Scientists prove that there is an alert line in the mouse retina

Recently, Current Biology published a research paper entitled "Instinctive Defense Response Triggered by Approximate Visual Stimuli Mediated by Transient Alpha Retinal Ganglion Cells".
The research was conducted by the Center for Excellence in Brain Science and Intelligent Technology of the Chinese Academy of Sciences (Neuroscience Research).
The research team of Zhang Yifeng, a researcher at the Shanghai Center for Brain Science and Brain-inspired Research, was completed.

The study screened the molecular markers of transient light-exhausted alpha retinal ganglion cells and constructed transgenic mice that can label and manipulate the cells, and found that such cells can encode the size of the approximate visual stimulus, and mediate the approximate visual stimulus trigger The instinctive defensive response of mice.

The study found for the first time molecular markers that mark transient light-exhausted alpha retinal ganglion cells, and proved that such neurons constitute an alarm line in the retina, which quickly triggers a defensive response in mice through subcortical pathways.


The visual system of the brain allows people to perceive the external visual environment; it also has other more conservative functions (such as feeling the circadian rhythm, regulating emotions, mediating some instinctive behaviors, etc.
).

Is there a difference between the information coding strategy used by the visual system to provide these functions and the coding strategy in traditional visual perception? Combined coding is a coding method for traditional visual perception, which can provide clear and complete images for the brain, but this method has disadvantages such as slow response time and redundant processing information.

Is there another way of fast coding in the vision system? Is there a special alert line to quickly transmit specific key information to the brain and trigger behavior? These are important scientific questions.


In order to study the above problems, the research team selected a paradigm that approaches visual stimuli to trigger escape or rigid behavior in mice.

The team guessed that in the behavior of mice quickly escaping from predators, there is a special alert line that transmits dangerous information to the brain, which then causes rapid defensive behavior.

How to find this alert line is the difficulty of this research.

The research team started with the mouse’s retina and believed that the mouse’s eyes had the beginning of this special thread.
If the beginning was found, the pathway behind it would be found step by step like a cocoon.

The study believes that a very conservative type of ganglion cells in the mouse retina may be the beginning of this alert line.

Such alpha retinal ganglion cells have been found to have distinctive characteristics from the very beginning-they have huge cell bodies and broad dendritic clusters, allowing them to search for information in a large area like a radar antenna.
.

At the same time, they transmit electrical signals to the brain through thick axons.

These axons, which can transmit signals at the fastest speed like cables, make them the first choice for this special alert line.

However, research on such hot star cells has been slow for a long time, because although researchers can see such cells and hear the signals from them, they have not been able to compare the tens of thousands of retinal ganglion cells.
They are all singled out, and it is impossible to make them make specific responses according to the ideas of researchers without interference from other cells, so as to accurately explore their functions.


Zhang Yifeng's team screened out the molecular marker Kcnip2 gene for transient light-extracted alpha cells, and "captured" such cells for the first time.

The research team constructed Kcnip2 transgenic mice.

Through genetically modified mice, such cells can be lighted up, making it stand out among many cells and more easily seen by researchers; such cells can also be manipulated through optogenetic methods to achieve the "taming of such wild cells" ".


The research team explored whether such cells are reporting to the brain’s alert line that predators are approaching.

They first recorded the response of such cells, and when given a visual stimulus that mimics a predator's head-on pounce, such cells responded strongly to the approaching visual stimulus.

Further research found that such cells can encode the approximate size of visual stimuli, and report to the brain through the frequency of action potentials: danger is approaching! It is not enough to be able to record the secret signals transmitted by such cells to the brain.
The research team has to forge such signals and transmit false signals to the brain by controlling the activities of such cells.

When they activated such cells to send emergency danger signals to the brain, the brain believed it to be true and quickly controlled the mice to make escape or rigid defensive behaviors to save their lives.

The research team can not only activate such cells, but also silence them, and fail to send out alarm signals when they see dangerous stimuli.

When the mice were given an approaching visual stimulus, the mice were still wandering in the courtyard as if they hadn't seen the danger, without any sense of fear.


Through experiments, the research team proved that the mouse retina has a special alert line composed of instantaneous light-withdrawing alpha cells, which can quickly transmit danger signals to the brain and cause the animal's defensive behavior.

This research provides a loop basis for the brain's rapid information coding, and helps to understand the way the brain encodes external stimuli.

This information transmission mode of the biological world also brings enlightenment to human society: for dangerous specific stimuli, humans not only need extensive information input, but also need a special dedicated line to make quick decisions.

Just as the army leader cannot obtain information about the enemy through daily news, the army needs a special reconnaissance system at the forefront.


The research was completed by Ph.
D student Fei Wang, Li E, Delei, and Wu Qiwen of the research group under the guidance of Zhang Yifeng, and was actively participated by other members of the research group.
It was also awarded by Sun Yangang, Xu Xiaohong and Xu Huatai from the Center for Brain Intelligence Excellence.
Strong support.

The research work was funded by the Ministry of Science and Technology and Shanghai.

By screening molecular markers and constructing transgenic mice, it is possible to label and manipulate transient light-exhausted α retinal ganglion cells (top).

When an approximate visual stimulus is given, such cells can encode the size of the approximate visual stimulus (medium).

Activation of such cells by optogenetic methods can trigger the instinctive defensive behavior of mice to escape to a safe place (bottom left).
When the activity of such cells is inhibited, even if dangerous approaching visual stimuli are given, the mice still move normally ( Lower right) Source: Center for Excellence in Brain Science and Intelligent Technology, Chinese Academy of Sciences