Altered Cortico-cerebellar effective connectivity of the Visuo-attentional system is associated with READ1 deletion...

Developmental dyslexia (DD) is a heritable neurodevelopmental disorder associated with altered brain connectivity. The influence of genetic risks on cortico-cerebellar effective connectivity (EC) remains unclear. The present study investigates how reading proficiency and the READ1 deletion (READ1d) in the DCDC2 gene modulate visuo-attentional network dynamics. Functional MRI data were acquired in 78 children (DD and typical readers, with/without READ1d) performing a coherent motion detection task. EC within a seven-region visuo-attentional network, including magnocellular, ventral attention, and cerebellar (crus I) regions, was estimated using Dynamic Causal Modelling. Group-level effects were assessed using Parametric Empirical Bayes within a hierarchical Bayesian framework, testing reading proficiency, READ1d status, and their interaction (posterior probability threshold, Pp > 0.95). Reading proficiency was associated with increased cerebellar influence on visual and frontal regions, alongside reduced intra-cortical connectivity within dorsal stream pathways. The presence of READ1d was associated with reduced EC from primary visual and cerebellar regions to magnocellular and ventral attention networks, and increased intra-cortical interactions. The interaction between DD and READ1d revealed further reductions in cortico-cerebellar connectivity and altered network dynamics. Group-level analyses revealed EC differences in cortico-cerebellar pathways, which are reported as exploratory findings. Cortico-cerebellar EC is modulated by both reading proficiency and genetic susceptibility. Altered cerebellar contributions to visuo-attentional processes may represent a potential imaging-genetic signature of dyslexia, warranting replication in independent samples and validation through longitudinal and multimodal approaches.