The complexity of event-related MEG signals decreases with maturation in human fetuses and newborns

Abstract

AbstractIt is unknown how cortical entropy or “complexity”, a marker of consciousness, evolves in early human development. To test the hypothesis that the entropy of cortical signals increases approaching birth, we conducted the first ever study to relate fetal cortical entropy to maturation. MEG recordings were obtained from a sample of fetuses and newborns with prior evidence of perceptual consciousness. Using cortical responses to auditory irregularities, we computed several measures of signal entropy. Despite our hypothesis, cortical entropy significantly decreased with maturation in fetuses and newborns, with the strongest effect occurring with 4 – 10 Hz permutation entropy in both groups. Decreases in permutation entropy were driven by amplitude changes in both fetuses and newborns, whereas phase and its interaction with amplitude drove increases in entropy, possibly related to consciousness. These results lay groundwork both for future measures of perinatal consciousness and new in utero estimates of risk for neurodevelopmental disorders.TeaserEven as birth nears, a neural marker of consciousness decreases with gestational age in late fetal development and continues to decline after birth.