The FIR assumes that your stimuli will be presented on a "clock", eg, on 
a TR (not necessarily ever TR, but every time a stimulus is presented, 
it starts on a TR). The "tick" of the clock can be the TR or it can be 
an integer divisor of the TR (eg, TR/2 TR/3). The finer you make it, the 
more flexibility you have as to when a stimulus can occur. But you loose 
power based on the divisor, eg, TR/3 means that you'll have 1/3 the power.

On 9/10/19 11:35 AM, Nasiriavanaki, Zahra wrote:
> Hi Doug
>
> Thank you very much for your reply. How does it make a difference if I 
> use FIR? Could you please explain a little bit more?
>
> Thanks
> Mona
>
> *Zahra (Mona) Nasiriavanaki*
>
> Postdoctoral Research Fellow
>
> Martinos Center for Biomedical Imaging
>
> Massachusetts General Hospital
>
> 149 13th Street, 149-2615
>
> Charlestown, MA, USA, 02129
>
>
>
> ------------------------------------------------------------------------
> *From:* freesurfer-boun...@nmr.mgh.harvard.edu 
> <freesurfer-boun...@nmr.mgh.harvard.edu> on behalf of Greve, Douglas 
> N.,Ph.D. <dgr...@mgh.harvard.edu>
> *Sent:* Tuesday, September 10, 2019 11:24 AM
> *To:* freesurfer@nmr.mgh.harvard.edu <freesurfer@nmr.mgh.harvard.edu>
> *Subject:* Re: [Freesurfer] Opseq2 question
> If you are going to assume a shape to the hemodynamic response, then I
> don't think it makes much difference. It will make a difference if you
> are going to use an FIR.
>
> On 9/9/19 10:49 AM, Nasiriavanaki, Zahra wrote:
> > Hi Freesurfer experts
> >
> > I have a question about designing an event related task. We are
> > designing a task for fear conditioning. Each stimuli presentation
> > lasts 4 seconds. My question is if we set the TR to 2 (which is a
> > multiply of 4), will it make the paradigm to have more power in signal
> > detection? Or does it not matter if the TR and stimuli presentation be
> > a multiply of each other or not?
> > I appreciate if you give me your comments on that.
> >
> > Thanks a lot
> > Mona
> >
> > *Zahra (Mona) Nasiriavanaki*
> >
> > Postdoctoral Research Fellow
> >
> > Martinos Center for Biomedical Imaging
> >
> > Massachusetts General Hospital
> >
> > 149 13th Street, 149-2615
> >
> > Charlestown, MA, USA, 02129
> >
> >
> >
> >
> > _______________________________________________
> > Freesurfer mailing list
> > Freesurfer@nmr.mgh.harvard.edu
> > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
>
>
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