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Dear SPM experts, I have a question regarding implicit baseline. I'm analysing a motor tapping task in which there are three conditions: right, left and rest. I initially included the three conditions in my GLM design matrix and then performed a PPI analysis in the contrast 'Right vs Rest' taking the left putamen as as seed region. I've been recently advised to not include the rest condition in my model (neither for the GLM activity analysis nor for the PPI connectivity analysis) and let it be the implicit baseline. I've compared the results and I see that in the GLM, the results are almost exactly identical in the two cases, that is, including the rest condition in the model in one case and letting the rest as a implicit baseline in the other case. However, the PPI analysis are completly different. I don't understand why is that and what is exactly the difference between the contrast 'Right vs Rest' and just 'Right' having the resting as a implicit baseline. Thank you very much for your help in advance, Clara