just a quick note: you want to take the con-Images. If you want to know
why, there are several good posts in the list archives at
As to your approach, it will tell you where activation is correlated
with performance. If this is what you want to know, then the approach
looks ok to me. One problem that you will run into, however, is sample
size: 9 subjects is considered not enough for a valid random effects
study. Perhaps a non-parametrical approach using SnPM helps
(alternatively, as usual, scan more subjects, but we all know this is
sometimes feasible and sometimes not).
Elliot Dickerson schrieb:
> Hello all,
> This is likely a somewhat silly question but I couldn't find
> a definitive answer in the SPM documentation.
> I have a 9-subject study in which I would like to carry out a regression
> analysis of amount of fMRI signal against task performance.
> I have done a first level analysis that specifies T contrasts with a
> vector of (1, -1) for task blocks and control blocks respectively. This
> seems to generate a *con *and *spmT *file in the output folder.
> For the second level analysis, I am specifying a regression analysis
> with 9 images against a 9x1 vector of task performance data. For the
> nine images, I am selecting the images which should represent increased
> activation during the task block of the experiment.
> 1. Is this generally an acceptable approach?
> 2. Have others had much success in regressing task performance
> against the amount of fMRI signal?
> 3. Most pressing, should I be using *con_00** images or *spmT_00**
> images in this type of analysis? On visual inspection, they seem
> very similar, but they scale differently and aren't quite the
> same. I can't intuitively figure out how or why they represent
> different things.
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Marko Wilke (Dr.med./M.D.)
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Universitäts-Kinderklinik University Children's Hospital
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