Dear Experts,
Based on whole-brain analysis via SPM8 (1st- and 2nd-level analysis), I want to extract signal value from atlas-based ROIs (e.g. amygdala) in four experimental conditions, compared with rest condition respectively, by AFNI rather than MarsBar. Specific steps are listed as follows:
1. Mask generation: by WFU pickatlas, an file of ROI in amygdala (named as "amy.nii") was generated
2. File conversion: by AFNI command "3dcopy", the "amy.nii" was converted to "amy+orig.BRIK/HEAD", which could be recognized by AFNI
3. ROI calculation: by AFNI command "3dmaskave", the average value within the ROI mask (amygdala) of each subject (sbj**) in certain condition (con_000*) could be obtained; Specifically, the full command is like that "3dmaskave -quiet -mask amy+orig sbj**_con_000*.hdr". The file "sbj**_con_000*.hdr" was generated after 1st-level analysis via SPM8.
So I just wonder the meaning of ROI value obtained through those steps mentioned above. Whether does the value mean percent signal change (PSC), contrast value (CV), or parameter estimates (PE) ? And what's the difference between the three terms (namely PSC, CV, PE) always used in ROI analysis?
Thanks a lot for your help and comment!
Yang Hu
ICN, ECNU, Shanghai, China
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