Features of the formation of interzonal connections of the brain according to quantitative electroencephalography in full-term and premature infants

Abstract

To study the features of functional interzonal integration and its dynamics in infants from 0 to 9 months during prospective observation, taking into account the timing gestation, clinical picture and morphological changes on neurosonography (NSG). A comprehensive unified examination was carried out in dynamics in 89 infants three times at the age of 3, 6, 9 months and included, in addition to assessing the neurological status, the Denver Developmental Screening Test (DDST), transfontanellar ultrasonography with a vector sensor according to the generally accepted method. We also evaluated the parameters of electroencephalography (EEG) recorded in the waking state with an analysis of background parameters, zonal differences, and the identification of pathological types of activity and calculation of the average coherence power (ACP). In accordance with the gestational age, infants are divided into two groups of full-term and premature babies. In the group of premature babies, the clinical picture in the neonatal period was dominated by cerebral ischemia of I and II degrees. The DDST parameters throughout the entire observation period did not reveal any deviations from the optimal development in all children. There were significant changes in functional connectivity (FC) in premature infants, which were more pronounced by 9 months. Functional hyperintegration was recorded in the intrahemispheric occipital-temporal and occipital-central regions bilaterally, in the anterofrontal-temporal leads on the left and in the interhemispheric anterofrontal regions. The ACP indicators were affected by changes in the NSG. An increase in ACP values in the occipitotemporal leads was associated with the presence of subependymal cysts in both preterm and full-term infants. Intraventricular hemorrhages and increased echogenicity in the periventricular zones in preterm infants were associated with an increase in coherence in the anterior frontal, left occipito-central, and temporo-anterofrontal leads. Thus, in preterm infants with cerebral ischemia of grades I and II, as well as in children with subependymal cysts, ACP indicators indicate hyperintegration of brain areas that are of fundamental importance for speech development and the formation of cognitive functions. Changes in the level of FC in the areas of the cerebral cortex in children with low gestational age, cerebral ischemia I and II, even at the optimal rate of motor and preverbal development, require further study, as it can reflect both the physiological processes of maturation in the postnatal period with transient deviations, and act as the role of possible early markers of future variants of deviant development.