Zaric, G. 1, 2 , Fraga González, G. 3 , Tijms, J. 3, 4 , van der Molen, M. 3 , Blomert, L. 1, 2 & Bonte, M. 1, 2
1 Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, University of Maastricht, Maastricht, Netherlands
2 Maastricht Brain Imaging Center (M-BIC), Maastricht, Netherlands
3 Department of Developmental Psychology, University of Amsterdam, Amsterdam, Netherlands
4 IWAL Institute, Amsterdam, Netherlands
The acquisition of letter-speech sound associations is one of the basic requirements for learning to read and deficient letter-speech sound associations may form the basis for reading difficulties in developmental dyslexia. Previous electrophysiological studies employing a cross-modal oddball paradigm revealed a late automation of these associations in normal readers and little automation in dyslexic readers. In the present study we employed the same cross-modal paradigm to extend these findings to dyslexic (n=22; 8.87±0.43 years) and normally reading (n=20; age: 8.68±0.37 years) children with 2.5 years of reading instruction. EEG data were recorded while the children listened to Dutch vowels /a/ (standard, 83%) and /o/ (deviant, 17%) in one auditory and two cross-modal conditions. In the cross-modal conditions the letter 'a' was presented either simultaneously with the vowels (AV0) or 200 ms before vowel onset (AV200). In line with previous findings, our results show comparable auditory mismatch negativity (MMN) responses to vowels in dyslexic and normal readers. In normal readers, the cross-modal conditions lead to enhanced MMN and late mismatch (~700 ms) responses for both the AV0 and AV200 conditions. Dyslexic children showed less cross-modal enhancement with an MMN enhancement only for the AV200 condition and a small late enhancement in the AV0 condition. These preliminary results indicate that after 2.5 years of reading instruction, normal readers show automatic integration of letters and speech sounds however at a different temporal window of integration in comparison with experienced readers. Furthermore, our results further confirm deficient letter-speech sound integration in dyslexic children.