The "active braking system" hidden around the amygdala-scientists have found this type of neuron

Click on the blue word to pay attention to that our animals have a set of biological systems that detect and resist environmental threats: through the associative learning mechanism, predict the stimuli of threats and mobilize defensive responses to reduce harm.

When the threat-related stimuli become harmless, these responses adapt through the process of dissipation.

Effective memory dissipation can weaken the transitional adverse reactions caused by threats or dangerous stimuli.

Intercalated neurons (ITC) are a type of inhibitory neurons around the basolateral amygdala (BLA), which can be distinguished from surrounding neurons by electrophysiological and molecular characteristics, just like a brake system that is always on standby to inhibit BLA neurons active.

On May 26, 2021, Andrew Holmes of the National Institute of Alcohol Abuse and Alcohol Addiction of the National Institutes of Health revealed that there is a special type of neuron group in the amygdala: dissection neurons, which play a role in the acquisition and extraction of fear dissipating memories The opposite effect.

Schematic diagrams of the anatomy of dm-ITC and vm-ITC.
Researchers used the deep brain region microscope multicolor calcium imaging technology to achieve the same time of the dorsal ITC (dm-ITC) and ventral (vm-ITC) calcium near the BLA brain area.
Changes in ion activity.

The results showed that the dm-ITC response was stronger under the stimulation of the plantar electric shock, while the vm-ITC neuron changes more intensely in the early stage of the sound stimulation.
There is no difference between the two types of neurons in the later stage (can be in the deep brain area).
, Such a small nucleus achieves two-color calcium imaging records, the editor worships!).

They further recorded the changes in the calcium ion activity of dm-ITC and vm-ITC during different stages of fear memory training, and found that the proportion of neurons that responded to dm-ITC during the above process was about 42.
4%, and that of these neurons was about 75.
% Is closely related to fear memory, called fear neurons; less than 15% of neurons are related to dissipation.

On the other hand, the proportion of vm-ITC neurons responding is only 24.
5%, most of which (74%) are related to dissipation, and less than 5% are fear neurons.

This indicates that dm-ITC and vm-ITC regulate different stages of fear memory.

Inhibition of vm-ITC neurons by chemical genetics impaired the formation of memory in the process of dissipating memory, and mice showed a higher degree of fear.

In addition, inhibiting vm-ITC neurons also hindered the retrieval process of dissipated memory.

However, activation of vm-ITC neurons reduces the stiffness response during memory disappearance.

Activating dm-ITC neurons promotes the fear response of mice in the process of memory retrieval, and inhibits this type of neuron to reduce the fear response.

These results indicate that after manipulating neuronal activity, dm-ITC neurons are indeed related to the fear response, while vm-ITC neurons are mainly related to the process of dissipating memory.

In fact, what is more interesting is that although the functions of dm-ITC and vm-ITC are different, they are inseparable anatomically and are inseparable.

By injecting the anterograde tracer virus into the above two nuclei, it was found that the two nuclei projected to each other a large number of connections, forming a local micro-loop.

Previous studies have shown that the marginal anterior cortex (PL) of the prefrontal cortex is mainly related to the fear response, while the inferior marginal cortex (IL) is mainly related to the dissipating process of memory.

After the retrograde tracer virus was injected into PL and IL, retrograde projection was observed in the BLA brain area.
After light activation of dm-ITC and vm-ITC, it was found that the synaptic connection function of dm-ITC and the BLA→IL neural circuit was higher than that of vm- The synaptic connection function between ITC and BLA→PL neural circuit is stronger.

In general, this article reveals that dm-ITC and vm-ITC can form a local network that inhibits each other, and achieve precise control of the neural loop of BLA output (BLA→IL and BLA→PL), as a neural loop for defense state transition basis.

The interaction of dm-ITC and vm-ITC in the process of fear memory retrieval can be converted into the inhibitory effect of vm-ITC on dm-ITC in the process of memory dissipation.

[References] 1.
https://doi.
org/10.
1038/s41586-021-03593-1, the pictures in the text are all from the reference original download link: https://pan.
baidu.
com/s/14B3o5xPD6L6LGXRBFXf0dQ Extraction code: dxwj