how to calculate the z score of different regions if i ONLY know the mean time series of these regions?

How to calculate the z score of different regions if i ONLY know the mean time series of these regions?

Do you mean that you are interested in the 'functional connectivity' or linear correlation between these timecourses?

You can use ROI-wise Funtional connectivity in REST to do this.
After Click ROI-wise, then define each ROI by specifing Time Courses.
Best wishes!