Perfect, thanks a lot! that will be helpful, best, David 2017-05-31 19:02 GMT+02:00 MCLAREN, Donald <[log in to unmask]>: > Hi David, > > Sorry for the delayed response. This makes sense. We actually used this > approach in Humbert and McLaren to show the effect of habitation on swallow > number. This should automatically be done if you are using the gPPI toolbox. > > https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4002228/ > > As for multiple orthogonalized PM, including one or both would probably > depend on your research question. I like to use the same comparisons in PPI > as in my task models and results (e.g. include everything). > > Best, > Donald > > Best Regards, > Donald McLaren, PhD > > > On Wed, May 31, 2017 at 12:41 PM, David <[log in to unmask]> wrote: > >> About my previous post, >> I believe that performing PPI on orthogonalized modulators should make >> sense. >> The rationale is to test brain voxels that correlate with activity in one >> VOI, as a function of its interaction with aspects of a parametric >> modulator that cannot be accounted for by other regressors. >> However, I would like to have the opinion of some expert on both PPI and >> pmod (e.g., Donald McLaren). >> >> Best, >> David >> > > -- --------------------- David Pascucci Postdoctoral Fellow University of Fribourg Department of Psychology Rue de Faucigny 2 1700 Fribourg Switzerland