Individual fMRI activation in orthographic mapping and morpheme mapping after orthographic or morphological spelling treatment in child dyslexics

Abstract

Four sets of word-form tasks were administered during fMRI scanning to 18 child dyslexics and 21 controls to identify unique brain activation associated with four kinds of mapping—orthographic, morpheme with and without phonological shift, and phoneme—before treatment, and to measure the effect on each kind of mapping after orthographic and morphological spelling treatment (to which dyslexics were randomly assigned). Dyslexics and/or controls showed significant pretreatment activation in group maps in 18 brain regions during one or more of the mapping tasks. Average fMRI z-scores were used to determine for each kind of fMRI mapping which of the 18 brain areas (a) differentiated dyslexics and controls before treatment; (b) showed significant pre- to post-treatment activation change in dyslexics; (c) showed post-treatment ‘normalization’ of activation; and (d) changed differently for dyslexics as a function of the kind of treatment received. Dyslexics in orthographic treatment showed reliable change, normalization, and treatment-specific response in right inferior frontal gyrus and right posterior parietal gyrus. Implications of the findings of the combined group map and individual (region of interest) analyses for neurolinguistics, including assessment, treatment and brain plasticity, and the role of different word forms in spelling at a specific developmental stage, are discussed.