Small-World Propensity in Developmental Dyslexia After Visual Training Intervention

Abstract

AbstractAltered functional networks in children with developmental dyslexia have been found in previous electroencephalographic studies using graph analysis. Whether learning with visual tasks can change the semantic network in this childhood disorder is still unclear. This study of the local and global topological properties of functional networks in multiple EEG frequency bands applies the method of small-world propensity in visual word/pseudo-word processing. The effect of visual training on the brain functional networks of dyslexics compared with controls was also studied. Results indicated that the network topology in dyslexics before the training is more integrated, compared to controls, and after training it becomes more segregated and similar to that of the controls in the theta, alpha, beta, and gamma bands for three graph measures. The pre-training dyslexics exhibited a reduced strength and betweenness centrality of the left anterior temporal and parietal regions in the θ, α, β1, and γ1-frequency bands, compared to the controls. In the brain networks of dyslexics, hubs have not appeared at the left-hemispheric/or both hemispheric temporal and parietal (α-word/γ-pseudoword discrimination), temporal and middle frontal cortex (θ, α-word), parietal and middle frontal cortex (β1-word), parietal and occipitotemporal cortices (θ-pseudoword), identified simultaneously in the networks of normally developing children. After remediation training, the hub distributions in theta, alpha, and beta1-frequency networks in dyslexics became similar to control ones, which more optimal global organization was compared to the less efficient network configuration in dyslexics for the first time.KeywordsEEGFunctional connectivityDevelopmental dyslexiaFrequency oscillations