Physiologic discrimination of stop consonants relates to phonological skills in pre-readers: a biomarker for subsequent reading ability?(†).

Travis White-Schwoch,Nina Kraus

doi:10.3389/fnhum.2013.00899

Abstract

Reading development builds upon the accurate representation of the phonological structure of spoken language. This representation and its neural foundations have been studied extensively with respect to reading due to pervasive performance deficits on basic phonological tasks observed in children with dyslexia. The subcortical auditory system – a site of intersection for sensory and cognitive input – is exquisitely tuned to code fine timing differences between phonemes, and so likely plays a foundational role in the development of phonological processing and, eventually, reading. This temporal coding of speech varies systematically with reading ability in school age children. Little is known, however, about subcortical speech representation in pre-school age children. We measured auditory brainstem responses to the stop consonants [ba] and [ga] in a cohort of 4-year-old children and assessed their phonological skills. In a typical auditory system, brainstem responses to [ba] and [ga] are out of phase (i.e., differ in time) due to formant frequency differences in the consonant-vowel transitions of the stimuli. We found that children who performed worst on the phonological awareness task insufficiently code this difference, revealing a physiologic link between early phonological skills and the neural representation of speech. We discuss this finding in light of existing theories of the role of the auditory system in developmental dyslexia, and argue for a systems-level perspective for understanding the importance of precise temporal coding for learning to read.

Highlights

Learning to read scaffolds on the development of more basic language skills
The Top phonological awareness group (Top PA) evinces a large phase distinction corresponding in time to the transitions in the stimuli, which occurs in the responses from approximately 300–700 Hz and a more moderate phase shift from approximately 750–1000 Hz
We assessed the physiologic discrimination of stop consonants in a group of 4-year-old children and reveal a link between this discrimination and phonological awareness

Summary

Introduction

Learning to read scaffolds on the development of more basic language skills. One such primitive is phonological awareness, the knowledge that spoken language is made up of smaller units such as syllables and phonemes (Sandak et al, 2004; Kovelman et al, 2012; Pugh et al, 2013). There are, for example, extensive performance gaps between dyslexic and typically developing children on a variety of basic auditory tasks (Wright et al, 1997; Goswami et al, 2002; Ahissar et al, 2006). Dyslexics have difficulty tracking amplitude envelope modulations in speech, such as in syllable onsets (Goswami et al, 2002, 2011). It remains unknown whether these deficits are each observed within an individual or if there are variable manifestations of developmental dyslexia

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Conclusion