Functional Connectivity Between Surgically Disconnected Brain Regions?

A new article posted on preprint site bioRxiv has generated a lot of interest among neuroscientists on Twitter. The article reports the existence of 'functional connectivity' between surgically disconnected distant brain regions using fMRI, something that in theory shouldn't be possible. This is big news, if true, because it suggests that fMRI functional connectivity isn't entirely a reflection of actual signalling between brain areas. Rather, something else must be able to produce connectivi