60. Spectral analysis of the neurophysiological activity in the human developing brain

Abstract

Brain maturation at early stages may be assessed by changes in spectral power frequencies of electroencephalogram, especially those in lower frequency range (Scher, 1997). Our aim was to determine differences in brain maturation between premature infants born at different gestational age by comparing the spectral power values obtained at comparable post-conceptional age. Electroencephalogram was recorded on forty infants (23–34 weeks) at 35 post-conceptional weeks. Infants were divided in groups according to gestational age: 23–27 (ELGA), 28–32 (VLGA) and 33–34 (LGA) weeks. In order to minimize handling in this very fragile population, one bipolar channel (C3–C4) was recorded. Electroencephalogram data were transformed into the frequency domain using a fast Fourier transform algorithm and divided in delta (0.5–4 Hz), theta (4–8 Hz), alpha (8–13 Hz) and beta (13–30 Hz) bands. Absolute and relative power values were compared between groups. Relative power values of ELGA differed significantly from those of LGA, showing an higher amount in delta and a lower amount in alpha and beta frequency bands. The comparison at the same post-conceptional age of infants born at different gestational weeks allowed to emerge early differences in brain electrical activity suggesting altered developmental trajectories for premature infants born at lower gestational ages.