Lost fish are able to find their way back home thanks to 'ancient' wiring of their brains, says new study

You might be able to refer to "Finding Nemo" as a documentary! According to recent research, lost fish can return home because of their brains' "ancient" wiring. Up to 500 million years ago, the neuronal circuit underwent an evolution and may have been transmitted to humans. It makes it possible for our slick ancestors to get back on the track themselves even after being carried away by swift currents. The finding provides new insight into how the prehistoric brain functioned and may be applicable to other vertebrates, including humans. It's quite unknown, as per co-author Dr. Misha Ahrens of the Howard Hughes Medical Institute in Maryland. According to Good News Network, "We think it might underlie higher order hippocampal circuits for exploration and landmark-based navigation." 

The study published in Cell, used the common zebrafish, a model for humans that has long been used in medical research, to identify the critical chemical pathways that cross various regions of the animals' brains to aid in regaining their bearings. In experiments, the tiny transparent fish moved through a 2D virtual environment while a simulated flow was present. The strong water unexpectedly pushed them off as they swam toward a target. In spite of this, they swam back to where they had begun, determined to complete the journey. In order to measure what is happening, the first author, Dr. En Yang and his colleagues used a "whole imaging" method created in their lab. It enabled researchers to examine the entire fish's brain to determine which circuits are turned on during their course correction—and to separate the various parts involved.

As per the scans, the hindbrain, a region that is conserved, determines its location. They make decisions about their next steps based on the information. Researchers anticipated that the hippocampus, which houses a "cognitive map" of an animal's environment, would trigger cells in the forebrain. To their surprise, they noticed activation in several medulla regions. Messages were being sent from a recently discovered circuit. It made its way from the cerebellum's motor circuits, which allow the fish to move through a region of the hindbrain known as the inferior olive. They were unable to find their way back to their starting point when these passageways were blocked. Research added that the parts of the brainstem recall a zebrafish's starting location and use that information to generate an error signal based on the fish's present and past locations.

The fish can swim back to its starting point thanks to the cerebellum, which receives this information. It reveals a new role for the inferior olive and cerebellum, previously thought to be involved in locomotion and reaching but not this kind of navigation. "We found the fish is trying to calculate the difference between its current location and its preferred location and uses this difference to generate an error signal," said Dr. Yang. "The brain sends that error signal to its motor control centers so the fish can correct after being moved by flow unintentionally, even many seconds later."

It is still unknown if the same networks are responsible for comparable animal behavior. However, the researchers hope that by now, mammal research labs will begin looking at the hindbrain for corresponding circuits used for navigation. Ahrens said the research might help us understand dementia and the basis for other navigational abilities, such as when a fish swims to a specific location for shelter. That fish has such a keen sense of direction and shouldn't surprise anyone. In a previous experiment, it was discovered that goldfish could operate a robotic vehicle!