Cortical region seeds in tractography

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?

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

Do they suppose there are intracortical fiber tracts?

I’m so confusing…

Thanks in advance for any advice!


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