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T A Stroganova

Publications and source records attributed to T A Stroganova.

At least 19 recordsLinked to original sources
PubMed2006

EEG theta rhythm in infants and preschool children.

OBJECTIVE: To study behavioral correlates of theta oscillations in infants and preschool children. METHODS: EEG was recorded during baseline (visual attention) and two test conditions--exploration of toys and attention to 'social' stimulation. Age specific frequency boundaries of theta and mu rhythms were assessed using narrow bin analysis of EEG spectra. RESULTS: Theta spectral power increased whereas mu power decreased under test conditions in both age groups. In preschoolers theta rhythm increased predominantly over anterior regions during exploratory behavior and over posterior regions during attention to social stimulation. Theta frequency range changed with age from 3.6 to 5.6 Hz in infants to 4-8 Hz in children, and mu range from 6.4-8.4 Hz to 8.4-10.4 Hz. CONCLUSIONS: In early life, theta oscillations are strongly related to behavioral states with substantial attentional and emotional load. The scalp distribution of theta spectral power depends on age and behavioral condition and may reflect engagement of different brain networks in control of behavior. SIGNIFICANCE: The findings contribute to the scanty knowledge about the developmental course of theta rhythm. Data on behavioral correlates of theta rhythm in early life may improve our understanding of cognitive and mental processes in healthy and neuropsychiatrically diseased children.

Age Factors↗
PubMed2005

Age-related and individual differences in the performance of a delayed response task (the A-not-B task) in infant twins aged 7-12 months.

The aim of the present work was to analyze the age-related dynamics and nature of interindividual differences in performing the A-not-B task, which addresses working memory in children aged 7-12 months. The cohort consisted of 150 children aged 7-12 months from mono- and dizygotic twin pairs. Working memory was assessed in terms of the maximum delay which the children could tolerate in a delayed response test (the A-not-B task). Performance of the task improved with age, such that a sharp change in the ability to tolerate the delay occurred between nine and ten months of age. Mental development as assessed using the Bayley scale showed a significant correlation with the duration of the delay in the task only after a threshold period (9-10 months of age) in the development of working memory. Analysis of intrapair correlations in mono- and dizygotic twins showed that interindividual differences in the A-not-B task delay at age 7-9 months were completely determined by individual environmental factors (including measurement errors), while at age 10-12 months the leading role in the interindividual variability in this measure was taken by the systematic environment. These results show that the abilities to tolerate delays at the beginning and end of the second six months of life are based on different mechanisms.

Age Factors↗
PubMed2003

Immunodetection and fluorescent microscopy of transgenically expressed hordeivirus TGBp3 movement protein reveals its association with endoplasmic reticulum elements in close proximity to plasmodesmata.

The subcellular localization of the hydrophobic TGBp3 protein of Poa semilatent virus (PSLV, genus Hordeivirus) was studied in transgenic plants using fluorescent microscopy to detect green fluorescent protein (GFP)-tagged protein and immunodetection with monoclonal antibodies (mAbs) raised against the GFP-based fusion expressed in E. coli. In Western blot analysis, mAbs efficiently recognized the wild-type and GFP-fused PSLV TGBp3 proteins expressed in transgenic Nicotiana benthamiana, but failed to detect TGBp3 in hordeivirus-infected plants. It was found that PSLV TGBp3 and GFP-TGBp3 had a tendency to form large protein complexes of an unknown nature. Fractionation studies revealed that TGBp3 represented an integral membrane protein and probably co-localized with an endoplasmic reticulum-derived domain. Microscopy of epidermal cells in transgenic plants demonstrated that GFP-TGBp3 localized to cell wall-associated punctate bodies, which often formed pairs of opposing discrete structures that co-localized with callose, indicating their association with the plasmodesmata-enriched cell wall fields. After mannitol-induced plasmolysis of the leaf epidermal cells in the transgenic plants, TGBp3 appeared within the cytoplasm and not at cell walls. Although TGBp3-induced bodies were normally static, most of them became motile after plasmolysis and displayed stochastic motion in the cytoplasm.

Blotting, Western↗
PubMed2001

Alpha activity as an index of cortical inhibition during sustained internally controlled attention in infants.

OBJECTIVES: The study examined the suggestion that infant ability to maintain attention in anticipatory task and to sustain interference is related to the active inhibitory processes in cortical neural networks. METHODS: The extent of selective EEG synchronization in the alpha range has been taken as a measure of cortical inhibition. EEG was registered in 60 infants aged 8-11 months during: (1) attention to an object in the visual field (externally controlled attention); (2) anticipation of the person in the peek-a-boo game (internally controlled attention). RESULTS: The infants who demonstrated longer periods of anticipatory attention had higher absolute spectral amplitude in the broad frequency range under both experimental conditions. It was suggested that the effect of 'overall' EEG synchronization is related to some stable individual differences in psychophysiological traits. To control for the effect of overall EEG synchronization the relation between relative alpha amplitudes in 6.4-10 Hz range and the duration of internally controlled attention was analyzed. The infants with longer compared to shorter anticipatory attention spans had relatively higher 6.8 Hz alpha synchronization at posterior parietal sites under this experimental condition. CONCLUSIONS: It was suggested that alpha synchronization over posterior parietal cortex reflects an active inhibition of certain parietal networks involved in maintaining attention to peripheral visual field rather than merely an 'idle' state of this cortical area. Such an inhibition appears to allow infants to avoid interference of concurrent visual stimulation at the periphery of the visual field.

Aging↗
PubMed2001

RNA-binding properties of the 63 kDa protein encoded by the triple gene block of poa semilatent hordeivirus.

The 63 kDa '63K' movement protein encoded by the triple gene block of poa semilatent virus (PSLV) comprises the C-terminal NTPase/helicase domain and the N-terminal extension domain, which contains two positively charged sequence motifs, A and B. In this study, the in vitro RNA-binding properties of PSLV 63K and its mutants were analysed. Membrane-immobilized 63K and N-63K (isolated N-terminal extension domain) bound RNA at high NaCl concentrations. In contrast, C-63K (isolated NTPase/helicase domain) was able to bind RNA only at NaCl concentrations of up to 50 mM. In gel-shift assays, C-63K bound RNA to form complexes that were unable to enter an agarose gel, whereas complexes formed by N-63K could enter the gel. Full-length 63K formed both types of complexes. Visualization of the RNA-protein complexes formed by 63K, N-63K and C-63K by atomic force microscopy demonstrated that each complex had a different shape. Collectively, these data indicate that 63K has two distinct RNA-binding activities associated with the NTPase/helicase domain and the N-terminal extension domain. Mutations in either of the positively charged sequence motifs A and B had little effect on the RNA binding of the N-terminal extension domain, whereas mutations in both motifs together inhibited RNA binding. Hybrid viruses with mutations in motifs A and B were able to infect inoculated leaves of Nicotiana benthamiana plants, but were unable to move systemically to uninoculated leaves, suggesting that the RNA-binding activity of the N-terminal extension domain of PSLV 63K is associated with virus long-distance movement.

Amino Acid Sequence↗
PubMed2000

Subcellular sorting of small membrane-associated triple gene block proteins: TGBp3-assisted targeting of TGBp2.

We studied subcellular distribution of green fluorescent protein (GFP)-tagged movement proteins encoded by the second and the third genes of poa semilatent hordeivirus (PSLV) triple gene block (TGB), 15K TGBp2 and 18K TGBp3. GFP-15K transiently expressed in Nicotiana benthamiana leaf epidermal cells was associated with the endomembrane system elements. GFP-18K appeared in the membrane bodies at cell periphery. Mutation analysis demonstrated that subcellular targeting of GFP-15K depended on the protein transmembrane segment(s), whereas the TGBp3 central hydrophilic region was responsible for targeting of GFP-18K. Coexpression of GFP-15K with the intact 18K protein induced drastic changes in the TGBp2 localization: GFP-15K appeared in the cell peripheral bodies similar to those in the cells expressing GFP-18K alone. Coexpression experiments with mutant forms of both proteins argue against involvement of direct interaction between small TGB proteins in the TGBp3-assisted targeting of TGBp2 to the cell peripheral compartments. This conclusion was further confirmed by similar effects on the PSLV 15K TGBp2 localization induced by TGBp3 proteins of PSLV and potato virus X, which have no detectable sequence similarity to each other.

Amino Acid Sequence↗
PubMed1999

Theta synchronization during sustained anticipatory attention in infants over the second half of the first year of life.

The neurophysiological basis of attention control has been investigated in infants during the second half of the first year of life. The marked improvement of voluntary control of attention and action is known to occur during this age period. EEG was registered in 60 infants aged 8-11 months under three experimental conditions: (1) attention to an object in the visual field (externally controlled attention or the 'baseline'); (2) anticipation of the person in the peek-a-boo game (internally controlled attention); and (3) attention to the 'reappeared' person in the peek-a-boo game ('control' condition). Spectral analysis of the data revealed sharp increase of the EEG theta activity (3.6-6.0 Hz) during internally controlled attention as compared to the 'baseline' and the 'control' conditions. The theta1 (3.6-4.8 Hz) increase was maximal at frontal electrode sites. The reactivity of the frontal theta1 during internally controlled attention differentiated subjects with different ability to maintain this type of attention. The theta2 (5.2-6.0 Hz) reactivity was maximal at right temporal electrode site and did not depend on the ability to maintain anticipatory attention. The data point to different functional significance of theta1 and theta2 rhythms in infants. It was suggested that the frontal theta1 synchronization in infants reflects activity of the anterior attention system subserving executive control of attention. The ability to maintain anticipatory attention increased, whereas the frontal theta1 synchronization decreased during the studied age period. There was the direct relationship between frontal theta1 synchronization and persistence of internally controlled attention in 8-month-olds. On the contrary, at 9 and 10 months, these variables were inversely-related. There was no link between theta1 reactivity and persistence of anticipatory attention in 11-month-olds. It was suggested that the age-dependant dynamic of the relationship between frontal theta1 reactivity and attention behaviour reflects the maturational shift in the functioning of anterior attention system. The shift leads to more economic and more efficient functioning of this system.

Age Factors↗
PubMed1999

EEG alpha rhythm in infants.

The 'functional topography' approach has been applied to study alpha rhythms in infant twins during the second half-year of life. The experimental sample included 154 normal infants born at 32-41 weeks of gestational age. Their chronological age varied from 7.4 to 12.4 months. EEG was registered during wakefulness under two experimental conditions: sustained visual attention and dark homogenous visual field. During darkness as compared with visual attention the sharp increase of spectral amplitudes within 5.2-9.6 Hz band was observed over the occipital-parietal cortex. The properties of the 5.2-9.6 Hz occipital rhythmic activity comply with the classical properties of alpha rhythm. The distinct spectral peak in 6.0-8.8 Hz band at precentral recording sites was observed during sustained visual attention. This rhythmic component was suppressed under the condition of total darkness. Arguments in favour of homology between the infant central rhythm and adult sensorimotor mu rhythm are advanced. The group mean of alpha peak frequency increased from 6.24 +/- 0.45 Hz at 8 months to 6.78 +/- 0.38 Hz at 11 months of chronological age. The frequency of infant alpha rhythm depended only on the period of extrauterine experience, regardless of gestational age at birth. This result points to the critical role of early visual experience in alpha rhythm development. The group mean of the peak frequency of mu rhythm also increased during the second half-year of life, from 7.03 +/- 0.47 Hz at 8 months to 7.42 +/- 0.46 Hz at 11 months. Unlike alpha rhythm, the peak frequency of mu rhythm depended on duration of both intra- and extrauterine development. We speculate that the development of sensorimotor mu rhythm is influenced by somatosensory stimulation, which, in sharp contrast to the visual input, is present in the uterus.

Age Distribution↗
PubMed1998

Externally and internally controlled attention in infants: an EEG study.

This work was designed to investigate EEG indices of Internally and Externally Controlled Attention in infancy. EEG was recorded in 15 infants aged 7-8 months under three experimental conditions: (1) visual attention to a new stimulation (Externally Controlled Attention or baseline condition); (2) attention guided by internal cognitive schemata during 'anticipatory' phase of the peek-a-boo game (Internally Controlled Attention); and (3) 'reappearance' phase of the peek-a-boo game when the experimenter talked and smiled to an infant (reappearance). The relative power (RP) in 4-5 single-Hz theta sub-band increased under both phases of the peek-a-boo game. The reactive changes of 4-5 single-Hz RP at prefrontal and frontal leads under the Internally Controlled Attention condition positively correlated with the total time during which an infant was able to maintain ICA. The RP in 5-6 single-Hz theta sub-band significantly increased only under the Internally Controlled Attention condition and did not correlate with the total time of this type of attention. The results support the concept of 'Diffuse Theta-Response System' that is active during expectancy and effortfully focused attention. In contrast to theta, the RP in 6-7, 7-8, and 8-9 single-Hz bands decreased during both phases of the game. The decrease was maximal at precentral leads and most probably reflected blockage of the sensorimotor (mu) rhythm due to higher motility and muscular tension in the game situation. It is concluded that EEG is an adequate vehicle for investigation of brain mechanisms of attention and voluntary control in infants.

Arousal↗
PubMed1986

[Electroencephalographic correlates of positive emotional reactions in children in the first year of life].

The authors investigated electroencephalographic correlates of positive emotional reactions in 28 infants aged from 3 to 10 months. An analysis of the space organization of the hypersynchronous 4 Hz frequency theta-rhythm attending emotional reactions has shown that depending on the type of impact, neural elements in the anterior or posterior cerebral cortex synchronously come into play. It is assumed that the arrangement of the above type of activity is due to both nonspecific activation of the cortex through the influence of the subcortical structures and due to the mechanisms of local activation becoming involved in the realization of the response depending on the biological quality of the irritant and the nature of the activity induced by it.

Action Potentials↗
PubMedDate not supplied

[Developmental and individual differences in delayed response task performance (A-not-B task) in 7- to 12-month-old infant twins].

The purpose of the study was to explore developmental and individual differences in the working memory that was assessed by performance of the A-not-B task in 7- to 12-month-old infant twins. The sample included 150 infant twins participating in genetic project, 18 of them were tested at 8 and 11 months of age. Information concerning birth weight and gestational age was collected from birth records. All infants were tested using Bayley Scales of Mental and Psychomotor Development. The infant's working memory (WM) was tested during A-not-B task performance, which was shown to depend on the maturity of the prefrontal cortex. The behavioral data were analyzed off-line using videotape records. The one-way ANOVA revealed that the AB performance improves with age. A highly significant improvement of the ability to tolerate the delay in A-not-B task was observed between 9 and 10 months of life. There was no longitudinal stability in individual infant performance of A-not-B across the period of 7-12 months of age. The AB delay was significantly correlated with psychomotor and mental development only after the crucial period of the rapid increase in the AB delay (9-10 months). The analysis of intraclass mono- and dizygotic correlations showed that individual differences in the WM (tolerance to AB delay) at 7-9 months and at 10-12 months are of different nature. There was a significant effect of shared environment on AB delay variance in 10-12-month-old group, whereas down to this age no systematic influence on individual variability was observed. These findings suggest that the ability to tolerate the AB delay can be provided by different brain mechanisms in 7-9 and 10-12-month-old infants.

Age Factors↗