A polygraphic study of bioelectrical brain maturation in preterm infants.

Bioelectrical brain maturation was studied in 26 low-risk preterm infants by serial polygraphic recordings. A modified method of visual EEG analysis was used, based on Parmelee's coding system, which allowed quantification. It gave the following results: (1) The main characteristics of EEG maturation in preterm infants were a progressive spatio-temporal differentiation, with an increase of rhythmic activities and a decrease of discontinuity. (2) A strong relationship was found between post-menstrual age of the infants and EEG maturity, but there were exceptions to this rule. (3) longer duration of extra-uterine life had a small accelerating influence on EEG maturation. (4) Certain basic types of EEG patterns were closely related to behavioural states, whereas EEG maturity was not state-dependent. (5) The relationship between EEG pattern types and behavioural states becomes more stable with increasing age.