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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