Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin

Here's a result that surprised almost everyone: when researchers gave volunteers psilocybin (the active ingredient in magic mushrooms) and watched their brains in a scanner, brain activity went down, not up. Every single region showed decreases — not a single area lit up more. The biggest drops hit the same default mode network hubs that quiet down during meditation — the thalamus, the cingulate cortex, and the medial prefrontal cortex. Even more telling, the stronger someone's brain activity dropped in one key region, the more intense their psychedelic experience felt. The connections between major DMN hubs also loosened up significantly. The researchers argue this supports a beautifully old idea from Aldous Huxley: that the brain normally acts as a "reducing valve," filtering the flood of possible consciousness down to a manageable trickle, and psychedelics work by opening that valve wider. This finding created a fascinating bridge to meditation research — both practices seem to quiet the brain's bossy default network, potentially unlocking less constrained ways of thinking. The paper became a landmark in psychedelic neuroscience and remains central to debates about whether consciousness might be broader than our everyday brain filtering allows.