Dear Christine,

If your covariate is subject-specific, you should:

1. define appropriate contrast on the individual level ,i.e. for each subject's model. According to your post these contrasts should be A+B and B-A, although I don't understand what do you mean by activation and deactivation.

2. One sample t-test --> enter all individual con images, enter your covariate (it should contain one value per subject). In your case you should do it twice, separately for each contrast.

3. Define contrasts: [0 1] for positive correlation, [0 -1] for negative correlation.

Hope this helps,


On Sun, Dec 8, 2013 at 3:08 PM, Christine Macare <[log in to unmask]> wrote:
Dear all,
 I am trying to link activation and deactivation during
an fMRI task with a covariate. The task has 2 conditions
A and B and I have assessed activation (AB) and
deactivation (A<B) during the task by using a one sample
ttest  as factorial design and entering 1 and -1
respectively as contrast weights. I would like to see if
the activation and/or deactivation is correlated to my
covariate and if so in what way, that is positively or
negatively correlated. I would use the factorial design
of one sample ttest and enter the covariate, what are the
contrast weights I would have to enter to get positive
and negative correlations between my covariate and
activation and deactivation?

 I would be grateful for any kind of help on this.
 Thank you,

Ella Gabitov
Ph.D. student
The E.J. Safra Brain Research Center for Learning Disabilities
The Laboratory of Human Brain and Learning
University of Haifa
Phone: +972-52-6722700
E-mail: [log in to unmask]