Zebrafish reveals decision-making in virtual reality

The mechanism for forecasting the future is an integral part of the decision making in fish as well as in humans. In order to better understand the brain processes involved in this mechanism, scientists from the RIKEN Center for Brain Science and collaborators in Japan carried out an experiment. It made it possible to highlight particular neurons in the brain playing a role in predicting the future.

The experiment required a zebrafish, an aquarium as well as the technology of virtual reality. According to the study, the neurons discovered by scientists allow fish to avoid risks and create a “Hazard map” allowing him toescape.

The choice of zebrafish for this experiment was based on a few factors. In reality, the small size zebrafish and its transparency facilitate the recording of its brain activity.

A whole population of neurons involved

In order to better understand the movements of the fish, the movements of its tail were recorded in real time, then projected to give it theimpression to swim. The fish then had the choice between red and blue virtual reality zones. It is up to him to associate each color with a situation of danger or security. Scientists found that while the fish avoided danger, its brain activity in the telencephalon a evolved.

The neurons representing theprediction error were thus discovered. Concretely, active populations of neurons appeared each time the fish associated the virtual blue environment with danger and the red zone with safety. After experimental reversal of this choice, these neurons were deactivated. It was concluded that neurons codified probably a behavioral rule.

To elucidate the mechanism, the scientists modified the virtual reality space of the fish. They have retouched the landscape so that it does not change according to the movements of the tail of the fish. For example, trying to swim forward did not decrease the view. They were able to highlight a group of active neurons only when the actions carried out by the fish did not give the expected result.

One step closer to understanding how the brain works

From the results obtained during the experiment, the scientists concluded that the telencephalon zebrafish corresponds to the area of ​​the brain affected by the predictive mechanism. This zone corresponds to Cerebral cortex in other mammals such asman. It is at this level that a whole population of neurons integrated the nervous messages received from the external environment to predict the future and make decisions.

“We now know how these predictions compare to what animals actually encounter in the world, and what parts of the zebrafish brain direct the decision-making that follows. “

Hitoshi Okamoto, Research Team Leader