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Dear Bosky The approach which I prefer is to let the high-pass filter cut-off be determined by your hardware (irrespective of your choice of paradigm). You can do this using a phantom and diagnostic statistics as implemented in SPMd. With this approach you can justify that the system drift is modelled adequately with a particular high-pass filter on your scanner using a particular sequence. Best regards, Torben Torben E. Lund Danish Research Centre for MR Copenhagen University Hospital Kettegaard Allé 30 2650 Hvidovre Denmark email: [log in to unmask] webpage: http://www.drcmr.dk On 30 Jul 2005, at 20:18, Bosky wrote: > Hello SPM experts: > > Is there a general rule for setting the High Pass Filter for a rapid > event related design? Our design has 3 blocks , each of a different > fixed duration. Within the first block , 2 types of stimuli are > presented in a random fashion; in the second block, 3 types of stimuli > are presented in a random fashion and the last block is the same as > the first block( i e , 2 types of stimuli). For the first > block, duration of each stimulus is 1 second and each stimulus is > followed by an orientation cross of varying duration. In the second > block, 2 stimulus is presented for 1 second while the 3rd one lasts > for 2 secs. > > What should be my High pass filter setting for such a design. I have > read that there is no strict rule for event related designs but one > can set is to atleast 50s. Kindly help. > > Thanks, > > Bosky Ravindranath > > > > Laboratory for the Study of Emotion and Cognition, > Department of Biomedical Engineering > Stony Brook University, > New York, 11790 > Phone- 631-444-8405/ 631-444-7868 >