Brain Responses to Changes in Speech Sound Durations Differ Between Infants With and Without Familial Risk for Dyslexia

TLDR

Developmental dyslexia is a strongly familial language disorder, and infants from high‑risk families are at elevated risk, yet early markers remain poorly understood. This study compares 6‑month‑old infants with and without a familial dyslexia risk by examining their brain electrical responses to changes in speech sound duration. Event‑related potentials were recorded while infants listened to pseudowords with varying /t/ durations in an oddball paradigm, presenting frequent standards and rare deviants every 610 ms. High‑risk infants showed reduced initial responsiveness and altered change‑detection responses relative to controls, indicating that they process auditory temporal cues differently before language acquisition.

Abstract

A specific learning disability, developmental dyslexia, is a language-based disorder that is shown to be strongly familial. Therefore, infants born to families with a history of the disorder are at an elevated risk for the disorder. However, little is known of the potential early markers of dyslexia. Here we report differences between 6-month-old infants with and without high risk of familial dyslexia in brain electrical activation generated by changes in the temporal structure of speech sounds, a critical cueing feature in speech. We measured event-related brain responses to consonant duration changes embedded in ata pseudowords applying an oddball paradigm, in which pseudoword tokens with varying /t/ duration were presented as frequent standard (80%) or as rare deviant stimuli (each 10%) with an interval of 610 msec between the stimuli. The infants at risk differ from control infants in both their initial responsiveness to sounds per se and in their change-detection responses dependent on the stimulus context. These results show that infants at risk due to a familial background of reading problems process auditory temporal cues of speech sounds differently from infants without such a risk even before they learn to speak.