The Beatles wrote songs about them and Aldous Huxley said they could be “extremely good for anybody with fixed ideas”. Now scientists are beginning to understand exactly what happens to our brain under the influence of psychedelic drugs, revealing intriguing insights into their well-observed link to creativity.

In a new analysis of a study which saw 15 volunteers undergo magnetic resonance imaging (MRI) scans while under the influence of psilocybin, the active ingredient of magic mushrooms, scientists have discovered that the patterns of activity seen in their brains bore “fascinating” similarities to those seen when dreaming.

The researchers found that while activity in parts of the brain responsible for high level thinking such as planning and analysing was “disjointed and uncoordinated”, activity in more primitive areas of the brain associated with emotional thinking was much more pronounced.

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They also saw that different areas of the brain were able to communicate in “novel” ways, giving the study volunteers a much larger range of potential brain states: something the researchers said could be a physical counterpart to the sensation of “mind expansion” often reported by users of psychedelics such as magic mushrooms, LSD and mescaline.

The study is published in the journal Human Brain Mapping today.

Aldous Huxley, when describing the experience of taking mescaline in his 1954 book The Doors of Perception, said that the experience was like “seeing what Adam saw on the morning of his creation”, and recalled in great detail the “labyrinth of endlessly significant complexity” visible even in the folds of his trousers. He said that the people who could gain most from taking LSD were “professors” because of the insights it could offer.

Scientists at Imperial College are currently researching whether psilocybin may help alleviate symptoms of depression.

Dr Robin Carhart-Harris, from Imperial’s department of medicine, said that the observed ability of psychedelics to give users a level of “emotional insight” was a strong argument for their use in psychotherapy, adding that they may even have a useful role in creative problem solving.

“There may be something in the loosening of the mind that occurs both in dreaming and in the psychedelic state that could be useful in terms of facilitating creative insight,” he said, adding that the scans showed that psychedelics could promote “a more exploratory kind of thinking”.

“Novel connections are made between different ideas and different topics,” he said. “There’s a fluidity and fluency to cognition. Only now are we forming ideas about what that might rest on in terms of changes in brain activity.”

A similar effect may be at work in forming the hallucinations and heightened perception of colour and pattern associated with a psychedelic trip.

“Much of what the brain does when we experience the world is to make predictions,” Dr Carhart-Harris said. “The brain gets quite adept at this and the world becomes more and more familiar and less surprising. Our predictions and our assumptions about the world begin firm up and we experience the world with assurance and confidence.

“What appears to happen with psychedelics is that process goes awry and the brain makes impetuous inferences about the world: this might be the basis of hallucinations. For instance, usually you look at the trunk of a tree and see the trunk of a tree. But on a psychedelic drug we may see a face in the trunk. It may be that the modules of the brain that normally process faces has ‘broken free’ and is making inferences in an impetuous way where there is no sensory evidence to call it up.”

Magic mushrooms are Class A drugs, but Dr Carhart-Harris said that any therapeutic use of psychedelics could be safe if appropriate cautions over dose and environment were observed.

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Samuel Taylor Coleridge

Coleridge famously composed the poem Kubla Khan after waking from an opium dream caused by “an anodyne” prescribed for an illness. He fell asleep reading about the Mongol emperor Kublai Khan, and dreamed of writing 200 to 300 lines of a poem, with all the images “[rising] up before him like things”. On waking he found he could only remember fragments, which nevertheless survive as one of his best-known poems.

The Beatles

Although conspiracy theories have linked more or less every Beatles song to drug use of one form or another, Paul McCartney has confirmed that the song “Day Tripper” is about LSD. “Lucy in the Sky with Diamonds”, despite featuring imagery reminiscent of a psychedelic trip (“cellophane flowers of yellow and green” etc) and having LSD subliminally in its title, was apparently inspired by a picture drawn by an infant Julian Lennon.

Aldous Huxley

The author of Brave New World was an exponent of the mind-expanding qualities of mescaline, which he first took “one bright May morning” in 1953. He later engaged in a discussion with the psychiatrist Humphrey Osmond about what such drugs should be called – suggesting phanerothymic, from the Greek “visible spirituality”. Osmond won though, with his suggestion ‘psychedelic’: from psyche (soul or mind) and delein (to manifest).