The relation of home literacy environment to brain specialization and sensitivity for phonological and semantic processing of spoken words

Purpose: Neural specialization is a developmental phenomenon across multiple domains of language processing. The home literacy environment (HLE) is observed to relate to brain activation during language and reading tasks; however, whether HLE relates to phonological and semantic functional specialization and sensitivity remains unknown. Method: Using an open-source dataset, the present study examined 33 5–6-year-olds and 76 7–8-year-olds. Data from fMRI sound and meaning judgment tasks were used to examine phonological and semantic functional specialization (contrasting tasks) and sensitivity (comparing conditions within a task). Then, voxel-wise regression analyses were used to test correlations between those brain indexes and HLE (i.e., family-to-child reading, child independent reading) measured using a parent survey. Results: We observed weak evidence of phonological specialization at 5 years old and weak evidence of semantic specialization at 7 years old associated with family-to-child reading. We also observed weak evidence of phonological sensitivity at 5 years old and strong evidence of semantic sensitivity at 7 years old associated with family-to-child reading. Across the cohorts, a progression from temporal to frontal brain regions was observed in those relations, in line with prior literature on language specialization and sensitivity across development. Conclusions: Overall, our results suggest that HLE is linked to functional specialization and sensitivity, with a relation of family-to-child reading to processing the sound structure of language at 5 years old and meaning at 7 years old. This finding supports the Interactive Specialization theory, which emphasizes the role of environmental inputs in neural specialization.