Sex Differences of Spectral Characteristics of Baseline EEG in Primary School-Aged Children

Abstract

The formation of brain bioelectrical activity occurs differently in girls and boys. The results of primary investigations show gender differences of functional brain organization in adolescents and adults. However, there is an opinion on the lack of gender distinctions in children before puberty. Objective: to define features of brain bioelectrical activity in primary school-aged children depending on a gender. Methods: on the basis of parental consent 200 7−9 aged right-handed schoolchildren took part in research (2012−2014). All children were divided into groups depending on biological age and gender. The monopolar electroencephalogram was registered according to 16 standard leads. Changes of the maximal amplitude, full power, the dominant frequency and the index of the main rhythms power of the electroencephalogram were assessed. Results: Prevalence of slow wave delta and theta activity in boys of 7 and 10 years, and also activities of theta range in 9-aged girls were revealed. The increase of the dominant alpha range frequency in 7-aged girls in occipital (p≤0,016) and temporal (p≤0,045) brain regions, and rising of full power of this rhythm in 8 aged girls in the left hemisphere (p≤0,023) while in 9-year aged girls ― in the right hemisphere (p≤0,040) were proved. At the age of 10 years full power of alpha range has the largest values in boys (p≤0,038). Among high-frequency components the predominance of the index beta-ranges in girls of 7 and 10 years were revealed. The increase in amplitude fluctuations in beta1-range mainly in the sensorimotor brain areas was typical for 7 aged boys. Conclusion: The revealed gender distinctions of the electroencephalogram testify to a larger maturity of the central nervous system in girls comparing with boys. It is shown that the age of 9 years is the active period of the cerebral cortex frontal lobes formation in girls.