Hi Jason,
The number of samples refers to the number of attempts made from each
voxel in your seed mask -- it is entirely independent of the number
of targets you specify. So if you set samples to 5000 -- 5000 paths
will run per voxel in your seed mask.
>2. What are the major factors that affect the connectivity
>distribution? For example, how much does the size of the target
>image affect the results? How much does the curvature threshold
>affect the results?
Depends, really. Obviously bigger target masks as likely to capture
more paths but you could normalize for target (and/or seed mask)
size. Smaller targets are anatomically more precise and may
therefore be more meaningful.
The curvature makes a difference but it often isn't a huge difference
unless you're looking at a tract that takes a significant bend (where
significant is defined by your curvature value). Try a few values
and see what happens.
Cheers,
- Joe
-------------
Joseph T. Devlin, Ph. D.
FMRIB Centre, Dept. of Clinical Neurology
University of Oxford
Headley Way
Oxford OX9 3DU
Phone: +44-(0)1865-222-494
Email: [log in to unmask]
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