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     

Developmental changes in the mechanisms of image classification in young schoolchildren with different cognitive styles

Testing of 7- to 8- and 9- to 10-year-old children with the matching familiar figures test revealed groups of children differing in the time and accuracy of the reaction of choice from several alternatives. Classification of simple images and images with additional information congruous with the main discriminative character improved with age in children without evident signs of reflectivity or impulsivity (the main group) and in reflective children. No significant improvement was revealed in impulsive children. Developmental changes in the event-related potentials during image classification differed in character and location in children with different styles of cognitive activity. In the children of the main group and in the reflective children, the developmental changes consisted of an increase in the amplitude of the late positive complex predominantly in the caudal areas of both brain hemispheres. In the impulsive children, in the age period from 7–8 to 9–10 years, the late negative component N350 became more distinct, especially in the left hemisphere, and substantial reorganization of the involvement of the frontal areas in the classification process took place. The opposite electrophysiological changes in children with different cognitive styles testify to different developmental changes in the mechanisms of visual recognition.Translated from Fiziologiya Cheloveka, Vol. 31, No. 1, 2005, pp. 15–23.Original Russian Text Copyright © 2005 by Beteleva, Petrenko.     

Role of the Right- and Left-Hemispheric Structures in Speech and Memory Formation in Children

The role of structures of the left and right cerebral hemispheres in formation of speech function and memory was studied on the basis of complex examination of children with developmental speech disorders. On the basis of EEG estimation of the functional state of the brain, children were classified in two groups depending on the side of localization of changes in electrical activity: those with local changes in electrical activity in the left hemisphere (group I) and those with changes in the right hemisphere (group II). The medical history suggested that the observed features of topography of local changes in electrical activity were linked with the character of prenatal and labor complications and their consequences leading to embryo- and ontogenetic disorders in development of different brain regions. Comparison of the results of neuropsychological examination of the two groups showed that different regions of the brain cortex of both the left and right hemispheres are involved in speech formation. However, a specific role of the right hemisphere in formation and actualization of automatic speech series was revealed. It was suggested that the integrity of gnostic functions of the right hemisphere and, primarily, the spatial organization of perception and movements is a necessary factor of development of auditory–speech and nominative memory.     

Structural analysis of associative chain rows in teenagers with deviant behavior

The lexical-semantic analysis of the internal lexicon structure has shown that teenagers with deviant behavior prefer calling the words designating objects of the environment; they are characterized by the highest frequency of words and predominance of the relatively narrow circle of themes—“interior” and “food, tableware.” Thus, the lexicon nucleus is very structural and is an object component of the world image. Such lexicon structure seems to be due to predominance of the right hemisphere activity. On the contrary, in children without the deviant behavior the nucleus of the verbal cognition can be presented as bipolar: on the one hand, school, school objects, on the other hand, the world of concepts. In the latter case the space of the potential probability activity is reflected. Such lexicon structure seems to be due to predominance of the left hemisphere activity.     

Young Toddlers’ Word Comprehension Is Flexible and Efficient

Much of what is known about word recognition in toddlers comes from eyetracking studies. Here we show that the speed and facility with which children recognize words, as revealed in such studies, cannot be attributed to a task-specific, closed-set strategy; rather, children’s gaze to referents of spoken nouns reflects successful search of the lexicon. Toddlers’ spoken word comprehension was examined in the context of pictures that had two possible names (such as a cup of juice which could be called “cup” or “juice”) and pictures that had only one likely name for toddlers (such as “apple”), using a visual world eye-tracking task and a picture-labeling task (n = 77, mean age, 21 months). Toddlers were just as fast and accurate in fixating named pictures with two likely names as pictures with one. If toddlers do name pictures to themselves, the name provides no apparent benefit in word recognition, because there is no cost to understanding an alternative lexical construal of the picture. In toddlers, as in adults, spoken words rapidly evoke their referents.     

Formation of interzonal interaction of cortical fields during verbal-mental activity

Verbal activity as the higher psychic brain function is performed as a result of systemic interactions of many cerebral structures and processes at various levels of organization. It is shown in this work that based on analysis of spatial-temporal relations of EEG waves during performance by adult examinees of such verbal-mnestic tasks as mental count, listening of a rhyme and its recalling, tests for verbal fluency, and search for homonyms there is revealed an enhancement of diagonal connections between activities of posterior parts of the left hemisphere cortex and anterior parts of the right hemisphere cortex. During performance by the examinees of recognition of grammatical or semantic errors in sentences the interhemispheric interactions on the whole are also enhanced statistically significantly, but without domination of diagonal interactions. These data show that during performance by examinees of verbal tasks of analytical character there also are simultaneously actualized intercentral interactions related to the functional system responsible for recognition not only of verbal, but also of any other stimuli. In children with motor alalia and dysarthria, disturbances of distant EEG connections were revealed either in the left or in the right hemisphere with a simultaneous enhancement of ipsilateral interactions in symmetrical parts of the contralateral hemisphere. A special attention is paid to significance of the degree of formation of neurophysiological systems of the general cerebral integration for realization of the verbal function.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 411–422.Original Russian Text Copyright © 2004 by Shepovalnikov, Tsitseroshin.To the 100-Anniversary of N. N. Traugott     

Peculiarities of interrelations of activation levels of frontal,temporal, and parietal cortex by parameters of ultraslow biopotentials in the 4–5-year-old children with the age norm and delayed speech development

Possibilities were considered of the integrative approach with use of parameters of the ultraslow informational-control brain and organism system in studying physiological grounds of the rest state, which determine structure and quality of the adaptive behavior. By using the proposal approach there were analyzed results of comparative studies of peculiarities of the wakefulness level, of its autonomous, hemodynamic, and oxygen-depended energy maintenance, and of activation levels and their interrelations in neocortical outputs of the brain systems of the frontal, temporal-parietal, and parietal cortex participating in organization of the higher integrative functions and speech in the 4–7-year-old children with the age norm of the general psychic and verbal development and with delay of the neuropsychic development, including development of speech.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 455–468.Original Russian Text Copyright © 2004 by Ilyukhina, Krivoshchapova, Matveev, Ponomareva, Shaptilei.To the 100-Anniversary of N. N. Traugott     

Study of Metaphoric and Associative Thinking in Children of Different Age Groups and in Patients with Childhood Autism

The study was performed on 35 healthy children and 9 patients with childhood autism (Asperger's syndrome). It was shown that formation of metaphoric thinking in norm begins as early as at the age of 7–8 years, the ability to understand metaphors decreasing suddenly at the age of 13–15 years. In the patients with childhood autism the inability was revealed of understanding metaphors and idioms widely used in the verbal communication. It is suggested that the deficit of the metaphoric thinking is due to introduction of the logic, theoretical thinking and, hence, to the underlying increased activity of the left hemisphere, as well as to the deficit of the imaginative-metaphoric thinking and to the underlying decreased activity of the right hemisphere. The study of the associative process has shown that the healthy school children have a high degree of association between the words meaning the sensory world of objects. In the patients with autism there were revealed an attenuation of the object association and the predominance of the first names, which indicates the left-hemispheric type of the association process.     

Synaptic mechanisms of spike generation in bursts by neurons of the carp tectum and olfactory bulb

Synaptic mechanisms of burst activity generation in certain neurons of the tectum opticum and mechanisms of generation of stimulation-induced group discharges by certain secondary neurons of the olfactory bulb were analyzed in carp (Cyprinus carpio L.). Spikes of the spontaneous discharge in neurons of the tectum were accompanied by depolarizing after-potentials, which caused the burst discharges of these cells. Evidence is given in support of the synaptic nature of the after-potential; it is suggested that it is generated by a recurrent collateral mechanism. Synaptic bombardment causing the appearance of a group discharge in olfactory bulb neurons and groups of spikes in their spontaneous activity was found to be intermittent in character. These features of unit activity in the olfactory bulb are shown to be connected with the presence of excitatory synaptic interaction between several neurons, probably dendro-dendritic in nature.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiay, Vol. 14, No. 5, pp. 483–490, September–October, 1982.     

Contribution of N. N. Traugott to the problem of the unconscious

The paper considers the short history of the problem of the unconscious in the aspect of evolutionary physiology and the role in its formation of the outstanding Russian physiologist Natalya Nikolaevna Traugott. There are traced the main approaches and stages of development of the problem of the unconscious, with analysis of difficulties in the pathway of its formation. N.N. Traugott was the first to put forward an original hypothesis that activity at the level of the first signal system, i.e., nonverbalized unrecognized components of behavior, are controlled by the right hemisphere and probably are subordinated to modulating influences of deep structures to the greater degree than the conscious activity.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 394–399.Original Russian Text Copyright © 2004 by Nikolaenko.To the 100-Anniversary of N. N. Traugott     

Systemic Interaction of the Cortical Areas during Performance of Verbal–Mnestic Activity

The dynamics of the interregional interaction of cortical areas was studied in adult test subjects who accomplished the tasks of listening to and memorizing a poem and of mental arithmetic. Analysis of the spatial and temporal relations of the oscillations of the brain biopotentials showed the participation of many regions of the left and right hemispheres in the verbal–mnestic activity. The interaction was most expressed between the posterior regions of the left hemisphere and the anterior regions of the right one. To find out whether these data agree with the classical concepts on the leading role of the left hemisphere in speech activity, the authors examined 3- and 4-year-old children with motor alalia. A comparison of 3-year-old alalics with the control group of healthy children of the same age demonstrated a marked weakening of the distant interaction of the activity of the ipsilateral antero- and posterotemporal regions of the left hemisphere (i.e., those that correspond to the Broca area and Wernicke zone) both between themselves and with the activity of other cortical regions of both hemispheres. These results confirm the important role of both the inter- and intrahemispheric relations, especially those between the Broca area and the Wernicke zone, in realizing verbal–mnestic functions. A significant weakening of the systemic interaction between EEG oscillations in these areas in alalic children suggests that the auditory feedback plays a special role during speech production in the ontogenetic development of the neurophysiological mechanisms that are responsible for speech function formation.     

Asymmetry of modifications of the electrical activity of the rat cortex induced by intraventricular injections of thyrotropin-releasing hormone

We studied modifications in the mass electrical activity of the cortex (ECoG) induced by injections of thyrotropin-releasing hormone (TRH) into the left or right lateral brain ventricle in rats kept under conditions close to free behavior. It was found that these effects are characterized by a significant interhemisphere asymmetry. We postulate that the pharmacological (in particular, antidepressive) effects of TRH are related to its ability to intensify inhibitory processes in the left cerebral hemisphere and activating processes in the right hemisphere.Neirofiziologiya/Neurophysiology, Vol. 36, Nos. 5/6, pp. 386–390, September–December, 2004.This revised version was published online in April 2005 with a corrected cover date and copyright year.     

Age Changes of Semantic Composition of Associative Reactions and Effect on Them of Emotional Sign of the Verbal Stimulus

Using method of the directed associative experiment, age changes of the semantic composition of the lexicon was studied in the 4–8-year old children. The emotional evaluation by the children of each of the presented verbal stimuli was taken into account. It was shown that the main role in formation of the verbal consciousness in the 4–8-year old children was played by the right hemispheric mechanisms of cognition and that it is for these mechanisms, with their very actual strategy of the comparison and contraposition, that of great importance were the emotional characteristics of the perceived information.     

Posttetanic changes in hippocampal minimal evoked potentials

Changes in the EEG induced by a single spike were recorded in the hippocampus of an unanesthetized rabbit. Summation of focal electrical activity synchronous with spontaneous single unit discharges at the symmetrical point of contralateral hemisphere revealed no stable potentials which could reflect these changes. In two cases discharges identified as activity of Shaffer's collaterals were recorded in area CA₁. Summation of post-spike changes in evoked activity recorded by the same microelectrode showed stable negative waves with an amplitute of 40–60 µV, which could have been evoked by single spikes. The curve of amplitude of the averaged evoked potentials versus near-threshold current strength stimulating the intrahippocampal pathways was not smooth in most experiments but stepwise in character. It is suggested that the minimal evoked potential corresponding to the first step (amplitude 40–80 µV) reflects a response to stimulation of one fiber. After above-threshold tetanization prolonged posttetanic potentiation of the minimal evoked potentials did not arise in CA₁ in response to stimulation of Shaffer's collaterals. Minimal evoked potentials recorded in area CA₃ in response to stimulation of the dentate fascia showed clear potentiation. The results are in agreement with the hypothesis of the synaptic localization of the mechanisms responsible for prolonged posttetanic potentiation.Brain Institute, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 9, No. 2, pp. 124–134, March–April, 1977.     

Significance of functional interactions for understanding of cerebral mechanisms of speech disturbances in children

The problems are considered of cerebral mechanisms of the main types of speech pathology developed in children in disturbances of interzonal interactions.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 407–410.Original Russian Text Copyright © 2004 by Vizel.To the 100-Anniversary of N. N. Traugott     

Late Albian dinoflagellate cyst paleobiogeography as indicator of asymmetric sea surface temperature gradient on both hemispheres with southern high latitudes warmer than northern ones

Late Albian temperature sensitive dinoflagellate cysts are characterized in order to better understand mid-Cretaceous sea surface temperature gradients. Distribution maps of thirty-seven species recovered from one hundred fifty outcrops and deep sea drilling holes (ODP, DSDP) Sites located from low and high paleolatitudes over the two hemispheres (75°N–70°S) are encountered. Fifty years of published data available in eighty-seven articles have been considered and synthesized using a database coupled with a Geographical Information System (GIS). The continuous and disjoint biogeographic patterns of dinocyst species along latitudes define seven climatic belts, four in the northern hemisphere (high, mid-high, mid-low, low latitude belts) and three in the southern hemisphere (low, mid-low, mid-high latitude belts). Dinocysts restricted along latitudes are temperature sensitive species. Limit ranges of temperature sensitive dinocysts of mid-low and mid-high latitude belts reveal mixing belts, located at 40–45°N and 50°–70°S. They represent major palaeofrontal systems as paleosubtropical fronts with strongly mixed water column. The northern frontal system (40–45°N) was located as in the modern ocean. The large southern frontal system (50°S–70°S) was 10°–20° poleward to Antarctica. Semi-quantitative temperature range limits for mid-Cretaceous dinoflagellates and SST gradients in the two hemispheres are suggested by setting dinocyst climatic belts against estimated δ¹⁸O temperature curve from fish teeth. A paleoecological classification is suggested. Latitudinal distribution of extant temperature sensitive dinoflagellate cysts follows the asymmetric modern temperature gradient. Asymmetric latitudinal ranges of Late Albian dinocyst species of mid-low latitude belts restricted between 45°N and 70°S demonstrate asymmetric temperature gradients with southern high latitudes being warmer than northern high latitudes.     

Patterns of restoration of soil physciochemical properties and microbial biomass in different landslide sites in the sal forest ecosystem of Nepal Himalaya

The pattern of natural restoration in soil components and processes was documented in five landslide-damaged (1–58-year-old) sites in the moist tropical sal (Shorea robusta) forest ecosystem of Nepal Himalaya. Comparisons were made with an undisturbed forest site in the same region. Concentrations of soil organic C, total N, total P and extractable nutrients (Ca, Mg and K) increased with the age of sites. The 58-year-old site showed concentrations of soil organic C, total N and total P that were 75–89% of concentrations in the undisturbed sal forest. The soil microbial biomass, the active fraction of soil organic matter, showed similar seasonal variations at all sites. The amount of mean microbial biomass (expressed as C, N and P contents) increased 4–5 times at the 58-year-old site relative to the 1-year-old site, and the bulk increase occurred within the initial 15 year. The increase in the C/N ratio of soil microbial biomass with age (9.4–11.6 years) reflected change in its composition. Although the net N-mineralization rate increased consistently until 58 years of age, the proportion of nitrification rate relative to ammonification rate distinctly decreased beyond 40 years. On the other hand, the soil available-N (both NO₃⁻ and NH₄⁺) concentrations increased from 1 to 40 year and then declined; with age the proportion of NH₄⁺ increased, however. Rates of restoration in soil properties were faster in the early successional stages (1–15 year) than late stages. Among different soil properties the restoration of soil microbial biomass (C and N) was faster than soil organic C and total N. Best fit power function models showed that the estimated times for the 58-year-old site to reach the level of the undisturbed, mature sal forest would be about 30–35 year for microbial biomass (C and N) and about 100–150 year for organic C and total N. Higher accumulation of soil microbial biomass and high N-mineralization rate at late successional stages indicated the re-establishment of enriched soil and restitution of nutrient cycling during the course of ecosystem restoration.     

EEG Spectral Characteristics in Junior Schoolchildren with Learning Problems

EEG spectral characteristics were studied in two age groups (7–8.5 and 8.5–10 years) of mentally healthy children and children with learning problems at rest and during performance of a Raven test. It was shown that slow frequencies are more pronounced in the EEG of 7- to 8.5-year-old children with learning problems than in EEG of healthy children of the same age group. An immature form of EEG activation, i.e., an increase not only in the but also in the frequencies during activity, was characteristic of these children. The reaction of the activation of the definitive type develops between the 8.5–10 years of age. This reaction is correlated with an increase in the efficiency of the sensory perceptive and sensorimotor activity. The distinctive feature of children with learning problems between 8.5–10 years of age is a greater expression of slow frequencies in the baseline EEG of the frontal (in particular, left frontal) areas of the cortex. The obtained results are considered as a reflection of a retardation of the functional maturation of the brain structures responsible for the deficit of involuntary and voluntary attention and the disorder of a systemic organization of perception and analytical–synthetic brain activity as compared to the normal age characteristics. Possible neurophysiological mechanisms responsible for learning problems in junior schoolchildren are discussed on the basis of the obtained results and evidence from the literature.     

Metaphorical and Associative Thinking in Healthy Children and in Children with Asperger's Syndrome at Different Ages

The study of healthy children and patients with childhood autism (Asperger's syndrome) showed that metaphorical thinking is normally efficient at the age of 7–8 years and that autistic children have an impaired ability to understand metaphors and idioms widely used in verbal communication. The deficit of metaphorical thinking in autism is thought to be due to a decreased activity of the right hemisphere. In a study of associative thinking, healthy schoolchildren displayed a high degree of association between words describing sensual objects and autistic patients displayed an impairment of objective associations and a predominance of proper names, which is indicative of the left-hemispheric type of association. The impairment of the speech and mental activity (metaphorical and associative thinking) testified to changes in the interhemispheric interaction in autistic children, which is likely to show up in a decreased functional activity of the right hemisphere and an increased activity of the left hemisphere.     

N2(C2H2−C2H4) fixation in two species of Ceanothus seedlings in second year postfire chaparral

Nitrogen fixation in excised root nodules of 2-year-old, postfireCeanothus tomentosus andC. leucodermis seedlings was measured over an 8-month period using the acetylene reduction method. High levels of NO₃–N and NH₄–N present in postfire soils were limited to the upper 10 cm and did not inhibit nodulation in these deeper-rooting seedlings. Decreases in acetylene reduction activity occurred with decreased soil moisture and increased soil temperature. Nitrogen gains from these two Ceanothus shrub seedlings totalled 1.6 kg N ha^–1 yr^–1.