Hi Doug Thanks for your email. I gave your suggestion a try - reduced the dPSD to 0.5 (as well as adjusted the PSDMAX, and no. of volumes to reflect the new TR - see full command line below). Unfortunately the efficiency is way down (0.03) and the VRF you previously suggested should be between 20-40 is 4.5! I now wonder if Optseq is trying to tell me this is now a bad design!!
Would be very grateful for any ideas for improvement?
optseq2 --ntp 240 --tr 2.5 --psdwin 0 20 0.5 --ev hf 3 50 --ev lf 3 50 --ev nf 3 50 --nkeep 3 --o test14 --nsearch 10000 --focb 100
many thanks Ella
Date: Sun, 28 Jul 2013 23:33:07 -0400 From: greve@nmr.mgh.harvard.edu To: freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] dPSD and ev duration
Hi Ella, it has an internal clock that events have to be syncrhonized to. Try setting the dPSD to 0.5
doug
On 7/28/13 4:05 PM, Ella Hinton wrote:
Hi
Quick question - why must the duration of the EVs be an integer multiple of the dPSD, which is also tied to the TR? I have event duration of 3 seconds, but would like to reduce my TR from 3 down to 2.5, but I can't seem to input the correct numbers for optseq to help me.
thanks in advance
Ella
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