RIKEN Center for Brain Science researchers and collaborators in Japan have recently found specific neurons in the brain that monitor if predictions fish are making do come true.
A Phys.org report specified that through the use of a new virtual-reality-outfitted aquarium where zebrafish's brain imaging can be done, as they learn and navigate through virtual reality hints, the study authors found neurons that enable efficient risk avoidance and make a "hazard sharp" in the brain that allows for an escape to safety.
Predicting the future, as specified in this report, is an integral part of decision-making for both humans and fish alike. When actual scenarios are not matching expectations, the brain is producing the so-called "prediction errors," letting one know that his expectations were off.
Essentially, expectations are made by the internal models of the environment. More so, like humans, this new study showed that fish have such prototypes in their brains.
Prediction-Error-Associated Brain Activity
In their study published in Nature Communications, scientists monitored prediction-error-associated brain activity in actual time as zebrafish learned to escape danger in their tank.
They discovered that the fish were trying to keep the prediction low to effectively avoid danger. Since risk avoidance is an evolutionarily conserved behavior, such outcomes shed light on essential brain circuits that are shared through all vertebrates, with humans included.
Zebrafish, as described in ScienceDaily are tiny and transparent, which is making it easy to record the activity of the entire brain. In the investigation, the fish saw a choice between red or blue reality zones as they swam virtually and learned to link to the colors of virtual zones with hazard or safety.
The study investigators were specifically interested in the brain's front part also known as the telencephalon, which is equivalent to the cerebral cortex and other structures in mammals, contributing to decision-making.
Escaping Danger in Virtual Reality
As zebrafish learned to avoid danger in virtual reality, the researchers recorded the time-lapse change in their brain activity, resulting in the discovery of neurons representing the prediction error, as explained in the National Library of Medicine.
Distinctive active neuron populations emerged as fish began to learn that opting for the virtual route through blue surroundings resulted in danger and opting for the red route would mean safety.
Following that, an experimental reversal of the link, in which red turned out to be dangerous instead of blue, resulted in an inactivation of such neurons.
This told the scientists that the neurons were possibly coding a behavioral rule, not just the color that the fish were seeing.
As specified in this report, in another change to the virtual reality space, the background was changed so that it did not change according to the fish's tail movements.
A Certain Way of Behavior
For instance, trying to swim forward by flipping the tail did not make the view retreat as expected. Such manipulations showed a group of neurons was stimulated only when actions the fish thought would enable them to reach safety did not have the projected result.
The study's lead author Mako Torigoe said, they think this "population of neurons is a prediction error in the brain," comparing the real view of their surroundings with the forecasted view that they have learned would get them safety if they exhibited a certain way of behavior.
Each animal needs to predict its future according to what it has previously learned, added Hitoshi Okamoto, the research team leader.
Now, he also said, how such predictions are compared to what animals actually encounter worldwide, and which parts of the zebrafish brain are driving the subsequent decision-making.
Related information about zebrafish is shown on Johns Hopkins Medicine's YouTube video below:
Check out more news and information on Fish on Science Times.