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Date: Wed, 19 Jul 2006 08:42:08 -0400 (EDT)

Hi Mike

A. the wm parcellation isn't released yet, but I think we'll do so soon

(Doug: what do you think). The current tools should allow you to correlate

demographic/neuropsych with parcellation units (e.g. superior frontal

gyrus).

B. The improved bias correction should help both the cortical and

subcortical streams.

C. The control points range of effect depends on the other control points

(auto and manual) near it). If a control point is anterior to all others it

can have an effect on the entire frontal region.

you should post these to the list - other people can answer some of them

(like A) better than I can.

cheers,

Bruce

On Wed, 19 Jul 2006, Mike Chee wrote:

> Hi Bruce,

> I have a couple of questions:

> A. We are interested in correlating parcellated brain volumes of brain lobes

> (not subcortical structures for openers) with neuropsych test scores. For

> example, middle frontal gyrus volume with executive function. Presently, it

> seems that it is possible to evaluate cortical thickness globally and then

> pick our areas that regress to a significant extent with variables of

> interest. At some point in time, it would be good to see if the combination

> of GM + the underlying WM would give additional / complimentary information.

> In this regard, I am not entirely clear how we are to realize this goal.

> According to David’s HBM 2006 poster, this would take place by adding the

> volume of the cortical rim and its underlying WM.

> B. If so, this would necessitate good quality segmentation along the

> volumetric pipeline (that generates the .aseg images). This in turn would

> require some adjustments in the segmentation of white matter using the

> volume processing stream. By dropping control points, we active improved

> segmentation along the surface processing stream (correct?) If so, how are

> benefits to volume measurement realized? As I understand our data, the

> surface processing pipeline is more or less satisfactory as is. So I wonder

> what the marginal benefit of dropping control points is?

> C. A final question relates to how laying control points in WM works. Jenni

> told us that dropping more points increases intensity in an additive

> fashion. If so what is the intensity shift and how extensive is the induced

> change?

> If you think these questions serve a general audience, feel free to post

> this question in the help website.

> Mike

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