For example, if I do a visual search task and I find the target after 1s, but the stimulus is on for 5 seconds; then I'd want to model the visual search for 1s and potentially model the visual stimuli for 5s.
Thus, you really need to think about the cognitive processes and the neural activity associated with them when you choose a event duration.
In your case, I'd look at the fear literature to see if the fear response is constant or is mostly at the beginning of the stimuli to guide you.
Hope this helps.
Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Postdoctoral Research Fellow, GRECC, Bedford VA
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
Office: (773) 406-2464
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On Sun, Nov 27, 2011 at 3:13 PM, adams adams
<[log in to unmask]> wrote:
Hello SPMers
Im studying fear circuit (
conditioning and extinction)
The Duration of the stimulus is 6s :
consist of face stimulus (3s) followed by the rating response (3s)
( during the rating response the
stimulus is still presented)
My question is : in the FMRI Model
specification what is the duration of my condition. Do I have to enter
: 3s or 6s, or 0
Thank you for your help
Adams
