Splenium microstructure is related to two dimensions of reading skill

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Cognitive Neuroscience

Background:

• Inconsistent findings exist regarding corpus callosum (CC) structural differences between dyslexic readers (DRs) and typical readers (TRs).
• The CC splenium's role in reading is not fully understood.
• Investigating specific white matter pathways is crucial for understanding reading development.

Purpose of the Study:

• To investigate microstructural differences in the CC splenium between DRs and TRs.
• To explore the association between CC splenium microstructure and reading-related skills.
• To identify potential neural correlates of reading abilities and difficulties.

Main Methods:

• Diffusion Tensor Imaging (DTI) was used to assess CC splenium microstructure.
• A comprehensive reading skills battery was administered to participants.
• Nine DRs and 18 TRs were included in the study.

Main Results:

• DRs exhibited higher fractional anisotropy (FA) and axial diffusivity (LA) in the CC splenium compared to TRs.
• Orthographic retrieval was negatively associated with splenium FA and LA in both groups.
• Phonological awareness correlated positively with splenium FA and LA in TRs, but not in DRs.

Conclusions:

• The CC splenium shows distinct microstructural properties in DRs.
• Specific white matter pathways in the CC splenium are differentially associated with reading skills.
• These findings contribute to understanding the neurobiology of reading and dyslexia.