Just one beam of ultra-violet light left this nematode worm completely paralyzed. A second beam of visible-spectrum light allowed it to move again. That's right - scientists have created behavioral "light switches," a way to control animals with light.
We've written about this kind of work before, specifically the research into optogenetics, which allows scientists to genetically-engineer light-sensitive reactions in animals or plants. What's different about this nematode experiment, however, is that no genetic engineering was involved - the little worm just ate a small amount of a chemical (basically the equivalent of popping a pill).
According to National Geographic:
After feeding a light-sensitive chemical to transparent, microscopic worms called nematodes, scientists at Simon Fraser University in British Columbia were able to paralyze the tiny creatures by exposing them to UV light. The paralysis works because UV light changes the structure of the ingested chemical, called dithienylethene.
Upon UV exposure, the normally clear chemical turns blue, and it shuts down the worms' metabolism, said study co-author Neil R. Branda. A shot of visible light restored the worms to normal, and the animals slowly began to wiggle around "as if they had never been paralyzed," the study authors say.
Will we be seeing the equivalent kinds of experiments taking place with humans? Yes indeed, though not for paralyzing people. Researchers are interested in light-activated medicines, which only get activated when exposed to light. This would allow doctors to activate drugs in very precise places in your body.