This rat has two green LED lights implanted near its bladder to help the animal regain control of its urination.
According to Washington University researcher Robert Gereau, the technology — which involves a metal ring around the bladder to sense its fullness and a wirelessly rechargeable battery — could eventually help humans with incontinence. Here's how it works, from New Scientist:
When the device was implanted in rats with bladder dysfunction, the metal ring measured changes in bladder size. When it detected that a rat was urinating more than two times an hour, the LED lights switched on.
These rats had previously received gene therapy, enabling their nerve cells involved in bladder-brain signaling to make a light-sensitive protein. When the LEDs were switched on, their light activated this protein, which in turn blocked urination signals from the bladder from reaching the brain.