A research team in Israel has discovered how fish navigate underwater without bumping into anything. Researchers at Ben-Gurion University performed surgery on 15 goldfish by wiring their brains to a computer to study their cognitive component. Navigation is an essential aspect of behavior for fish to find food, shelter, and escape predators. For the study, researchers recorded the activity of neurons in the central area of the goldfish telencephalon while the fish swam around a tank embedded in a 3D environment.
To conduct the study, the researchers attached electrodes to the fish’s brain, which were the size of human hair, and monitored their brain activity. The surgeries had to be performed out of the water, so the fish’s mouths were pumped with water and anesthetics to ensure they survived the surgery. The monitors were sealed in waterproof cases with plastic foam to keep them buoyant so that the fish could swim around normally.
After the fish recovered from the surgery, they participated in swimming trials that involved navigating a special tank. Researchers discovered that the navigational cells in their brains fired up when the fish swam closer to the tank’s edge. Fish can navigate the deep underwater world and get around constantly shifting currents and low visibility that would disorient a mammal because they know the distance from a salient feature in the environment, whereas mammals know their exact position.
Dr. Lear Cohen, a member of the research team, believes that other animals have various navigation circuits in their brains designed to accommodate their particular habitats. The experiments are important to understand how animals navigate in their environments, especially because many animals’ environments have been modified.
The fish were euthanized after the experiment was completed to examine their brains further. The experiment was approved by Oxford’s animal welfare committee.
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