Title: Gradient synchronization as a measure for brain functional connectivity
Authors: Hans-Georg Mueller - University of California Davis (United States)
Yang Zhou - UC Davis (United States)
Jane-Ling Wang - University of California Davis (United States) [presenting]
Owen Carmichael - Pennington Biomedical Research Center (United States)
Abstract: Quantifying the association between components of multivariate signals is a key to assess brain functional connectivity. Recent research suggests temporally changing patterns of functional connectivity. We propose new similarity measures for pairs of temporal functions that reflect the dynamic features of their functional similarity. We introduce a gradient synchronization measure that is based on the aggregated concordance and discordance of the gradients between paired smooth random functions, which can also be used to quantify the relative frequency of changes from concordance to discordance or vice versa. Asymptotic normality of the proposed estimates is obtained under regularity conditions and the new methods are illustrated via simulations and an application to resting state fMRI signals from Alzheimer's patients and healthy subjects.