Hi Wanyong,

Thanks for the answer, it did clarify more.

The functions I used are in matlab. In general what I did what just to load the card_pestica.dat file (with 10,800 rows or slices), then for each 36 slices I extracted the MAX value to represent volume PMU and wrote that into an array file of 300 rows (volumes)

What I usually do (aka the correct way) is to run SLOMOCO + PESTICA and use those resulting 4D brains. However, in this case my team is using CONN Toolbox for SPM. CONN is configurable but not so friendly when you want to change things. Therefore, I wanted to run everything in CONN and add the physiological data from PESTICA as if they were acquired in the scanner (nuisance regression). That way, CONN would run smoothly.

This is why I'm trying to find out the best way to do this. So, then my xxx_pestica.dat files are 0.56s.
In this sense, it is not enough to change the sampling rate to 2s. I'm looking at the CONN forums and it seems I could use RETROICOR regressors if I can extract them.

I'll see how that goes

Thanks

Eduardo