Poster E63, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Phonetic representations in young children with dyslexia
Maaike Vandermosten1,2,3, Joao Correia2, Jolijn Vanderauwera1, Jan Wouters1, Pol Ghesquiere1, Milene Bonte2; 1KU Leuven, 2Maastricht University, 3Uuniversity of California San Francisco (UCSF)
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 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 itself but decreased temporoparietal-to-frontal connectivity (Boets et al., 2013). The current study aims to capture the developmental trajectory of potential deficits in phonetic representations by applying a multimodal approach (fMRI MVPA and diffusion MRI) at the start of reading onset. Fifty-two children (grade 2), of whom half had a family risk for dyslexia and 15 developed dyslexia later on, participated in this study. In the scanner, children listened to various acoustic utterance of /baba/ and /dada/. MVPA analyses indicated that controls (i.e. typical reading children without a family risk) displayed distinctive phonetic decoding in bilateral superior temporal lobe (left: p =.037; right: p =.019), whereas children with dyslexia could not significantly decode (left: p = .241; right: p =.946). Children with dyslexia had less distinct neural phonetic representations than controls (left: p =.031; right: p =.041). In addition, white matter organization of the left arcuate fasciculus, examined prior to reading onset (kindergarten), predicted phonetic distinctiveness in grade 2 (r = .373, p = .039). Finally, typical reading children with a family risk for dyslexia show no deviances in neural connectivity but displayed the same problems in neural distinctiveness as dyslexic children.
Topic Area: LANGUAGE: Development & aging