Hello FSL experts,
we want to get the event-related average for a certain condition, so we are using the FIR to estimate our HRF, but we have some doubts on how this works.
- Which is the statistical estimator that FSL uses to derive the coefficients in FIR? Is there a specific, formal description of this somewhere? Is it along the lines of the description provided by Henson for SPM in page 14 of the handbook (http://www.mrc-cbu.cam.ac.uk/personal/rik.henson/personal/Henson_HBF2_fMRI_preprint.pdf)?
- But if it is so, how can it be that we put ``duration = 0’’ in the three column file that we load to specify the onsets and still get meaningful results? In this case we are not convolving a Dirac with an HRF, so why is it not mandatory to use a box car with non-zero length?
- How do we interpret the beta’s? They are not normalized in any way, correct?
Thanks in advance for any input you can provide.
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