Maaike Vandermosten|Bart Boets|Hanne Poelmans|Stefan Sunaert|Jan Wouters|Pol Ghesquière
A tractography study in dyslexia: neuroanatomic correlates of orthographic, phonological and speech processing
KU Leuven|KU Leuven|KU Leuven|KU Leuven|KU Leuven|KU Leuven
diffusion tensor imaging tractography structural magnetic resonance imaging technique allowing reconstruction assessment integrity three dimensional white matter tracts indexed fractional anisotropy assumed left arcuate fasciculus plays crucial role reading development connects two regions reading network left temporoparietal region left inferior frontal gyrus atypical functional activation lower fractional anisotropy values reported dyslexic readers addition explored potential role left inferior frontooccipital fasciculus might connect third region reading network left ventral occipitotemporal region left inferior frontal gyrus present study 20 adults dyslexia 20 typical reading adults scanned using diffusion tensor imaging bilateral arcuate fasciculus left inferior frontooccipital fasciculus delineated group comparisons show significantly reduced fractional anisotropy left arcuate fasciculus adults dyslexia particular segment directly connects posterior temporal frontal areas fractional anisotropy reduction might reflect lower degree myelination dyslexic sample cooccurred group difference radial diffusivity contrast significant group differences fractional anisotropy found right arcuate fasciculus left inferior frontooccipital fasciculus correlational analyses controlled reading status demonstrated specific relation performance phoneme awareness speech perception integrity left arcuate fasciculus indexed fractional anisotropy orthographic processing fractional anisotropy values left inferior frontooccipital fasciculus present study reveals structural anomalies left arcuate fasciculus adults dyslexia finding corroborates current hypotheses dyslexia disorder network connections addition study demonstrates correlational double dissociation might reflect neuroanatomical correlates dual route reading model left arcuate fasciculus seems sustain dorsal phonological route underlying graphemephoneme decoding left inferior frontooccipital fasciculus seems sustain ventral orthographic route underlying reading direct word access