[Development of bioelectric activity in children 7 to 11 years old]

Three kinds of EEG records may be found in healthy children observed from 7 to 11 years of age. Records with alpha rhythm, where the degree of modulation was differently expressed and asynchroneus theta waves were diffusely localized, are found most frequently. Records with alpha rhythm without addition of slow frequencies and records with synchronized theta waves occur less frequently. Development of records in further years is mostly irregular (in 44% of our series), the individual types given above alternating in the same child without any order. No interrelation was found between the EEG curve and the mental level of children in the framework of healthy population. In children aged 11 years, a greater number of records (in our series 34% as against 10% in children aged 10 years) occurs in which the theta waves in synchronized groups appear again. Relation with pubertal manifestations is not univecal as time synchronization was found in 1 girl only. The case may be that of EEG registered subclinical manifestations of developmental phases of puberty. The incidence of synchronized theta waves which disappears spontaneously in children's later years seems to be connected with the process of maturation. With persistence of this finding in further years, an increased disposition to seizures must be thought of.