Hi Jenifer,
Below are some answers: Quoting "Juranek, Jenifer " <[EMAIL PROTECTED]>:
Hi, We've run LGI and have looked at the overlay. 1) Is there a txt-type file containing the actual LGI values as computed across aggregates of vertices? Noticed that the recon-all.log file does contain a quantitative value summarizing an average of each hemisphere.
Yes, the ?h.pial_lgi is a curv file containing one lgi value per cortical vertex. You can easily convert it in a text file using mri_convert, or read it in Matlab.
2) Is there a way to plot the computed LGI info along the rostral-caudal extent of each hemisphere?
What kind of rostro-caudal extent are you thinking about? Something like in the Zilles et al paper in 1988? These kind of rostro-caudal made sense before the 3D, when GI was computed on 2D coronal sections. As you had one value per slice with, representing them along the rostro-caudal extent was useful to get more precision on the localization of the differences. I would say that the vertex-wise approach is more sensitive to local differences that only the rostro-caudal axis... That said, if you have a rationale for that, everything is possible in Matlab!
3) Best method to compare across subjects (or groups)? Seems like qdec is based on vertex-wise analyses, whereas LGI uses aggregates of vertices.
In the validation paper, we compared group on a vertex-wise basis, exactly as you would do it for cortical thickness measurements (i.e. using Qdec). As a first step before the vertex-wise, you can also take the average lGI values provided in the recon_all.log in order to compare them between groups and see the direction of the difference.
Hope it helps, Marie
Many Thanks for any assistance anyone can provide Jenifer ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
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