Contrary to expectations, psilocybin decreased cerebral blood flow, particularly to brain regions that act as "connector hubs" responsible for filtering and co-ordinating the flow of information through the brain. These hubs impose a top-down control on our awareness, integrating sensory inputs and prior expectations into a coherent, organised and censored experience of the world.
thus the guardian, reporting on possible therapeutic effects of psychoactive drugs of 'abuse.' i just want to make sure that y'all are clear that connector hubs etc are metaphors. and the metaphors used for brain activity always seem to draw on whatever the contemporary technology might be. now: i guess maybe you could see on an mri things that sort of look like connector hubs. but can you see the 'top-down control' they supposedly exercise? possibly this is a notion you are bringing to the data rather than deriving from it. when you look at an mri scan, do you see a political system? a hierarchy of powers? you might ask yourself how a connector hub, much less a whole bunch of connector hubs, exercise(s) top-down control over anything. so maybe when you say that connector hubs exercise top-down control, you mean that they effect events elsewhere in the brain, but are not by affected by such events. this would, however, sort of keep them from being connector hubs.