The effects of psilocybin were revealed in brain-imaging study

Jan 24, 2012 15:15 GMT  ·  By

A group of scientists at the University of Bristol says that a series of new brain-imaging studies they conducted reveals the effects that the active chemical in magic mushrooms – psilocybin – has on the human brain.

In order to figure out how this psychedelic drug works, the team asked a number of test subjects to subject themselves to brain scans while they were under the influence of this chemical. Two separate studies were conducted on this topic.

Details of the first investigation appeared in the January 23 issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS), whereas the second study will be detailed in the January 26 online issue of the British Journal of Psychiatry (BJP).

Due to the fact that the UB team used Magnetic Resonance Imaging (MRI) scanners to image the test subjects' brain, researchers now know the exact areas of the brain that are activated during the “trip.”

Interestingly, experts also figured out which regions of the brain are inhibited when people consume psilocybin. Based on these data, they hypothesize that the chemical allows users to remember and experience their memories more vividly and in depth.

In the PNAS paper, a study of 30 participants revealed that the hubs of the brains – the areas that are known to be responsible for underlying important connections with many other regions – were found to exhibit reduced levels of activity.

In the BJP study, Bristol experts learned that recollecting personal memories became a lot easier for people once they were administered psilocybin. This raises the prospect for the chemical to be used in psychotherapy, as a method of encouraging amnesiacs to remember their pasts.

“Psychedelics are thought of as ‘mind-expanding’ drugs so it has commonly been assumed that they work by increasing brain activity, but surprisingly, we found that psilocybin actually caused activity to decrease in areas that have the densest connections with other areas,” says David Nutt.

He holds an appointment as a professor at the Imperial College London (ICL) Department of Medicine and is currently a visiting fellow at the UB School of Social and Community Medicine. The scientist was also the senior author of both studies.

“These hubs constrain our experience of the world and keep it orderly. We now know that deactivating these regions leads to a state in which the world is experienced as strange,” he goes on to explain.

A decrease in oxygenation and blood flow in the medial prefrontal cortex (mPFC) and the posterior cingulate cortex (PCC) may be responsible for the altered sense of space and time, weird bodily sensations and visions of geometric patterns that test subjects who took psilocybin reported.