Dear SPMers,
first, thanks for providing answers to questions from me and others.
I have found them very informative and useful.
Now, for my current problem. I am performing a drug study. The
design is basically a simple block design with three conditions. The
subjects perform six cycles of the three conditions. This paradigm
is repeated 5 times: with no drug, low drug, medium drug, high drug,
and then again after drug reversal. I am looking for areas which are
either more or less active as a function of drug concentration. Any
suggestions on how to set up a design matrix? Should I make one big
matrix including all 5 scans? Should I use parametric modulation?
and if so, what should be the values of the regressors?
thanks,
Alex
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