afni.nimh.nih.gov

It's a little more complicated than that. The dataset is stored with a scale factor as bytes, and each ROI sub-brick has a different scale factor. Use this method instead to extract the region.

3dcalc -a $HOME/abin//TT_desai_ddpmaps+tlrc'[ctx_lh_G_insular_short]' -prefix insular_short -float -overwrite -expr 'step(a-0.3)'

3drefit -denote insular_short+tlrc.

That particular atlas has a very long history in the header, so I just trimmed it away with the 3drefit command.