Directed fMRI connectivity mapping reveals a flexible functional hierarchy in the mouse brain

Motivation: fMRI connectivity is widely used to probe brain functional organization. However, measures of fMRI connectivity are typically undirected and insensitive to the information transfer between brain regions. Goal(s): We hypothesized that directed fMRI connectivity mapping would reveal a novel dimension in the functional organization of the mammalian brain: do brain regions exchange information equally, or are there regional sources or sinks of information? Approach: We validated the use of directed connectivity mapping via transfer entropy to characterize directed connectivity in the resting mouse brain. Results: We reveal a robust, intrinsic source-to-sink organization in the mouse brain that flexibly reconfigures depending on brain state. Impact: Our study shows that resting state fMRI can be reliably used to probe directed information transfer between brain regions.