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How ‘extinction neurons’ help us block out our worst memories
A recent study could help improve treatments for PTSD, anxiety and phobias.
- A new study examined how the effects of fear-related memories can be silenced in the brain.
- Forming new and positive "extinction memories" can help to silence fearful memories.
- The study found that the hippocampus plays a significant role in "extinction training."
Memories associated with traumatic events can cause unexpected problems in everyday life. A woman with a phobia of dogs might experience a rush of fear when she happens to find herself right next to a dog without a leash in the park. In cases like this, a psychologist might recommend exposure therapy, in which people with specific fears are voluntarily and incrementally exposed to the very things they fear. The goal is to create new positive memories to silence the fearful ones. These are called "extinction memories."
Scientists have long associated a part of the brain called the amygdala with fear. However, a new study focuses on the hippocampus — a brain region generally associated with memory and spatial navigation — and describes how extinction memories work not by replacing fearful memories, but rather by competing with them. This competition acts in two ways: by decreasing or silencing the activation of fear-inducing neurons and by activating a distinct set of neurons that help to reduce the fear response.
The study was published April 1 in the journal Nature Neuroscience.
"Extinction does not erase the original fear memory but instead creates a new memory that inhibits or competes with the original fear," said Michael Drew, associate professor of neuroscience and the senior author of the study, to Science Daily. "Our paper demonstrates that the hippocampus generates memory traces of both fear and extinction, and competition between these hippocampal traces determines whether fear is expressed or suppressed.
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In the study, Drew and his colleagues placed mice inside a box and induced fear with a minor electric shock. The mice then associated the box with pain and displayed fearfulness when placed inside it again. But after repeatedly being placed in the box without getting shocked, the mice formed extinction memories and eventually stopped showing fear.
Using optogenetics — a method that uses light-based tools to modulate molecular events — the researchers were able to artificially induce fear in the mice in two ways: stimulating neurons associated with fear, and silencing neurons associated with the extinction training. Similarly, the researchers managed to reduce fear by silencing the fear-related neurons and stimulating the extinction neurons.
The researchers hope their findings can be used to improve treatments for post-traumatic stress disorder, phobias and anxieties.
"Artificially suppressing these so-called extinction neurons causes fear to relapse, whereas stimulating them prevents fear relapse," Drew said. "These experiments reveal potential avenues for suppressing maladaptive fear and preventing relapse."
Ever since we've had the technology, we've looked to the stars in search of alien life. It's assumed that we're looking because we want to find other life in the universe, but what if we're looking to make sure there isn't any?
Here's an equation, and a rather distressing one at that: N = R* × fP × ne × f1 × fi × fc × L. It's the Drake equation, and it describes the number of alien civilizations in our galaxy with whom we might be able to communicate. Its terms correspond to values such as the fraction of stars with planets, the fraction of planets on which life could emerge, the fraction of planets that can support intelligent life, and so on. Using conservative estimates, the minimum result of this equation is 20. There ought to be 20 intelligent alien civilizations in the Milky Way that we can contact and who can contact us. But there aren't any.
Frequent shopping for single items adds to our carbon footprint.
- A new study shows e-commerce sites like Amazon leave larger greenhouse gas footprints than retail stores.
- Ordering online from retail stores has an even smaller footprint than going to the store yourself.
- Greening efforts by major e-commerce sites won't curb wasteful consumer habits. Consolidating online orders can make a difference.
A pile of recycled cardboard sits on the ground at Recology's Recycle Central on January 4, 2018 in San Francisco, California.
Photo by Justin Sullivan/Getty Images<p>A large part of the reason is speed. In a competitive market, pure players use the equation, <em>speed + convenience</em>, to drive adoption. This is especially relevant to the "last mile" GHG footprint: the distance between the distribution center and the consumer.</p><p>Interestingly, the smallest GHG footprint occurs when you order directly from a physical store—even smaller than going there yourself. Pure players, such as Amazon, are the greatest offenders. Variables like geographic location matter; the team looked at shopping in the UK, the US, China, and the Netherlands. </p><p>Sadegh Shahmohammadi, a PhD student at the Netherlands' Radboud University and corresponding author of the paper, <a href="https://www.cnn.com/2020/02/26/tech/greenhouse-gas-emissions-retail/index.html" target="_blank">says</a> the above "pattern holds true in countries where people mostly drive. It really depends on the country and consumer behavior there."</p><p>The researchers write that this year-and-a-half long study pushes back on previous research that claims online shopping to be better in terms of GHG footprints.</p><p style="margin-left: 20px;">"They have, however, compared the GHG emissions per shopping event and did not consider the link between the retail channels and the basket size, which leads to a different conclusion than that of the current study."</p><p>Online retail is where convenience trumps environment: people tend to order one item at a time when shopping on pure player sites, whereas they stock up on multiple items when visiting a store. Consumers will sometimes order a number of separate items over the course of a week rather than making one trip to purchase everything they need. </p><p>While greening efforts by online retailers are important, until a shift in consumer attitude changes, the current carbon footprint will be a hard obstacle to overcome. Amazon is trying to have it both ways—carbon-free and convenience addicted—and the math isn't adding up. If you need to order things, do it online, but try to consolidate your purchases as much as possible.</p><p>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a>, <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank">Facebook</a> and <a href="https://derekberes.substack.com/" target="_blank">Substack</a>. His next book is</em> "<em>Hero's Dose: The Case For Psychedelics in Ritual and Therapy."</em></p>
Chronic irregular sleep in children was associated with psychotic experiences in adolescence, according to a recent study out of the University of Birmingham's School of Psychology.