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Thanks a lot for the advice! We are using FIR to re-analyse an old event-related paradigm in which videos of 7.5 s duration were presented. Our idea is now that FIR will allow us look at activity related to different temporal segments of the video because of not having to counterbalance. Similar to a mental chronometry approach. Does this sound plausible? Best, Leonhard Am 26.03.2007 22:34 Uhr schrieb "Neggers, S.F.W." unter <[log in to unmask]>: > 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 > > > -------------------------------------------------- > 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 > Tel : +31 (0)30 2503386 > Fax : +31 (0)30 2505443 > E-mail : [log in to unmask] > Web : http://www.fmri.nl/people/bas.html > -------------------------------------------------- > > > > -----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 > >