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Here is the solution to my previous posting inquiring about PPI in SPM5. First, Thank you Darren G, for your help. To conduct PPI in SPM5 where I have the following 6 conditions: Rest = Silence Click = Clicking (A non-vocal sound) Bell = a school bell ringing Whistle Whistle = A shrill coaches whistle NFV Lang = A non -familier Voice Reading non-ambiguous paragraphes aloud NFV SON = A non-familiar voice calling subject's name aloud I want to compare NFV Lang with NFV SON using PPI to see which voxels are correlated with a VOI of interest. This is what worked: First I CREATED VOI by : * After "Specifying 1st Level" I selected Results and SPM.Mat file. * Selected NFV Lang - NFV SON - Rest contrast (that I had previously created) * Selected a group of voxels in the frontal area (Near Superior Frontal Gyrus), * Clicked on VOI button * Named the VOI * Selected sphere with 6 mm Then set up for PPI analysis by: * I clicked on PPI button * Selected corresponding spm.mat file * Chose psychophysiolgoic ... * Sleeted saved voi.mat file * Included NFV Lang condition with contrast weight = 1 (positive) * Included NFV SON condition with contrast weight = -1(negative) Then I set up a NEW MODEL by: First I changed directories (so nothing would get written over) * Copied over my PPI file (that was created from step above) to my new directory * Clicked on specify 1st level * Selected Directory of Choice * Select Seconds or Scans whichever is appropriate * Select HRF with Time derivatives (if indicated) * NO CONDITIONS entered * Select the Regresssors option (so that three regressor pop up windows appear) Enter in this order: 1. Regressor 1: Name = Name PPI.ppi or whatever you want Value = PPI.ppi (Make sure you use this case -SPM5 is case sensitive; the values will automatically populate into this field after you press enter) 2. Regressor 2: Name = PPI.Y (or whatever you want to call it) Value = PPI.Y (Again the values will automatically populate into this field after you press enter) 3. Regressor 3: Name = PPI.P (or whatever name you choose) Value = PPI.P * Click run Then to Estimate the model I: Clicking on Estimate and selected newly created spm.mat file (From the new directory ) Clicked run To explore results: * YOU CAN HAVE 2 CONTRASTS THAT LOOK AT PPI. The first is 1 0 0 0 which means: 1 0 0 0 ^ ^ ^ ^ ppi y p mean assuming you put regressors in that order. This will look at areas showing activation relative to the interaction of (NFV Lang - NFV SOn) x Y, while discounting the effects of Y and P. the other contrast is -1 0 0 0 which looks at the opposite interaction. To better understand the above function you can go to: http://www.umich.edu/~fmri/course/2005/files/spm2/spm_peb_ppi.m Thanks again Darren G. for your help with the above Theresa Louise-Bender Pape, Dr.PH, MA, CCC-SLP/L Career Development Transition Award Scientist Department of Veterans Affairs Rehabilitation Research & Development Service Research Service, Hines VAH Research Health Scientist Center for Management of Complex Chronic Care Center of Excellence, Hines VAH Research Assistant Professor Northwestern University Feinberg School of Medicine Department of Physical Medicine and Rehabilitation Clinical Research Scientist Marianjoy Rehabilitation Hospital Senior Associate Northwestern University Feinberg School of Medicine, Institute for Health Care Studies Preferred Contact Information: Voice Mail: (708) 202-4953 Confidential Fax: (708) 202-7487 Email: [log in to unmask] Pager : (312) 707-3345 Mailing Address: Hines VA, Research Service, PO BOx 5000, MC 151H, Hines, IL 60141 Shipping Address: HInes VA, 5th Ave and Roosevelt Ave., Building 1, Room C 318, Hines, IL 60141