Symposium: Development of auditory and speech processing in infants and children
Wednesday, Sep 9, 2015
Hörsaal 3

Atypically large brain response to deviant speech sounds in dyslexic children – compensatory effects on reading related skills?

Kaisa Lohvansuu1, Jarmo Hämäläinen2, Annika Tanskanen2, Leena Ervast3, Heikki Lyytinen2, & Paavo Leppänen2

1Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
2University of Jyväskylä, Jyväskylä, Finland
3University of Oulu, Oulu, Finland

Dyslexia is a neurobiological disorder impairing reading acquisition of around 10% of school-aged children despite adequate cognitive level, reading instruction, and other extraneous factors. Dyslexia is characterized by a phonological deficit, but the way the impaired phonological processing mediates resulting dyslexia or reading disabilities is unclear.

We used ERPs to study speech sound processing in 30 dyslexic children with familial risk for dyslexia, 51 typically reading children with familial risk for dyslexia, and 58 typically reading control children. In dyslexics with familial risk enhanced brain responses to shortening of a phonemic length in pseudo-words (/at:a/ vs. /ata/) were found as compared to other groups. The enhancement was related with better behavioral phonemic length discrimination performance, and with better reading and writing accuracy. Source analyses showed the brain responses of a sub-group of dyslexic children with largest responses to originate from a more posterior area of the right temporal cortex as compared to the responses of the others.

We concluded that the best readers within the dyslexic group have probably developed alternative strategies employing compensatory mechanisms to substitute their possible earlier deficit in phonological processing. Consequently they could perform better in phoneme length discrimination, as well as in reading and writing accuracy tasks. Nevertheless, we found no association to reading fluency, which as usually has been found, seems to need more effort and time to compensate.