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

Background: 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. Results: 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. Conclusion: 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

Phonological development of Finnish speaking children at 3;6 and associations to previous and simultaneous lexical ability

Previous studies of Finnish children's phonological development focus mainly on children under 2;0. Earlier findings have suggested that phonological and lexical development are strongly associated at an early age. However, less is known about the longitudinal association. This study describes the phonological skills of Finnish-speaking children at 3;6 and compares them with early lexicon size at 2;0 and lexical ability at 3;6 (N = 67). The children's phonological development was measured using The Finnish Phonology Test. Lexical development was evaluated using the Finnish, long-form version of the Communicative Development Inventory at 2;0 and the Boston naming test at 3;6 At 3;6, all children mastered the vowels and diphthongs fully, and most of the children also mastered the consonants, with the exception of the phonemes/d/and/r/. Phonotactic skills had also been acquired well at this group level, although the word-medial and, especially, word-initial consonant clusters were still challenging. The percentage of phonemes correct was 95. Both paradigmatic and phonotactic skills at 3;6 were significantly associated with lexicon size at 2;0. In addition phonotactic skills correlated with naming ability at 3;6. Lexical development at 2;0 explained 21% of the variance in the phonological development at 3;6, whereas, the explaining value of simultaneous lexical skill was limited (9%). Present findings propose that associations between lexical and phonological skills weaken as phonological skills become more honed.Peer reviewe

Connexin 26 mutations and nonsyndromic hearing impairment in Northern Finland

Objective: The aims of the present study were to evaluate the role of the gap junction protein beta-2 gene (GJB2), encoding connexin 26 (Cx26), in children with moderate to profound prelingual nonsyndromic sensorineural hearing impairment (HI) and to investigate the carrier frequencies of the GJB2 gene mutations in a control population in Northern Finland. Methods: Mutation analysis was performed by direct sequencing and carrier detection by conformation sensitive gel electrophoresis further confirmed by direct sequencing. Results: Cx26 mutations were found in 15 of 71 (21.1%) (67 families) children with HI. Homozygosity for the mutation 35delG was shown to be the cause of HI in 13 of 15 (86.7%) children. Homozygosity for the M34T genotype was found in one child, and compound heterozygosity for the M34T/V37I genotype was found in another. Five families of those with suspected familial HI (29.4%) and six families out of those with sporadic HI (12.0%) had a homozygous or compound heterozygous mutation. The carrier frequency for the mutation 35delG was 1 of 78 (4 of 313) and that for the M34T was I of 26 (12 of 313). Conclusion: 35deIG/35deIG genotype was found to be a significant cause of moderate to profound prelingual. nonsyndromic sensorineural HI in Northern Finland. M34T/M34T genotype was seen in only one child, but the carrier frequency of the M34T allele was about three times higher than that of the 35delG mutation