Okay, thanks.
So there is not somebody from the SPM group or so, that should be considered, because they implemented the function in the program?

Nils



-------- Original-Nachricht --------
> Datum: Tue, 13 Jan 2009 09:19:19 -0500

> Von: Jason Steffener <[log in to unmask]>
> An: [log in to unmask]
> Betreff: Re: [FSL] Basis functions

> Nils,
> I would suggest the following two references. The Glover paper really laid
> out the double gamma model as a parametrization of the HRF and Jack does a
> great job discussing how the HRF varies with increasing intensities and
> durations of neural activity.
>
> Have fun,
> Jason.
>
> Glover, G. H. (1999), 'Deconvolution of impulse response in event-related
> BOLD fMRI', *Neuroimage,* vol. 9, no. 4,* *pp*.* 416-29.
>
> Grinband, J., Wager, T. D., Lindquist, M., Ferrera, V. P. & Hirsch, J.
> (2008), 'Detection of time-varying signals in event-related fMRI designs',
> *
> NeuroImage,* vol. 43, no. 3,* *pp*.* 509-520.
> On Tue, Jan 13, 2009 at 8:28 AM, Nils Richter <[log in to unmask]> wrote:
>
> > Hi Jason,
> >
> > thanks for all your help.
> > I just have one mor question. Who should be cited when using any of
> those
> > graphs and any other data generated using that function?
> >
> > Nils
> >
> >
> >
> >
> > -------- Original-Nachricht --------
> > > Datum: Fri, 9 Jan 2009 08:43:57 -0500
> > > Von: Jason Steffener <[log in to unmask]>
> > > An: [log in to unmask]
> > > Betreff: Re: [FSL] Basis functions
> >
> > > Dear Nils,
> > > Hello. Column 2 refers to the "on" time of a regressor which changes
> the
> > > convolved HRF shape.
> > >
> > > The code below will create some graphs to demonstrate the
> relationships
> > > between "on" time and HRF shape. The program uses the spm_hrf function
> > > call
> > > to create the HRF. I have also attached the figures. Also Jack
> Grinband's
> > > NeuroImage 2008 paper discusses the effects you are referring too and
> has
> > > fMRI data also demonstrating the relationships between on time and
> BOLD
> > > response.
> > >
> > > I hope this helps.
> > > Jason.
> > >
> > >
> > > TR = 0.1;
> > > Hrf = spm_hrf(TR);
> > > On = [0.1:0.2:20];
> > > InputLength = 400;
> > > Out = zeros(InputLength, length(On));
> > > time = [0:TR:(InputLength-1)*TR];
> > > H = zeros(1,length(On));
> > > W = zeros(1,length(On));
> > > for i = 1:length(On)
> > >     Input = [ones((On(i)/TR),1); zeros(InputLength - (On(i)/TR),1)];
> > >     temp = conv(Input,Hrf);
> > >
> > >     H(i) = max(temp);
> > >     tempW = find(temp > 0.5*H(i));
> > >     W(i) = time(max(tempW)) - time(min(tempW))
> > >     Out(:,i) = temp(1:InputLength);
> > > end
> > > figure(1)
> > > plot(time,Out)
> > > xlabel('time (s)');
> > >
> > > figure(2)
> > > plot(On,W)
> > > xlabel('On Period')
> > > ylabel('FWHM')
> > > figure(3)
> > > plot(On,H)
> > > xlabel('On Period')
> > > ylabel('Height')
> > >
> > >
> > > On Thu, Jan 8, 2009 at 6:33 PM, Nils Richter <[log in to unmask]>
> wrote:
> > >
> > > > Hello FSL Team,
> > > >
> > > > could you please tell me where I can find some information on the
> exact
> > > > formulas with which the different basisfunctions are implemented in
> > FSL?
> > > > I especially need to know what exactly changing column 2 of '3
> column
> > > > logfiles' does to the shape of the HRF. I gather it changes width
> and
> > > > height, but how much?
> > > > Is this information perhaps found in some tech report?
> > > >
> > > > Greetings,
> > > > Nils
> > > > --
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> > > >
> >
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> >

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