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-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu on behalf of Greve, Douglas N.,Ph.D. DGREVE@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

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Thank you so much.

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-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu on behalf of Greve, Douglas N.,Ph.D. DGREVE@mgh.harvard.edu Sent: Tuesday, September 10, 2019 11:46 AM To: freesurfer@nmr.mgh.harvard.edu freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] Opseq2 question

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-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu on behalf of Greve, Douglas N.,Ph.D. DGREVE@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

---

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