Summary: A recent research has identified a mental circuit that is responsible for identifying threats and creating fear memories. The brain, known for spatial transportation, also plays a role in recognizing risks, with the subiculum transferring risk data to the brain.
When the dorsal premammillary nucleus ( PMd ) is inactivated, animals no longer avoid dangerous environments, showing the PMd’s crucial role in fear detection and memory reconsolidation. These findings emphasize specific neurological pathways that are involved in memory development and fear reaction.
Important Information:
- The brain receives economic risk information from the subiculum.
- PMd detection is crucial for fear reaction and memory reconsolidation.
- Animals ‘ protective behavior is significantly reduced when they are inactivated by the PMd.
Origin: FAPESP
An article , published , in the journal , Present Biology , describes tests that mapped a brain circuits responsible for suddenly detecting threats and forming memories of anxiety.  ,
According to Newton Sabino Canteras, full professor in the Department of Anatomy at the Brazilian University of So Paulo’s Biomedical Sciences Institute ( ICB-USP) and the final author of the article,” we were interested in locating a brain region associated with fear signaling and finding out how it could identify environments previously associated with physical or predatory threats.”
It is known that the brain is involved in directional and geographical routing. Additionally, this area of the brain recognizes dangers coming from the environment. Anything risky leaves a mark, Canteras explained, to help determine the threat’s exact location. The subiculum is a crucial component of the brain.  ,
The subiculum is essentially the show’s sun. It transmits data about the brain ‘ environmental hazards. We set out to examine how the bird reacts when it encounters an environment that has previously been associated with a negative stimulus, he said.
The researchers monitored exercise in the subiculum using grain calibration. We put a pathogen inside that contains a calcium-sensitive proteins that can identify biological activity. It emits light in response to mobile activity”, Canteras said.
The method of behavior employed by them was to habituate a keyboard to a pair of boxes connected by a hall. The mouse first was only allowed to use one box, and it also received aversive physical cues (electrical shocks to the legs ). It was put in the machine the day after to prevent the aversive box the following day.
” In this type of test, the animal stretches and sniffs, moves one way and another, but does n’t go back into the box where its paws were shocked. It displays what we call mitigation behavior”, he said.
A critical interface of the neural circuit investigated by photometry analysis focusing on the dorsal premammillary nucleus ( PMd ) revealed that the PMd becomes particularly active when the animal approaches and avoids the threatening source.
It interacts automatically with the supply and is a very accurate threat detector. If the mouse turns its back on the source, the PMd is n’t activated, but if it looks at the source or moves close to it, the PMd ‘ sounds the alarm’. That’s one of the important findings of the study”, he said.
The scientists then used a commonly used chemogenetic strategy known as DREADDs, which stands for custom receptors that are only activated by custom medications, to inactivate the PMd.
We injected a disease with a receptor [the protein hM4Di] that, in the presence of a particular substance, silenced the PMd. The medication prevented the fire of the cell. When the substance was removed, they resumed regular activities.
The dog dramatically reduced its protective reaction when the PMd was silenced in this way. It returned as if it were a safe environment, as if nothing had happened, he said, as opposed to avoiding the threatening box.
They came to the conclusion that PMd suppression had an impact on both reconsolidation of anxiety memories and contextualized fear responses. The bird therefore feels secure in the environment after PMd inactivation and behaves as though there are no dangers the day after.
Next, they examined the functional roles of the periaqueductal gray or PAG ( in the brainstem ) and the ventral anteromedial thalamus ( in the thalamus ).  ,
There is a method to specifically stop the forecast to the brainstem or brain. I inject a disease that contains a protein known to function as a light-sensitive chlorine channel into the PMd. These abortions are silenced when I light up the terminal fields, and I can influence a particular projection route,” Canteras said.
The researchers found that the animal responded well to dread the day after it was inactivated, which did not affect its fear storage.
” Expression of conduct is affected, but never fear memory reconsolidation. On the other hand, he said that the silencing of the brain pathway has a significant impact on fear memory reconsolidation and that it is primarily mediated by various centre projection sites.
The co-first authors of the article are Juliette Viellard ( ICB-USP and , Institute of Neurodegenerative Diseases, Bordeaux University, France ), and , Fernando Melleu , ( ICB-USP).
The other co-authors are  , Alicia Tamais,  , Alisson de Almeida,  , Carolina Zerbini,  , Juliane Ikebara,  , Karolina Domingues,  , Miguel de Lima,  , Simone Motta, ( all ICB-USP), and , Fernando A. Oliveira , ( Cellular and Molecular Laboratory, Center for Mathematics, Computation and Cognition, Federal University of the ABC ).
Concerning this information from the fear and storage research
Author: Heloisa Reinert
Source: FAPESP
Contact: Heloisa Reinert – FAPESP
Image: The image is credited to Neuroscience News
Original Research: Start exposure.
By Newton Sabino Canteras and albert.,” A subiculum-hypothalamic road functions in active danger detection and storage updating.” Recent Biology
Abstract
A subiculum-hypothalamic road functions in active danger detection and memory updating
Highlights
- Pets need to be able to identify dangers and recall where they took place.
- There is a popular subiculum-hypothalamic (S-H) loop performing these things
- In intimidating circumstances, this S-H loop senses active changes.
- This loop updates its anxiety memory to take account of ominous situation modifications.
Summary
Pets need to find risks, initiate defensive responses, and, in reverse, remember where the danger occurred to avoid the possibility of re-encountering it.
By probing creatures capable of detecting and avoiding a shock-related disturbing spot, we were able to show a septo-hippocampal-hypothalamic loop that is also engaged in ethological risks, including exploitative and cultural threats.
The dorsal premammillary nucleus ( PMd ), a crucial interface of this circuit, appears to be ideal for using as a threat detector in freely tested animals to sense dynamic changes as the animal approaches and avoids the threatening source.
We also discovered that PMd chemogenetic silencing altered defense responses by preventing any behavioral responses from being directly affected by a loss to detect a threat, and that it also altered the state of fear memory to reflect a low-threat state.
The periaqueductal black and the front lateral thalamus, which are the primary PMd targets, were shown to have a significant impact on both defense responses and, to a lesser extent, cultural memory, whereas the projection to the front medial thalamus has a more significant impact on memory processes.
Our findings provide crucial insight into how animals interact with the threat imminence continuum by revealing a circuit that is actively monitoring threat and that also serves as an updater of the memory process in order to adapt changes under disturbing circumstances.
