Teruyuki Ogawa

Characterization of developmental changes in EEG-gamma band activity during childhood using the autoregressive model

Abstract Background : We characterized developmental changes in the EEG‐gamma band during childhood using the autoregressive (AR) model, which was previously developed and described in our laboratory.

Ontogenic development of EEG-asymmetry in early infantile autism

Autoregressive (AR) analysis and component analysis were done on EEGs during sleep stage 2 in normal and autistic children, since AR-coefficients of EEG characterize the autocovariance and power spectral density of EEG. In addition, as the generalized distance of the average AR-coefficient vector of an EEG group at one side from that at the opposite side exhibits an F-distribution, the statistical inferences were determined, as to whether there is hemispheric specialization in EEG in 21 right-handed autistic children and whether there is a difference between the AR-spectral pattern of EEG in the autistic children and that of 28 normal children of the same age range. The results obtained are as follows: 1. Significant hemispheric lateralization in EEG at the significant level of 0.01 was observed in normal children, whereas no lateralization was confirmed in autistic children. 2. Random click stimulation had cumulative effects on the hemispheric lateralization in the normal children, but not in the autistic children. On the contrary, the effects of random flash light stimulation on hemispheric asymmetry were verified in the autistic children as well as in the normal children. 3. The EEG components of autistic children were significantly different from the normal ones in the frequency range of alpha-2 component waves at bilateral frontal (Fp1 and Fp2) regions and the activity of these component waves was higher in the autistic children than in the normal ones over 5 years old. 4. These findings suggest that autistic children are not only less responsive to external stimuli, but also neurophysiologically less active in the internal regulatory mechanism.

DEVELOPMENT OF RELATIVE POWER CONTRIBUTION RATIO OF THE EEG IN NORMAL CHILDREN : A MULTIVARIATE AUTOREGRESSIVE MODELING APPROACH

The relative power contribution ratio using a multivariate autoregressive model was applied to determine the spread of delta, theta, alpha and beta activity over the scalp in childhood. EEGs of 264 normal healthy subjects from 3 to 26 years were recorded from Fp1, Fp2, C3, C4, O1 and O2 with linked ears during the resting relaxed state with eyes closed. After selecting the epoch to remove artifacts, the relative power contribution ratio at each frequency band was calculated from the digitized EEG. The most noticeable developmental change was seen in the alpha frequency, where the relative power contribution ratio from its own area decreased significantly with age, and ratios from the other areas increased significantly. The change was larger at the frontal and smaller at the occipital region. Consequently, the occipital alpha wave was stable after 3 years of age. Developmental change at beta frequency was similar to alpha activity, but the number of components with significant change was smaller at delta and theta frequencies. Thus the relative power contribution of the EEG enabled us to observe how relationships among each location of EEG matured.

Hydrops Fetalis Caused by Fetal Kasabach-Merritt Syndrome

There have been only 2 previous reports of nonimmunologic hydrops fetalis (NIHF) caused by fetal Kasabach‐Merritt syndrome, both of which were pathological studies. This is the first clinical case report of NIHF due to fetal Kasabach‐Merritt syndrome that was prenatally diagnosed by sonography, computerized tomography, and percutaneous umbilical blood sampling.

Normal developmental profiles of CSF gangliotetraose-series gangliosides from neonatal period to adolescence

The normal developmental profiles of cerebrospinal fluid (CSF) gangliosides were examined from the neonatal period to adolescence, using 1 ml of clinically available CSF, by the thin-layer chromatography/enzyme-immunostaining method. The level of total gangliotetraose-series gangliosides, including GM1, GD1a, GT1a, GD1b, GT1b, and GQ1b, increased 3.8-fold from the neonatal period to age 5 years, followed by a plateau, and then a mild decrease. The developmental profiles of individual gangliosides differed from each other. CSF gangliosides change with age, reflecting the maturational changes of the central nervous system gangliosides in situ. CSF ganglioside analysis and this developmental profile might be useful for examining ganglioside aberrations and basic neurochemical mechanisms underlying neurologic disorders, especially age-dependent diseases.

Developmental changes in electroencephalogram for term and preterm infants using an autoregressive model

The purpose of the present study was to clarify the developmental changes of electroencephalogram (EEG) background activity in term and preterm infants that take place with increasing conceptional age (CA) through an autoregressive (AR) model. Polygraphical EEG recordings were obtained from 76 healthy term and preterm infants with a CA ranging between 31 and 40 weeks. Decreases in total power and component power of δ were noted with CA during burst activity (BA) in quiet sleep (QS) and during active sleep (AS). Increases in total power and component power of δ were noted with CA during interburst interval activity (IBIA) of QS. Regression analysis (RA) of the information amount (IA) indicated a negative correlation with increasing CA in AS and in the monopolar EEG tracings Fp1, C3, O1 and O2 in BA, and a positive correlation in O1 in IBIA. Regression analysis of the IA of δ indicated a negative correlation with increasing CA in AS and in Fp1, C3, O1 and O2 in BA, and a positive correlation in O1 in IBIA. Regression analysis of the IA of δ indicated a negative correlation with increasing CA in BA and AS. These results showed that the high voltage slow wave component changed to a low voltage slow one with development in AS and that BA was longer in duration and lower in power with increasing CA, while IBIA was shorter in duration and higher in power. In conclusion, significant developmental changes occur in all derivatives of AS. Even though the EEG of BA and IBIA change separately, they are followed by EEG of QS in a continuous pattern.

Microstructure of longitudinal 24 hour electroencephalograms in healthy preterm infants.

Abstract Background: The aims of the present study were to find electroencephalographic parameters that appropriately represent the microstructure of electroencephalograms (EEG) in different sleep states and to find quantitative criteria for an automatic system of sleep‐state classification in preterm infants.

Low levels of CSF gangliotetraose-series gangliosides in West syndrome: Implication of brain maturation disturbance☆

One ml of cerebrospinal fluid (CSF) from each patient with West syndrome and patients from disease control groups were analyzed separately by highly sensitive thin-layer chromatography/enzyme-immunostaining method. The levels (mean +/- S.D.) of GM1, GD1a, sum of GD1b, GT1b, and GQ1b, and total gangliotetraose-series gangliosides in West syndrome patients (n = 14) and in an age-matched control group (n = 14) were as follows: 11.6 +/- 7.8 and 30.9 +/- 12.3 ng/ml CSF, 51.5 +/- 23.2 and 91.7 +/- 41.2 ng/ml CSF, 129.6 +/- 57.6 and 195.9 +/- 123.6 ng/ml CSF, and 192.7 +/- 78.6 and 318.4 +/- 131.6 ng/ml CSF, respectively. The differences were statistically significant except for the sum of GD1b, GT1b, and GQ1b (by 2 sample t test). Because they are abundant in the outer surface of neuronal plasma membranes, gangliosides may play an important role in the transformation of a neuroblast into a functionally mature neuron. Low levels of CSF gangliotetraose-series gangliosides, especially GM1 and GD1a, in patients with West syndrome may suggest a maturation disturbance of the brain from an early developmental stage.

Ontogenic development of autoregressive component waves of waking EEG in normal infants and children

Waking EEGs of 150 normal children aged from 20 days to 15 years were subjected to analysis. Discrete time series of an artifact free segment of the EEG record at 50 samples/sec for twenty seconds was generated and autoregressive (AR) and component analyses were carried out with a minicomputer PDP 11/40 (DEC). The results may be summarized as follows: 1) In the group of 1 year old and less, the power increased with the monthly age, whereas the bio-informing activity amount decreased. In those older than 1 year, both parameters showed maximal values at 1 year and then decreased with age, and the decreases were marked from 1 to 3 years. 2) The first- and second-order component activities of 129 and 677 waves, respectively, were obtained by applying component analysis to 152 EEG records. The frequency polygons of natural frequency of second-order component waves verified several modes, each of which was enhanced in the frequency range of the well-known delta 0, delta 1, theta 1, theta 2, alpha 1, alpha 2, beta 1, beta 2 and beta 3 waves, respectively. 3) The average percent-power of the delta wave (delta 0 + delta 1) decreased with age, especially from 1 to 3 years old, whereas those of beta- and alpha-waves increased with advancing age. That of the theta wave tended to increase from 2 to 4 years of age, and thereafter decreased gradually with increasing age. 4) With increasing age, the durations of damped oscillations were significantly lengthened in delta 1, alpha 1 and beta 3 waves, whereas that in the theta 1 wave was significantly shortened. 5) The bio-informing activity amounts of alpha waves increased from 1 to 3 years with increasing age, whereas those of delta and theta waves decreased. No significant developmental change in the parameters, however, was observed in the beta wave. The results indicate that AR-power spectral and component analyses of EEG are sensitive methods for obtaining valuable information regarding the electrical brain maturation in childhood.

Normal developmental changes in carotid arterial blood flow measured by Doppler flowmetry in children

We examined the developmental changes in carotid arterial blood flow in a group of neonates, infants, and children using a Doppler flowmeter. The mean, maximum and minimum carotid arterial blood flow (CABF) were measured serially in 35 healthy newborns during the first 5 days of life (total 175 records), and in 62 healthy children aged 1 month to 13 years. In newborns, the mean CABF increased significantly on the second day of life, while the maximum and minimum CABFs increased significantly every day during the first 3 days of life. The mean, maximum, and minimum CABFs increased steadily and significantly in those older than 1 month but reached a plateau after 2 to 4 years of age. Our results indicate that CABF changes with age in early life, reflecting a change in cardiac contraction and carotid-cerebral circulatory system. The measurement of CABF by Doppler flowmetry may be useful for examining cardiac and carotid-cerebral circulatory disorder.