To Whom it May Concern,
I have a question regarding the use of contrasts when generating
subtraction images. Basically, we have mutiple subjects with
different conditions. Here is the question:
- Say for subject 1 we have two scans: A,B
- In SPM's selection window I select the order: A=1, B=2 (A-B)
- Then I select two contrasts, the first contrast being "1 -1"
and the second being "-1 1"
- Then does contrast 1 correspond to:
1. pixels significantly higher in condition A vs. B
2. pixels significantly lower in condition A vs. B
3. pixels significantly higher in condition B vs. A
4. pixels significantly lower in condition B vs. A
Thank you very much for your time, and I look forward to hearing
from you soon.
Nathan White
College of Medicine
Department of Anesthesiology
University of California, Irvine.
=====
Nathan S. White
[log in to unmask]
__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|