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Dear all, I am running an analysis with parametric modulations. The contrast "1" is supposed to reveal areas with increasing signal while "-1" with decreasing signal (https://www.jiscmail.ac.uk/cgi-bin/wa.exe?A2=ind05&L=SPM&P=R168802). However, when I plot the contrast "-1", I am getting some areas with increasing activation and other areas decreasing. You can see the effect at the attached pictures. How is this possible? I have observed that the attached examples are one for for response at 5.1 seconds and the other at 15.8 seconds. This is how SPM plots that, I just used the plot button. Any clue on what kind of modulations I am getting? Dorian. PhD Student Ruhr University Bochum.