I have a question regarding extraction of fMRI time series':
As I understand, there are 2 ways to extract a time series once
I have selected a significant cluster using the Results tab:
1. use the plot feature, then use "Fitted Response", select the contrast,
select "Predicted response" and then plot "against time".
2. specify co-ordinates and select the "eigenvariate" button, select
"don't adjust" and pick a 2x2x2 box (1 voxel).
Here are my questions for which I could not find any answers:
I assume that both these time series' are corrected for patient motion
and scanner drift, is that correct?
Why are these time series' different, given that I am using both times
the same voxel? There can be only one time series once the data is
corrected for nuisance variables (patient motion and scanner drift).
#1 will be a function between -2 and 2 (I assume in % of signal change).
Is that correct?
#2 will be a function between 130 and 180. Why?
For what is #2 "adjusted"?
#2 will also have outliers and the first and last time point which need to
be corrected before correlating time series'. Why are outliers present?
I would really appreciate if somebody could point me in the right direction.
I've been thinking about this for a while but I am really stuck.
Many thanks!!
Otto
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