Mapping the Psychedelic Brain
Drugs like psilocybin, the active ingredient in hallucinogenic mushrooms, play all sorts of tricks on the mind. They distort the perception of time, space, and self, and even untether the senses. Some researchers thought these strange effects might result from the drugs overexciting the brain. But the first study to use functional magnetic resonance imaging (fMRI) to examine brain activity in people who’ve taken psilocybin finds that the drug reduces neural firing in key communication hubs, essentially disconnecting some brain regions from each other.
In Central America and elsewhere, hallucinogenic drugs have been used for centuries in healing and religious ceremonies. Recent years have seen renewed interest in exploiting them to explore the neural basis of spirituality and potentially to treat depression, anxiety, and other mental illnesses. Yet neuroscientists know little about how these compounds act on the brain to cause such intensely altered experiences. Hallucinogenic drugs are tightly regulated, and few previous studies have tried to gauge their effects on the human brain. One study, using positron emission tomography (PET), found that psilocybin increases brain metabolism, especially in the frontal cortex.
