Hi Giovanni,
I think the type of analysis you want to perform is a conjunction. If
you have contrast one for event A and contrast two for event B, you can
hold down the shift key and select both contrasts, upon which spm will
perform a conjunction for you. As to the different types, there are a
couple of papers on this (of which you may want to start with the most
recent ones as the concept evolved somewhat :)
Cheers,
Marko
Giovanni Cosmati wrote:
> Dear SPMers,
>
> I'm running a group study.
>
> I have 2 event types, A and B, from which I obtain 2 contrasts (cA, cB) at the single subject stage (i.e. 1st level analysis).
>
> Assuming that at the group level stage (i.e. 2nd level analysis) I want to show areas that are activated both by event A AND by event B, how should I proceed?
> Is there a specific design at the 2nd level that I can use for this purpose? Or can I use some kind of computation with ImCalc, like cA*cB with a certain thresholding or scaling factor? Or the correct way is to generate a t-contrast at the 1st level for the logical AND of A and B (how?) and then run a t-test on this contrast at the 2nd level?
>
> Thank you in advance for you answer,
>
> Giovanni
>
--
____________________________________________________
PD Dr. med. Marko Wilke
Facharzt für Kinder- und Jugendmedizin
Leiter, Experimentelle Pädiatrische Neurobildgebung
Universitäts-Kinderklinik
Abt. III (Neuropädiatrie)
Marko Wilke, MD, PhD
Pediatrician
Head, Experimental Pediatric Neuroimaging
University Children's Hospital
Dept. III (Pediatric Neurology)
Hoppe-Seyler-Str. 1
D - 72076 Tübingen, Germany
Tel. +49 7071 29-83416
Fax +49 7071 29-5473
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