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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]