Fig. 2.

Schematic of approach for calculating the temporal relationship between functional connectivity and heart rate variability. A sliding-window analysis of heart rate variability is performed on the heart rate time series (upper left), producing a sequence of HRV values across the scan (upper right). Similarly, a sliding-window analysis of correlation between the BOLD signal of the seed time series and that of each voxel in the brain is performed (illustrated for one voxel; lower left), producing a sequence of functional connectivity values (lower right). Finally, the HRV and functional connectivity sequences are compared using linear regression.