Dear Pilar,
There are some useful references that explain how to best model activity in a mixed design (see Visscher et al., 2003, NeuroImage).
Here's the synopsis:
1) When modeling sustained activity, use a canonical HRF.
2) When modeling event-related activity, use a FIR model.
Best and hope this helps!
Daniel
Daniel Weissman, Ph.D.
Assistant Professor
Department of Psychology
University of Michigan
Room 4052
1012 East Hall
530 Church Street
Ann Arbor, MI 48109
________________________________________
From: SPM (Statistical Parametric Mapping) [[log in to unmask]] On Behalf Of MCLAREN, Donald [[log in to unmask]]
Sent: Tuesday, December 14, 2010 10:58 AM
To: [log in to unmask]
Subject: Re: [SPM] HRF or FIR ?
HRF
FIR wouldn't work well because you need lots of trials and you have a limited number of blocks.
Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Postdoctoral Research Fellow, GRECC, Bedford VA
Research Fellow, Department of Neurology, Massachusetts General Hospital and Harvard Medical School
Office: (773) 406-2464
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On Tue, Dec 14, 2010 at 10:56 AM, Pilar Archila-Suerte <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Dear SPM Users,
Just to double check with the rest of the SPM community, what basis function is best to use for a mixed experimental design that consists of blocks with short duration events in each block ? HRF or FIR?
Thanks,
Pilar A.
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