Our memory comes from an ancient virus, neuroscientists say

This study is radically changing how we view the process of evolution.

Artist depiction of neurons inside the brain.
Artist depiction of neurons inside the brain. Credit: geralt, Pixababy.

The particulars surrounding how our memory works has baffled neuroscientists for decades. Turns out, it’s a very sophisticated process involving several brain systems. What about on the molecular level? Inside the brain, proteins don’t stick around longer than a few minutes. And yet, our memories can hang on for our entire lifetime.


Recently, an international collaboration of researchers from the University of Utah, the University of Copenhagen, and the MRC Laboratory of Molecular Biology in the UK, discovered something strange about a protein called Arc. This is essential to long-term memory formation. What they found was that it has very similar properties to how a virus infects its host. Their findings were published in the journal Cell.

In it researchers write, “The neuronal gene Arc is essential for long-lasting information storage in the mammalian brain, mediates various forms of synaptic plasticity, and has been implicated in neurodevelopmental disorders.” They go on to say, “little is known about Arc’s molecular function and evolutionary origins.”

As a result of the study, researchers now believe that a chance encounter occurring hundreds of millions of years ago, led to Arc’s centrality in our memory function today. Assistant professor of neurobiology Jason Shepherd, Ph.D. of the University of Utah, led this research project. He’s dedicated himself to the study of the protein for the last 15 years.

A protein in our memory behaves like a virus. Pictured: the Simian virus 40. Credit: Phoebus87, Wikimedia Commons.

“At the time, we didn’t know much about the molecular function or evolutionary history of Arc,” Dr. Shepherd said in a press release. “I had almost lost interest in the protein, to be honest. After seeing the capsids, we knew we were onto something interesting.” Using electro-microscopy, Shepherd and colleagues studied the protein closely. They realized from an image they’d taken, that the way that Arc assembles itself looks a lot like how the HIV retrovirus operates.

Researchers were intrigued by the idea that a protein could behave like a virus and serve as the platform through which neurons communicate. What Arc does is open a window through which memories can become solidified. Without Arc, the window cannot be opened.

Previous work had shown that Arc is required for long-term memory formation. In one study, mice lacking Arc had little plasticity in their brains and couldn’t recall what happened to them, just 24 hours before. But no one suggested a mechanism mimicking a foreign entity at work, until now.

Shepherd and colleagues now believe that 350-400 million years ago, the ancestor to the retrovirus, the retrotransposon, injected its genetic material into a land-based, four-limbed creature. This led to the development of the Arc protein, as it operates in our neurochemistry today. According to a recent University of Massachusetts study, the same process developed in fruit fries, independently, sometime later, around 150 million years ago.

An HIV capsid. Credit: Thomas Splettstoesser, Wikimedia Commons.

Shepherd and colleagues found that Arc acts like a viral capsid. Capsids are a hard, outer shell which are hollow inside and carry a virus’s genetic information. A virus uses the capsid to spread its genetic material from one cell to another, causing an infection.

How Arc mimics this is, it encapsulates its RNA in order to transfer it from one neuron to another. Elissa Pastuzyn, Ph.D. is a postdoctoral fellow and the lead author of this study. She said in a press release, “We went into this line of research knowing that Arc was special in many ways, but when we discovered that Arc was able to mediate cell-to-cell transport of RNA, we were floored.” She added, “No other non-viral protein that we know of acts in this way.”

The study is changing how we view the evolutionary process. Rather than random mutations, it suggests that organisms may borrow from one another in order to develop. To test the theory, Shepherd and colleagues devised a number of experiments to see whether or not Arc operates like a virus.

What they found was, the protein replicates several copies of itself in capsids, which carry its mRNA inside. They then took these capsids and placed them into petri dishes containing mouse neurons, where they observed Arc transferring its mRNA from one to the next. It appears that activating a neuron triggers more Arc, which causes the release of more capsids, and so a domino effect occurs.

To learn more about this study, click here:

Golden blood: The rarest blood in the world

We explore the history of blood types and how they are classified to find out what makes the Rh-null type important to science and dangerous for those who live with it.

What is the rarest blood type?

Abid Katib/Getty Images
Surprising Science
  • Fewer than 50 people worldwide have 'golden blood' — or Rh-null.
  • Blood is considered Rh-null if it lacks all of the 61 possible antigens in the Rh system.
  • It's also very dangerous to live with this blood type, as so few people have it.
Keep reading Show less

China's "artificial sun" sets new record for fusion power

China has reached a new record for nuclear fusion at 120 million degrees Celsius.

Credit: STR via Getty Images
Technology & Innovation

This article was originally published on our sister site, Freethink.

China wants to build a mini-star on Earth and house it in a reactor. Many teams across the globe have this same bold goal --- which would create unlimited clean energy via nuclear fusion.

But according to Chinese state media, New Atlas reports, the team at the Experimental Advanced Superconducting Tokamak (EAST) has set a new world record: temperatures of 120 million degrees Celsius for 101 seconds.

Yeah, that's hot. So what? Nuclear fusion reactions require an insane amount of heat and pressure --- a temperature environment similar to the sun, which is approximately 150 million degrees C.

If scientists can essentially build a sun on Earth, they can create endless energy by mimicking how the sun does it.

If scientists can essentially build a sun on Earth, they can create endless energy by mimicking how the sun does it. In nuclear fusion, the extreme heat and pressure create a plasma. Then, within that plasma, two or more hydrogen nuclei crash together, merge into a heavier atom, and release a ton of energy in the process.

Nuclear fusion milestones: The team at EAST built a giant metal torus (similar in shape to a giant donut) with a series of magnetic coils. The coils hold hot plasma where the reactions occur. They've reached many milestones along the way.

According to New Atlas, in 2016, the scientists at EAST could heat hydrogen plasma to roughly 50 million degrees C for 102 seconds. Two years later, they reached 100 million degrees for 10 seconds.

The temperatures are impressive, but the short reaction times, and lack of pressure are another obstacle. Fusion is simple for the sun, because stars are massive and gravity provides even pressure all over the surface. The pressure squeezes hydrogen gas in the sun's core so immensely that several nuclei combine to form one atom, releasing energy.

But on Earth, we have to supply all of the pressure to keep the reaction going, and it has to be perfectly even. It's hard to do this for any length of time, and it uses a ton of energy. So the reactions usually fizzle out in minutes or seconds.

Still, the latest record of 120 million degrees and 101 seconds is one more step toward sustaining longer and hotter reactions.

Why does this matter? No one denies that humankind needs a clean, unlimited source of energy.

We all recognize that oil and gas are limited resources. But even wind and solar power --- renewable energies --- are fundamentally limited. They are dependent upon a breezy day or a cloudless sky, which we can't always count on.

Nuclear fusion is clean, safe, and environmentally sustainable --- its fuel is a nearly limitless resource since it is simply hydrogen (which can be easily made from water).

With each new milestone, we are creeping closer and closer to a breakthrough for unlimited, clean energy.

The science of sex, love, attraction, and obsession

The symbol for love is the heart, but the brain may be more accurate.

Videos
  • How love makes us feel can only be defined on an individual basis, but what it does to the body, specifically the brain, is now less abstract thanks to science.
  • One of the problems with early-stage attraction, according to anthropologist Helen Fisher, is that it activates parts of the brain that are linked to drive, craving, obsession, and motivation, while other regions that deal with decision-making shut down.
  • Dr. Fisher, professor Ted Fischer, and psychiatrist Gail Saltz explain the different types of love, explore the neuroscience of love and attraction, and share tips for sustaining relationships that are healthy and mutually beneficial.

Sex & Relationships

There never was a male fertility crisis

A new study suggests that reports of the impending infertility of the human male are greatly exaggerated.

Quantcast