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Cambridge University Science Magazine
PSYCHEDELIC ‘MAGIC’ MUSHROOMS | have been utilised by humans and our ancestors for thousands of years. Their popularity is not surprising, given their potent hallucinogenic effects. There have been drastic changes to the utilisation of psychedelic mushrooms, and attitudes towards this use, over time. They have a rich cultural history in religious and spiritual ceremonies globally and are still used recreationally and therapeutically today in Western cultures.

ON THE HISTORY OF PSYCHEDELIC MUSHROOMS | The oldest representations of the use of hallucinogenic mushrooms were discovered in the Sahara Desert. Cave paintings dating back to around 9,000 years ago depict dancing shamans with mushrooms sprouting from their bodies. These cave paintings are assumed to be a form of pre-literate communication between people of the Neolithic era and indicate the involvement of hallucinogenic mushrooms in religious and ritual practices. Evidence of hallucinogenic mushroom use in prehistoric Europe comes from the Selva Pascuala mural discovered in Spain in 1918. The mural displays fungoid figures which are similar in morphology to the Psilocybe hispanica fungus: small brown mushrooms with convex caps, which is one of many species of mushroom that contains the psychoactive chemical psilocybin. These cave paintings provide supporting evidence for the historical use of hallucinogenic mushrooms; however, they are not conclusive evidence as we can only infer the message that the people were intending to convey.

Terence McKenna, an ethnobotanist, believed that magic mushrooms may have supported the evolution of human cognition. This hypothesis more recently became known as the ‘Stoned Ape’ theory. Psychedelics can profoundly influence cognition in the short-term, but the idea that they could drive evolutionary cognitive development appears very speculative. The theory is not generally supported by the scientific community.

Western societies began consuming magic mushrooms in the 1950s. R. Gordon Wasson, a mycologist, had heard about perception-altering mushrooms; and searched for them in Mexico, where he took part in a ritualistic ceremony with the Mazatec people in 1955. In 1957, he wrote an article for Life magazine, introducing hallucinogenic mushrooms to the American public. Wasson also sent samples of the mushrooms to Albert Hofmann, a Swiss chemist, who was able to successfully isolate the psychoactive compound of the mushrooms: psilocybin.

Mind-altering substances had a profound influence on the creative industries in the 1950s and 1960s. Popular musicians, such as The Beatles, were known to have experimented with hallucinogenic drugs. This may have encouraged The Beatles to experiment with unusual musical modes, such as the Lydian mode, which Blue Jay Way is written in. These modes, rarely used in pop and rock music, have a mysterious, ‘out-of-this-world’ presence that is, interestingly, rather reflective of psychedelic perception.

RECREATION, RELIGION AND COGNITION | The use of psychedelics, such as psilocybin-containing mushrooms, often induces vivid visual imagery, an enhanced sensory experience and a detached sense of self, known as ego-dissolution. In some, it produces mystical experiences, whereby individuals are able to transcend usual states of consciousness to connect with a ‘higher power’. This may explain the use of psychedelics in religious ceremonies.

The risks of psychedelic substance use appear to be markedly lower than that of other psychoactive substances such as alcohol or heroin. The risk of addiction is low, and overdose is highly unlikely. However, danger can quickly arise when individuals use hallucinogenic drugs unsupervised or in unsafe environments. Due to the altered perceptual experience, individuals are at greater risk of injuring themselves, and deaths have been reported.

Most psychedelic research focuses on the perceptual experience of psychedelics, and there is limited research into the cognitive effects. Perception refers to the processing and interpretation of sensory information by the central nervous system. Cognition uses this perceptual information for higher-order processes such as memory, attention and reasoning. The current literature suggests that reasoning, decision-making, and reaction times might be particularly impaired. However, psilocybin use has also demonstrated cognitive enhancements in recent exciting studies.

PSYCHEDELIC MUSHROOMS AS THERAPEUTICS | More recently, psychedelics have been utilised as therapeutics to treat a wide range of psychological disorders such anorexia, obsessive compulsive disorder and substance use disorders. Robin Carhart-Harris is currently investigating the therapeutic use of psilocybin for treatment-resistant depression. He demonstrated that orally-administered psilocybin produces an antidepressant response that is rapid and sustained for a period after the subjective effects of the psychedelic have worn off. This is an exciting advancement in the field of psychedelic therapeutics. The mechanism of action is not well understood but psilocybin is thought to act via 5-HT2A receptors in the brain. The current idea from Carhart-Harris’ research is that there might be altered functional connectivity (FC) associated with different brain states. He states that, in depression, there appears to be increased FC within discrete brain networks (increased modularity) and decreased FC between brain networks, possibly reflecting the restrictive, narrow cognition that is symptomatic of the disorder. Psilocybin treatment appears to reduce FC within discrete networks and increase FC between networks, hence increasing the global network integration. He describes ‘the broadening of the brain’s functional repertoire of states’. Following treatment, subjects describe feeling ‘liberated’, and having increased behavioural positivity, and cognitive and psychological flexibility. The networks that are most affected by psilocybin appear to be those with the highest density of 5-HT2A receptors, one of which is the default mode network (DMN). Functionally, the DMN is associated with introspection and self-referential thinking and is found to be overactive in depression, reflecting the ruminative thinking style present in the disorder.

Furthermore, Martin K. Madsen showed that psilocybin treatment decreased modularity within the DMN. This might contribute to a reduced sense of self during the psychedelic experience, whilst simultaneously reducing cognitive restraints, reducing depressive symptoms. These experiments provide potential neural correlates which nicely reflect the subjective experiences of the depressive and psychedelic states and suggest a mechanism for the action of psilocybin in the brain. However, it is important to appreciate that this is a novel area of research, and more studies need to be conducted to provide more conclusive evidence.

  • Cave paintings by our hominin ancestors may signify the use of ‘magic mushrooms’ in ancient cultures.
  • Discovery in the West led to recreational use, which inspired the creative industries.
  • The risks of psychedelic substance use are markedly lower than that of other psychoactive substances, but they must still be treated with caution.
  • There has been plenty of research into the perceptual aspects of psychedelics, although cognitive effects remain misunderstood.
  • Psychedelics are now being used to effectively treat a wide range of psychological disorders.


Functional connectivity (FC): a measure of the temporal coincidence of neural activity between distinct brain regions. It is generally assessed using functional magnetic resonance imaging (fMRI), or electroencephalography (EEG). Synchronisation is used as a proxy for communication between the regions.

Default mode network (DMN): a ‘task-negative’ brain network which shows strong activity at rest, and suppressed activity during cognitive tasks. It includes areas such as the posterior cingulate cortex and the medial prefrontal cortex. The DMN is believed to facilitate self-referential thinking and an egotistical perspective.

Network modularity: the extent to which a specific brain network is connected to or interacts.

Isabella Bentham-Clark is a Natural Sciences student at Cambridge, specialising in Physiology and Neuroscience. Artwork by Leonora Martínez.