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Even though hallucinations are a fairly common occurrence in people with different types of mental illness, as well as those subject to a stroke or a plethora of other medical conditions, surprisingly little is known about their underlying mechanisms.
Now, a study published in the journal Cell Reports suggests that hallucinations might be the result of the brain overcompensating for a lack of information coming in from the external world.
“Understanding what’s happening in the world is a balance of taking in information and your interpretation of that information,” said lead author on the study Cristopher Niell from the University of Oregon in Eugene. “If you’re putting less weight on what’s going on around you but then over-interpreting it, that could lead to hallucinations.”
In the study, Niell and colleagues wanted to find out how the hallucinogen DOI (4-iodo-2,5-dimethoxyphenylisopropylamine) affects the ability of mice to see and perceive the world around them, which could, in turn, further our knowledge into how animals, including humans, create representations of the world using vision.
Just like LSD and psilocybin, DOI has its effect by acting on the brain’s serotonin system – mostly known for its involvement in fostering the sense of general well-being and happiness – or, more specifically, a receptor of serotonin called serotonin-2A.
Hallucinations might be the result of our brains scrambling to make sense of the world in cases where inputs from the outside world have been restricted. Image: Viscious-Speed via pixabay.com, Pixabay License
As the mice watched a series of pictures on a screen, the research team peered into their skulls to see how the drug affected their brain activity, finding that DOI inhibits the amount of incoming visual information, thereby leading to wild “trips” which might be the result of the brain working too hard to make sense of the world given scant information.
“You might expect visual hallucinations would result from neurons in the brain firing like crazy, or by mismatched signals,” Niell said. “We were surprised to find that a hallucinogenic drug instead led to a reduction of activity in the visual cortex.”
While Niell and his team do not claim that their findings constitute “smoking gun” evidence for hallucinations being nothing more or less than a kind of strange informatic illusion, they do, however, likely constitute a significant part of it.
Sources: abstract, blogs.discovermagazine.com