Scientists Made Mice Hallucinate By Beaming Laser Holograms Into Their Brains


Hallucinations are often a confusing phenomenon in which the brain conjures images that aren’t really there. But there may be a way we could use them for good. Strange new research published Thursday in Science shows that it can be useful to shine light directly on the brains of mice to make them think they’re seeing something that isn’t really there.

In a new study, Stanford University School of Medicine stimulated nerve cells in the visual cortex of mice to induce an illusory image in the animals’ minds. The scientists needed to stimulate a surprisingly small number of nerve cells, or neurons, in order to generate the perception, which caused the mice to behave in a particular way.

Deisseroth’s team showed mice images of either horizontal or vertical bars, and trained the animals to lick from a tube of water whenever they saw the vertical bars. The scientists monitored the animals’ brains and recorded which neurons fired when the mice saw the vertical bars. They eventually identified about 20 cells per animal that seemed to be consistently associated with the vertical image.

Deisseroth, who is a Howard Hughes Medical Institute investigator and holds the D. H. Chen Professorship, pioneered optogenetics, a technology enabling researchers to stimulate particular neurons in freely moving animals with pulses of light, and to observe the resulting effects on the animals’ brain function and behavior.

The technique promises to provide clues to how the billions of neurons in the brain make sense of the environment. Eventually the research also may lead to new treatments for psychological disorders, including uncontrollable hallucinations.

“This is spectacular — this is the dream,” said Lindsey Glickfeld, a neuroscientist at Duke University, who was not involved in the new study.

Something that’s new about this study is that while in the past it was possible to influence the behavior of brain cells using light, it wasn’t possible to measure the effects this stimulation had on the animal’s perception.

This research suggests that not only can we influence an animal’s perception, but it can be done with great precision, down to just a few specific neurons.

Advocates of human brain hacking say that optogenetics could allow humans to enhance their central nervous systems by essentially creating new systems of neurotransmitters in their own brains that don’t interact with other existing systems. Since altered genes would require light to be activated, the chances (theoretically) would be low that they’d misfire.


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