Hi all,
Just want to confirm my understanding and naming of extracted fMRI response. In a block-design paradigm consisting of alternating “on” and “off”, I want to get fMRI response between "on" and "off" in a ROI. I know three ways to get fMRI response data:
METHOD 1: using Marsbar
(1) (matlab directory is in the first-level t contrast of a subject) “design” – “set design from file” – select the contrast image of subject 1
(2) “data” – “extract ROI data (default” – select this ROI mask
(3) “Result” – “estimates results”
(4) “Results” – “% signal change” – enter “on” and “off” duration. Then I got the value using data of event 1 minus data in event 2.
I then repeat these procedures in each subject.
METHOD 2: using Marsbar
(1) (matlab directory is in the 2nd-level analysis file now!) “design” – “set design from file” – select the contrast image of 2nd-level SPM file.
(2) “data” – “extract ROI data (default)” – select this ROI mask
(3) “Result” – “estimates results”
(4) “Data” – “Export data” – “Export summary timecourse for region” – “Export to text file”
I then get all subjects' data.
METHOD 3: in SPM8 GUI
(1) (matlab directory is in the 2nd-level analysis file now!) I load and display the 2-level group analysis result using an uncorrected threshold of 1 (i.e. let all voxels are activated).
(2) eigenvariate --> don't adjust --> mask --> select the ROI mask
Then 20 numbers would be obtained in Matlab command window.
In my scatter plots, I would use the term "percent signal change" in METHOD 1 and "parameter estimates" in Methods 2 and 3. Am I correct?
Thanks in advance. Mark
|