ANALYSIS OF THE INTERRELATIONS BETWEEN A LOW-FREQUENCY AND A HIGH-FREQUENCY SIGNAL COMPONENT IN HUMAN NEONATAL EEG DURING QUIET SLEEP

It can be shown that dominant rhythmic signal components of neonatal E EG burst patterns (discontinuous EEG in quiet sleep) are characterised by a quadratic phase coupling (bispectral analysis). A so-called 'ini tial wave' (narrow band rhythm within a frequency range of 3-12 Hz) ca n be demonstrated within the first part of the burst pattern. The dete ction of this signal component and of the phase coupling is more succe ssful in the frontal region. By means of amplitude demodulation of the 'initial wave' and a subsequent coherence analysis the phase coupling can be attributed to an amplitude modulation, i.e. the envelope curve of the 'initial wave' shows for a distinct period of time the same qu alitative course as the signal trace of a 'lower' frequency component (0.75-3 Hz). The results were derived from six neonates (20 burst patt erns for each neonate; 8 channel recordings). (C) 1997 Elsevier Scienc e Ireland Ltd.