Vandermosten, M. 1, 2, 3 , Correia, J. 2 , Vanderauwera, J. 1 , Wouters, J. 1 , Ghesquiere, P. 1 & Bonte, M. 2
1 KU Leuven
2 Maastricht University
3 UCSF
Currently, there is an ongoing debate whether phonological deficits in dyslexics should be attributed to less well specified phonetic representations per se or rather to an impaired access to these speech sound representations. A recent study in adults with dyslexia, using a combination of fMRI multi-voxel pattern analysis (MVPA) and diffusion MRI connectivity measures, demonstrated intact neural quality of phonetic representations but decreased temporoparietal-to-frontal connectivity (Boets et al., 2013). These adult data support the hypothesis of intact phonetic representations, yet they conflict with findings from EEG and speech perception studies in young dyslexic children. Therefore, the current study aims to capture the developmental trajectory of potential deficits in speech sounds representations by applying a multimodal approach (fMRI MVPA and diffusion MRI) at the start of reading onset. Of the 60 participating children, 15 went on to develop dyslexia, and they showed already prior to reading onset, an aberrant temporoparietal-to-frontal connectivity, indexed by a lower FA in left and right Arcuate Fasciculus. In addition, in contrast to adults, poorer decoding of the speech sounds was observed in dyslexics 7- to 8-year olds relative to their typically reading peers, supporting an access ànd representational deficit in young dyslexic children.