Intra-Areal Visual Topography in Primate Brains Mapped with Probabilistic Tractography of Diffusion-Weighted Imaging

Area of Science:

• Neuroscience
• Neuroimaging
• Primate Brain Anatomy

Background:

• Noninvasive diffusion-weighted MRI (dMRI) maps neural connectivity but is limited by resolution.
• Understanding brain organization requires sensitive mapping techniques.

Purpose of the Study:

• To assess high-resolution postmortem dMRI and tractography for mapping visual pathways in macaque brains.
• To compare dMRI-based maps with established retinotopy in the visual cortex.
• To investigate the differential connectivity of magnocellular and parvocellular compartments.

Main Methods:

• Utilized high-resolution postmortem diffusion-weighted MRI (dMRI) and probabilistic tractography.
• Mapped retinotopic organization of the lateral geniculate nucleus (LGN) and visual area V5/MT.
• Compared dMRI-derived maps with established functional retinotopy of primary visual cortex (V1).

Main Results:

• Predicted topographic maps from dMRI data closely matched established retinotopy for LGN and V5/MT.
• Differential connectivity of LGN compartments (magnocellular/parvocellular) was replicated.
• Tractography using in vivo dMRI data also produced comparable topographic maps.

Conclusions:

• Tractography based on dMRI is sufficiently sensitive to map intrinsic organization of topographically organized neural structures.
• This technique can reveal the functional organization resulting from these connections.
• dMRI provides a powerful tool for noninvasive brain connectomics.