RESUMEN
By the use of an autoregressive (AR) model, development of beta-waves in quantitative EEG parameters was studied in 1,340 normal children aged from 3 to 12 years. The results were summarized as follows. The beta band(13.5-25 Hz) was divided into three frequency ranges; beta-1(13.5-17.4 Hz), beta-2(17.5-21.4 Hz) and beta-3 (21.5-25 Hz) waves. The average power and percent-power of the beta-1 and beta-2 waves increased with advancing age, whereas these of the beta-3 wave showed no change with advancing age. By means of EEG pattern discrimination, critical period of beta band in the developing EEG was observed at the age of 4 years in frontal region, 10 years in central region and 3 to 7 years in occipital region. Those results suggest that the development of beta activity may be faster in frontal, occipital areas and relatively slower in central area.