Hi Lucy,

The AFNI program "3dTcat" can be used to split up and/or concatenate a time series dataset.

For instance, suppose you have a dataset called joe+orig, which contains 5000 time points (or sub-bricks). You can divide this big dataset into two smaller ones using 3dTcat. To do this, you would specify on the command line the sub-bricks you want included in your two smaller datasets. In this example, the first dataset could contain time points 0-2499 (AFNI begins its numbering of timepoints with "0") and the second one would contain timepoints 2500-4999:

3dTcat -prefix joe_firsthalf 'joe+orig[0-2499]'
3dTcat -prefix joe_secondhalf 'joe+orig[2500-4999]'

(Don't forget to include the single quotes on the command line)

Your output files would be:
joe_firsthalf+orig -- this would consist of the first 2500 time points
joe_secondhalf+orig -- this would consist of the last 2500 time points

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To concatenate them together, you would use 3dTcat like this:

3dTcat -prefix joe_all joe_firsthalf+orig joe_secondhalf+orig

The output would be joe_all+orig, which contains all 5000 time points.

For more information on this program, type "3dTcat -help"

Peggy