Novel word learning deficits in infants at family risk for dyslexia

Decoding of speech information using EEG in children with dyslexia: Less accurate low-frequency representations of speech, not "Noisy" representations

The amplitude envelope of speech carries crucial low-frequency acoustic information that assists linguistic decoding. The sensory-neural Temporal Sampling (TS) theory of developmental dyslexia proposes atypical encoding of speech envelope information < 10 Hz, leading to atypical phonological representations. Here a backward linear TRF model and story listening were employed to estimate the speech information encoded in the electroencephalogram in the canonical delta, theta and alpha bands by 9-year-old children with and without dyslexia. TRF decoding accuracy provided an estimate of how faithfully the children's brains encoded low-frequency envelope information. Between-group analyses showed that the children with dyslexia exhibited impaired reconstruction of speech information in the delta band. However, when the quality of speech encoding for each child was estimated using child-by-child decoding models, then the dyslexic children did not differ from controls. This suggests that children with dyslexia encode neither "noisy" nor "normal" representations of the speech signal, but different representations.

A short-form version of the Australian English Communicative Development Inventory

Purpose: The Australian English Communicative Development Inventory (OZI) is a 558-item parent report tool for assessing language development at 12-30 months. Here, we introduce the short form (OZI-SF), a 100-item, picture-supported, online instrument with substantially lower time and literacy demands.Method: In tool development (Study 1), 95 items were drawn from the OZI to match its item distribution by age of acquisition and semantic categories. Five items were added from four other semantic categories, plus 12 gestures and six games/routines. Simulations computed OZI-SF scores from existing long-form OZI norm data, and OZI and projected OZI-SF scores were correlated. In an independent norming sample (Study 2), parents (n = 230) completed the OZI-SF for their children aged 12-30 months. Child scores were analysed by age and sex.Result: OZI-SF and OZI scores correlate highly across age and language development levels. Vocabulary scores (receptive, expressive) correlate with age and the median for girls is higher until 24 months. By 24 months, 50% of the sample combine words "often". The median time to OZI-SF completion was 12 minutes.Conclusion: Fitted percentiles permit working guidelines for typical (median) performance and lower cut-offs for children who may be behind on age-based expectations and/or at risk for a communication difficulty. The OZI-SF is a short-form of the OZI that has promise for research and clinical/educational use with Australian families.

Language acquisition and speech rhythm patterns: an auditory neuroscience perspective

All human infants acquire language, but their brains do not know which language/s to prepare for. This observation suggests that there are fundamental components of the speech signal that contribute to building a language system, and fundamental neural processing mechanisms that use these components, which are shared across languages. Equally, disorders of language acquisition are found across all languages, with the most prevalent being developmental language disorder (approx. 7% prevalence), where oral language comprehension and production is atypical, and developmental dyslexia (approx. 7% prevalence), where written language acquisition is atypical. Recent advances in auditory neuroscience, along with advances in modelling the speech signal from an amplitude modulation (AM, intensity or energy change) perspective, have increased our understanding of both language acquisition and these developmental disorders. Speech rhythm patterns turn out to be fundamental to both sensory and neural linguistic processing. The rhythmic routines typical of childcare in many cultures, the parental practice of singing lullabies to infants, and the ubiquitous presence of BabyTalk (infant-directed speech) all enhance the fundamental AM components that contribute to building a linguistic brain.