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I'm trying to use pickatlas with SPM and I'm running into a problem. I have a ROI that appears to be just under the threshold for significant after small volume correction (.049 FDR). However, when I use pickatlas and .05 FDR as my threshold, my activation does not reach threshold. HOWEVER, if I use .072 FDR my activations show up, and in the table the corrected p value is properly listed as .05 To sum, my problem is that the threshold has to be relaxed by ~.022 in order for the actual threshold (.05) to be seen by SPM. I've included 3 screen shots that illustrate my problem: "uncorrected" shows what happens if i set an uncorrected p-value and then use SPM's SVC function. you can see that the FDR corrected is .05 "pickatlas_05" shows what happens if i use pickatlas and set the p-value to .05 FDR. no activations reach the threshold and finally, "pickatlas_072" shows what happens if i use pickatlas and set the p-value to .072 FDR. at this point it appears most of the activations that reach the .05 threshold appear. This isn't a rounding error. The activations do not show up if I try .051 or .06, only at .072. Also matlab shows that the FDR corrected p-value is ~.049. I was wondering if this is a bug in the software and if there is a workaround? Or is it a problem in my data? I was hoping to use this program in order to produce accurate activation maps of just the small volume corrected ROI. So alternatively, if anyone can recommend a separate method for doing so I would be quite appreciative. Wei-chun Wang