Decoding dyslexia - functional organization of letter-speech sound association in children at risk of developmental dyslexia (National Science Centre HS6/05584)

Project Leader:Project Leader: Katarzyna Jednoróg, PhD

Laboratory of Language Neurobiology, Nencki Institute of Experimental Biology



Learning to read is an important milestone in individual cognitive development characterized by the complex interplay of various kinds of skills and knowledge. However, the first critical step in reading development is to learn the correspondences between visual letters and auditory units of speech (speech sounds). This skill is essential for development of phonological awareness and fluent reading. According to the newest definition, it is mainly problems in automatic decoding (integration and transformation of letters to speech sounds) that characterize dyslexia. Developmental dyslexia is regarded as a serious social problem that affects 5 to 17% of population and is characterized by persistent difficulties in reading and/or spelling that are unexpected in relation to age, motivation or other cognitive abilities. Learning the neuronal correlates of letter speech-sound association will allow us to better understand the mechanisms behind dyslexia.

The proposed study has two main goals. First, thanks to studding children who are just at the beginning of school (6-7 year old), we want to examine how decoding skill (i.e. letter–speech sound integration) develops in the brain of and what brain regions are responsible for automatization of this process. Second, we plan to investigate what is the neuronal activity pattern in a decoding task in case of children at risk of dyslexia (having either genetic/familial or behavioural risk or both). We aim to conduct a longitudinal study and select those children from the at risk group who will develop the full spectrum dyslexia (RD+) at the age of 9 years and the ones who will not be diagnosed as having dyslexia (RD-) and compare these two groups – examining both the brain activity and brain structure.  We hypothesize that we can find differences in the neural responses to speech-sound integration task between dyslexic RD+ and control children even when they only begin formal education. We further hypothesize that that a neural deficit in letter–speech sound integration will be predictive of reading failure.