Brain activation profiles in dyslexic children during non-word reading: a magnetic source imaging study

The purpose of the study was to identify spatiotemporal brain activation pr ofiles associated with phonological decoding in dyslexic children using mag netic source imaging. For this purpose maps of regional cerebral activation were obtained from eleven children diagnosed with dyslexia and ten childre n without reading problems during engagement in a pseudoword rhyme-matching task. All dyslexic children showed aberrant activation maps consisting of reduced activity in temporoparietal areas in the left hemisphere (including the posterior part of the superior temporal, angular and supramarginal gyr i) and increased activity in the right homotopic region. In contrast, the t wo groups of children did not differ in the degree of activity in basal tem poral areas that typically precedes temporoparietal activation. This is the first study to demonstrate the existence of distinct activation profiles a ssociated with phonological decoding in individual dyslexic children. (C) 2 000 Published by Elsevier Science ireland Ltd.