Hi Matt and Saad,
To clarify my point, we found that as the mean FA of the entire skeleton increased, the number of samples decreased between an ROI in the corpus callosum and cortical regions. We did this correlation for different cortical regions (seeds_to_...) and it is almost systematic.
One explanation was that the higher is your anisotropy the smaller is your dispersion, and so, the lower is the number of streamlines that go from one seed to the targets. Could you tell me if this is an over-interpretation.
Which kind of data would you see to have a good sense of what is going on?
Thanks again,
Hervé
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De : FSL - FMRIB's Software Library [[log in to unmask]] de la part de Matt Glasser [[log in to unmask]]
Date d'envoi : vendredi 23 septembre 2011 17:45
À : [log in to unmask]
Objet : Re: [FSL] Correlation between FA and tractography
To clarify, you found that as FA increased the number of streamlines
decreased and vice versa?
Increased amounts of crossing fibers could lead to reduced FA, but more
connectedness between many regions.
You would probably have to show more data for me to be able to better
interpret your findings, however.
Peace,
Matt.
-----Original Message-----
From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf
Of Herve Lemaitre
Sent: Friday, September 23, 2011 8:17 AM
To: [log in to unmask]
Subject: [FSL] Correlation between FA and tractography
Dear FSL users,
we ran tbss on several subjects and also bedpostx/probtrackx to do
tractography between one part of the corpus callosum and different regions
of the cortex.
Computing the average number of samples between the seed and each cortical
region, we found a negative correlation between global mean skeleton FA and
number of samples for each cortical region.
Is it normal to have this kind of negative correlation and how can we
explain it?
Thanks,
Hervé Lemaître
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