[A power spectral analysis of the EEG in the newborns. I. Developmental changes of normal babies]

Power spectral analysis of the EEG at the neonatal period was performed in 50 premature babies and 36 mature babies. The gestational age ranged from 26 to 40 weeks, and birth weight from 762 g to 3,232 g. All EEGs were recorded when the babies reached to 37-41 weeks of conceptional age, and analyzed using fast Fourier transformation. The relative power in active sleep was evaluated in this study. The percent power of the delta 1 band ranging from 0.5 to 2.0 Hz decreased immediately with increasing conceptional age, while that of the delta 2 (2.2-3.8 Hz), theta 1 (4.0-5.4 Hz) and theta 2 (5.6-7.8) increased with conceptional age. However, no significant change was recognized in the alpha (8.0-12.8 Hz) and beta 13.0-29.8 Hz). These results suggest that the development of the EEG depends on the post conceptional age. The percent power of delta 1 to beta bands was compared among the frontal, central, parietal and occipital regions. The development of EEG in the central region was prominent among other 3 regions in EEG development. The EEGs of premature babies were compared to those of mature babies at the same conceptional age. The percent power of premature babies was higher at the delta 1 band, whereas lower at the delta 2, theta 1 and theta 2 bands than that of mature babies. The data showed that premature babies were more immature than age-matched mature babies in the development of EEGs.