Hi,
Have you made sure that the timings of the events are in seconds and
not TRs?
Cheers.
On 27 Feb 2008, at 19:10, Jeffrey Miller wrote:
> Hello,
> I'm having a problem with regressors (EVs) that I've loaded in as
> 3-column text files. For a 160-volume epi, I have two regressors:
>
> negbase is "on" (value =1) for 1 volume at a time at volumes 32, 40,
> 64, 88,
> 112, and 120, and "off" (value=0) the rest of the time. I am not
> convolving
> it with a hemodynamic response function.
>
> negact is on for 4 volumes at a time beginning at volumes 35, 43,
> 67, 81,
> 115, and 123.
>
> When I put these in as EV's and look at the resulting model, there
> are two
> problems, which can be seen on the accompanying screenshot:
>
> 1) negbase only shows two episodes with valence of 1, not the six
> that exist
> in the regressor text file.
> 2) the timing doesn't seem correct: the first episode of valence 1 in
> negbase should occur at volume 32, but it looks like it occurs in
> the model
> around volume 20.
>
> Any idea why the image of the model seems not to correspond to my
> regressor
> text files?
>
> Thanks,
> Jeff
> <model.tiff>
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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
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