mental health, neuroscience

Fear can save your life. It can also make you miserable. Whereas a normal fear response may compel us to escape from a life-threatening situation, an exaggerated one is a hallmark of anxiety disorders.

We know that fear and anxiety involve brain circuits connecting the prefrontal cortex and the amygdala. Now, researchers in Sweden have identified an epigenetic mechanism for over-consolidating fear memories in these circuits.

Researchers at Linköping University had previously shown that alcohol dependence in rodents reduces levels of a protein called PRDM2, and that this down-regulation is associated with an increased stress response. PRDM2 is enriched in the dorsomedial prefrontal cortex (dmPFC), where it silences genes by chemically modifying them, and mice with lower levels of the protein in that region are more prone to stress-induced alcohol seeking.

The researchers therefore reasoned that reduced PRDM2 levels in dmPFC might contribute to pathological fear by altering gene expression changes in the brain.

Extinguishing fear memories

For this new study, the researchers “knocked down” activity of the PRDM2 gene in rats’ dmPFC, using a genetically engineered virus containing RNA that inhibits protein synthesis. They then tested the animals’ fear responses by placing them in cages that deliver mild electric shocks to their feet.

Subscribe for counterintuitive, surprising, and impactful stories delivered to your inbox every Thursday

The animals quickly learned to associate the electrical shocks with sounds they hear while receiving the shocks. Later, they exhibited fear when they heard the sounds alone. If, however, they repeatedly hear the sounds without receiving shocks, the fear memory eventually fades away.

PRDM2knockdown did not affect how the animals learned fearful memories, but rather produced an abnormal, long-lasting conditioned fear response, such that their fear memories took longer to extinguish than control animals. The genetic manipulation did not affect other anxiety-related behaviors.

Another set of experiments further revealed that the exaggerated fear response is mediated by dmPFC neurons that send fibers to the amygdala. One consequence of PRDM2knockdown was increased release of the excitatory neurotransmitter glutamate in the amygdala, which increased the activity of amygdala cells in response to the sounds the animals had learned to associate with the electric shocks.

RNA sequencing showed that PRDM2knockdown modulated the expression of more than 3,600 genes in these cells, many of which are involved in neurochemical transmission, or have previously been implicated in anxiety, emotion, fear conditioning, and memory.

Numerous animal studies show that PFC-amygdala circuits are important for regulating the fear response, and brain scanning shows an increase in functional connectivity between these regions while healthy people process threats.

This study identifies some of the molecular mechanisms within this pathway. Decreased PRDM2expression in the dmPFC appears to increase synaptic responses in the amygdala in response to stress, and this may contribute to an enduring and pathological fear response. The findings also help reveal why anxiety disorders are often associated with excessive alcohol use.


What Makes Hawaii's Erupting Volcanoes Special

Lava flows from the Mauna Loa volcano on December 4, 2022 near Hilo, Hawaii. Mauna Loa is the largest active volcano in the world. Justin Sullivan/Getty Images hide caption toggle caption Justin Sullivan/Getty Images Just after Thanksgiving, for the first time in almost 40 years, Hawaii’s Mauna Loa volcano ...

View more: What Makes Hawaii's Erupting Volcanoes Special

Could new cancer drugs come from potatoes and tomatoes?

Credit: CC0 Public Domain Everyone knows someone who has had cancer. In 2020, around 19 million new cases—and around 10 million deaths—were registered worldwide. Treatments are improving all the time, but can damage healthy cells or have severe side effects that are hard on patients. In the search for ...

View more: Could new cancer drugs come from potatoes and tomatoes?

Researchers find an elusive European parent of lager yeast in Ireland

Credit: CC0 Public Domain A new paper in FEMS Yeast Research reports that, for the first time in Europe, scientists have discovered the ancestor of the yeast species necessary for the production of lager beer. Brewing is one of the oldest human industries. Scientists have uncovered evidence of fermented ...

View more: Researchers find an elusive European parent of lager yeast in Ireland

A faster way to preserve privacy online

New research enables users to search for information without revealing their queries, based on a method that is 30 times faster than comparable prior techniques.

View more: A faster way to preserve privacy online

Improving Antibiotic Treatment: Scientists Test “Smart” Red Blood Cells

An illustration of the new drug delivery system. Credit: Ella Marushchenko The “smart” red blood cells deliver antibiotics that target specific bacteria. A natural delivery system that uses red blood cells as a vehicle to transport powerful antibiotics throughout the body safely has been developed by physicists at McMaster ...

View more: Improving Antibiotic Treatment: Scientists Test “Smart” Red Blood Cells

NASA didn’t test one of Orion’s most important systems in first flight

Orion’s first flight is coming to an end soon, and its return to Earth is an exciting moment for space fans. But what might be most intriguing about this mission is that NASA didn’t test one of the most important systems the Orion will need to have if it plans ...

View more: NASA didn’t test one of Orion’s most important systems in first flight

JBL Quantum TWS wireless earbuds review: Great earbuds for gamers on the go

JBL has a long history of delivering high-end, great-sounding headsets, and in recent years it has built many of the best wireless earbuds out there. Now, the company is back with a fresh pair that are specifically targeted at gaming, in the JBL Quantum TWS wireless earbuds. Earbuds aren’t commonly ...

View more: JBL Quantum TWS wireless earbuds review: Great earbuds for gamers on the go

Scientists Discover New Permanent Changes Caused by Giving Birth

The researchers discovered that females who had given birth had lower levels of calcium, magnesium, and phosphorus. A study of primates reveals permanent changes in bone composition after birth and breastfeeding. Reproduction permanently alters females’ bones in ways not previously known, a team of anthropologists has found. Its discovery, ...

View more: Scientists Discover New Permanent Changes Caused by Giving Birth

New find suggests ankylosaur’s tail clubs were for bashing each other

Ankylosaurs battled each other as much as they fought off T. rex

The moon as it looked 50 years ago: Newly-remastered images from humanity's last lunar landing in December 1972 reveal the incredible view of Apollo 17 astronauts

Severe COVID-19 Linked With Molecular Signatures of Brain Aging

James Webb telescope breakthrough lets us ‘see’ dark matter

Violent Supershear Earthquakes Are Much More Common Than Previously Thought

SpaceX reveals 'Starshield' satellite project for national security use

A new Hubble Image Reveals a Shredded Star in a Nearby Galaxy

Will We Ever Go Back to Explore the Ice Giants? Yes, If We Keep the Missions Simple and Affordable

Amazon tests machine learning software to analyze satellite images from space

Listen to the Artemis 1 Orion capsule phone home from deep space

Group Exercise Boosts Physical and Mental Health for Older Adults


Breaking thailand news, thai news, thailand news Verified News Story Network