Language networks in Autism Spectrum Disorder: A systematic review of connectivity-based fMRI studies

Autism Spectrum Disorder (ASD) is a heterogeneous condition associated with differences in functional neural connectivity relative to neurotypical (NT) peers. Language-based functional connectivity represents an ideal context in which to characterize connectivity because language is heterogeneous and linked to core features in ASD, and NT language networks are well-defined. We conducted a systematic review of language-related functional connectivity literature on individuals with ASD using PubMed, PsychInfo, Scopus, ProQuest, and Google Scholar, yielding 96 studies. Language-task studies indicated local over-connectivity within the language network and global under-connectivity of language with out-of-network regions in ASD. Resting-state studies showed mixed patterns, and connectivity was associated ASD symptomology and language skills. This evidence indicates language-task elicited local over-connectivity and global under-connectivity in ASD, but not a local versus global distinction of resting-state language-related connectivity. Associations with behavior suggest that local over-connectivity and global under-connectivity characterize ASD, and heightened language-related connectivity may support social function.