A Mixed Longitudinal EEG Study of Sensorimotor Rhythm Modulation and Its Relationship with Language Development in Children Aged 3–10 Years

Background: Sensorimotor (mu) rhythms reflect the functional state of sensorimotor cortical networks and are of increasing interest for understanding typical and atypical neurodevelopment. However, the developmental trajectories of mu rhythm modulation in preschool and early school-age children remain poorly characterized. Objectives: We studied age-related changes in alpha (8–13 Hz) and beta (13–30 Hz) sensorimotor rhythms in children aged 3 to 10 years using a mixed longitudinal design and investigated their relationship with language development. Methods: EEG was recorded twice (interval ~1 year) in 44 typically developing children during three conditions: passive hand movement (PHM), video hand movement observation (VHM), and a control condition (video fractal movement, VFM). Language was assessed with the Preschool Language Scales—Fifth Edition (PLS-5) in a subset of 32 of the 44 participants at the first time point. Modulation indices (log10(experimental/control)) were computed, and repeated-measures ANOVAs and Spearman correlations were performed. Results: PHM elicited desynchronization in both alpha and beta bands, while VHM induced alpha synchronization only. Alpha desynchronization showed contralateral lateralization during right- and left-hand movements, without age-related changes. Beta desynchronization showed no lateralization. Beta desynchronization during PHM correlated negatively with Auditory Comprehension and Total Language scores (ρ up to −0.62, FDR-corrected p < 0.05), indicating that more pronounced desynchronization of sensorimotor rhythms relates to better language abilities. Conclusions: These findings support the involvement of sensorimotor networks in auditory language comprehension and suggest that beta mu rhythm may serve as a sensitive marker of individual differences in language development, though replication in larger samples is warranted.