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,

Ella



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,
 Christine
 



--
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
Israel
Phone: +972-52-6722700
E-mail: [log in to unmask]