Hi,
yep - then you can probably use the 1-column format.
fix>A resp. B is simply -1(A/B>fixation).
Cheers-
Andreas
________________________________________
Von: FSL - FMRIB's Software Library [[log in to unmask]] im Auftrag von Graeme Schwindt [[log in to unmask]]
Gesendet: Freitag, 2. April 2010 20:03
An: [log in to unmask]
Betreff: Re: [FSL] AW: [FSL] AW: [FSL] FEAT model set up with Block design with irregular block spacing
Hi Andreas,
No, there's no jitter, and each block is the same length of 24 seconds, so I assume the single column design will work?
How will I specify higher level contrasts of Fixation > A or B if it is not a defined EV?
Thanks again, last question, I promise...maybe.
Graeme
On Fri, Apr 2, 2010 at 12:56 PM, Andreas Bartsch <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Hi,
yes - sounds good. Do you jitter? Then you might be better off with the 3-column format. Also don't model the baseline, i.e. fixation.
Cheers-
Andreas
________________________________________
Von: FSL - FMRIB's Software Library [[log in to unmask]<mailto:[log in to unmask]>] im Auftrag von Graeme Schwindt [[log in to unmask]<mailto:[log in to unmask]>]
Gesendet: Freitag, 2. April 2010 17:42
An: [log in to unmask]<mailto:[log in to unmask]>
Betreff: Re: [FSL] AW: [FSL] FEAT model set up with Block design with irregular block spacing
Thanks Andreas,
I should have been more specific - I am wondering how to actually set up the model. For full model setup in the GUI I would use a square wave, but because each condition does not have a simple periodicity to it, there is not a constant on-off cycle for a condition, so I cannot enter each condition as an EV this way.
e.g., ABBABAAB, the timing between B blocks is not constant in a run.
I think I need to use a custom file as described in the manual for single events.
Would it be appropriate to simply model each condition as a column, with "1" for each timepoint within the block, and "0" off, hence being a square wave, and then this is convolved with FLOBS?
Also, would I model my fixation baseline condition as a third EV or keep it unspecified? I am interested in looking at the contrast of baseline > A+B
Sorry if this is not making much sense, I am brand new to FEAT.
Thanks,
Graeme
On Wed, Mar 31, 2010 at 2:32 PM, Andreas Bartsch <[log in to unmask]<mailto:[log in to unmask]><mailto:[log in to unmask]<mailto:[log in to unmask]>>> wrote:
Hi,
this is no issue. Everything will be taken care of by the copes/varcopes.
Andreas
________________________________
Von: FSL - FMRIB's Software Library [[log in to unmask]<mailto:[log in to unmask]><mailto:[log in to unmask]<mailto:[log in to unmask]>>] im Auftrag von Graeme Schwindt [[log in to unmask]<mailto:[log in to unmask]><mailto:[log in to unmask]<mailto:[log in to unmask]>>]
Gesendet: Mittwoch, 31. März 2010 21:24
An: [log in to unmask]<mailto:[log in to unmask]><mailto:[log in to unmask]<mailto:[log in to unmask]>>
Betreff: [FSL] FEAT model set up with Block design with irregular block spacing
Hello everyone,
I am analyzing an fMRI data set with two runs, each with two stimulation conditions (A,B). Each block of stimulation is followed by a shorter block of baseline fixation.
However, the spacing varies between block types over the run.
Example, for subject 1:
Run1: ABBA BAAB
Run2: BAAB ABBA
So we can see that the spacing between 'A' blocks is not regular over the run. Should this be a source of concern?
Is it possible to set up the EVs in FEAT model set up to reflect this irregular spacing between block types?
Thanks
--
Graeme C. Schwindt, HBSc
MD/PhD Student
University of Toronto
[log in to unmask]<mailto:[log in to unmask]><mailto:[log in to unmask]<mailto:[log in to unmask]>>
--
Graeme C. Schwindt, HBSc
MD/PhD Student
University of Toronto
[log in to unmask]<mailto:[log in to unmask]>
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