Multidimensional semantic activation in children's discourse reading is associated with their reading ability.

Around fourth grade, children transition from learning-to-read to reading-to-learn, yet how their multidimensional semantic representation during discourse reading differs from that of adults and relates to reading ability remains unclear. This study investigated multidimensional semantic activation in 42 fourth-to sixth-grade children (mean age 10.3 years) and 44 adults (mean age 25.1 years) during story reading using fMRI. Children were stratified by reading ability using inverse efficiency scores from comprehension questions. Semantic activation across six dimensions (visual, motor, social, emotional, spatial, temporal) was modeled using the Six Semantic Dimension Database. Results showed that high-reading-ability children exhibited significantly stronger temporal but weaker social semantic activation compared to adults, whereas low-reading-ability children showed adult-like patterns. Brain-behavior association analyses revealed that multidimensional semantic activation patterns were linked to reading performance in children (explaining 25.0% of variance), whereas no such relationship was evident in adults. Additionally, high-reading-ability children demonstrated enhanced activation in cognitive control networks relative to both low-ability peers and adults. These findings suggest that high-reading-ability children may strategically modulate multidimensional semantic processing through cognitive control to compensate for limited reading experience, highlighting the flexible, strategy-dependent nature of multidimensional semantic representation during developmental reading.