Dear SPM users,
I have run an fMRI experiment where each stimulus presentation is followed
by a gap (to allow for response), followed by a scan. I therefore have
obtained a perfomance (%correct) score for each Task scan. I am interested
in the brain regions where fMRI signal correlates with performance.
However, I have inserted some "Rest" scans as well so I can explore the
main effect (Task vs Rest) irrespective of performance. I have a total of
60 scans (20 are Rest).
When I use the simple regression option in SPM2, I am asked to enter 60
values. If I allocate a 0 to the Rest scans, then my results are,
expectedly, very similar to those obtained when doing the Task vs Rest t
contrast. It does not however make sense to allocate a 0% correct
performance to a rest period, so I would like to SPM to IGNORE these Rest
scans.
Is there a simple way to do this?
It would be great if I did not have to remove the 20 Rest scans manually...
Many thanks in advance for your help,
Frederique
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Frederique Liegeois, PhD
UCL Institute of Child Health
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