I have some simple questions regarding the meaning of a couple of the
fields in the SPM8 Volume of Interest utility, which I'd like to use
to extract time-series based on a predefined binary mask.
I'm clear on the meaning of these fields:
matlabbatch{1}.spm.util.voi.spmmat =
{'/Applications/fmri/data/analysis/SPM.mat'};
matlabbatch{1}.spm.util.voi.adjust = 5;
matlabbatch{1}.spm.util.voi.session = 1;
matlabbatch{1}.spm.util.voi.name = 'my_voi_name';
matlabbatch{1}.spm.util.voi.roi{1}.mask.image =
{'/Applications/fmri/data/ACT45/showandtell/ACT45_501/analysis/delta_rtmod/cj_w-h_fwe05_dmpfc_ba8.img,1'};
But am less clear on these:
matlabbatch{1}.spm.util.voi.roi{1}.mask.threshold = 0;
matlabbatch{1}.spm.util.voi.expression = 'i1';
I don't understand what the threshold refers to for a mask, which is
typically binary. In the same way, I'm unsure how to use the
expression field. I realize the format is the same as spm_imcalc,
which I'm familiar with, but again am not sure how this would apply to
a binary mask. With the above settings I get an error upon execution:
Error using ==> svd
Input to SVD must not contain NaN or Inf.
Any information would be much appreciated, thanks in advance!
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Bob Spunt
Postdoctoral Fellow
Social Cognitive Neuroscience Lab - www.scn.ucla.edu
Department of Psychology
University of California, Los Angeles
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