COMPARISONS OF EEG SPECTRAL AND CORRELATION MEASURES BETWEEN HEALTHY TERM AND PRETERM INFANTS

Continuous 12-hour electroencephalography (EEG)-sleep studies were acq uired by a computerized monitoring system under environmentally contro lled conditions for 2 groups of neonates. Eighteen healthy preterm inf ants at a postconceptional term age were matched to 18 term infants. T hese 2 groups were also matched for gender, race, and socioeconomic cl ass. For the entire 12-hour recording, relative spectral power values (i.e., ratio of specific EEG power in specific frequency band compared to total EEG power) were significantly reduced in the preterm group f or theta (P less than or equal to.007), alpha (P less than or equal to .001), and beta (P less than or equal to.018) frequency bands, while d elta remained unchanged. Correlations between 91 pairs of EEG channels were also calculated and the preterm infants had significantly higher correlation values in 27 of the 91 pairs of channels (P<.05); 14 inte rhemispheric, 8 intrahemispheric, and 5 sagittal combinations, while 3 intrahemispheric combinations were higher in the term group. Fewer fu nctional neuronal aggregates generate less oscillatory potential (i.e. , Lower spectral power) in the theta through beta frequency ranges in the preterm infant, while greater cortical connectivity (i.e., higher correlations) exists in many brain regions by postconceptional term ag es in this group. These findings suggest a functional alteration in br ain development of the preterm infant as a result of prolonged extraut erine experience and/or prematurity.