I have performed PALM analysis on CIFTI files (myelin maps from HCP). I used tail approximation and 500 permutations. I did it with the -logp option so that when I visualise the results I set the threshhold with the minimum at 1.3 (which corresponds to 0.05) and max to whatever max there is in the picture. Now my results seem a bit peculiar and I wanted to ask your advice.

I have six contrasts (g1>g2, g2>g1 and positive and negative effects of age and gender). In g1>g2 contrast literally almost whole brain is significant, whereas in the g2>g1 I cannot even threshhold anything because everything is zero. The positive effect of age, however, is also significant almost everywhere. 

Now I am a bit confused, a) if the positive effect of age is significant in almost all regions, should the g1>g2 comparison be not as strong (because it should be adjusted for the age effect?) Is it normal that g1>g2 still shows so much significance everywhere (same regions as the positive age effect)? and b) Even though it is line with my expectations I am a bit wary to see significant differences covering the whole brain. Is there maybe some error that might have led to that or something I have to double check? So far I checked my GLM and input files and cannot find anything weird/wrong there.

Sorry for the probably basic question and thanks a lot for the help!

Lisa