More than half a century ago, author Aldous Huxley titled his book on his experience with hallucinogens The Doors of Perception. Huxley posited that ordinary consciousness represents only a fraction of what the mind can take in. In order to keep us focused on survival, Huxley claimed, the brain must act as a "reducing valve" on the flood of potentially overwhelming sights, sounds and sensations. What remains, Huxley wrote, is a "measly trickle of the kind of consciousness" necessary to "help us to stay alive." A new study by British researchers supports this theory. It shows for the first time how psilocybin - the drug contained in magic mushrooms - affects the connectivity of the brain. Researchers found that the psychedelic chemical ... does not work by ramping up the brain's activity as they'd expected. Instead, it reduces it. Under the influence of mushrooms, overall brain activity drops, particularly in certain regions that are densely connected to sensory areas of the brain. When functioning normally, these connective "hubs" appear to help constrain the way we see, hear and experience the world, grounding us in reality. Psilocybin cuts activity in these nodes and severs their connection to other brain areas, allowing the senses to run free. Huxley ... had predicted what turns out to be a key finding of modern neuroscience: many of the human brain's highest achievements involve preventing actions instead of initiating them, and sifting out useless information rather than collecting and presenting it for conscious consideration.