When people take the psychedelic drug LSD, they sometimes feel as though the boundary that separates them from the rest of the world has dissolved. Now, the first functional magnetic resonance images (fMRI) of people’s brains while on LSD help to explain this phenomenon known as “ego dissolution.”
As researchers report in the Cell Press journal Current Biology on April 13, these images suggest that ego dissolution occurs as regions of the brain involved in higher cognition become heavily over-connected. The findings suggest that studies of LSD and other psychedelic drugs can produce important insights into the brain. They can also provide intriguing biological insight into philosophical questions about the very nature of reality, the researchers say.
“There is ‘objective reality’ and then there is ‘our reality,'” says Enzo Tagliazucchi of the Royal Netherlands Academy of Arts and Sciences in Amsterdam. “Psychedelic drugs can distort our reality and result in perceptual illusions. But the reality we experience during ordinary wakefulness is also, to a large extent, an illusion.”
Take vision, for example: “We know that the brain fills in visual information when suddenly missing, that veins in front of the retina are filtered out and not perceived, and that the brain stabilizes our visual perception in spite of constant eye movements. So when we take psychedelics we are, it could be said, replacing one illusion by another illusion. This might be difficult to grasp, but our study shows that the sense of self or ‘ego’ could also be part of this illusion.”
It has long been known that psychedelic drugs have the capacity to reduce or even eliminate a person’s sense of self, leading to a fully conscious experience, Tagliazucchi explains. This state, which is fully reversible in those taking psychedelics, is also known to occur in certain psychiatric and neurological disorders.
But no one had ever looked to see how LSD changes brain function. To find out in the new study, Tagliazucchi and colleagues, including Robin Carhart-Harris of Imperial College London, scanned the brains of 15 healthy people while they were on LSD versus a placebo.
The researchers found increased global connectivity in many higher-level regions of the brain in people under the influence of the drug. Those brain regions showing increased global connectivity overlapped significantly with parts of the brain where the receptors known to respond to LSD are found.
LSD also increased brain connectivity by inflating the level of communication between normally distinct brain networks, they report. In addition, the increase in global connectivity observed in each individual’s brain under LSD correlated with the degree to which the person in question reported a sense of ego dissolution.
Tagliazucchi notes in particular that they found increased global connectivity of the fronto-parietal cortex, a brain region associated with self-consciousness. In particular, they observed increased connection between this portion of the brain and sensory areas, which are in charge of receiving information about the world around us and conveying it for further processing to other brain areas.
“This could mean that LSD results in a stronger sharing of information between regions, enforcing a stronger link between our sense of self and the sense of the environment and potentially diluting the boundaries of our individuality,” Tagliazucchi said.
They also observed changes in the functioning of a part of the brain earlier linked to “out-of-body” experiences, in which people feel as though they’ve left their bodies. “I like to think that our experiment represents a pharmacological analogue of these findings,” he says.
Tagliazucchi says the findings highlight the value of psychedelic drugs in carefully controlled research settings. He plans to continue to use neuroimaging to explore various states of consciousness, including sleep, anesthesia, and coma. He also hopes to make direct comparisons between people in a dream versus a psychedelic state. Meanwhile, researchers at the Imperial College London are investigating other psychedelic drugs and their potential use in the treatment of disorders including depression and anxiety.
Learn more: How LSD can make us lose our sense of self
Drugs researcher David Nutt discusses brain-imaging studies with hallucinogens.
Researchers have published the first images showing the effects of LSD on the human brain, as part of a series of studies to examine how the drug causes its characteristic hallucinogenic effects.
David Nutt, a neuropsychopharmacologist at Imperial College London who has previously examined the neural effects of mind-altering drugs such as the hallucinogen psilocybin, found in magic mushrooms, was one of the study’s leaders. He tells Nature what the research revealed, and how he hopes LSD (lysergic acid diethylamide) might ultimately be useful in therapies.
Why study the effects of LSD on the brain?
For brain researchers, studying how psychedelic drugs such as LSD alter the ‘normal’ brain state is a way to study the biological phenomenon that is consciousness.
We ultimately would also like to see LSD deployed as a therapeutic tool. The idea has old roots. In the 1950s and 60s thousands of people took LSD for alcoholism; in 2012, a retrospective analysis of some of these studies suggested that it helped cut down on drinking. Since the 1970s there have been lots of studies with LSD on animals, but not on the human brain. We need that data to validate the trial of this drug as a potential therapy for addiction or depression.
Why hasn’t anyone done brain scans before?
Before the 1960s, LSD was studied for its potential therapeutic uses, as were other hallucinogens. But the drug was heavily restricted in the UK, the United States and around the world after 1967 — in my view, due to unfounded hysteria over its potential dangers. The restrictions vary worldwide, but in general, countries have insisted that LSD has ‘no medical value’, making it tremendously difficult to work with.
How did you get approval to give volunteers LSD?
United Nations conventions and national laws do permit academic research on heavily-restricted drugs such as LSD. In the UK, this sort of study is legal so long as the drug is not being used as a therapeutic. This was not a clinical trial: we gave LSD to volunteers who were already experienced with the drugs and took their brain scans over eight hours in the lab in Cardiff, in 2014. It took us nine months to get approval from a UK ethics committeefor the work: the research was funded by the Safra Foundation [a philanthropic foundation in Geneva, Switzerland] and the Beckley Foundation [a charity near Oxford, UK, that promotes drug-policy reform] though we needed to crowdfund through Walacea.com for the resources to analyse the data.
What were the results of the study?
To take advantage of the “long trip” produced by LSD — an eight-hour experience, compared to say four on psilocybin — we put our participants through a huge range of tests.
Learn more: Brain scans reveal how LSD affects consciousness