from the flobs directory
cheers-
andreas
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Von: FSL - FMRIB's Software Library [[log in to unmask]] im Auftrag von Stefano Peca [[log in to unmask]]
Gesendet: Donnerstag, 24. Juni 2010 22:32
An: [log in to unmask]
Betreff: [FSL] For Jack on [FSL] Obtaining non-canonical HRF from fMRI data in FSL
Thank you Jack, you've been very helpful. Bu I'm stuck on the last bit:
"Then do a weighted sum i.e. HRF = pe1*flob1 + pe2*flob2 + pe3*flob3. "
That is, I obtained the 3 numbers pe1, pe2, pe3, but where can I get the data (text files?) for the 3 curves flob11, flob2, flob3 (the basis set)?
thanks a lot,
Stefano
Thanks to you too Christian, I'll look into the FIR later on, but as you suggest, FLOBS should be fine.
On Thu, Jun 24, 2010 at 11:22 AM, Jack Grinband <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Hi Stefano,
You can use FLOBS to estimate HRFs for individual subjects. You will need a task that produces a reliable and predictable primary sensory activation. A flashing checkerboard is probably best, though, depending on the task, it may be possible to extract the HRF from the task itself, as long as you are careful to avoid circularity. For optimal estimation make sure your stimulus/checkerboard varies in duration but not in intensity. Enter the stimulus regressor into FEAT with FLOBS as the convolution. Turn on F-test and run FEAT.
Create a mask of the primary sensory region (i.e. visual cortex) and multiply the mask by the fzstat1.nii.gz, then threshold and binarize. Take those voxels, multiply by the parameter estimate map (pe1.nii.gz) for flob1, and average the parameter estimates for those voxels. Repeat for pe2 and pe3. Then do a weighted sum i.e. HRF = pe1*flob1 + pe2*flob2 + pe3*flob3. This will give you a customized impulse response for each subject. For more details see Grinband et al, Neuroimage 2008.
cheers,
jack
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