Dear SPM users,
I would like to perform a PPI analysis across two sessions with a condition differing among the sessions („medication“, i.e. stimuli perceived with placebo and drug). However, I cannot figure out how to exactly do this.
My first idea was to model the two different sessions, extract the VOIs for each session separately and combine them subsequently. However, I don’t know how to include the condition “medication” for the PPI analysis, since this would be a contrast across the two sessions, but SPM only offers to choose input variables of the first session. Or am I missing something?
My next idea was to concatenate the data pretending to have only one session and add a regressor that accounts for the session effects. But I am unsure how to do this. Is it valid to use the already preprocessed data and simply combine the movement regressors? Or would it be better to preprocess the two sessions in one run?
Thanks a lot for your help!!
carmen
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