Neuroimaging Reveals How LSD Affects the Brain


Since its invention some 80 years ago, LSD has been considered one of the most powerful psychedelic drugs, with a mysteriously high ability to expand the conscious experience beyond the confines of the body. But what does this enigmatic drug actually do inside the brain? Thanks to the first-ever study of LSD with modern brain-imaging techniques, we now have a glimpse of the psychedelic in action.

Robin Carhart-Harris and David Nutt of Imperial College London and their colleagues looked at changes in brain activity patterns during the hallucinatory and consciousness-altering effects of LSD (lysergic acid diethylamide). They found a pattern of communication across the brain that could explain the drug's profound sensory and mind-altering effects. They published their findings today in the journal Proceedings of the National Academy of Sciences.

In the study, divided into two sessions that took place on two days, 20 participants received an IV infusion of either LSD or a salt-water placebo. They then lay in a brain scanner with their eyes shut. During each roughly four-hour session, the participants underwent neuroimaging with multiple techniques, including functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG).

During the session when subjects had LSD in their system, much more of the brain was involved in visual processing compared with the placebo session. Moreover, the visual cortex, the part of the brain involved in processing visual information, showed greater synchronous activity with many areas of the brain. The greater this connectivity, the higher the participants’ reporting of complex visual hallucinations.

Carhart-Harris et al. in PNAS

“What was really intriguing was the magnitude of this expanded visual processing, which was correlated with people's ratings of complex visual hallucinations—the kind of dreamlike visions they describe with psychedelics, involving landscapes and people,” Carhart-Harris told mental_floss.

Meanwhile, as expected, people experienced altered consciousness states as well. One such experience involved a disintegration of the sense of self, or what researchers call ego-dissolution; it was linked with decreased connectivity between two brain regions, the parahippocampus and retrosplenial cortex, suggesting this connection is linked to a sense of self. This was part of a general disruption in the default mode network—a network of brain regions that normally shows a robust pattern of connectivity as people are awake and resting, thinking, remembering the past, and planning for the future.

“The findings are quite consistent with previous findings on psychedelics,” Carhart-Harris said. “We are now getting more confidence in understanding what underlies subjective experience produced by psychedelics.”


Putting together these results with brain imaging findings of other psychedelics points to some general principles, Carhart-Harris said. It seems that LSD breaks the boundaries between well-established brain networks, giving rise to a different, more flexible form of communication among them.

During the development of the brain, neural networks become specialized in the tasks they perform. As these networks become more and more distinct from each other, the communication between them becomes less flexible. “With LSD, these networks in the brain begin to lose their integrity. You see a desegregation of brain systems, where networks start to blend with each other. On the whole, the brain becomes more globally connected, operating in a more flexible way,” Carhart-Harris said. “And this seems to map with some of the fundamental changes in consciousness that you see with LSD.”

"This powerhouse of a study employs a number of cutting-edge human neuroscience techniques to examine the effects of LSD on brain activity,” said Gaurav Patel, a psychiatrist at the New York State Psychiatric Institute at Columbia University Medical Center, who was not involved with the study. The use of multiple techniques in single individuals to study the changes in brain activity helps free the researchers from potential confounds in any one technique, Patel said. “Moreover, the findings were relatively specific, and had high correlations with behavioral measures,” Patel told mental_floss.


For an old drug with such intense effects on the brain, very little is known about LSD. After it was first synthesized by Albert Hofmann in 1938, LSD found its way into psychiatric settings and was in use throughout the 1950s and '60s. The drug also presented an intriguing opportunity for research. Between 1953 and 1973, the U.S. government alone funded more than 100 studies of LSD. But the drug was ultimately banned under the United Nations Convention on Psychotropic Substances, and fell off the radar of researchers due to political and social stigma.

But in recent years, LSD and other psychedelics have gained a renewed interest as potentially untapped resources useful for mental health treatment or studying consciousness. This interest is shared by scientists and nonscientists alike. For the present study, the researchers asked the public to cover the remainder of the cost for finishing the experiment in a crowdfunding campaign last year, ultimately raising £53,390 (about $80,000)—more than double their original goal (the study was also funded by the Beckley Foundation).

“The response was amazing,” said Carhart-Harris, who sees this as evidence of a genuine intellectual interest among the public for understanding the curious effects of the drug.

Screenshot from a crowdfunding video describing the researchers' LSD project 

Carhart-Harris and colleagues previously studied psilocybin, the active compound in psychoactive mushrooms. They found psilocybin allowed for bypassing the brain's normal control, lifting the typical limits on our perception—an idea reminiscent of what Aldous Huxley suggested in his 1954 book on psychedelics, The Doors of Perception.

The new findings on LSD, too, suggested the drug disrupts the normal pattern of activity in important brain networks, allowing the brain to operate in a more flexible, fluid way, Carhart-Harris said. 

The researchers suggest this modification of normal brain communication underlies ego-dissolution. There isn’t a clear definition of this phenomenon yet, but Carhart-Harris describes it as a feeling of becoming less sure of the self, identity, and personality. “You begin to see your ‘self’ more as something objective as opposed to subjective," he said. "This often is accompanied by certain insights about oneself, one's background and relationships with others and with the world in general. And actually it often goes hand-in-hand with feelings of a spiritual and mystical nature.”


In another article published online in the May issue of Psychological Medicine, the team detailed the findings on psychological effects of LSD. One paradoxical effect of the drug, the team said, was that it includes psychosis-like symptoms when it’s taken—yet seems to improve psychological well-being afterward. It is possible that LSD increases cognitive flexibility and leaves a residue of “loosened cognition” that leads to improved psychological well-being, the researchers said.

A few other studies, too, have explored the possible positive effects of LSD or other psychedelics on mental health. A 2014 study with 12 people with life-threatening diseases, for instance, found LSD useful for easing anxiety. And when researchers followed up with nine of the people a year later, they found the effects to be long-lasting.

Studying how psychedelics affect the brain can reveal new insights about how the brain works, in both health and disease.

“In psychiatric research, we struggle with understanding how the brains of individuals may or may not be different from what they could have been if healthy,” Patel said. “Here, we get to see how psychiatric-like symptoms correlate with circuit-level changes in brain activity. It is rare to see a study of this nature performed so rigorously, and to have found such clean results.”

Department Of Classics, University Of Cincinnati
Stones, Bones, and Wrecks
Ancient Poop Contains First Evidence of Parasites Described by Hippocrates
Department Of Classics, University Of Cincinnati
Department Of Classics, University Of Cincinnati

The long-held mystery of Hippocrates and the parasitic worms has finally been solved, and it’s all thanks to a few samples of ancient poop.

Researchers don’t know much about the parasites that plagued the Greeks thousands of years ago, and what they do know is largely from the Hippocratic Corpus, the medical texts that the father of medicine and his students put together between the 4th and 3rd centuries BCE. Modern historians have spent years trying to figure out which diseases and parasites Hippocrates and his followers were referring to in their writing, relying solely on their descriptions to guess at what ailments the ancient Greeks might have suffered from. Now, they finally have concrete evidence of the existence of some of the intestinal worms Hippocrates mentioned, Helmins strongyle and Ascaris.

As part of a study in the Journal of Archaeological Science: Reports, an international group of researchers analyzed the ancient remains of feces in 25 prehistoric burials on the Greek island of Kea to determine what parasites the people were carrying when they died. Using microscopes, they looked at the soil (formed by the decomposed poop) found on the pelvic bones of skeletons dating back to the Neolithic, Bronze, and Roman periods.

A roundworm egg under the microscope
A roundworm egg

Around 16 percent of the burials they studied contained evidence of parasites. In these ancient fecal samples, they found the eggs of two different parasitic species. In the soil taken from the skeletons dating back to the Neolithic period, they found whipworm eggs, and in the soil taken from the Bronze Age skeletons, roundworm.

With this information, researchers deduced that what Hippocrates called the Helmins strongyle worm was probably what modern doctors would call roundworm. The Ascaris worm probably referred to two different parasites, they conclude, known today as pinworm (which was not found in this analysis) and whipworm (pictured below).

Whipworm under a microscope
A whipworm egg

Though historians already hypothesized that Hippocrates's patients on Kea had roundworm, the Ascaris finding comes as a particular surprise. Previous research based solely on Hippocrates’s writing rather than physical evidence suggested that what he called Ascaris was probably a pinworm, and another worm he mentioned, Helmins plateia, was probably a tapeworm. But the current research didn’t turn up any evidence of either of those two worms. Instead of pinworm eggs, the researchers found whipworm, another worm that’s similarly small and round. (Pinworms may very well have existed in ancient Greece, the researchers caution, since evidence of their fragile eggs could easily have been lost to time.) The soil analysis has already changed what we know about the intestinal woes of the ancient Greeks of Kea.

More importantly, this study provides the earliest evidence of ancient Greece’s parasitic worm population, proving yet again that ancient poop is one of the world’s most important scientific resources.

Arctic Temperatures are Rising So Fast, They're Confusing the Hell Out of Computers

This past year was a brutal one for northern Alaska, which saw temperatures that soared above what was normal month after month. But you wouldn't know that by looking at the numbers from the weather station at Utqiaġvik, Alaska. That's because the recent heat was so unusual for the area that computers marked the data as incorrect and failed to report it for the entirety of 2017, leaving a hole in the records of the Climate Monitoring group at the National Centers for Environmental Information (NCEI), according to the Huffington Post.

The weather station in the northernmost tip of Alaska has been measuring temperatures for nearly a century. A computer system there is programed to recognize if the data has been influenced by artificial forces: Perhaps one of the instruments isn't working correctly, or something is making the immediate area unnaturally hot or cold. In these cases, the computer edits out the anomalies so they don't affect the rest of the data.

But climate change has complicated this failsafe. Temperatures have been so abnormally high that the Utqiaġvik station erroneously removed all its data for 2017 and part of 2016. A look at the region's weather history explains why the computers might have sensed a mistake: The average yearly temperature for the era between 2000 and 2017 has gone up by 1.9°F from that of the era between 1979 and 1999. Break it down by month and the numbers are even more alarming: The average temperature increase is 7.8°F for October, 6.9°F for November, and 4.7°F for December.

"In the context of a changing climate, the Arctic is changing more rapidly than the rest of the planet," Deke Arndt, chief of NOAA's Climate Monitoring Branch, wrote for The higher temperatures rise, the faster Arctic sea ice melts. Arctic sea ice acts as a mirror that reflects the Sun's rays back into space, and without that barrier, the sea absorbs more heat from the Sun and speeds up the warming process. “Utqiaġvik, as one of a precious few fairly long-term observing sites in the American Arctic, is often referenced as an embodiment of rapid Arctic change,” Arndt wrote.

As temperatures continue to grow faster than computers are used to, scientists will have to adjust their algorithms in response. The team at NCEI plans to have the Utqiaġvik station ready to record our changing climate once again within the next few months.

[h/t Huffington Post]


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