Dear Experts,
I know the slice-timing problem in event related fmri is very complex and
controversial (Henson, Buchel, Josephs & Friston ...).
Can you tell me if the following sentences are correct?
1) If I've an event related design with TR >= 3 sec and I don't perform
slice timing correction and the time and dispersion derivatives are
statistical significant, this result could be attributable to the different
acquisition time among slices (noise) and it couldn't be attributable to the
"bold response" (signal). Is this correct?
2) If yes, I can think to perform slice timing correction to make more valid
my inference when I use an informed basis set but I know that the spm 2
algorithm brings in errors with TR >= 3 sec so it is better not to perform
slice timing correction. Is this correct?
3) Can I use a less constrained set of multiple basis functions as fourier
set or gamma functions or also a FIR model to fix this problematic
situation? For example if I use a fourier set am I sure to find statistical
significant results attributable to the "bold response" (signal) and not
attributable to the different acquisition time among slices (noise)?
4)If I've an event related design with TR <= 2 sec the precedent problems
are less relevant, the spm 2 algorithm doesn't bring in errors so I can
perform slice timing correction but it is not necessary because the TR <=2.
Is this correct?
In practice what do you suggest me?
Thank you in advance.
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