afni.nimh.nih.gov

Dear AFNI gang,
We are wondering the following: does AFNI take the absolute difference between two groups when computing a t-test when there is deactivation in one or both groups? If not, how do people handle negative values in their t-test results? Secondly, if there are voxels with zero values, and the t-test performs a voxel by voxel comparison, are some voxels with activation eliminated?

Thanks again.