Neural deficits in children with dyslexia ameliorated by behavioral remediation: evidence from functional MRI

Abstract

Developmental dyslexia, characterized by unexplained difficulty in reading, is associated with behavioral deficits in phonological processing. Functional neuroimaging studies have shown a deficit in the neural mechanisms underlying phonological processing in children and adults with dyslexia. The present study examined whether behavioral remediation ameliorates these dysfunctional neural mechanisms in children with dyslexia. Functional MRI was performed on 20 children with dyslexia (8-12 years old) during phonological processing before and after a remediation program focused on auditory processing and oral language training. Behaviorally, training improved oral language and reading performance. Physiologically, children with dyslexia showed increased activity in multiple brain areas. Increases occurred in left temporo-parietal cortex and left inferior frontal gyrus, bringing brain activation in these regions closer to that seen in normal-reading children. Increased activity was observed also in right-hemisphere frontal and temporal regions and in the anterior cingulate gyrus. Children with dyslexia showed a correlation between the magnitude of increased activation in left temporo-parietal cortex and improvement in oral language ability. These results suggest that a partial remediation of language-processing deficits, resulting in improved reading, ameliorates disrupted function in brain regions associated with phonological processing and produces additional compensatory activation in other brain regions.

Figures

Figure 1

Neural effects of remediation in children with developmental dyslexia. (A) Left hemisphere activations of control children and children with dyslexia are shown during rhyming (as compared with matching) letters (P < 0.025, 20-voxel threshold; ref. 12). (B) Brain areas that showed increased activity during phonological processing in the dyslexic group after remediation. Shown at P < 0.01, 20-voxel threshold. Black circles highlight left temporo-parietal region, which is disrupted in children with dyslexia and affected by remediation. Purple circles highlight the left frontal region that is active in control children and is affected by remediation in children with dyslexia.

Figure 2

Language improvement and increased brain function. Correlation between magnitude of change in left temporo-parietal ROI (BA 39) and improvement in oral language (r = 0.41, P = 0.03). Left temporo-parietal ROI encompassed brain areas that showed underactivation and increases after training in children with dyslexia. Change in effect size is on the vertical axis; change in total language score (CELF-3) is on the horizontal axis. Effect size is the weighted sum of parameter estimates from the multiple regression for rhyme vs. match contrast pre- and posttraining.