White matter fascicles and cortical microstructure predict reading-related responses in human ventral temporal cortex

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Reading engages specific brain regions, notably the lateral ventral temporal cortex (VTC).
• The consistent spatial organization of reading responses in the lateral VTC across individuals is not fully understood, especially given that reading is a learned skill.

Purpose of the Study:

• To investigate whether white matter fascicles and gray matter microstructure predict the precise location of reading-related activity in the lateral VTC.
• To determine the contribution of specific white matter tracts and cortical microstructure to the individual mapping of reading responses.

Main Methods:

• Acquired functional MRI (fMRI), diffusion MRI (dMRI), and quantitative MRI (qMRI) data from 30 adults.
• Mapped reading-related responses using fMRI by contrasting reading tasks with control tasks (adding, color).
• Analyzed white matter fascicle endpoint densities (arcuate fasciculus - AF, inferior longitudinal fasciculus - ILF, vertical occipital fasciculus - VOF) and cortical gray matter microstructure (proton relaxation time - T1) using dMRI and qMRI.

Main Results:

• Endpoint densities of the AF, ILF, and VOF significantly predicted reading-related responses in the lateral VTC.
• Cortical T1 measurements further improved the predictive accuracy of the fascicle model.
• A combined model including T1, AF, ILF, and VOF accurately predicted the spatial map of reading responses and the location of the visual word form area.

Conclusions:

• White matter architecture (AF, ILF, VOF) and gray matter microstructure (T1) are key determinants of the individual spatial layout of reading-related activity in the lateral VTC.
• This data-driven approach elucidates the neural basis for the consistent organization of reading networks in the human brain.