An experiment by neuroscientists examined directional positioning in fish that differed from the majority of mammals, perhaps due to the use of brain circuits differently from the general population.
The eye-catching hat looks no different from the handcrafted fashion items featured at the famous Kentucky Derby horse racing festival. But more than that, the hat is part of the “cyborg” goldfish.
Fish “cyborg” is the term to refer to the enhancement of the goldfish’s mechanical abilities with technological solutions.
Scientists performed goldfish brain surgery to place electrodes inserted through small holes in the fish’s skull, to a head-mounted recording device that can monitor neuronal activity. (Photo: New York Times).
The scientists weren’t making this device for fun: They were studying how fish brains navigate and the mechanisms involved in the development of orientation in all vascular creatures.
Ronen Segev, a neuroscientist at the Ben-Gurion University of the Negev in Israel, was part of a study published April 25 in the journal PLOS Biology that transplanted 15 fish into the heads of 15 fish. Experimental hat, said: “Navigation is an extremely important ability in the life of some animals because they help navigate to find food, find shelter, hide from predators.” .
Implanting the device into goldfish to study how neurons in their brains work when navigating isn’t easy.
Care must be taken because the goldfish’s brain, which looks a bit like a small bunch of lentils, is just over 1cm long.
Lear Cohen, a neurologist and doctoral student at Ben-Gurion, who performed the surgery to attach the devices, said: “Under the microscope, we dissect the brain and put electrodes in it. inside. Each of those electrodes is about the diameter of a human hair.”
It is difficult to experiment on fish transplants because “fish need water and you need it not to move”. (Photo: Fishkeeping World).
It is also difficult to perform this procedure in a dry area without harming the test subject. “Fish need water and you need it not to move,” he says. He and his colleagues solved both problems by injecting both water and anesthetic into the fish’s mouth.
Once the electrodes were in the brain, they were connected to a small recording device that could monitor neuronal activity and sealed in a waterproof case, mounted on the fish’s forehead. In order for the device not to weigh down the fish and interfere with its ability to swim, the researchers added floating plastic foam.
After recovering, the fish revealed its latest appearance with a headgear. The experiment allowed the goldfish to swim in a tank 60 cm long and 15 cm wide. The closer the fish swim to the edge of the tank, the more directional cells in their brains light up.
The device in the fish brain has revealed that goldfish use a different navigation system than what scientists have found in mammals. For humans (and other species of the same class), navigator cells usually determine our exact location in the environment and build a map around that location themselves. Mammals have specialized neurons that generate “you are here” pins on a simulated map of their subconscious, but the researchers did not find those cells in fish.
Instead, goldfish rely on a type of neuron that activates to let them know they are approaching a boundary or encountering an obstacle. By combining information about distances from different barriers, the fish can orient itself in space.
The way the fish’s navigational cells work is somewhat different from usual. (Photo: The Spruce Pets).
Dr Segev said the mammalian navigation system consists of cells that allow an animal to determine, “I’m here, I’m here, I’m here” . In goldfish, he says, the cells act to convey another flow of information: “I am in this position along this axis, and this is along another axis.”
Cohen speculates that the animals’ neural variations in orientation may be the result of the various adaptations they face as they move around their habitats. For example, he says, in an area full of water, with ever-changing currents, fish will “easier to discern the distance from a particular point in the environment than from an exact location.”
All experiments were approved by the university’s animal welfare committee, so the researchers killed the fish after swimming so that their brains could be further examined. The team hopes to be able to learn more about how and why the fish’s navigation system is different from ours.
Adelaide Sibeaux, a biologist at the University of Oxford, was not involved in the study, but said she found the project “quite amazing” and important.
Dr Sibeaux said: “We are changing the environment of a lot of animals and if you understand how an animal navigates, you know if they can cope with the changes that are taking place in the world. world at this time or not. For fish, for example, this explains whether they can adapt to cloudy vision caused by water pollution.”