[MINC-users] cortical surface inflation

[Jonathan Harlap]

I believe the idea was more that you can take a signal measured on the 
surface (or mapped to the surface from the volumetric data) and then 
perform registration and subsequent analyses with the surface data. 
i.e., you don't map back from the surface to a volume.

Inflating a surface to a sphere is actually pretty trivial due to the 
way that the cortices are extracted, in that a sphere is shrinkwrapped 
down onto the cortex.  Thus, the function that maps vertices in your 
cortical surface back to vertices on the inflated sphere is simply the 
identity.  In other words, once you have a signal at each vertex on the 
cortex you can simply use the same signal on a sphere of identical 
structure (such as, say, the one used to generate the cortical surface) 
and you will have mapped the signal onto a sphere.

Surface registration is a topic I really can't comment on with any 
authority.  As to signals on the surface, Jason Lerch wrote about 
cortical thickness analysis on the wiki 
(http://wiki.bic.mni.mcgill.ca/index.php/CorticalThickness).  Noting 
that cortical thickness is just one example signal you can have on the 
surface, most of the information there should be easily applicable to 
other signals.

J

Marc Schoenwiesner wrote:
> Hi,
> 
> in his BIC seminar talk some weeks ago Alan Evans mentioned the possible
> advantages of coregistering anatomical volumes on a sphere to decrease
> intersubject variability for fMRI analysis. Once the cortical surfaces are
> extracted how would one proceed to do this with the MINC tools? The cortical
> surfaces need to be inflated into spheres and a transformation to get from the
> volume- to spherical space and back in needed, I guess.
> 
> Cheers,
> Marc
> 
> ===============================
> Marc Schoenwiesner, PhD
> Department of Neuropsychology
> Montreal Neurological Institute
> 3801 Rue University
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> tel: 514-398-2579    (+)/ (+)
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> www.bic.mni.mcgill.ca/~marcs
> lab website: www.zlab.mcgill.ca
> ===============================
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> 
> 
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