Correction: FI = Sum-over-vertices[ |kmax|(|kmax|-|kmin|)]/SurfaceArea

On Sep 28, 2011, at 1:38 PM, Donna Dierker wrote:

My understanding is that GI is also a global summary stat across the whole hem, while lGI is *local* GI (vertex-wise). It measures how folded the cortex is at that vertex. GI and lGI are based on area, while the folding index is based on curvature. Truly different measures.

Gyrification Index (GI) = Pial surface area / Convex hull surface area (Zilles et al., 1988)

Folding Index (FI) = |kmax|(|kmax|-|kmin|) Van Essen and Drury 1997

On Sep 28, 2011, at 10:48 AM, Nick Schmansky wrote:

...

have a look at this page:

https://surfer.nmr.mgh.harvard.edu/fswiki/LGI

folding index is typically a single number summarizing the amount of folding overall on a surface. freesurfer puts these measures in subjid/stats/?h.curv.stats.

gyrification index is a new method created by maria schaer to create a surface-based measure of folding (points across a surface describing the local folding measures).

n.

On Wed, 2011-09-28 at 11:05 -0400, Alan Francis wrote:

...

Hi Bruce, Nick & Doug:

How does Folding index differ from Gyrification index?

thanks,

Alan

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