Figure 2A. Validating Laminar Myelin Mapping.

Figure3. Charting cortical area boundaries using cortical layer-specific myeloarchitectonic transitions.

Figure 4. Equivolumetric Layer-specific Myelin Transitions provide Improved Sensitivity to Cortical Area Boundaries Compared to Midthickness-weighted Gradients.

Figure 5. Comparison of Cortical Area Atlases from Four Studies.

Figure 7A, C. Comparison of macaque and human parcellation of cerebral cortex.

Supplementary Figure 7. Charting Bands of Baillarger in the macaque cerebral cortex.

Supplementary Figure 8. Comparison of equivolumetric, midthickness-weighted and cortical thickness gradients.

Supplementary Figure 9. Charting Area Boundaries and Areal Subdivisions in the Sensorimotor Cortices.

Supplementary Figure 10. Charting Area Boundaries in the Auditory and Vestibular Cortex.

Supplementary Figure 11. Charting Area Boundaries in Insular Cortex.

Supplementary Figure 12. Charting Area Boundaries adjacent to MT complex (MT+).

Supplementary Figure 13. Charting Area Boundaries in Intraparietal Cortex.

Supplementary Figure 14. Charting Area Boundaries in Orbitofrontal Cortex.

Autio2026_wwmGp.scene

FULL TITLE:
Charting cortical layer-specific area boundaries using Gibbs’ ringing attenuated T1w/T2w-FLAIR myelin MRI

SPECIES:
Macaque

DESCRIPTION:
The equivolumetric layer scheme of macaque cerebral cortex used to delineate putative cortical area boundaries.

ABSTRACT:
Cortical areas have traditionally been defined by their distinctive layer cyto- and/or myelo- architecture using postmortem histology. Recent studies have delineated many areas by measuring overall cortical myelin content and its spatial gradients using T1w/T2w ratio MRI in living primates, including humans. While T1w/T2w studies of areal transitions might benefit from using the layer profile of this myelin-related contrast, a significant confound is Gibbs’ ringing artefact, which produces signal fluctuations resembling cortical layers. Here, we address these issues with a novel approach using cortical layer thickness-adjusted T1w/T2w-FLAIR imaging in the macaque cortex, which attenuates the amplification of opposite-phase Gibbs ringing seen in the conventional T1w/T2w ratio by exploiting the in-phase Gibbs pattern of T2w-FLAIR relative to T1w, thereby reducing ringing artefacts and improving intracortical myelin contrast. Whole-brain MRI measures were mapped onto twelve equivolumetric layers, and comparison with histological Gallyas myelin stains explains over 80% of the variance in the laminar T1w/T2w-FLAIR profiles, substantiating the validity of the method. Layer-specific sharp myeloarchitectonic transitions were then identified using spatial gradients, resulting in a putative 182 area/subarea partition of the macaque cerebral cortex. The myelin maps exhibit notably high homology with those in humans, suggesting cortical myelin shares a similar developmental program across species. Altogether, our approach provides a non-invasive means for precision mapping of laminar myeloarchitecture in the primate cerebral cortex, advancing the pioneering work of classical neuroanatomists.

PUBLICATION:
Imaging Neuroscience