Dear list,
I recently posted the question if it's possible to plot trial specific
signal against a parametrical modulator.
I didn't receive any response from the spm-list on the issue, so I
thought to come up with an idea myself.
My question to you is whether you think the method is valid or not.
With spm_graph it's possible to plot a reconstruction of a parametric
response per subject.
In short -as I do understand line 558-584 correct -, the parameter is
orthogonalized, convolved with the basis functions and multiplied with
beta for that
specific voxel. For these trial specific responses, the max (peak)
value is used to plot the linear effect (2nd plot when using the gui).
So, my thought was to reconstruct the linear function for each subject
and mean the intercept and slope over subjects to get a 'group-
function'.
However, since the response is a reconstruction, and as such an ideal
representation of the real data, I wonder if this methode is valid
to show effects of a parametric modulator.
Any comments are welcome
Thanks,
Martijn
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