Functional connectivity in preterm infants derived from EEG coherence analysis

Objective: To quantify the neuronal connectivity in preterm infants between homologous channels of both hemispheres. Methods: EEG coherence analysis was performed on serial EEG recordings collected from preterm infants with normal neurological follow-up. The coherence spectrum was divided in frequency bands: delta(newborn)(0-2 Hz), theta(newborn)(2-6 Hz), alpha(newborn)(6-13 Hz), beta(newborn)(13-30 Hz). Coherence values were evaluated as a function of gestational age (GA) and postnatal maturation. Results: All spectra show two clear peaks in the delta(newborn) and theta(newborn)-band, corresponding to the delta and theta EEG waves observed in preterm infants. In the delta(newborn)-band the peak magnitude coherence decreases with GA and postnatal maturation for all channels. In the theta(newborn)-band, the peak magnitude coherence decreases with GA for all channels, but increases with postnatal maturation for the frontal polar channels. In the beta(newborn)-band a modest magnitude coherence peak was observed in the occipital channels, which decreases with GA. Conclusions: Interhemispherical connectivity develops analogously with electrocortical maturation: signal intensities at low frequencies decrease with GA and postnatal maturation, but increase at high frequencies with postnatal maturation. In addition, peak magnitude coherence is a clear trend indicator for brain maturation. Significance: Coherence analysis can aid in the clinical assessment of the functional connectivity of the infant brain with maturation.