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![](https://www.popsci.com/wp-content/uploads/2019/03/18/HN4HADHUW46Q5NKV4ETNE7LASY.jpg?quality=85&w=485)
This is not your typical light show. The neon light piping into the brain of a mouse with Parkinson’s disease stops the animal’s tremors instantly. Neuroscientist and psychiatrist Karl Deisseroth and his colleagues at Stanford University believe the laser light can “turn on” damaged or inactive brain cells.
What: A laser device that can treat neurological and mental disorders, including Parkinson’s and depression
Where: Palo Alto, Calif.
Why: The World Health Organization predicts that depression will be the second biggest killer after heart disease by 2020.
Wow: Stops tremors in rodents with the flick of a switch.
To demonstrate the technology, the scientists genetically engineered Parkinson’s-afflicted mice with light-sensitive cells and inserted an optical fiber inside their brains. When blue laser light struck cells connected to the motor cortex, a brain region responsible for movement, the mice stopped shaking. This discovery points to laser-precision therapies for neurological and mental disorders, like depression and autism, that could one day treat faulty cells while sparing the rest of the brain.
See more machines that heal here, including a Japanese robotic nurse and a holodeck for the human body.