I would like to perform some Bayesian analyses implemented in SPM, but with the data normalized with FreeSurfer. I would like to merge together surface and subcortal normalized timeseries into a single 4d timeseries in volumetric space, which could be used as an input to spm. I tried using vlrmerge, but it produces only a single volume. One method would be splitting the timeseries for each space into single volumes, using vlrmerge on each triplet and then merging the results. However, this would take enourmous ammout of time. Do you know any quicker workarounds?