Letter-sound processing deficits in children with developmental dyslexia: An ERP study

The time course during letter-sound processing was investigated in children with developmental dyslexia (DD) and typically developing (TD) children using electroencephalography.

Thirty-eight children with DD and 25 TD children participated in a visual-auditory oddball paradigm. Event-related potentials (ERPs) elicited by standard and deviant stimuli in an early (100-190 ms) and late (560-750 ms) time window were analysed.

In the early time window, ERPs elicited by the deviant stimulus were delayed and less left lateralized over fronto-temporal electrodes for children with DD compared to TD children. In the late time window, children with DD showed higher amplitudes extending more over right frontal electrodes. Longer latencies in the early time window and stronger right hemispheric activation in the late time window were associated with slower reading and naming speed. Additionally, stronger right hemispheric activation in the late time window correlated with poorer phonological awareness skills.

Deficits in early stages of letter-sound processing influence later more explicit cognitive processes during letter-sound processing.

Identifying the neurophysiological correlates of letter-sound processing and their relation to reading related skills provides insight into the degree of automaticity during letter-sound processing beyond behavioural measures of letter-sound-knowledge.