Hi Philipp,

To be sure, are you really acquiring a single run that is more than an hour long, without any breaks in the scanning?

In such a case, it might be better not to use polor detrending, but rather sinusoid. It might include a similar number of regressors, but be better behaved.

That would be doing bandpassing, but only as a high-pass filter. But since BP does not really account for quadratic trends, also include polort 2. For example, consider something like:

-regress_polort 2         \
-regress_bandpass 0.01 1

Here the upper frequency of 1 could be anything at least as large as your Nyquist frequency of 0.25 Hz.


You would have to verify how many regressors this would end up corresponding to, it might still be similar.


On a separate note, if you want to decrease the RAM needs for this, consider adding -regress_compute_fitts .

- rick