Hi Ellen, you can create a contrast to do this, something like:
mkcontrast-sess -a 1 -c 0 -sumdelays -setwdelay
-sumdelays will sum across the different time points -setwdelay will cause it to prompt you for a list of weights, one for each time point. You should give the timpoints in the fir window that you don't want a value of 0, and a value of 1 for the time points you do want.
Once you have this, you can just run isxconcat-sess and mri_glmfit as usual
doug
On 04/12/2012 12:38 PM, Ellen Lau wrote:
Hi,
We ran a first-level FIR analysis on our functional data with selxavg3-sess, which outputs a single ces.nii file for each subject containing the contrast images for all timepoints. Now we would like to create an image representing the sum of a subset of these images in a time-window of interest (e.g. contrast4s + contrast6s + contrast8s) and then bring this single 4-8s contrast for each subject forward to the second-level (presumably by concatenating these summed 4-8s images into a single file that mri_glmfit will accept). Could someone advise us on the best way to do these two steps?
thanks, Ellen _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer