Efficacy of RAN Training in Children with Dyslexia: Behavioral and Brain Correlates

Vander Stappen, C. 1, 2, 3 & Van Reybroeck, M. 1, 2, 3

1 Université catholique de Louvain (UCLouvain, Belgium)
2 Psychological Science Research Institute (IPSY)
3 Development of Literacy Lab (DeLi Lab)

Although studies on RAN are abundant, no study has demonstrated the efficacy of RAN training among children with dyslexia so far. Besides, the brain basis of RAN and its contribution to phonological and orthographic reading strategies are still not well understood. This study aimed to address these gaps with a RAN-objects intervention administered to children with dyslexia, and with behavioral and brain measures to assess its efficacy. Trained children (n = 18) were compared to untrained normal-reading children (n = 13) on RAN, word reading, word spelling, and diffusion MRI measures, before and immediately after the intervention. Results showed significant improvements of the trained children in RAN. These gains were correlated with increased regular word reading speed. They were also associated with increased fractional anisotropy in several white matter tracts, including the left anterior and the left long segments of the arcuate fasciculus (i.e. dorsal pathway), the right inferior fronto-occipital fasciculus (i.e., ventral pathway), and the left inferior cerebellar peduncle. Importantly, RAN improvements were associated the most with fractional anisotropy changes in the left long segment of the arcuate fasciculus. Our findings open up new perspectives for remediation of dyslexia, and suggest that RAN is mainly involved in phonological processing.