reading. It is suggested that the shifts of direct current potentials reflects the dynamics of intensity of the cerebral energy metabolism.

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The pronounced benzodiazepine (antiphobic) modulation of the amplitude-temporal parameters of different components of the thalamocortical responses (TCR) of the sensorimotor cortex is observed in rabbits in their early postnatal ontogeny. This modulation is of a dose-dependent character and is registered not after the injection of tazepam in a concentration of the "therapeutic tranquilizing window" but also in the psychotoxic plasma range. A gradual increase in blood tazepam concentration in a young rabbit pup is accompanied by the wave-like and differential decrease in the amplitude of the second and third positive (P2 and P3) and third negative (N3) TCR components, while the second negative (N2) and fourth positive (P4) components tend to a wave-like increase. The dose-dependent dynamics of tazepam modulation of the P2, P3, and N3 latencies is characterized by a wave-like and differential increase. The latency of P4 decreases slightly and that of the N2 increases with a low degree of significance. The selective dynamics of benzodiazepine modulation appears to be related with peculiarities of the electrogenesis of each of the components. The dose-dependent modulation of the level of cortical DC potential is of the same character as the respective amplitude changes in P2, P3, and N3, but its fluctiatuons are more pronounced.

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The resulting data give evidences, that after injection of the low doses of amphetamine the decrease of amplitudes both negative (NC-3), and positive components (PC-3) of the thalamo-cortical responses (TCR) of the sensorimotor cortex (SMC) takes place in 2nd-3d-weeks-old rabbits of their postnatal life. At the same time the amplitudes of these phases in 45-50-days-old animals change to greatly less extent, without any system, with low level of statistical significance. After injection of medium doses of amphetamine in 2nd-3d-weeks-old rabbits, the increase in amplitudes of both components of TCR SMC in observed, at the same time in definitive animals the amplitudes of these responses decrease greatly. After injection of the high doses of amphetamine in 2nd-3d-weeks-old rabbits the further increase in amplitude PC-3 and NC-3 is displayed, at the same time the growth of amplitude parameters of TCR SMC appears for elder animals under this concentration of amphetamine only. Neurophysiological and neurochemical analyses of these phenomena are developed. Neuro-ontogenesis hypothesis of causes of high vulnerability of the nervous system in young animals and children during critical period of increased risk under the exposure to both psychotropic drugs and endogenous psychopathogenic factors being proposed, that can simplify search for adequate psychopharmacology protector, etc.

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The fact of marked neuroleptic modulation of the amplitude-temporal parameters of thalamo-cortical responses (TCR) of the sensorimotor cortex (SMC) in the range of "the therapeutic haloperidol window" and the psychotoxical phase was established in early postnatal ontogeny of rabbits. The gradual increase of blood haloperidol concentration was accompanied by non-harmonic increasing variations of the level of neuroleptic modulation of the amplitudes of separate TCR components. These dose-dependent variations with alternation of depression and potentiation of TCR components were observed not only in psychotoxical phase, but also inside "the therapeutic haloperidol window". In retarded, infantile individuals the lower threshold of haloperidol modulation of amplitude parameters of TCR SMC was observed in comparison with normally developing animals. In contrast to the amplitude parameters, dose-dependent modulation of latent periods of different components of TCR SMC was not of oscillatory but exponential character. This can testify to participation of different (by electrogenesis, biochemistry, and structure) neuronal pools in the processes of neuroleptically induced reorganization of amplitude and time markers of TCR SMC.

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The complex dynamics of the changes in the spatial-temporal disposition of the heterocomponent thalamocortical responses (TCR) when traversing the sensorimotor cortex (SMC), are governed by the characteristics of the electrogenesis of each of the components of the TCR, the age of the animal, and the frequency of stimulation of the ventroposterolateral (VPL) nucleus of the thalamus. At the same time, the transformation of the electrical profile of the second positive component (PC-2) of the TCR during traversal of the SMC may suggest the algebraic summation in this component of the bioelectrical processes of several sources of generation (of the inverted and noninverted PC-2). The characteristics of the ontogenetic dynamics of the profiles of the biological fields of the third negative component (NC-3) of the TCR which were found may be the result of age-related stages of development and of a change in the embryonal mechanisms of electrogenesis to the definitive mechanisms in the presence of outwardly similar negativities.

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The data obtained in the paper showed that complex dynamics of changes of spatial-temporary situation of heterocomponent thalamocortical responses (TCR) at passing the sensorimotor cortex (SMC) was conditioned by the properties of electrogenesis of each TCR component, age and frequency of stimulation of ventroposterolateral (VPL) thalamus nucleus transformation of electric profile of the second positive component (PC-2) of the TCR at passing SMC might testify to algebraic summation in this component of bioelectric processes of several generation sources (invertible and non-invertible PC-2). The revealed properties of ontogenetic dynamics of the bioelectric fields profiles of the third negative component (NC-3) of the TCR might be the consequence of the age stages of the development and change of embryonal mechanisms of electrogenesis of the definitive ones in extremely similar negativities.

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It has been demonstrated that rhythmic stimulation of the relay thalamic nucleus in rabbits at the second half of the first month of postnatal life does not significantly affect the amplitude of the second and third positive components (PC-2 and PC-3) of the positive phase of the thalamocortical responses. Combination of rhythmic stimulation of this nucleus and that of lateral hypothalamic structures is accompanied by a significant increase of the amplitude of both positive components of the thalamocortical responses, the degree of potentiation of PC-3 being higher than that of PC-2. The described potentiation is most evident at the third week of postnatal development of rabbits.

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Data have been obtained on development of evoked potentials in the sensorimotor cortex to electrical stimulation of the thalamic ventroposterolateral nucleus (VPL) in rabbits in early ontogeny. In 3-5 days rabbits, under four times increase of threshold electric stimulation of VPL the thalamocortical response (TCR) is presented by a positive-negative potential with a long latency and minimum amplitude parameters. Second and third TCR positive components to increasing of threshold value of electric stimulation 4 times, are differentiated from 7-8 days age. Age dynamics of TCR amplitude-temporal parameters is characterized by a shortening of latency and an increase of oscillations amplitude, most expressed at 2-3 weeks of postnatal life. TCR of one month rabbit to increased threshold electrical stimulation of VPL is presented by short-latency positive-negative oscillation with a positive phase consisting of three components with successively increasing amplitudes.

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Periodical pyramidal tract (PT) stimulation in freely moving rats has been shown to be accompanied by statistically significant increased functional activity of neuronal populations of the sensorimotor cortex (SMC) manifesting as potentiation of the primary positive phase of the pyramidal-cortical response (PCR). When periodical PT stimulation is combined with the lateral hypothalamus (LH) stimulation of the same periodicity, a statistically significant increase in the magnitude of potentiation of the PCR positive phase compared to that occurring without the LH activation is observed. When the periodical PT stimulation is combined with the LH and SMC stimulation of the same periodicity, the potentiation of the PSR positive phase increases significantly in comparison with the potentiation occurring without the SMC stimulation.

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The effect of early locomotor training (running in a squirrel cage from an age of 1 month for 3-6 months) on evoked potentials of the rat visual cortex during ontogeny was investigated. It was established that intensified proprioceptive afferentation causes a statistically significant reduction of both the latent periods and the recovery cycles of excitability of primary responses of the visual cortex to paired light flashes, whereupon the increase in functional activity is more pronounced with respect to the indices of the excitability recovery cycle than with respect to the latent periods or primary responses. The indicated functional changes correlate with the quantitative increase in the density of dendritic spines on neurons of the visual cortex of both layer V, which are primarily the integrative-triggering apparatus of the cortex, and of the complex of layers II + III, which are primarily associative with respect to their functional significance.

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The influence of long-term (3 months) locomotor deprivation of rats in a month age, on the evoked potentials (EP) of the sensorimotor and the visual cortex was studied in conditions of presentation of single and paired stimuli. Changes were revealed in both cortical zones. An increase of peak latency of the initial positive EP phase in the sensorimotor cortex, and prolongation of the process of changes in excitability of neural elements, elicited by conditioning stimulus, was revealed both in the sensorimotor and the visual areas. The effect of deprivation on the dynamics of changes in neuronal systems excitability was greater in the visual evoked responses.

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The data obtained attest that not only prolonged (three months) motor training of rats in a tretbahn, but also mass alimentary-motivated training in mazes at the same period of postnatal ontogenesis and of the same duration is attended with enhanced activity of the sensorimotor cortex as manifested in the reduction of evoked potential latencies. Such enhancement was more pronounced after training in mazes than in a tretbahn. Mass alimentary-motivated training of rats in mazes resulted in shorter latencies of the caudate nucleus EP to peripheral stimulation, which testifies to a close functional connection of this striatum structure with the sensorimotor cortex in formation of plastic reorganizations in an enriched sensory medium.

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Young rats, beginning with the age of 1 month, were kept in small size cages for 3 months, i.e., were exposed to 3-month motor deprivation. This exposure caused a modulating effect of a diminished activity of neuronal populations in the sensorimotor cortex which manifested as a prolongation of the latent periods of primary responses and recovery cycles of excitation of the neuronal populations generating the responses. The differences in the opposite changes in the sensorimotor cortex of the young animals that developed following prolonged deprivation and training of similar duration were seen in the parameters of excitation recovery cycles rather than in the latent periods. The reserve capabilities of the developing cortical structure associated with the modulation of excitation recovery cycles during training were 2.0-2.5 times greater than the dysfunctional changes in the same neuronal populations during motor deprivation. Both early motor deprivation and training did not influence the heterochronic development, emergence and subsequent attainment of the maximum amplitude of components of the testing primary response in the process of a gradual increase of the stimulus-to-stimulus interval.

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Obtained data witness to the fact that increased proprioceptive afferentation influenced by rat running in tretbun during 3-6 months beginning from 1 month age arouses statistically true decrease of latencies, as well as excitation reduction cycles of initial responses of visual cortex on light-flash pairings. Increase of functional activity is registrated better on indices of excitation-reduction cycles, than on latencies of initial responses. Functional reorganization of rat visual cortex correlates with density changes of impregnated dendritic spines. It has been morphologically established that already 3 month-motor training results in statistically true density increase of dendritic spines on neurons of layers II+III and layer V complex. This can be interpreted as indication of increase of afferent flow to neurons of superior and inferior layers of visual cortex.

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Motor training (during 3-6 months) of rats in a treadmill started at the age of 1 month, leads to statistically significant increase in the activity of neuronal populations in the visual cortex judged by both latencies of primary responses and recovery cycles of responses to paired stimuli. It has been found that the significance of functional changes following locomotor training is more manifest in the recovery cycles than in the latencies of primary responses. The comparison of locomotor training effects in the visual cortex with those in the sensorimotor cortex reveals a more pronounced modulating influence of environment on the visual cortex. However the differences in these functional changes are more evident by absolute (msec) than by relative (%) cues.

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A 30-day motor training of rats started at a month's age does not reduce the duration of the excitability recovery cycles of neuronal populations in the sensorimotor cortex. A three-month training is accompanied by a considerable reduction of excitability recovery cycles. This coincides with a pronounced increase of the average density of spines on the apical and oblique dendrite branches of the pyramidal cells in the cortical layer V, which exceeds that observed after a 30-day locomotor training. In 30 days, the rats with a three-month training reveal a partial recovery of functional and structural parameters, and in two months, approach their initial values.

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Investigation into the influence of motor training on the functional activity of the rat sensorimotor cortex in ontogenesis has shown that three to four-month training, starting at the age of four weeks, leads to a statistically significant enhancement of sensorimotor cortex activity both by latencies and recovery cycles durations. A similar six to seven-month locomotor training produces the same statistically significant results. The differences in the shifts of functional activity after motor training observed between two age groups are not statistically significant. The probability of changes in the average definitive electrophysiological parameters of functional activity after motor training observed between two age groups are not statistically significant. The probability of changes in the average definitive electrophysiological parameters of functional activity of the sensorimotor cortex is suggested in rats aged more than a month, as a result of individual experience.

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