Hi Leslie
The number of samples used in building up the probability distribution in probtrackx is stored in a file called "waytotal" in the output directory.
This file contains the number of sample streamlines that haven't been rejected by the sampler (e.g. if you used exclusion/inclusion masks).
You need to divide your results (e.g. fdt_paths file, or the seed_to_target files) by this number to get probabilities that are comparable (i.e. mean the same thing) across subjects. You can do that easily with fslmaths.
Cheers,
Saad.
On 27 Jun 2011, at 09:00, Leslie Engineering wrote:
> In order to compile group probability tracks, I have transformed all single subject results to standard space and now need to normalize results. Where do I obtain the quantities for normalization?
>
> THanks so much,
> Leslie
--
Saad Jbabdi
University of Oxford, FMRIB Centre
JR Hospital, Headington, OX3 9DU, UK
(+44)1865-222466 (fax 717)
www.fmrib.ox.ac.uk/~saad
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