Hi, Eduardo

I do not understand your functions, but I think I can give you a general information of PESTICA, which would answer partially for your question.

Pestica generates card_pestica.dat and resp_pestica.dat files, which are vectors with a length of slice number x volume (measurement). These files has temporal resolution of TR/slice #. For example, if you have 100 measures of fMRI with 30 slices and TR of 2s, xxx_pestica.dat is sampled every 0.067s. Note that real measure of PMU has commonly 1/50 or 1/200 temporal resolution (1/sec). You can treat xxx_pestica data with different temporal resolution or sampling rate, in the similar way that you use PMU data.

Since TR of fMRI is relatively large (~2s) to be compared to a cycle of card.(~1s) and resp. (~5s), representative or mean pmu data for each volume might not be good idea. If you'd like to do slice-timing correction before PMU data correction, you might pick the first slice timing data in each volume. However, keep in mind that the phase of PMU or PESTICA data is calculated first then, assumed N order of sine/cosine model using the calculated phase (see retroicor payer by Glover), the signal is regressed out.

Hope it helps.

-Wanyong