Disentangling influences of dyslexia, development, and reading experience on effective brain connectivity in children.

• Age-, reading-level-matched and developmental connectivity analyses in children. • Effective connectivity was assessed in children with and without dyslexia. • Connectivity was also assessed in development of children with and without dyslexia. • Feedforward connections from the visual word form area (VWFA) increased with age. • Connectivity from the inferior parietal lobule to the VWFA was altered in dyslexia. Altered brain connectivity between regions of the reading network has been associated with reading difficulties. However, it remains unclear whether connectivity differences between children with dyslexia (DYS) and those with typical reading skills (TR) are specific to reading impairments or to reading experience. In this functional MRI study, 132 children (M = 10.06 y, SD = 1.46) performed a phonological lexical decision task. We aimed to disentangle (1) disorder-specific from (2) experience-related differences in effective connectivity and to (3) characterize the development of DYS and TR. We applied dynamic causal modeling to age-matched (n dys = 25, n TR = 35) and reading-level-matched (n dys = 25, n TR = 22) groups. Developmental effects were assessed in beginning and advanced readers (TR: n beg = 48, n adv = 35, DYS: n beg = 24, n adv = 25). We show that altered feedback connectivity between the inferior parietal lobule and the visual word form area (VWFA) during print processing can be specifically attributed to reading impairments, because these alterations were found in DYS compared to both the age-matched and reading-level-matched TR. In contrast, feedforward connectivity from the VWFA to parietal and frontal regions characterized experience in TR and increased with age and reading skill. These directed connectivity findings pinpoint disorder-specific and experience-dependent alterations in the brain's reading network. [ABSTRACT FROM AUTHOR]