Targeted Laser Takes Control of Tiny Animal’s Brain

The scientists from Harvard have taken control over an animal's brain by using precisely targeted lasers. This new revolutionary development could help in understand human nervous system. The Harvard researchers can instruct the tiny worm C. Elegans to turn in any direction they choose. They can even implant false sensory information into the animal.

The details of this were described in the Sept 23 paper published in Nature. Led by Sharad Ramanathan, an Assistant Professor of Molecular and Cellular Biology, and of Applied Physics along with Askin Kocabas, a Post-Doctoral Fellow in Molecular and Cellular Biology, Ching-Han Shen, a Research Assistant in Molecular and Cellular Biology, and Zengcai V. Guo, from the Howard Hughes Medical Institute through this study there were able to control Caenorhabditis elegans.

This is a tiny transparent worm of which the researchers took control by manipulating neurons in the worms' brain.

The work is important said Ramanathan because "by taking control of complex behaviors in a relatively simple animal - C. Elegans have just 302 neurons -we can understand how its nervous system functions."

"If we can understand simple nervous systems to the point of completely controlling them, then it may be a possibility that we can gain a comprehensive understanding of more complex systems," Ramanathan said. "This gives us a framework to think about neural circuits, how to manipulate them, which circuit to manipulate and what activity patterns to produce in them."

"Extremely important work in the literature has focused on ablating neurons, or studying mutants that affect neuronal function and mapping out the connectivity of the entire nervous system. " he added. "Most of these approaches have discovered neurons necessary for specific behavior by destroying them. The question we were trying to answer was: Instead of breaking the system to understand it, can we essentially hijack the key neurons that are sufficient to control behaviour and use these neurons to force the animal to do what we want?"

But prior to this the team had to overcome a number of technical challenges. With the help of genetic tools, the researchers engineered worms whose neurons gave off fluorescent light, allowing them to be tracked during experiments. The genes in the worms were altered which made neurons sensitive to light, meaning they could be activated with pulses of laser light.

Though it was difficult for them to develop the hardware necessary to track the worms and target the correct neuron in a fraction of a second.

"The goal is to activate only one neuron," he explained. "That's challenging because the animal is moving, 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 particularly neuron -- and do it all in 20 milliseconds, or about 50 times a second. The engineering challenges involved seemed insurmountable when we started. But Askin Kocabas found ways to overcome these challenges"

"The system researchers eventually developed uses a movable table to keep the crawling worm centered beneath a camera and laser. They also custom-built computer hardware and software," Ramanathan said, "to ensure the system works at the split-second speeds they need."

"The end result was a system capable of not only controlling the worms' behavior, but their senses as well. In one test described in the paper, researchers were able to use the system to trick a worm's brain into believing food was nearby, causing it to make a beeline toward the imaginary meal," he said.

Further the team plans to explore what other behaviors the system can control in C. Elegans.

"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," 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."