An Animal Model of Neonatal Intensive Care Unit Exposure to Light And Sound in The Preterm Infant.

According to the World Health Organization, approximately 15 million children are born prematurely each year. Many of these infants end up spending days to weeks in a neonatal intensive care unit (NICU). Infants who are born prematurely are often exposed to noise and light levels that affect auditory and visual development. Children often have long term impairments to cognition, visuospatial processing, hearing, and language. We have developed a rodent model of NICU exposure to light and sound using the Mongolian gerbil (Meriones unguiculatus), which has a low frequency human-like audiogram and is altricial. To simulate preterm infancy the eyes and ears were opened prematurely, and animals were exposed to the NICU-like sensory environment throughout the gerbil's cortical critical period of auditory development. After the animals mature into adults, auditory perceptual testing was carried out followed by auditory brainstem response recordings and then histology to assess white matter morphology of various brain regions. Compared to normal hearing control animals, NICU sensory exposed animals had significant impairments to learning at later stages of training, increased auditory thresholds reflecting hearing loss, and smaller cerebellar white matter volumes. These have all been reported in longitudinal studies of preterm infants. These preliminary results suggest that this animal model could provide researchers with an ethical way to explore the effects of the sensory environment in the neonatal intensive care unit on the preterm infant's brain development.