Yes thanks, I understand now.

It still won't write the whole 64x64x13x1 matrix. Upon reading the source code itself, it says that if min(Slices)>1 or min(Frames)>1 then it assumes that the header has already been written. Which it of course has not been written, that is why i am using WriteBrik in the first place. But yes, the number of slices is > 1 (in fact, it is 13). And so the function is looking for an existing dataset. What should it be?

(by the way, there is no explanation about what Frames refer to).

Maybe my problem is the original file i used to copy the header information from (using BrikLoad). I tried using 1) a functional map, 2) a functional timeseries (3D + time), and 3) an anatomical file. After copying the Info i modified the attributes accordingly. I am not having success with any of these options. Can you please recommend which one I should keep working at?

Much, much appreciated!
cnan