Almost, you'll have to use

--psdwin 0 18 0.5
dPSD should be a multiple divisor of your TR and your stimulus length. Does your fMRI run only last for 15 time points? That's not very long

doug


Tamara Cristescu wrote: 
Thanks a lot for your message. It definitely helped me because I really need
optseq but I am not very confident with it. 
If I understand correctly, for 10 stim of 1.5 sec and a protocol with a TR of
4s, a correct optseq sequence would be like that:
--ntp 15 --tr 4 --psdwin 0 18 1.5 (or 0.5) --ev ev1 1.5 10 --   etc..

dPSD or samplng interval should be a multiple of stimulus and PSDmin and max are
set to correspond to haemodynamic response function (in this case I just
multiplied the length of the stimulus by 12 to give enough time to accommodate
the stim). 
Thanks you again for your help.
Yours,
Tamara

In message <462E641C.2000508@nmr.mgh.harvard.edu> Doug Greve
<greve@nmr.mgh.harvard.edu> writes:
  
The stim duration does not have to be a multiple of the TR. If has to be 
a mult of the dPSD, which you can set to 0.5sec.


Tamara Cristescu wrote:

    
Hello list,
I am new to optseq2 and I would need some help with it. 
I have a very long experiment (many stimuli) and on top of that I have a long TR
(4s) because I collect 60 coronal slices covering all the brain. 
My stimuli are quite short 1.5s or 2.5s but according to optseq the stimuli
duration should be a multiple of TR. Therefore, the min stim duration I can use
is 4s. I thought of modelling stimuli as having a duration of 4sec (1.5 stim and
a  2.5 artificial "null" event which is different than the null event optseq
estimates). 

I have a couple of questions:
1 I would like to know whether is better to include psdwin when I estimate a
sequence or leave it out and use the TR value instead? 
 

      
You have to set psdwin.

    
2 Also, would a psdwin of 20s be enough for a 4 sec stimulus? 
 

      
I'd probably go to 24.

    
3 My aim is to get a good sequence estimation with minimum time. I noticed that
although I give a certain ntp, optseq estimates a sequence that may run longer. 
 

      
It should not, though the last stimulus may extend behyond the last time 
point.

    
4 Is the previous version of optseq still available? I only found optseq2 on
your website.
 

      
It should still be in the freesurfer distribution.

    
Thanks a lot for your help.
Tamara

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-- 
Douglas N. Greve, Ph.D.
MGH-NMR Center
greve@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:
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-- 
Douglas N. Greve, Ph.D.
MGH-NMR Center
greve@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