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>If you think the neural processes engaged by your trials
>last more than ~1s, then you should model them as epochs (ie
>duration>0), rather than events (duration 0). This is
>because the predicted BOLD response, after convolving your
>"neural model" with your "haemodynamic model" (eg, SPM's
>canonical HRF), will differ in shape for events >~1s.

Rik said it is better to use durations equal to the RT
if the real neural response in the ROI
take time longer than 1s (or much longer than the length of
time bin, I think).

What if there are two regions of intersest
and they are expected to engage in neural activitis
of different durations?
For example, what if one region is related to very short
neural activity (e.g., identifying digits) and the other
is responsibe for somewhat longer activity (e.g., calculation)?

>Note however that this model will not be as good for other
>brain regions in which the response is more transient (e.g,
>in V1, if the visual stimulus in each trial is brief). (See
>Question VII at the end of
>http://www.mrc-cbu.cam.ac.uk/Imaging/Common/fMRI-efficiency.shtml
>for more details).

My guess is that we can test both models (one uses 0 durations
and the other uses RT durations).
The duration=0 model tells us regions which are related
to a very short cognitive process and the duration=RT model
shows regions responsible for somewhat longer cognitive
process.

Is my guess correct?