Formation of the Interaction between the Wave Components of the Main EEG Rhythms in Children up to Five Years of Age

Abstract

Using the analysis of the interaction between EEG components [1], the authors studied the regularities of the formation of the EEG wave structure in 36 children aged 4 to 7 months, 2 to 3 years, and 4 to 5 years. The EEG of 4- to 7-month-old children had a relatively organized temporal structure, whose components were connected mainly with those of the slow-wave range. This structure is reproduced in most of the leads and is more stable in the anterior cortical areas than in the posterior ones. The waking 2- to 5-year-old children had two “functional” nuclei in the relation structure of the EEG components characterized by statistically significant enhancement in the probability of the consecutive appearance of waves of certain ranges. These nuclei include a slow-wave nucleus in the range of the Δ2–θ1-frequencies and an “alpha”-nucleus in the α1- and α2-ranges (θ2 and α1 2- to 3-year-old children) of the EEG frequencies. The relations between the components of the slow-wave nucleus begin to form in infants, prevail in 2- to 3-year-old children, and weaken by the age of 4 to 5 years. A trend is observed in 2- to 5-year-old children towards an increase in the average frequency of the waves that form the slow-wave nucleus. The temporal (strengthening interaction between the waves) and spatial organization of the interaction between the wave components of the “alpha”-nucleus is accelerated at the age of 4 to 5 years. The average frequency of the components forming this nucleus gradually increases with the children's age from 4 to 7 months to 4 to 5 years. Competitive relations exist between the two nuclei, characterized by a significant decrease in the probability of transitions between the components of different nuclei. The θ2-component may play a special role of the connecting link between the nuclei at the age of 4 to 5 years, the interwave transition from the Δ- to θ-frequencies and from the latter to the α-range being effected by a leaplike rather than smooth frequency increase. The character of local and spatial rearrangements of the EEG temporal structure detected in this study reflects a gradual morphofunctional maturation of the brain as a system that maintains the specific features of self-regulation mechanisms and coordination of the intersystem interactions at various stages of a child's development.