Functional connectivity fingerprints of emerging reading skill in the first months of schooling

The transition from pre-reading to early word reading skill in early childhood is a time of profound developmental change. To understand changes in brain wiring associated with reading development, this study examined individual differences in functional connectivity of the reading network at the start of formal literacy instruction. Sixty-six kindergarteners (ages 5-6) completed a visual word processing task during functional magnetic resonance imaging (fMRI). Based on standardized literacy assessments, participants were characterized as Pre-Readers (alphabetic knowledge but unable to read words) or Beginning Readers (some word reading ability). We compared patterns of task-based functional connectivity between children at different stages of literacy development using confirmatory subgroup Group Iterative Multilevel Model Estimation (cs-GIMME). cs-GIMME is a data-driven method that estimates directed, time-indexed, and individualized network connections between a priori regions of interest. Pre- and Beginning Readers did not differ in overall network complexity (number of functional connections between regions of interest). However, distinct periods of reading development corresponded to differences in network centrality, defined as the proportion of network connections involving specific regions of interest. Specifically, Pre-Readers had more distributed connections and greater within-right hemisphere connectivity. Beginning Readers demonstrated more symmetrical network organization, and greater centrality of the Visual Word Form Area and other left hemisphere language hubs. Increased reading skill was associated with increased left lateralization, potentially reflecting more mature networks and greater print processing efficiency. These findings provide novel insights into child brain development during the first year of formal schooling by revealing links between emerging literacy skills and functional neural connectivity.