I think your constraint of 5-7 null time is too tight for optseq, and you may still have too much time in your run to make 5-7 work. It's hard to say whether the VRFAvg is good enough or not. You are using sub-TR estimation during the optimization. If you are going to assume a shape to the HRF, then it's probably fine. If you are going to use an FIR, then you'd need about 7 runs or so.
doug 杨宏宇 wrote: > Hi Doug, > > I reduced the total time points, however, I found the eff and VRF > value all became smaller as the time points decreased, and I still got > some null events more than 7s. If I set the time points as 470s, I got > most 5-7 null events, except the last 35s null event, and then its eff > is 0.007, and VRFAvg is 1.7. Compared with 500 time points (eff 0.01, > VFRAvg 2.58), 470s is bad design. From one paper, I learned that > exponential distribution produced less variance compared with unity > distribution, and maybe optseq2 likes exponential distribution more, > so can I use the 470s design without the last 35s null events? Is the > value of eff and VFRAvg OK? > > > ...... > ...... > 819.0000 5 13.000 1.0000 diamond > 832.0000 0 5.000 1.0000 NULL > 837.0000 2 13.000 1.0000 star > 850.0000 0 5.000 1.0000 NULL > 855.0000 2 13.000 1.0000 star > 868.0000 0 5.000 1.0000 NULL > 873.0000 3 14.000 1.0000 star > 887.0000 0 6.000 1.0000 NULL > 893.0000 4 12.000 1.0000 diamond > 905.0000 0 35.000 1.0000 NULL > > > > On Tue, Oct 20, 2009 at 11:59 AM, Douglas N Greve > <gr...@nmr.mgh.harvard.edu <mailto:gr...@nmr.mgh.harvard.edu>> wrote: > > I think this is partially a bug in optseq and partially a > problem with your design. You have a total amount of > stimulation time = 12*9+13*8+14*8+12*9+13*8+14*8 = 648 sec. > Your run lasts 500*2 = 1000 sec, so the total amount of > fixation time is 1000-648 = 352 sec. You have 8*4+9*2 = 50 > stimuli, so the average time between stimuli (ie, average > null) will be 352/50 = 7.04s. Yet you have constrained optseq > to give you nulls between 5 and 7 sec. You need to relax this > constraint or reduce the total number of time points. > > doug > > 杨宏宇 wrote: > > Hi list, > > I am using optseq2 to design my fMRI study. These are my > scripts: > > optseq2 --ntp 500 --tr 2 --psdwin 0 40 1 --ev star 12 9 > --ev star 13 8 --ev star 14 8 --ev diamond 12 9 --ev > diamond 13 8 --ev diamond 14 8 --tnullmin 5 --tnullmax 7 > --nkeep 3 --o ex.event12.13.14s --nsearch 5000 > > I have 2 events, which last for 12,13, and 14s. I found > that the schedule documents I got had many null events > more than 7s, however, I have set the maximam as 7s. In > the sum logfile, I found that my script was recorded > correctly, so could you please tell me the reason, and how > to solve the problem? > > Many thanks, > Hongyu > Division on Addiction, > Psychiatry Department, > UT Southwestern Medical Center > > > ------------------------------------------------------------------------ > > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > <mailto:Freesurfer@nmr.mgh.harvard.edu> > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > > > -- > Douglas N. Greve, Ph.D. > MGH-NMR Center > gr...@nmr.mgh.harvard.edu <mailto:gr...@nmr.mgh.harvard.edu> > Phone Number: 617-724-2358 Fax: 617-726-7422 > > In order to help us help you, please follow the steps in: > surfer.nmr.mgh.harvard.edu/fswiki/BugReporting > <http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> > > > > > -- Douglas N. Greve, Ph.D. MGH-NMR Center gr...@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422 In order to help us help you, please follow the steps in: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
