Language laterality in autism spectrum disorder and typical controls: a functional, volumetric, and diffusion tensor...

Area of Science:

• Neuroscience
• Developmental Psychology
• Linguistics

Background:

• Language and communication deficits are core features of autism spectrum disorder (ASD).
• Reduced or reversed language asymmetry is observed in ASD and other disorders.
• Previous research linked language laterality to anatomy in healthy adults, but not systematically in ASD.

Purpose of the Study:

• To investigate differences in gray matter volume of perisylvian language regions and white matter connections between language regions.
• To compare language abilities in individuals with typical left-lateralized language versus atypical (bilateral or right) language asymmetry.
• To examine the relationship between language laterality and neuroanatomy in adolescents with and without ASD.

Main Methods:

• Compared 14 adolescent boys with ASD and 20 typically developing adolescent boys.
• Included equal numbers of left- and right-handed individuals in each group.
• Examined gray matter volume of language regions and fractional anisotropy of the arcuate fasciculus.

Main Results:

• Individuals with typical left-lateralized language showed smaller frontal language region volume and higher arcuate fasciculus fractional anisotropy.
• These anatomical differences were observed across both ASD and control participants.
• Atypical language laterality was more prevalent in the ASD group than the control group.

Conclusions:

• Findings support an association between language function laterality and the anatomy of language regions.
• Anatomical differences may be more related to variations in language laterality than specifically to ASD.
• Language laterality could be a novel method for subdividing samples to create more homogenous groups for developmental disorder research.