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Why Researchers Turned This Goldfish Into a Cyborg

On the one hand, this headgear looks like something a Cyberfish would wear.

But scientists didn’t put the device on just for laughs. They explore the underlying brain mechanisms that allow fish to navigate the world, and how such mechanisms relate to the evolutionary roots of navigation in all creatures with brain circuits. I’m interested in

“Navigation is a very important aspect of behavior because we navigate to find food, find shelter, and escape predators.” Fish in cybernetic headgear for research To do. Published Tuesday in the journal PLOS Biology.

Attaching a computer to a goldfish to study how neurons fire in the brain during migration was no easy task.

Goldfish brains, which look like little chunks of lentils, are only half an inch long, so be careful. “Under the microscope, we exposed the brain and put electrodes inside,” said Leah Cohen, a neuroscientist and doctoral candidate at Ben-Gurion who performed the surgery to install the device. Each of these electrodes was the diameter of a human hair.

It was also difficult to find a way to perform the procedure on dry land without harming the subjects. He and his colleagues solved both problems by pumping water and an anesthetic into the fish’s mouth.

Once the electrodes were inserted into the brain, they were connected to a small recording device that could monitor neural activity and were sealed in a waterproof case that was attached to the fish’s forehead. To keep the computer from weighing the fish down and interfering with their ability to swim, the researchers attached buoyant foam plastic to the device.

After recovering from surgery, the fish debuted the headgear in an experiment. The closer a swimming fish is to the edge of the tank, the more activated the navigation cells in the brain.

A fish brain computer helped reveal that goldfish use navigation systems that are subtly different than those scientists have discovered in mammals. Humans (and other members of our class ), the navigation cell specializes in pinging a precise location in the environment and creating a map around that location. Mammals have specialized neurons, mental he creates these “you are here” pins on the map. The researchers didn’t find those cells in the fish.

Instead, goldfish rely on a type of neuron that fires to let the animal know it’s approaching a boundary or obstacle. You can orient yourself.

According to Dr. Segev, a mammal’s navigation system is equivalent to the cells that make an animal think, “Here I am, I am here.” The goldfish’s cells, he said, function to convey a different message: “I’m in this position along this axis, and I’m in this position along another axis.”

Cohen believes that differences in animals’ navigational circuitry may correspond to different challenges they face in navigating habitats. For example, the constantly changing currents of a house of water could mean that it is easier for fish to know their distance from a salient feature in their environment than it is to know their exact location.

All experiments were approved by the university’s Animal Welfare Committee, and researchers euthanized the fish after the swim test so that their brains could be examined further. The team hopes to continue learning how and why the fish’s navigation system differs from ours.

Adelaide Thibault, a biologist at the University of Oxford who was not involved in the study, said the project was not only significant, but “pretty amazing.”

“We are changing the environment of many animals, and understanding how they move will tell us whether they are able to cope with the changes that are happening in the world right now,” Dr. Sibeaux said. Told. For fish, it may contain turbid water due to contamination.

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