Scientists find location of “threat detector” in the brain 20:21

Brazilian scientists from the University of Sao Paulo have mapped a brain network that not only detects immediate threats but also creates long-term memories of the danger factors. The research was published in the scientific journal magazine Current Biology (CurBio).

The team conducted experiments on mice. The rodents were placed in a secure cage connected to a room with a low-voltage floor. It was thought that the unpleasant sensations resulting from the electrical discharges created a sense of a hostile environment in the animals.

To monitor and manage brain activity, the researchers used fiber photometry, a technique that measures neural activity in specific areas of the brain by detecting changes in fluorescence from calcium-sensitive tracers. They focused on the dorsal premammillary nucleus (PMd), a brain region involved in threat detection.

One key finding was that PMd acts as a critical “threat detector.” The nucleus became highly active when the mouse approached the area where it had previously received a shock. This activity decreased when the mouse moved away from the danger area or turned its back on it.

To further examine the role of the premammillary nucleus, the scientists used chemogenetic inhibition, a method in which certain receptors in the PMd are shut down with special drugs.

When the core was suppressed, the mice’s behavior changed dramatically. Instead of avoiding the electric cage, the mice entered it without hesitation, as if they no longer perceived it as dangerous.

The findings suggest that PMd is not only critical for detecting threats, but is also required for the formation of memories related to those threats.

Scientists say understanding circuits in the brain could shed light on new treatments for anxiety-related disorders such as post-traumatic stress disorder (PTSD).

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