Hi surfers: I have a two questions. 1) how does freesurfer calculate ?h.sulc file and ?h.curv. Are they calculated after gray/white/csf segmentation? Are they calculate based on gray/white boundary? So, difference between ?h.sulc or ?h.curv will directly come from white matter change, right? 2) what's the difference between ?h.sulc and ?h.curv? In terms of sulcal structure, does ?h.sulc indicate sulcal depth and ?h.curv somehow indicate sulcal width? To me, from the display, ?h.sulc seems a smoothed version of ?h.curv. From some reference, I know .sulc is also called average convexity, so is the convexity for each vertex averaged within a small region or is it averaged through the whole hemisphere brain surface? Thanks much for your help! BestJing
They are computed from the ?h.white surface. The ?h.curv is the spatially smoothed mean curvature, and the ?h.curv is the integrated dot product of the movement vector with the surface normal during inflation. Therefore the curv is a local differential measure that will highlight small scale structure, while the sulc is insensitive to small local geometry and highlights larger scale structure (e.g. was the point deep even though it was folded out)
On Tue, 7 Feb 2012, Jing Ming wrote:
Hi surfers: I have a two questions. 1) how does freesurfer calculate ?h.sulc file and ?h.curv. Are they calculated after gray/white/csf segmentation? Are they calculate based on gray/white boundary? So, difference between ?h.sulc or ?h.curv will directly come from white matter change, right? 2) what's the difference between ?h.sulc and ?h.curv? In terms of sulcal structure, does ?h.sulc indicate sulcal depth and ?h.curv somehow indicate sulcal width? To me, from the display, ?h.sulc seems a smoothed version of ?h.curv. From some reference, I know .sulc is also called average convexity, so is the convexity for each vertex averaged within a small region or is it averaged through the whole hemisphere brain surface? Thanks much for your help! Best Jing
I think Bruce meant:
"the ?h.sulc is the integrated dot product of the movement vector with the surface normal during inflation."
Peace,
Matt.
-----Original Message----- From: freesurfer-bounces@nmr.mgh.harvard.edu [mailto:freesurfer-bounces@nmr.mgh.harvard.edu] On Behalf Of Bruce Fischl Sent: Wednesday, February 08, 2012 10:48 AM To: Jing Ming Cc: Freesurfer Subject: Re: [Freesurfer] Question about ?h.sulc and ?h.curv
They are computed from the ?h.white surface. The ?h.curv is the spatially smoothed mean curvature, and the ?h.curv is the integrated dot product of the movement vector with the surface normal during inflation. Therefore the curv is a local differential measure that will highlight small scale structure, while the sulc is insensitive to small local geometry and highlights larger scale structure (e.g. was the point deep even though it was folded out)
On Tue, 7 Feb 2012, Jing Ming wrote:
Hi surfers: I have a two questions. 1) how does freesurfer calculate ?h.sulc file and ?h.curv. Are they
calculated after gray/white/csf segmentation? Are they calculate based on gray/white boundary?
So, difference between ?h.sulc or ?h.curv will directly come from white
matter change, right?
2) what's the difference between ?h.sulc and ?h.curv? In terms of sulcal
structure, does ?h.sulc indicate sulcal depth and ?h.curv somehow indicate sulcal width?
To me, from the display, ?h.sulc seems a smoothed version of ?h.curv. From
some reference, I know .sulc is also called average convexity, so is the convexity for
each vertex averaged within a small region or is it averaged through the
whole hemisphere brain surface?
Thanks much for your help! Best Jing
oops, thanks Matt Bruce On Wed, 8 Feb 2012, Matt Glasser wrote:
I think Bruce meant:
"the ?h.sulc is the integrated dot product of the movement vector with the surface normal during inflation."
Peace,
Matt.
-----Original Message----- From: freesurfer-bounces@nmr.mgh.harvard.edu [mailto:freesurfer-bounces@nmr.mgh.harvard.edu] On Behalf Of Bruce Fischl Sent: Wednesday, February 08, 2012 10:48 AM To: Jing Ming Cc: Freesurfer Subject: Re: [Freesurfer] Question about ?h.sulc and ?h.curv
They are computed from the ?h.white surface. The ?h.curv is the spatially smoothed mean curvature, and the ?h.curv is the integrated dot product of the movement vector with the surface normal during inflation. Therefore the curv is a local differential measure that will highlight small scale structure, while the sulc is insensitive to small local geometry and highlights larger scale structure (e.g. was the point deep even though it was folded out)
On Tue, 7 Feb 2012, Jing Ming wrote:
Hi surfers: I have a two questions. 1) how does freesurfer calculate ?h.sulc file and ?h.curv. Are they
calculated after gray/white/csf segmentation? Are they calculate based on gray/white boundary?
So, difference between ?h.sulc or ?h.curv will directly come from white
matter change, right?
2) what's the difference between ?h.sulc and ?h.curv? In terms of sulcal
structure, does ?h.sulc indicate sulcal depth and ?h.curv somehow indicate sulcal width?
To me, from the display, ?h.sulc seems a smoothed version of ?h.curv. From
some reference, I know .sulc is also called average convexity, so is the convexity for
each vertex averaged within a small region or is it averaged through the
whole hemisphere brain surface?
Thanks much for your help! Best Jing
Thanks, Bruce and Matt. bestJingDate: Wed, 8 Feb 2012 11:53:44 -0500 From: fischl@nmr.mgh.harvard.edu To: matt@ma-tea.com CC: freesurfer@nmr.mgh.harvard.edu; mj_coming@hotmail.com Subject: Re: [Freesurfer] Question about ?h.sulc and ?h.curv
oops, thanks Matt Bruce On Wed, 8 Feb 2012, Matt Glasser wrote:
I think Bruce meant:
"the ?h.sulc is the integrated dot product of the movement vector with the surface normal during inflation."
Peace,
Matt.
-----Original Message----- From: freesurfer-bounces@nmr.mgh.harvard.edu [mailto:freesurfer-bounces@nmr.mgh.harvard.edu] On Behalf Of Bruce Fischl Sent: Wednesday, February 08, 2012 10:48 AM To: Jing Ming Cc: Freesurfer Subject: Re: [Freesurfer] Question about ?h.sulc and ?h.curv
They are computed from the ?h.white surface. The ?h.curv is the spatially smoothed mean curvature, and the ?h.curv is the integrated dot product of the movement vector with the surface normal during inflation. Therefore the curv is a local differential measure that will highlight small scale structure, while the sulc is insensitive to small local geometry and highlights larger scale structure (e.g. was the point deep even though it was folded out)
On Tue, 7 Feb 2012, Jing Ming wrote:
Hi surfers:
I have a two questions.
- how does freesurfer calculate ?h.sulc file and ?h.curv. Are they
calculated after gray/white/csf segmentation? Are they calculate based on gray/white boundary?
So, difference between ?h.sulc or ?h.curv will directly come from white
matter change, right?
- what's the difference between ?h.sulc and ?h.curv? In terms of sulcal
structure, does ?h.sulc indicate sulcal depth and ?h.curv somehow indicate sulcal width?
To me, from the display, ?h.sulc seems a smoothed version of ?h.curv. From
some reference, I know .sulc is also called average convexity, so is the convexity for
each vertex averaged within a small region or is it averaged through the
whole hemisphere brain surface?
Thanks much for your help!
Best Jing
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