Hello All,
I used probtrackx2 to track between A and B (with B as a waypoint and termination mask) and calculated the seeds_to_target (B) file. I wish to compare the connectivity between groups but I wonder how best to handle any necessary normalization to allow for equivalent across-subject comparisons on the connectivity values (i.e., mean of the seeds_to_target). I read that using the waytotal may be a good approach.
https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind1106&L=fsl&P=R50105&1=fsl&9=A&I=-3&J=on&K=2&d=No+Match%3BMatch%3BMatches&z=4
https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind1205&L=fsl&P=R7773&1=fsl&9=A&I=-3&J=on&d=No+Match%3BMatch%3BMatches&z=4
However, in this case, where I have one seed and one classification target, the waytotal = the mean of seeds_to_target x the number of seed voxels. In that way, it doesn't seem appropriate to divide the seeds_to_target value by the way total since that ends up being (1/# voxels), when averaged across the ROI (A).
When I use more the one classification target, the waytotal no longer has that relationship, which may be why this approach was suggested previously (or maybe I am missing something here).
If I divide the mean of seeds_to_target by 5000 then I get the % of streamlines from the seed that reach the target, correct? This seems to me to be a possible measure to use for cross group comparisons.
Any advice on this topic is very welcome,
P
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