Thank you so much for your helpful reply Doug.
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: Friday, January 4, 2019 2:26:00 PM To: freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] gammafit flag in mkanalysis-sess
On 1/4/19 1:27 PM, Nasiriavanaki, Zahra wrote:
Hi Freesurfers
I have a few questions about gammafit flag in mkanalysis-sess command and I appreciate if you could respond whenever you had time.
-How should we decide which function is best to apply on hemodynamic response signal? I have used both spmhrf and gammafit and I see slightly different results.
Hard to say. Mostly, it does not make much of a difference, especially if you have a block design. In theory, you could see which one has the lowest residual error, but in general I would not agonize over it.
-Does Freesurfer has a default function that applies on hemodynamic response signal if I don't use these flags?
No, you have to supply one. I usually use --spmhrf 0
-Where should I get gfdelta and gftau from?
We always used delta=2.5 and tau=1.25. These are from Dale and Buckner, HBM 1997, Selective Averaging of Rapidly Presented Individual Trials Using fMRI
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
_______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edumailto:Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer