Atypical perceptual narrowing in prematurely born infants is associated with compromised language acquisition at 2 years of age
1 Faculty of Humanities, Logopedics, University of Oulu, Finland
2 Department of Clinical Neurophysiology, Neurocognitive Unit, Oulu University Hospital, Finland
3 Cognitive Brain Research Unit, Institute for Behavioural Sciences, University of Helsinki, Finland
4 Turku Institute for Advanced Studies, Centre for Cognitive Neuroscience, Department of Behavioural Sciences and Philosophy, University of Turku, Finland
5 Finnish Centre of Excellence in Interdisciplinary Music Research, University of Jyväskylä, Finland
6 Department of Signal Processing and Acoustics, Aalto University, Helsinki, Finland
7 Institute for Research in Child Development, School of Psychology, UK
8 Department of Phoniatrics, P.O. Box 25, Oulu University Hospital, Finland
9 Department of Paediatrics, Oulu University and University Hospital, Finland
BMC Neuroscience 2010, 11:88 doi:10.1186/1471-2202-11-88Published: 30 July 2010
Early 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.
Our 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.
Our 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.