Hello Dr Donald,
thank you very much for your answer!
We had five conditions (three blocks of the same condition per experiment). The blocks were presented in pseudorandomized order (so participants could not get blocks with the same condition twice in a row). So the onset-to-onset time for blocks of the same condition varied for each study participant and condition. Do you recommend to compute the value for the high-pass filter setting for each participant individually using the longest interval between blocks of the same condition?
I apologize if my question is quite basic as I am relatively new to the field.
Best regards
Friederike Tam
Medical doctor
Department for Child and Adolescent Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus Dresden
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Von: MCLAREN, Donald [[log in to unmask]]
Gesendet: Montag, 6. April 2015 16:27
An: Tam, Friederike
Cc: SPM
Betreff: Re: [SPM] Temporal filter fMRI block design
The filter you want to use is slightly more than twice the time of the onset to onset of the blocks of the same condition. This is less of an issue with blocks and pauses that vary, but its better to be conservative and not remove signal of interest. Compute the longest interval between blocks of the same type, then multiple by 2, add a few seconds, then use this time in the high-pass filter settings.
Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
Postdoctoral Research Fellow, GRECC, Bedford VA
Website: http://www.martinos.org/~mclaren
Office: (773) 406-2464
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On Sun, Apr 5, 2015 at 10:48 AM, Tam, Friederike <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Hello all,
I have a question concerning temporal filters. What would be the optimal filter for an fMRI experiment with block design (block length 50 to 56 seconds, 10 to 15 seconds pause between blocks, 15 blocks in total)?
Would you use a different filter for a block length of 30 s or 2 min?
Thank you very much for taking time to read this!
Friederike Tam
Medical doctor
Department for Child and Adolescent Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus Dresden
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