Hi Laura, what is your command line? doug On 06/04/2013 09:02 AM, Laura Dekkers wrote: > > Dear Dr Greve, > > Together with Dr Hilde Huizenga I am implementing an fMRI study in > which we would like to optimize the design by using Optseq2. We have a > few questions. Could you please help us out? > > Our task consists of 3 runs of 72 trails each, in which participants > are presented with a fixation cross that remains on the screen for a > fixed duration of 1 sec, followed by one out of nine different stimuli > that remains on the screen for a fixed duration of 4 sec. > This gives a scan duration of 360 sec. We would then like to add 25% > jitter, which results in a scan duration of 450 sec, and as TR = 2.0, > this results in 225 time points. > However, Optseq yields an error if ntp is set to 225, ev duration set > to 4.0, psdwin dPSD to 1.0 , tnullmin to 1.0 and tnullmax to 6.0 > ERROR: could not enforce tNullMax=6 (ntries=100000) > You will need to reduce the number of time points > or increase the number of presentations. > However, reducing the number of time points makes Optseq to only > insert null events of 1.0 or rarely 2.0 sec without much variation. > Optimization with ntp set to 225, ev duration set to 5.0 (=fixed > duration of fix + stimulus), psdwin dPSD to 1.0 , tnullmin to 0.0 (1.0 > does not work) and tnullmax to 6.0 does work. However, this renders > Optseq to insert null events of a fixed duration op 1.0 sec, which is > not what we want. > Could you please advise us in how to set these parameters? > Thank you in advance. > Best regards, > Laura Dekkers > > -- > Laura M.S. Dekkers, MSc > Research assistant > University of Amsterdam - Department of Developmental Psychology > Weesperplein 4 > 1018 XA Amsterdam - The Netherlands > E-mail: [email protected] <mailto:[email protected]> > > > _______________________________________________ > Freesurfer mailing list > [email protected] > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
-- Douglas N. Greve, Ph.D. MGH-NMR Center [email protected] Phone Number: 617-724-2358 Fax: 617-726-7422 Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ _______________________________________________ Freesurfer mailing list [email protected] https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
