functional connectivity correlation matrix

Dear Authors,
I would like to obtain, for each subject, a matrix of the correlation between the seed and all the voxels of the brain.
Is it possible to obtain such a ".mat" file from a functional connectivity analysis?

yes you can do it. 
the simplest way to do this is using REST functional connectivity toolbox. 

In this toolbox, you need to define a seed region, then input your data. The toolbox will output an image file "XXX.nii".

Then you can use  "rest_ReadNiftiImage", a REST function in matlab, to read your XXX.nii into mat format.

Thank you,
I've tried to run the function "rest_ReadNiftiImage", but I got this error:
"File doesn't exist: Volumes\Dati_new\Analysis\Results\seed_cerebellum\FCMap1.nii"

However the nifti file is located into the folder "seed_cerebellum". What would you suggest?
Best,
Manuela