Audiovisual integration in reading among school-aged children: Evidence from combined fMRI and EEG.

Reading fluency depends on rapid integration of print and speech, yet the spatiotemporal mechanisms supporting this integration in school aged children remain poorly understood. This study combined fMRI and EEG to examine AV integration (i.e., additive enhancement and congruency effects) during single- and multi-letter detection tasks in 7-10-year-old children (N = 56). Multiple neural indices were examined to capture complementary spatial and temporal aspects of AV integration. fMRI results revealed additive enhancement in bilateral STG and Heschl's gyrus, congruency effects in the left IFG and left STG and increased functional connectivity between left IFG and STG during incongruent trials. EEG showed convergent temporal dynamics, with AV-related enhancement in P200 amplitude (190-230 ms) and theta-band (4-7 Hz) power over left frontotemporal electrodes. Individual differences analyses showed that additive enhancement in left STG was associated with higher spelling (β = 0.28, p = 0.034). Congruency effects in left STG (β = 0.31, p = 0.018) and left IFG (β = 0.38, p = 0.004), as well as IFG-STG connectivity (β = 0.34, p = 0.011), were linked to higher reading efficiency. Larger P200 amplitude (β = 0.32, p = 0.015) and greater theta power (β = 0.31, p = 0.021; β = 0.28, p = 0.034) were associated with higher spelling and fluency, respectively. Findings delineate complementary sensory-convergence and conflict-monitoring pathways for print-speech integration and show that integrating spatial and temporal neural indices improves explanation of reading skills in school-aged children.