Lateralized neonatal EEG coherence during sleep predicts language outcome.

BACKGROUND: Enriched language exposure may benefit infants in the neonatal intensive care unit. We hypothesized that changes in neonatal EEG coherence during sleep, in response to maternal voice exposure, predict language development. METHODS: Convalescent neonates underwent 12-hour polysomnography. A recording of the mother’s voice was randomized to continuous playback in the first or second 6 hours. We calculated the imaginary coherence (ICOH – a measure of functional connectivity) between EEG leads. Spearman correlations were computed between ICOH and 18-month Bayley-III Language scores. RESULTS: Thirty-five neonates were included (N=18 33-to-<35 weeks gestation; N=17 ≥35 weeks). Predictive value of ICOH during neonatal non-rapid eye movement (NREM) sleep was left-lateralized and varied with gestational age and voice playback. ICOH in the left-hemispheric (C3-Cz; T3-Cz) channels across multiple EEG frequency bands was associated with 18-month language scores (rho= −0.34 to −0.48). The association was driven by neonates born at 33-34 weeks gestation, and a trend suggested a possible effect of maternal voice at some EEG frequencies. Right-hemisphere ICOH (C4-Cz; T4-Cz) was not associated with language outcome. CONCLUSION: Left-hemispheric EEG functional connectivity during neonatal NREM sleep shows early signs of physiologic asymmetry that may predict language development. We speculate that sleep analyses could have unique prognostic value.