The Impact of the Auditory Environment on Auditory Processing of Maternal Voice and Auditory Cortex Maturation in Preterm and Term Infants

PROJECT SUMMARY/ABSTRACT In the United States, 10% of infants are born before 37 weeks’ gestation and considered premature. Although survival has improved, preterm infants remain at increased risk for impairment in neurodevelopment, including language development. Nearly 35% of infants born between 31- and 34-weeks’ gestation and 50% of infants born at fewer than 30 weeks’ gestation demonstrate compromised auditory memory and expressive and receptive language, which persist into adolescence. It is hypothesized that prematurity, which often results in physiologic insults and white matter injury, as well as the atypical auditory environment of the Neonatal Intensive Care Unit (NICU) impact language development during critical periods. The aberrant auditory environment is of particular interest because it can be modified to promote experience-dependent plasticity and improve long-term language outcomes in premature infants. The primary objective of this K23 Mentored Patient-Oriented Research Career Development Award is to characterize the influence of the NICU’s sensory environment on auditory processing of maternal voice as well as auditory cortex maturation and circuitry while accounting for variables known to influence language development including gestational age, sex, medical condition, socioeconomic status, and maternal stress and depression. To achieve this, Dr. Hammond will recruit a group of pregnant women and their fetuses who are subsequently born at term and a group of premature infants. In the first aim, attention to maternal voice will be compared in fetuses and premature infants using HR responses to a maternal voice stimulus. In the second aim, auditory recognition memory for maternal voice and auditory cortex maturation will be compared in term and preterm infants using auditory event-related potentials. In the third aim, infants born preterm and at term will return at a corrected age of two months and resting-state functional connectivity in the language regions of the brain will be compared. In all three aims, the impact of characteristics of the auditory environments in utero and in the NICU on these outcomes will also be evaluated. The findings from the proposed work will advance the field of developmental neuroscience’s understanding of critical periods for language development and will identify the characteristics of the auditory environment that promote or impede language development. The results will be used to design developmentally-appropriate interventions in the NICU that improve the outcomes of premature infants. Through the proposed work, Dr. Jennifer Hammond, a clinical neonatologist, will acquire mentored training in developmental neuroscience as well as neurobehavioral, neurophysiologic, and neuroimaging assessments of fetal and infant brain development to become a successful, independent physician-scientist. Dr. Hammond will have the support of a rich institutional environment and the commitment of her mentorship team including Dr. Catherine Monk, Dr. Patricia Kuhl, and Dr. Rachel Marsh, who will ensure that she transitions to independence and becomes a leader in the fields of developmental neuroscience and neonatology.