BrainSync

BrainSync is an orthogonal transformation that allows direct comparison of resting fMRI (rfMRI) time series across subjects. For this purpose, we exploit the geometry of the rfMRI signal space to conjecture the existence of anorthogonal transformation that synchronizes fMRI time series across ses-sions and subjects. The method is based on the observation that rfMRIdata exhibit similar connectivity patterns across subjects, as reflected inthe pairwise correlations between different brain regions. The orthogonal transformation that performs the synchronization is unique, invertible, efficient to compute, and preserves the connectivity structure of theoriginal data for all subjects. Similarly to image registration, where wespatially align the anatomical brain images, this synchronization of brainsignals across a population or within subject across sessions facilitates longitudinal and cross-sectional studies of rfMRI data.