Hi. It's fine to specify stimulus timings via the 1-entry-per-volume
option (though often the 3-column format is easier to generate).
1) Is there a reason for turning off convolution? You still need to
convert stimulation timings into expected haemodynamic response timings.
(Also, you should probably leave the temporal filtering on as well).
2) If you have jitter - i.e., the stimulus timings do not exactly
correspond to whole volumes in time, then you should be using 3-column,
where you can specify the timings exactly (in seconds, to sub-TR temporal
It seems quite likely that without the above things set right, you won't
find any activation in an event-related experiment.
On Wed, 28 Apr 2004, Katherine Turner wrote:
> I am trying to analyze an event related study and having difficulty getting
> the appropriate output. I have three EV's: positive, negative, and
> baseline. In FEAT, for the EV's I have used the custom 1 entry per volume.
> I entered none for convolution and deselected temporal filtering. The
> matrix and model look appropriate but no stats come out. Should I have
> entered a separate column for the jitter? Any other reason FEAT would fail
> to produce the basic z-stats?
Stephen M. Smith DPhil
Associate Director, FMRIB and Analysis Research Coordinator
Oxford University Centre for Functional MRI of the Brain
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve