Before revision:  Due to image acquisition and physiological noise , the direct use of the sample correlation matrices is not reliable for the subsequent modeling of the dynamically-evolving connectivity matrices. To overcome this limitation , we propose a new regression approach that smooths out the noise by exploiting the geometric structure of correlation matrices.
After revision:  Due to image acquisition and physiological noise , the direct use of the sample correlation matrices is not reliable due to the image acquisition and processing noises in resting-sate fMRI. New method: To overcome these limitations , we propose a new regression approach that smooths out the noise by exploiting the geometric structure of correlation matrices.