AJP - Regulatory, Integrative and Comparative Physiology, Vol 265, Issue 3 706-R714, Copyright © 1993 by American Physiological Society
A quantitative method for classification of EEG in the fetal baboon
M. M. Myers, R. I. Stark, W. P. Fifer, P. G. Grieve, J. Haiken, K. Leung and K. F. Schulze
Department of Psychiatry, Columbia College of Physicians and Surgeons, New York, New York.
Electroencephalographic (EEG) activity is used as a primary indicator of
sleep states in adults and infants of many species and in the ovine fetus.
We recently reported that the baboon fetus exhibits visually discernable
patterns of EEG activity. One pattern of activity, characterized by the
intermittent presence of repetitive bursts of high-voltage EEG, is
indistinguishable from trace alternant (TA). TA is a distinctive pattern of
EEG activity found only during early stages of development in primates. TA
is the predominant pattern of EEG activity during quiet sleep in human
infants < 2 mo of age. The focus of this study was to derive
quantitative parameters that would discriminate TA from other activity and
then to develop a method for automated categorization of EEG patterns.
Results demonstrate that several parameters derived from frequency-domain
analyses are related to visually coded EEG states. Among these parameters,
high-frequency power (12-24 Hz) and spectral-edge frequency are good
discriminators of EEG patterns. This paper describes a new parameter, EEG
ratio, computed as spectral power in the rectified EEG within a band that
corresponds to the frequency of bursts of activity during TA (0.03-0.20 Hz)
divided by power in the 12- to 24-Hz band. This new composite parameter of
EEG activity provides a markedly better correlate of visually coded EEG
than any of the individual parameters tested. Using cluster analysis, we
devised a method for objective minute-by-minute dichotomization of EEG
ratio. The method produces results that agree with visual coding of EEG
activity 87.1% of the time.(ABSTRACT TRUNCATED AT 250 WORDS)
