Complex estimation of adaptation abilities of the organism in children using the indices of responsiveness of the cardiovascular system and characteristics of EEG

Based on the complex analysis of the data of cardiointervalographic (CIG) and rheoencephalographic (REG) examination of 37 healthy children and 63 children suffering from bronchial asthma (BA), we identified the most informative indices characterizing reactions of the cardiovascular system under conditions of an active orthostatic test (coefficient of autonomic responsiveness and index of responsiveness of the vessels). We conclude that the relation between the values of these indices allows one to identify the level of strain of the regulatory mechanisms and the state of the adaptation systems of the organism, which determine the adequacy of control of the autonomic sphere. The following gradations can be classified: an optimum level, compensated adaptation disorders (strain and overstrain of the regulatory mechanisms), and decompensated adaptation disorders (exhaustion of the regulatory mechanisms and failure of adaptation). Among clinically healthy children, we found a risk group (about 30%) with manifestations of lowering of the organism’s adaptive abilities. It is shown that groups of healthy children and children suffering from BA differ from each other in the shares of different patterns of EEG and variants of EEG responses to a hyperventilation test. Qualitative and quantitative characteristics of EEG in children, despite high interindividual variability, clearly correlate with the state of adaptation processes. The expedience of a complex approach in estimating the adaptation ability of the child based on the data of CIG, REG and EEG examinations is discussed. Neirofiziologiya/Neurophysiology, Vol. 38, No. 1, pp. 72–84, January–February, 2006.     

Peculiarities of EEG in hard-of-hearing children of primary school age

Electroencephalographic examination of 7-to 9-year-old children with sensorineural deafness of degrees II and III included EEG recording in the resting state, in the course of reaction of activation (at opening of the eyes), under conditions of rhythmic photostimulation with frequencies of 4, 6, 9, and 12 sec⁻¹ and under those of the hyperventilation test. The results allow us to conclude that systems responsible for generation of EEG in hard-of-hearing children demonstrate some functionally immaturity. The following facts confirm the above conclusion. As compared with the norm, greater normalized spectral powers (SPs) of the delta and theta rhythms, a higher intensity of electrogenesis (integral power of oscillations) within all frequency ranges, and a smaller mean frequency of the dominant rhythm were typical of hard-of-hearing children. In these children, the reaction of activation in the majority of cases looked like incomplete suppression of the alpha rhythm. Upon rhythmic photostimulation, hard-of-hearing boys and girls demonstrated following of the rhythm at frequencies of 4 and 6 sec⁻¹ while children with normal hearing demonstrated that at 9 and 12 sec⁻¹ frequencies. The characteristics of EEG reactions under the conditions of the hyperventilation test reflected the immaturity of the fronto-thalamic controlling system, as well as certain dysfunction of lower brainstem regions in children with disorders of hearing. Neirofiziologiya/Neurophysiology, Vol. 40, No. 2, pp. 137–146, March–April, 2008.     

EEG in Children: Periodometric Analysis,Typology, and Age Peculiarities

We carried out a computer analysis of the EEG of 169 healthy schoolchildren (6 to 17 years old) with the use of a periodometric approach allowing us to obtain a number of quantitative indices that characterize the temporal structure of the analyzed EEG segment (histogram of distribution of the frequencies of EEG oscillations within the analyzed time period, indices of the different rhythms, and matrix of the probabilities of conversion from waves of one frequency range to waves of other ranges). We demonstrated that data of the periodometric analysis can be used for objective classification of EEG patterns. In children of different age groups, five types of background EEG activity were classified and described; we also demonstrated that the intragroup frequencies of these EEG types vary in healthy children with age. We discuss the advantages and disadvantages of the periodometric analysis of EEG, as well as the prospects and expediency of use of this analysis in physiological studies and in clinics.     

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.     

Interrelations of hypocapnia, hypoxia, cerebral blood flow and electrical activity of the brain under voluntary hyperventilation in humans

Changes of different physiological parameters in human caused by hyperventilation of 3-min and longer duration were investigated and correlated. It was found that during 3-min hyperventilation, resulting in 4.5-5 fold increase of the respiration velocity, similar phasing changes of the central and cerebral haemodynamics occurred. The blood flow velocity according to the rheographic data during the hyperventilation first increases, reaching maximum at 1st - 2nd min of the test, and then decreases, reaching minimum at 2nd - 3rd min after it's end, and then slowly increases. Cerebral blood flow velocity during all the 3 min of the hyperventilation in most of the subjects keeps being increased, and after the test - decreased. At the same time transcutaneous pressure of carbon dioxide changes differently - decreases to minimum (approximately 25 mmHg) at the end of the test and then increases, reaching approximately 90% of the background level, at 5th min after the end of the test. Oxygen saturation of the blood during the test is found to be 98-100% and decreases to 90% at 5th min after it's end, which in overall with cerebral blood flow decrease appears to be the factor of the brain's hypoxia. In different subjects "mirror" changes of the EEG spectral power of different EEG ranges in relation to transcutaneous pressure of carbon dioxide dynamics were revealed by the hyperventilation. Taking into account the factors of duration or recurrence of the hyperventilation is important for the understanding the interrelations of cerebral haemodynamics, hypocapnia, hypoxia and electrical activity of the brain. It was found that after the recurrent hyperventilation of increasing amount (several times in hour by 3 min) cerebral blood flow might decrease markedly against the background of relatively small changes of electrical activity of the brain. The discussing of the data presented in the paper is carried out from the point of view of important role of tissue oxygen utilization mechanisms of the brain in adaptation to hypoxia and hypocapnia.     

The multicomponent composition of the EEG alpha-band in schizophrenic patients

The functional characteristics of the frequency components ofalpharhythm was studied in schizophrenic patients. The frequency components of the alpha-range EEG were elicited by spectral analysis with FFT-transform. In 80% cases of the patients, the power spectra EEG have multimodal distribution in alpha-range. Spectral analysis from the left and right occipital leads have revealed multimodality in spectral EEG in 20 out of 25 patients. The hyperventilation test in the patients revealed a decreased multimodality and increased unimodality.     

Age and the structural organization of the EEG of children and adolescents in different functional states of the brain

The present paper deals with age characteristics of EEG reactions, at the level of integral cues, to functional loads in children of 7-14 years and juveniles. Modelling of tense and emotional states leads to a reconstruction of the organization of the EEG of quiet waking state, with formation of integral characteristics specific for these states and reflecting various mechanisms of the brain activity. At the age of 9-12 years emotional loads bring about disturbances of EEG integral characteristics, testifying to a lowering of brain reactivity.     

Intensity and type of EEG reactions to a hyperventilation test and their relationship with changes in patients’ subjective state of health and some characteristics of the initial EEG pattern

Some EEG characteristics at rest and after a 3-min hyperventilation test (HVT) were studied in 100 adult patients along with the changes in their current subjective state of health, assessed with the help of a special three-stage survey and a questionnaire. Our findings demonstrated a clear correlation between the rate of changes in the current subjective state of health of a patient, the average number of observed symptoms, and the intensity of the EEG reaction. With regard to the methodological aspect, we recorded a difference in the assessment of subjective data obtained through the different types of survey. The frequency of two types of high-amplitude slow waves during the HVT (recorded in 21% of patients), as well as of paroxysmal epileptiform activity, was studied, and their correlation with the clinical manifestations of epilepsy was analyzed. Our study showed that the intensity of the general EEG reaction to the HVT is correlated with the presence of EEG disorders, such as minor bursts in the initial EEG pattern; the probability of high-amplitude slow activity during the HVT is especially high if these minor bursts are recorded at rest. We also noted a certain relationship between the intensity of hyperventilation-related EEG changes (and, therefore, the rate of changes in the current subjective state of health of a patient) and characteristics of the initial pattern, such as α-rhythm disorders and an increase in the intensity of slow or slow and frequent activity at rest.     

Alpha-Theta Effects Associated with Ageing during the Stroop Test

The Stroop effect is considered as a standard attentional measure to study conflict resolution in humans. The response of the brain to conflict is supposed to change over time and it is impaired in certain pathological conditions. Neuropsychological Stroop test measures have been complemented with electroencephalography (EEG) techniques to evaluate the mechanisms in the brain that underlie conflict resolution from the age of 20 to 70. To study the changes in EEG activity during life, we recruited a large sample of healthy subjects of different ages that included 90 healthy individuals, divided by age into decade intervals, which performed the Stroop test while recording a 14 channel EEG. The results highlighted an interaction between age and stimulus that was focused on the prefrontal (Alpha and Theta band) and Occipital (Alpha band) areas. We concluded that behavioural Stroop interference is directly influenced by opposing Alpha and Theta activity and evolves across the decades of life.     

Rhythmic components of the EEG of 6-month-old children

Spectral EEG characteristics were studied in 12 six-month healthy children in a state of attention, attracted by visual stimuli and also at lowering of the level of visual afferentation and in drowsiness. 12 parts of EEG records free from artefacts were used, with analysis epoch 5 s and discretion frequency 100 counts/s. Three independent rhythmic EEG components have been revealed in alertness state, corresponding by criteria of functional reactivity and topographic localization to theta, alpha and mu EEG rhythms of the adult man. It is suggested that formation of dominating EEG rhythm with age occurs due to changes in dominant relations of the key rhythmic successions with independent genesis.     

Transitions from Wakefulness to Sleep at Different Times of Day: Old vs. Young Subjects

In order to assess age effects upon the daytime level of alertness, both subjective and objective measures of alertness were obtained in 19 healthy elderly males (mean age 65 years) and 19 healthy young males (mean age 21 years). Subjects were recorded during a Multiple Sleep Latency Test (MSLT), administered at 5 different times of day (9 a.m., 12 a.m., 3 p.m., 6 p.m., 9 p.m.). Before each test, subjects filled out an alertness questionnaire. During the entire 20 minutes of each test electroencephalographic (EEG) recordings were made and transformed into 40 averaged spectra, one for each 30 s epoch. For the delta, theta, alpha, sigma and beta bands of the EEG 6 consecutive values were averaged to obtain 1 value per 3 minutes. On the basis of the visually guided detection of the first spindle, sleep onset was determined. The elderly subjects obtained a higher overall level of subjective alertness than the young subjects. No age effect was observed for sleep latency, which followed a U-shaped diurnal trend. Overall, the mean relative EEG energy values followed a diurnal trend that was the reverse of that for sleep latency. The mean relative delta EEG energy gradually increased, and the mean relative alpha EEG energy gradually decreased across the MSLT. For the young subjects the respective ranges of variation of these EEG bands were very similar, while for the elderly subjects the range of variation of the alpha values was less than half of that for the delta band. Apparently, alpha EEG activity during the wake-sleep transition does not simply covary with delta EEG activity. Moreover, age appears to have a significant effect upon the dynamics of alpha EEG activity during the wake-sleep transition.     

EEG θ rhythm in preterm and full-term infants at the age of five months in endogenous attention

EEG indicators of endogenous attention (EnA) were studied in healthy infants carried to term and extremely preterm infants at a corrected age of five months. The cortical topography of the spectral amplitudes of the EEG θ rhythm was studied during long-term attention of the children to a new visual stimulus (exogenous attention, ExA) and during the retention of anticipatory attention under the conditions of constant appearance and disappearance of a stimulus in the paradigm of visual expectation (EnA). The relationship between reactive changes in the EEG θ rhythm during the retention of EnA and the behavioral parameters of the infant’s ability to retain this type of attention was also assessed. In five-month-old infants, the retention of EnA, in contrast to simpler types of attention to an exogenous stimulus, was accompanied by the appearance of a highly synchronized EEG θ rhythm (3.6–5.2 Hz) with a topical amplitude maximum in the lower temporal associative areas of the cortex. The ability to maintain EnA in children of this age is directly related to the reactive increase in the θ rhythm in the lower temporal areas of the cortex during the retention of EnA as compared to ExA. The deficit of EnA control in healthy extremely preterm (HEP) infants was associated with a relative deficit of the functional synchronization of the θ rhythm in the lower temporal areas of the cortex during the retention of EnA compared to full-term infants. In HEP infants, a decreased synchronization of the θ rhythm was equally typical of EnA and ExA. However, its cortical location depended on the type of attention. The functional nature of the θ rhythm inhibition in HEP infants suggests that this abnormality was related to alterations in the neurotransmitter interactions between the limbic and cortical structures, rather than to structural defects. These alterations could be one of the causes of the partial deficit of EnA in HEP infants.     

Relationships between EEG θ and α spectral amplitudes and cognitive ability in preschool children

Relationships between individual θ and α EEG amplitudes and intelligence were studied in five- to six-year-old children. EEG was recorded in 83 children in three functional states: eyes closed, sustained visual attention, and attention to adult’s speech. Intelligence was assessed using Kaufman’s K-ABC test. Relationships between the EEG parameters and intelligence were studied using correlational and regression analyses. The results suggest that stable individual differences in local spectral amplitudes (SA) in the EEG θ and α bands predict reliably (when the covariant proportions of their variances is controlled) the level of simultaneous data processing in children under the conditions of sustained attention but not at rest. Thus, the individual features of the limbic thalamocortical and corticothalamic attentional systems are expected to influence cognitive abilities at the preschool age.     

Activation of epileptic electrographic phenomena in the human EEG by nasal air flow.

The activating effect of deep oral breathing (with the nose closed) and nasal hyperventilation (with mouth closed) was examined in 62 patients with three different kinds of epileptic EEG abnormalities: unilateral localized temporal (fronto-temporal, occipito-temporal) abnormalities - group F, bilateral episodic theta-delta abnormalities - group TH, and bilaterally synchronous spike and wave abnormalities - group SW. Nasal hyperventilation was much more effective in group F and TH. Its effect was already significant 30-60 seconds after the start of deep breathing. In the group SW there were no statistically significant differences between the effects of nasal and oral hyperventilation. Unilateral nasal hyperventilation (the other nasal cavity being closed by tamponade) demonstrated a more pronounced activating effect on ipsilateral localized temporal EEG abnormalities. These effects of deep nasal breathing can hardly be explained by metabolic-vascular mechanisms, which probably are involved in the course of oral hyperventilation. On the other hand they are in agreement with animal experiments demonstrating that the mechanical stimulus of nasal air flow operates as a synchronizing impulse for certain rhinencephalic structures.     

EEG Dynamics in Women during Pregnancy and after Delivery

Clinical and spectral analyses of EEG recorded in the first trimester of pregnancy and six to nine months postpartum were performed in 11 women. It was shown that, in all examined women, the spectral power of virtually all rhythms of baseline postpartum EEG was uniquely decreased compared to the EEG during pregnancy in all derivations. To a lesser extent, this was characteristic of the ₂ rhythm. Changes in the postpartum EEG were most manifest during hyperventilation, predominantly, in the form of burst and paroxysmal activity. The women were divided into groups with and without postpartum paroxysmal activity. It was observed that abnormal pregnancy was more frequent in women with burst EEG activity in the nopregnant state. This index can be used as a test to reveal the group of risk of unfavorable course of pregnancy.     

Comparative EEG study in normal and autistic children

The work represents the results of a comparative study of spectral power as well as averaged coherence in alpha, beta and gamma EEG bands in 5-to-7-year-old autistic and healthy boys in the state of rest and under cognitive load (mental calculation). The mean age of the examined children was 6 years 4 months. In both healthy and autistic children, there was a clear-cut baseline frontal-occipital gradient of the alpha activity. Performance of the cognitive task led to enhancement of spectral power in the alpha1 band and shifting its maximum to the left hemisphere, did not change the activity in the alpha2 band, and considerably increased the spectral power in the alpha3 band. In healthy children, the spectral power and average coherence of the fast rhythms increased in the central and frontal areas of the left hemisphere. The right-side dominance of the spectral power of the alpha band was revealed in autistic children both in the baseline and during cognitive task. The spectral power of the gamma band was higher in autistic children than in healthy children in the baseline. The cognitive task did not change this fast activity in autistic children.     

Adverse reactions to 1975 bivalent influenza vaccine in children.

A questionnaire survey was undertaken to investigate incidence and types of reactions to a bivalent, zonally purified, killed influenza vaccine administered to 155 children aged 1 to 18 years in 1975. Local or systemic reactions or both occurred in 42 children (27%). However, these reactions were not considered serious and should not constitute a major drawback to future influenza programs in children under 3 years of age.     

Developmental features of the brain bioelectrical activity in children with remote consequences of a perinatal lesion of the CNS. II. EEG typology in normal and mental disorders

This research represents EEG - investigation by children with remote consequences of perinatal CNS pathology. Its described the different EEG types in normal and mental disorders in children. Its showed a early EEG - markers of abnormal ontogenesis in longitudinal study. The data obtained gives to prevent a negative dynamic of mental and speech development (learning disability, motor alalia, autism).     

Changes of dopamine-beta-hydroxylase activity during ontogenesis in healthy subjects and in an experimental model (rats)

In children and adolescents (250 healthy subjects) serum dopamine-beta-hydroxylase (DBH) activity (23.9+/-5.2 to 57.1+/-17.5 micromol/min/ml) increases with the age between 3-10 years, later it decreases approximately by the age of 10-14 years. At the age of 21 to 60 years DBH level is stable. Our study described decreasing DBH activity in adolescents at the age of 10-14 years in the studied sample of healthy persons. Experimental animals (200 Wistar rats, 5-120 days old) show the same trend of enzymatic activity, similarly as in humans. DBH activity in rats is between 0.85+/-0.1 to 2.8+/-0.05 micromol/min/ml. This activity is highest in 5-day-old rats; it decreases till the age of 14 days and increases mainly in 14- to 35-day-old animals. Decrease of DBH activity in rats between 35 to 40 days is significant and corresponds to the reduction of DBH activity in adolescent humans (10-14 years). Adult rats (aged 90-120 days) show a stable DBH activity. DBH activity intermediately decreases in 10- to 14-year-old children. This decrease corresponds to the intermediate developmental changes of electrophysiological parameters (decreasing EEG activity in healthy adolescents occurs in 10-14 years old children). Puberty is coupled with intermediate decreasing of DBH activity in man and also in experimental animals in the period of prominent psychological and physiological changes.     

Electrophysiologic characteristics of functional interhemispheric asymmetry

Change of biopotentials spatial synchronization under functional loads addressed predominantly to one or the other hemisphere (correlative analysis of the first EEG derivative of more than two thousands healthy subjects of various age), allowed to single out three phenotypes of hemispheric relations differing mainly by different types of information processing: right-hemispheric, left-hemispheric or mixed. Expressed EEG activation in both hemispheres (judged by alpha-index change) is manifest when the subject is presented with a task, the context of which does not correspond to the initially dominating type: in right-hemispheric--at solution of tasks, oriented to logical-verbal context and in left-hemispheric--to spatial-image one. The high level of non-specific EEG activation may be considered as an attempt of compensation of relative functional insufficiency of the right hemisphere systems in initially left-hemispheric or left-hemisphere systems in right-hemispheric individuals.