Dear Leonard,
You might also find some of the literature on FIR models to be helpful. Miezin et al. (2000) and Ollinger et al. (2001a,b) both include good descriptions.
Hope this helps!
Daniel
________________________________
From: SPM (Statistical Parametric Mapping) on behalf of Neggers, S.F.W.
Sent: Mon 3/26/2007 4:34 PM
To: [log in to unmask]
Subject: Re: [SPM] FIR
Dear Leonard, list,
a finite impulse response (FIR; I guess that is what you want??) model is nothing more than another set of basis functions modelling the hemodynamic response to your event, in the context of a general linear model. And it is the least informed one, i'd say, perhaps also fourier basis functions are pretty uninformed too.
It is simply 1 dirac delta function per event in a regressor, and in an additional series of subsequent regressors this first regressor is shifted in time with 1 scan each time. By doing so you estimate each timepoint in your BOLD response separately. This however implies that you also have to specify your contrast per time point, which is not always easy (see earlier FIR question today) as you have to ask specific questions regarding your hemodynamics.
FIR basis functions can simply be selected when you specify your model in SPM, you specify how many regressors (eg time points) you want. Have a close look at the resulting design matrix, and perhaps the above makes more sense.
I do not know a specific reference for it, but perhaps medline or "google scholar" does?
Good luck,
Bas
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Dr. S.F.W. Neggers
Division of Brain Research
Rudolf Magnus Institute for Neuroscience
Utrecht University Medical Center
Visiting : Heidelberglaan 100, 3584 CX Utrecht
Room A.00.1.24
Mail : Huispost A.01.126, P.O. Box
3508 GA Utrecht, the Netherlands
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Web : http://www.fmri.nl/people/bas.html
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-----Oorspronkelijk bericht-----
Van: SPM (Statistical Parametric Mapping) namens Leonhard Schilbach
Verzonden: ma 26-3-2007 22:01
Aan: [log in to unmask]
Onderwerp: [SPM] FIR
Dear all,
we are interested in using an FIR approach for the re-analysis of a
previously acquired event-related design. As I am unfamiliar with this
method, I would be very grateful if someone could point out relevant
literature pertaining to the underlying ideas and assumptions. Thanks very
much in advance!
Best regards,
Leonhard
--
Leonhard Schilbach
Department of Psychiatry
University of Cologne
Kerpener Str. 62
50924 Cologne
Germany
