Hello,

I have a statistical map populated with t-stats that were derived from a functional dataset. I would like to use AFNI’s GUI functionality to dynamically threshold this image based on the associated p-value. The problem is that AFNI doesn’t seem to recognize that it’s dealing with t-statistics, and so it’s not giving me the options available on other datasets we’ve worked with, namely setting the p-value and adding FDR curves.

The image I’m currently working with was converted to a BRIK file from NIFTI format using 3dcopy (with only the input file specified; no additional arguments). When I compare the .HEAD files of the old, working dataset with the new, problematic data, I notice a few dissimilarities: the old datasets are denoted with “3DIM_HEAD_FUNC” under the TYPESTRING field, whereas the new dataset has “3DIM_HEAD_ANAT”. The old headers also contain the fields BRICK_LABS, BRICK_STATSYM (under which “Ttest(14)” is one of the values) and a series of FDR_CURVE_00000# fields, among several other things that the newer data lacks.

I’m assuming that the omission of fields like these is the reason I’m not able to use the p-value thresholding with the new data. My question (assuming my hunch is correct) is how (or if) I can recover the p-value thresholding functionality in this situation. I should note that the output of the new dataset is separated from the raw data by multiple intermediate images, but that it ought to still be functional rather than anatomical data. Is there some option I’ve neglected in the 3dcopy call, or am I using the wrong function entirely? And if the information used to generate those missing fields are truly not present in my new dataset, am I out of luck, or would there be a way to manually add them to the header file myself?

To make it clearer what I'm after, I’ve attached images of the “Define Overlay” section with the old and new data (respectively). On the old data, I’m able to select “t” (the label for Ttest(14)) and have the p-value show up in the bottom left corner; with the new data, I have no options to change the value from #0, and the p-value section remains “N/A”.

Any help sorting this out would be appreciated.