Hi Doug, I figure out why this happened and how to solve the problem. Because My trials always lasted for 12,13,14s, and optseq2 believed that the baseline should last about 12-14s, which means null time should be as many as one task condition or the average of the task conditions. I set my trials as 5,6,7s, revised the time points, then I got very good sequence. I think now I need to do is to change the trial duration back and recode the time line.
On Thu, Oct 22, 2009 at 10:31 AM, 宏宇 <yanghy...@gmail.com> 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> 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 >>>> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >>>> >>> >>> -- >>> 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 >>> >>> >>> >> > >
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