Dear SPM users.
Could someone please clarify this plotting enigma to me...
So I have a session with 5 different trials with a random number of
repetitions for each trial. Then I do the analysis and try to plot the
values. So I choose plot -> fitted responses -> trial 1 (for example) ->
predicted (for example) -> scan or time.
What I get is a solid curve and a dotted line. I assume that the solid line
is what I am trying to fit my data to - the sum of all hrf's I used to model
the response, and the dotted line is the actual BOLD values for each time
point and I am trying to fit this data to the solid line.
But what are they really?
If I stay in this voxel and plot the same thing for another trial, then
obviously the solid line changes to reflect the new theoretical response,
BUT the dotted line also changes! It is the same voxel, so I would assume
that the "raw" BOLD values should be the same! So what does this dotted
line represent? And how are the values obtained?
Now if I choose "adjusted" instead of "predicted", what happens is even
more mysterious to me. What does the solid line represent now? Is it what
we were able to fit to our data? It doesnt look like it if it was modeled
as a sum of hrf's with different onset times and amplitudes. And what does
the dotted line represent now? It is not the "raw" BOLD signal values
either because it changes if I choose a different trial.
The solid line in this case looks more like smoothed dotted line in this
case. Is it so?
Please tell me how values are obtained in each of these 4 cases?
So you any good places I could read about it?
Thank you very much!
Regards,
Renat.
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