mris_glm does not correct for multiple comparisons itself. However, you can use fdr inside of tksurfer, or ...

Steve Smith and I just worked out how to use the FSL randomise program to compute the vertex-wise threshold. Randomise implements permutation testing, which is much less conservative than FDR or GRF.

When you run mris_glm, make sure to specify the --y output (something like --y y-lh.mgh). then run mri_surf2surf to convert it to nifit, something like:

mri_surf2surf --srcsubject average7 --trgsubject average7 \
 --srcsurfval y-lh.mgh --src_type mgh \
 --trg_type nii  --trgsurfval y-lh.nii --hemi lh

You will also need to convert the design matrix produced by mris_glm (something like y.X.mat) into ascii. This can be done in matlab with something like:

load y.X.mat
save('X.asc','X','-ascii')

Then run:

randomise -i y-lh -o y-lh \
-d X.asc -t design.con -n 5000 -V

Where design.con has your contrasts

The output will be something like: y-lh_max_tstat1.mgh, which you can view with tksurfer with something like:

tksurfer average7 lh inflated -overlay y-lh_max_tstat1.mgh

We're still working out the details on this (obviously:), you may have to play with this a little to get the command lines exactly correct.

Note that randomise program cannot do cluster-based thresholding because it is not aware that these values are really on the surface (not in a volume), but the max stat will work.

doug


Antao Du wrote:

Hi,

I am running mris_glm to compare the cortical thickness between two groups.
I have a question, which method is used for correcting multiple comparison
in the analysis? Thanks,

Antao

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--
Douglas N. Greve, Ph.D.
MGH-NMR Center
[EMAIL PROTECTED]
Phone Number: 617-724-2358 Fax: 617-726-7422

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