Dear FSL experts,
I was hoping you would help clarify two points with respect to PPI analyses.
Quick overview: We employed a noxious heat paradigm and would like to identify connectivity during noxious heat stimuli in a rest vs. placebo condition.
At the first level, we entered non-preprocessed 4D bold data.
We ran our standard preprocessing steps.
For the PPI: Our psychological variable was set as a custom 3 column text file of all our regressors of interest (i.e., noxious and innocuous heat). We included their respective onset times, duration, and a 1 to designate our noxious heat stimuli and 0 to designate all others, respectively. We enabled temporal derivative and temporal filtering and did not orthogonalise.
The physiological variable is a text file corresponding to the MTS values of our ROI, we did not orthogonalise or add temporal derivative/filtering. We had 147 time points (from all the volumes).
The interaction term was set as centre for EV1 and EV2 as mean. We did not orthgonalise or add temporal derivative/filtering.
We entered 6 contrasts (+1 and -1) for the 3 EVs.
Does this look correct?
Second, we are unclear on how FSL “knows” to multiply the appropriate time points of the psy EV with the phy EV? In particular, it is unclear to us because the psy and phy text files have a different number of rows from each other. That is, the psy EV consists of 40 rows of data, and the phy consists of 147.
Per usual. Thank you,
Jenny
########################################################################
To unsubscribe from the FSL list, click the following link:
https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=FSL&A=1
|