Zebrafish anticipate the future to avoid virtual danger
Date:
September 29, 2021
Source:
RIKEN
Summary:
Scientists have discovered particular neurons in the brain that
monitor whether predictions made by fish actually come true. By
making use of a new virtual reality-outfitted aquarium where brain
imaging of zebrafish can be done as they learn and navigate through
virtual reality cues, researchers found neurons that allow efficient
risk avoidance.
FULL STORY ========================================================================== Scientists from the RIKEN Center for Brain Science (CBS) and collaborators
in Japan have discovered particular neurons in the brain that monitor
whether predictions made by fish actually come true. By making use of a
new virtual reality-outfitted aquarium where brain imaging of zebrafish
can be done as they learn and navigate through virtual reality cues, researchers found neurons that allow efficient risk avoidance and create
a "hazard map" in the brain that allows for escape to safety. The study
was published in Nature Communications on September 29.
========================================================================== Predicting the future is an integral part of decision-making for fish and humans alike. When real situations do not match expectations, the brain generates "prediction errors," which let us know that our expectations
were off. Expectations are formed by internal models of the environment,
and just like people, the new study found that fish have such models in
their brains.
The researchers monitored prediction-error associated brain activity
in real- time as zebrafish learned to avoid danger in their tank. They
found that the fish tried to keep the prediction error low to efficiently
avoid danger.
Because risk avoidance is an evolutionarily conserved behavior, these
results shed light on important brain circuits that are shared across
all vertebrates, including humans.
Zebrafish are small and transparent, which makes it easy to record
the activity of the whole brain. In the experiment, the fish saw a
choice between red or blue virtual reality zones as they virtually swam
and learned to associate the colors of the virtual zones with danger
or safety. The researchers were particularly interested in a front
part of the brain called the telencephalon, which corresponds to the
cerebral cortex and other structures in mammals, and which contributes
to decision-making. As zebrafish learned to avoid danger in virtual
reality, the time-lapse change in their brain activity was recorded,
leading to the discovery of neurons that represent the prediction error.
Distinct active populations of neurons emerged as fish started to learn
that choosing the virtual route through blue surroundings led to danger
and choosing the red route meant safety. Later, an experimental reversal
of the association, in which red became dangerous instead of blue, led
to an inactivation of these neurons. This told the researchers that the
neurons were likely coding a behavioral rule, not simply the color that
the fish were seeing. In another change to the virtual reality space,
the scenery was altered so that it did not change based on the tail
movements of the fish. For example, trying to swim forwards by flipping
the tail did not make the view recede as expected. These manipulations
revealed a group of neurons that was activated only when actions the
fish thought would allow them to reach safety did not have the expected
result. "We think this population of neurons is encoding a prediction
error in the brain, comparing the actual view of their surroundings with
the predicted view that they have learned would get them to safety if
they behaved in a certain way," says lead author Makio Torigoe.
"Every animal has to make predictions for its future based on
what it has learned before," adds research team leader Hitoshi
Okamoto. "Now we know how these predictions are compared to
what animals actually encounter in the world, and which parts
of the zebrafish brain drive the subsequent decision-making." ========================================================================== Story Source: Materials provided by RIKEN. Note: Content may be edited
for style and length.
========================================================================== Journal Reference:
1. Makio Torigoe, Tanvir Islam, Hisaya Kakinuma, Chi Chung Alan
Fung, Takuya
Isomura, Hideaki Shimazaki, Tazu Aoki, Tomoki Fukai, Hitoshi
Okamoto.
Zebrafish capable of generating future state prediction error
show improved active avoidance behavior in virtual reality. Nature
Communications, 2021; 12 (1) DOI: 10.1038/s41467-021-26010-7 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2021/09/210929080300.htm
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