Why do you always feel that you have more moments of social death? Nature: The brain is more inclined to characterize memories as negative

Heng Yu from the Concave Non-Temple
Qubit | Official number QbitAI

I don't know if you have such an experience:

When you tell someone about a social death with great pain, people say, "Are you okay?" ”

Maybe you think it's just someone else's comfort to you
.

But now, a study on Nature shows that this is not necessarily the case!

Because whether a memory is beautiful or terrifying is determined by a molecule in the
brain.

That is, when the brain encodes the information, it will "subjectively" characterize the experience as good or bad
.

Moreover, the brain will tend to characterize the information as bad
.

This time, why do people always repeatedly whip corpses "social death" memories, anxiety, and fear, there must be a solution!

So, what is the name of this brain molecule? How does it drive our emotions?

The molecule in the brain, called neurotensin (NT), is distributed throughout the central nervous system and is most
abundant in the hypothalamus, amygdala, and nucleus.

Studies have shown that it regulates the amygdala in the brain and determines whether the information received is positive or negative
.

The amygdala (BLA) is a very small almond-like region of the brain that has traditionally been called the brain's "fear center," but it also responds
to happiness and other emotions.

The basal-lateral complex, part of the amygdala, is responsible for associating
stimuli in the environment with positive or negative outcomes.

However, the amygdala itself cannot distinguish between positive and negative information
.

So, who defines memory as negative or positive?

When studying genes that form negative/positive memory expression, the team noticed neuropeptides
.

It is a small, versatile protein that slowly and steadily strengthens the prominent connections between neurons
.

Early studies have shown that neurotensin is a neuropeptide that is only 13 amino acids long, is involved in regulating the release of luteinizing hormone and prolactin, and has significant interactions
with the dopaminergic system.

At the same time, it is also involved in the reward and punishment of memory, including fear response.

△ Expression of various genes and proteins (white, red and green) in neurons in mouse brain cells (blue).

To verify what happens by changing the levels of neurotensin in the brains of mice, the researchers began experiments
with CRISPR gene editing to selectively remove neurotensin from cells.

(This is the first time CRISPR has been used to isolate specific neurotransmitter functions
.
) ）

Neurons within the amygdala don't make neurotensive, so the team had to figure out where it came from
.

By scanning the brains of mice, it was found that neurons in the thalamus produced a large amount of neurotensin and poked the long axis into the amygdala
.

△ Neurons from several areas of the cerebral thalamus extend axons to the amygdala

The experiment officially began
.

The process is simple, performing a tone-sucrose/plantar shock experiment that teaches mice to associate
a tone with sucrose (reward learning) or electric shock (punishment learning).

These mice are admitted to a customized sound attenuation chamber that is also equipped with a mouse condition fear instrument
.

Each box contains a modular test cage with an electric floor mesh and a speaker
inside.

Start by playing a tone
.

After the pitch is finished, the mice will randomly perform a sucrose test (delivering sucrose for free food in mice), neutral test (no additional behavior after pitching), and shock test (shock achieved by plantar shock)
with a probability of 50%, 25%, and 25%, respectively.

Before the first tone appears, there is a period
of adaptation that lasts 3 minutes.

The team found that after performing the sucrose test, the level of neurotensin in the amygdala of mice increased and decreased
after the shock test.

i.
e.
increased neurotensin promotes rewarding learning; After the reduction, the punishment study
is strengthened.

That being the case, by genetically modifying the thalamic neurons of mice, it is possible to control how and when
neurons release neurotensin.

The brain's ability to record environmental cues and experiences as good or bad memories is critical for survival, and studies have also shown that judging environmental cues influences the behavioral response
of mice.

That is, if your system collapses, the amygdala can't sense emotions correctly, what effect will this have?

The researchers gave the example that even if you encounter a tiger, you will not be afraid in this situation, but will only be indifferent
.

And the next time you encounter a tiger, the memories of the past will tell you that you don't need to escape
.

The experimental results also show that the brain must make and release neurotensin to understand the reward; Learning to punish doesn't require so much work
in the brain.

That is, the brain is more inclined to define information as negative (laziness as it is
).

If neurotensin is removed and there is no neurotensin signal in the amygdala, the mice would not associate "tone" with the subsequent "sucrose test" — a lack of neurotensin that would hinder learning rewards
.

Interestingly, this does not prevent learning punishment, but rather a stronger
correlation between the two.

For example, when the mouse enters the sound attenuation chamber, it does not know whether it will face a reward or punishment
after the tone.

The researchers speculate that the unknown new stimulus is automatically given a negative value until the thalamic neurons begin to release neurotensin that allows the mice to react with sweetness
.

In this way, the brain is a natural pessimist
.

No wonder you will frantically play back the scene of social death in your head, let yourself die in the skull society a hundred times, but others think that you are making a big fuss
.

The researchers say such a factory setup makes sense from an evolutionary standpoint: because it helps people avoid potential dangers
.

Although neurotensin is not as widely known as dopamine, its small size does not prevent it from being effective, and studying it can be very helpful
in understanding the fear circuit and the role of the amygdala.

If the role of neurotensin and thalamic neurons in allocating titer can be understood, they may be ideal targets for drugs designed to treat neuropsychiatric disorders
.

Because theoretically, if you can be clear about the distribution of potencies, you can treat these diseases
.

Pharmacologically, this is not easy, after all, peptides are notoriously difficult to do (because they cannot cross the blood-brain barrier, which protects the brain from foreign substances and blood chemical fluctuations
).

In addition, can therapeutic drugs for neurotensin change the impression of existing memories? It's unclear
.

However, the research team is already on the road to exploration
.

The study is a Chinese brother named Hao Li
.

Born in Beijing, he moved to the United States after receiving a bachelor's degree from Shandong University and completed his doctorate
.

Currently, he is a postdoctoral fellow
at the Salk Institute for Biological Research in California.

Reference link:
[1] making-a-memory-positive-or-negative/
[3]— Ends —

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