Hi,

I'm running a PPI analysis where I would like to contrast the connectivity of one parametrically modulated condition to another. So I have ConditionA pmodA and ConditionB pmodB, and I'm interested in seeing where those two pmods differentially affect connectivity. I'm unsure how to set up the gPPI analysis to do this. The relevant lines of my code that I have so far are: 

P.Tasks={'1','ConditionA','ConditionB'};
P.Contrasts(1).left={'ConditionA'}; 
P.Contrasts(1).right={'ConditionB'};
P.Contrasts(1).Contrail=?? {'xpmodA^1' 'xpmodB^1}? how do I specify both pmods?

In general, is this the right setup to get what I'm looking for (PPI of task w/parametric modulators)? 

Thank you for your help!
Vanessa

Vanessa,

In the typical experiment, if you are comparing PM, then the PMs have the
same trailing name for each condition. In that case, you can just list the
single contrail. The contrail can be determined from SPM.Sess and/or
SPM.Sess([sesssion]).U(condition).P.name.

If the contrails are different names, then you'll need to specify
contrail.L={};
and contrail.R={}. This should work, although has not be thoroughly tested
across systems as most pmods have a common name across conditions.

Hope this helps.

Donald

thanks for the information Donald, that seems to have worked.

Thanks,
Vanessa