> I now understand the motivation for using the middle slice of the scans as the reference in the slice timing routine and setting the refences bin in the statistcs default to 8 (of 16), but,
>
> shouldn't the onset of the first stimulus be 0.5 scans rather than 0 scans.?
No, the onset of the first stimulus (assuming it is coincident with the
first scan)
should still be 0. The point of setting the reference time-bin (fMRI_T0)
to 8/16
is precisely to use the value of the HRF 0.5xTR seconds after stimulus
onset
as the value of the covariate for that scan.
Rik
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DR R HENSON
Wellcome Department of Cognitive Neurology
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England
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