Cortical region seeds in tractography

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1

Hi everyone:

I have a question related to cortical region seeds in tractography:

Generally, we perform tractography in white matter.
But why FSL FDT set grey matter as the seed region?
https://fsl.fmrib.ox.ac.uk/fsl/fslwiki/FDT/UserGuide

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and this powerful paper also set every fusiform voxels as seeds (using FSL methods above)

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Do they suppose there are intracortical fiber tracts?

I’m so confusing…

Thanks in advance for any advice!

2

Hello,

I believe the streamlines are only propagated from the WM boundary of these GM regions.

Best,
Steven