Anti-phasic oscillatory development for speech and noise processing in cochlear implanted toddlers

SUMMARY Human brain demonstrates amazing readiness for speech and language learning at birth, but the auditory development preceding such readiness remains unknown. Cochlear implanted (CI) children with prelingual deafness provide a unique opportunity to study this developmental stage. Using functional near-infrared spectroscopy, we revealed that the brain of CI children was nearly irresponsive to sounds at CI hearing onset. With increasing CI experiences up to 32 months, the brain demonstrated function, region and hemisphere specific development. Most strikingly, the left anterior temporal lobe showed an oscillatory trajectory, changing in opposite phases for speech and noise. In addition, speech responses increased linearly in left sylvian parieto-temporal area and right inferior frontal gyrus, and noise responses changed in U shape in right supramarginal gyrus. Such cortical development predicted behavioral improvement. The study provides the first longitudinal brain imaging evidence for early auditory development preceding speech acquisition in the human brain. Graphic abstract Highlights The brain of cochlear implanted toddlers is functionally inferior to neonates Hearing experiences drive functional development in auditory related cortical areas Speech and noise processing develop in anti-phasic oscillatory trajectories Auditory cortical development predicts post-implantation behavioral improvement