Using lasers, researchers were able to take control of Caenorhabditis elegans — tiny, transparent worms — by manipulating neurons in the worms’ brain and instruct it to turn in any direction they chose. They implanted false sensory information, fooling the worm into thinking food was nearby. By taking control of such complex behaviors, researchers hope to understand how a worm's nervous system functions. The work is important because, by taking control of complex behaviors in a relatively simple animal — C. elegans have just 302 neurons — researchers can understand how its nervous system functions.
The hairy goal is to activate only one neuron, which is challenging because the animal is moving quickly, and the neurons are densely packed near its head, so the challenge is to acquire an image of the animal, process that image, identify the neuron, track the animal, position your laser, and shoot the particular neuron — and do it all in 20 milliseconds, or about 50 times a second. The system that researchers eventually developed uses a movable table to keep the crawling worm centered beneath a camera and laser.
The system was not only capable of controlling the worms’ behavior, but their senses as well. In one test, the researchers were able to trick a worm’s brain into believing food was nearby, causing it to make a beeline toward the imaginary meal.
“By manipulating the neural system of this animal, we can make it turn left, we can make it turn right, we can make it go in a loop, we can make it think there is food nearby,” the principal investigator Ramanathan said. “We want to understand the brain of this animal, which has only a few hundred neurons, completely, and essentially turn it into a video game, where we can control all of its behaviors.”