Back to PLS HelpPosted on 12/09/13 08:42:16
Number of posts: 1
Dear all,
I am doing the first attempt to analyse my fMRI data using PLS so I had 2 basic questions I did not find a good answer to:
1) What is an optimal smoothing kernel for preprocessing the images. Would 8mm be good? this is my standard for SPM.
2) My design is a fast event related fMRI with simuli comming every 5.1s (with some jitter). The TR is 2.5s. What would be an optimal size for the temporal window? (hemodynamic period).
Julian
Replies:
Posted on 12/09/13 08:49:23
Number of posts: 394
Hi Julian,
for smoothing, we usually use 2x the resampled voxel size - so if your final image is 4mm^3m, then 8mm smoothing is good. Less than that is not helpful and more may help a bit with misalignments between subjects but can attenuate signals from smaller regions
for the temporal window - that's less fixed. I would try with 8TRs and see how the results look at the end of the epoch. If you get hints of 'bleed' (e.g. effects coming up that are there earlier in the window) then shorten the window.
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