Research has found that psilocybin can desynchronize networks in the brain and increase brain plasticity. Sarah Moser/Washington University School of Medicine in St. Louis Hide caption
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Sarah Moser/Washington University in St. Louis School of Medicine
Dr. Nico Dosenbach has scanned his own brain dozens of times in the name of science, but this was the first time he ingested a mind-altering substance before entering the MRI tunnel.
“I was falling deeper and deeper into a strange world,” he recalls. “I had no idea where I was. It was like time had stopped and I was everyone.”
Dosenbach, an associate professor of neurology at Washington University School of Medicine in St. Louis, had been given large doses of psilocybin, the active ingredient in magic mushrooms, by his colleagues.
This was all part of a seven-person study to demonstrate how psilocybin produces mind-altering effects.
The findings, published in the journal Nature, suggest that psychedelics work by disrupting certain brain networks, particularly those that help shape our sense of space, time and self.
“For the first time, we understand in great detail which networks are changing, how drastically they are changing, and what remains after the experience,” said Dr. Petros Petridis of the New York University Langone Center for Psychedelic Medicine, who wrote an editorial accompanying the study.
The study also looked in detail at how these drugs temporarily increase the brain’s ability to adapt and change, a phenomenon known as plasticity.
Dr Joshua Siegel, a researcher at the University of Washington and lead author of the study, said disruption of brain networks appears to be “the source of the plasticity effects of psychedelics.”
If that’s true, he says, it could explain why psychedelics seem to help people with addiction and depression.
Travel smart
Dosenbach and the other participants were randomly assigned to receive either stimulants or 25 milligrams of psilocybin, enough to cause hallucinations.
“It was definitely an amazing experience for a neuroscientist,” he says.
“Watching the brain break down is really fascinating, because the way something breaks can tell us something about how something works.”
Dosenbach’s travels have taken him to places only a neuroscientist might go.
“I was inside the brain, on the brainwaves. I was Mark Reichl,” he says, referring to his colleague and co-author on the study, Dr. Marcus Reichl, a great figure in the world of neuroscience.
As part of the study, participants’ brains were scanned an average of 18 times over a three-week period, and four of them were then repeated the experiment six to 12 months later.
“By collecting the same person multiple times, we can get a very detailed and precise map of their brain networks,” Siegel says.
The scans revealed that psilocybin caused rapid and dramatic changes in specific brain networks, with neurons within a given network typically firing simultaneously and often in conjunction with other networks.
“When you take psilocybin, populations of neurons that are normally synchronized become desynchronized,” Siegel says.
The brain appears to respond by “collapsing” and entering a state of enhanced plasticity for several weeks.
“Synchronization could be an important clue as to where the plasticity effects of psychedelics come from,” Siegel says.
The loss of synchronization was most evident in a group of neurons throughout the brain called the default mode network, which is active when the brain is daydreaming or not focusing on the outside world.
The network was discovered by scientists including Reichl, Dosenbach’s alter-ego within the scanner.
The default mode network is crucial for self-referential memory, helping the brain keep track of information like “who am I?” and “what was I doing?”, Siegel said.
Change your mind
The study suggests how psychedelics could be incorporated into the treatment of patients with addiction, depression and post-traumatic stress disorder.
“This appears to be an active period of change that therapists can take advantage of,” Petridis said.
For example, he says, an addicted person may be able to re-establish their relationship with the drug within days or weeks of taking psilocybin.
But the approach has risks, says Dr. Ginger Nicol, a psychiatrist at the University of Washington, whose husband took psilocybin twice in the study.
“The first time, he had almost a religious experience,” she said. “The second time, he saw the devil.”
Still, Nicol says psychedelics may have a way of helping people with mental illness realise their own potential for change.
“It takes years of therapy to understand that,” she says, “and it helps you think differently about learning and recovery.”
