Atypical perceptual narrowing in prematurely born infants is associated with compromised language acquisition at 2 years of age

Abstract

BackgroundEarly auditory experiences are a prerequisite for speech and language acquisition. In healthy children, phoneme discrimination abilities improve for native and degrade for unfamiliar, socially irrelevant phoneme contrasts between 6 and 12 months of age as the brain tunes itself to, and specializes in the native spoken language. This process is known as perceptual narrowing, and has been found to predict normal native language acquisition. Prematurely born infants are known to be at an elevated risk for later language problems, but it remains unclear whether these problems relate to early perceptual narrowing. To address this question, we investigated early neurophysiological phoneme discrimination abilities and later language skills in prematurely born infants and in healthy, full-term infants.ResultsOur follow-up study shows for the first time that perceptual narrowing for non-native phoneme contrasts found in the healthy controls at 12 months was not observed in very prematurely born infants. An electric mismatch response of the brain indicated that whereas full-term infants gradually lost their ability to discriminate non-native phonemes from 6 to 12 months of age, prematurely born infants kept on this ability. Language performance tested at the age of 2 years showed a significant delay in the prematurely born group. Moreover, those infants who did not become specialized in native phonemes at the age of one year, performed worse in the communicative language test (MacArthur Communicative Development Inventories) at the age of two years. Thus, decline in sensitivity to non-native phonemes served as a predictor for further language development.ConclusionOur data suggest that detrimental effects of prematurity on language skills are based on the low degree of specialization to native language early in development. Moreover, delayed or atypical perceptual narrowing was associated with slower language acquisition. The results hence suggest that language problems related to prematurity may partially originate already from this early tuning stage of language acquisition.

Predicting Individual Variation in Language From Infant Speech Perception Measures

“…This pattern of results could indicate reduced phonetic sensitivity in preterms (among many other explanations). Contrastingly, Jansson-Verkasalo et al (2010) reported that preterm 12-month-olds showed larger electrophysiological responses for a subtle nonnative vocalic contrast than full-term infants, suggesting greater sensitivity to it; notably, the groups did not differ for the native contrast or for the nonnative contrast when tested at 6 months.…”

“…With the exception of Jansson-Verkasalo et al (2010), the research reviewed previously focused on full-term, healthy, typically developing infants, with no familial history of language impairments. In this section, we point out some problems facing the clinical translation of such approaches.…”

Auditory event-related potentials are related to cognition at preschool age after very preterm birth

“…One study has failed to show such correlations at 2 y of age (27), while a recent study using speech sounds on term-born and premature newborns showed that AERP at term was predictive of outcome in infancy (28). Alterations in AERP and particularly MMN have been shown in children with learning disabilities (29), reading and language-related disorders (17), autism spectrum disorders (6,13,30), distractibility, and attention deficit hyperactivity disorder (30). In our study, AERP difference waves to all three deviants in children with brain damage and lower cognitive scores were displaced negatively, leading to stronger MMN and weaker P3a responses.…”

“…Smaller P1 and larger N2 amplitudes were found in Articles 5-y-old children born with mean gestational ages below 28 GW (2,16). In children born at less than 32 GW studied at 2 y of age, MMN responses reflected abnormal phoneme discrimination, which was related to a slower native language acquisition (17).…”

The Effect of Prenatal Auditory Enrichment on Perceptual Narrowing in Bobwhite Quail Neonates

“…Conversely, infants still discriminating among non-native phonemes at 7.5 months were less linguistically advanced at 24-months. Intriguingly, a comparison of prematurely born infants and fullterm infants found that at 12-months post-partum, premature infants had a differential "electric mismatch [neural] response" while effectively discriminating non-native phonemes, indicating a lack of usual perceptual narrowing (Jansson-Verkasalo, Ruusuvirta, Huotilainen, Alku, et al, 2010). Later at 2-years-old, the premature infants continued to display language delays typical of their group.…”