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Sam, Thank you very much for your advice. I have done what you suggested and it has worked. Excellent. I have just one further query on the display of the activation map for exp2. Even though it has been masked by the activation map of exp1, the 3D orthogonal view does not reflect that. The statistical table however does list only those clusters significant under the mask. I wonder if, in SPM by button pressing, one could display ONLY those areas of activation in exp2 which are under the mask of exp1? Many thanks in advance. Ying ----- Original Message ----- From: "Sam Reyes" <[log in to unmask]> To: "Ying Zheng" <[log in to unmask]> Sent: Wednesday, November 07, 2001 4:08 PM Subject: Re: Fw: masking > Ying, > > If you already have the two studies analyzed. I would use IMCalc to > make an image of all the supra threshold voxels in exp1. Then > Results->select exp2->select contrast of interest->threshold at lower > than usual values (p<0.005 uncorrected, for example on a PET > experiment)->Push S.V.C button->image mask->pick the image you made with > ImCalc from exp1. > > The corrected p-values you see in the Graphics windows list will be > corrected for a smaller search volume (your mask image) but only those > voxels which passed your initial threshold will be listed. This is why > you use a lower than usual significance threshold initially. > > Hope it helps, > > ---sam >