Dear Ben
> Dear SPMers,
> I want to extract data which reflects the mean level of activity in
> a predefined
> ROI. The aim is to correlate the individual mean activity during an
> fMRI memory
> paradigm with other subject characteristics. I have computed the
individual
> first level contrasts (active – rest / block design).
> My question: which images should be used for extracting the average
activity
> in the ROIs? cons, betas or spmTmaps?
this is reflected in your beta images (this is the 'activity' of each regressor) - the con images are simply the linear combination of the betas so if what you want is the 'activity' from a contrast you can either read the con images or combine results from the betas :-) .. as for how to extract data may I suggest EasyROI from my own website ..
Best
Cyril
http://www.sbirc.ed.ac.uk/cyril