The Science of Implanting False Memories

By Chris Gayomali

We all have a dubious memory or two that we are convinced is real, even if it never happened. For some the memory is harmless, like the song that played during a first kiss. For others, like courtroom witnesses convinced they saw a suspect only to have their account overturned later by DNA testing, the strange whims of memory can result in real-world disaster.

Which is why a new experiment by neuroscience researchers at MIT's Center for Neural Circuit Genetics is equal parts important and terrifying. Writing in the journal Science, Nobel laureate Susumu Tonegawa outlines how he and his team were able to plant false memories in the brains of mice, tricking them into believing in events that never actually occurred.

The technique they employed is called optogenetics, which allows researchers to manipulate individual brain cells with near-pinpoint precision using a tiny, fiber-optic beam of light. As Ars Technica notes, optogentics "has brought surprising technical advances and changed the way many neuroscientists work."

In this case, Tonegawa suggests that all memories, both real and dreamed, rely on the same basic neural circuitry that can be tampered with. Alok Jha at the Guardian explains:

[Researchers] engineered brain cells in the mouse hippocampus, a part of the brain known to be involved in forming memories, to express the gene for a protein called channelrhodopsin. When cells that contain channelrhodopsin are exposed to blue light, they become activated. The researchers also modified the hippocampus cells so that the channelrhodopsin protein would be produced in whichever brain cells the mouse was using to encode its memory engrams.

In the experiment, Tonegawa's team placed the mice in a chamber and allowed them to explore it. As they did so, relevant memory-encoding brain cells were producing the channelrhodopsin protein. The next day, the same mice were placed in a second chamber and given a small electric shock, to encode a fear response. At the same time, the researchers shone light into the mouse brains to activate their memories of the first chamber. That way, the mice learned to associate fear of the electric shock with the memory of the first chamber. [Guardian]

Then, when researchers placed the mice back in the first chamber, the mice responded in a way that clearly communicated fear: They froze.

"We call this 'incepting' or implanting false memories in a mouse brain," Tonegawa tells Science.

What does that mean for human memory formation? Admittedly, not much for now. At that level of brain activity, "the difference between a mouse and a human are quite small," Edvard I. Moser, a neuroscientist who was not part of the experiment, tells the New York Times. "[But] what I find fascinating about this is that you actually can point to a physical substrate to memory," or an engram. It's like pointing to a specific spot in the brain, and being able to say, "That is the memory."

If the thought of being implanted with a fake memory creeps you out, that's totally understandable. But Tonegawa says his research isn't malicious, Inception-inspired Nolan-ites be damned.

Instead, Tonegawa tells the Timesthe hope is that his advances will illustrate just "how unreliable human memory is." Especially in the courtroom.

More from The Week...

6 Vintage Surfing Photos


The Ultra-Violent Origin of Monogamy


5 of History's Biggest Killjoys

Today's Wine Glasses Are Almost Seven Times Larger Than They Were in 1700

Holiday party season (a.k.a. hangover season) is in full swing. While you likely have no one to blame but yourself for drinking that second (or third) pour at the office soiree, your glassware isn't doing you any favors—especially if you live in the UK. Vino vessels in England are nearly seven times larger today than they were in 1700, according to a new study spotted by Live Science. These findings were recently published in the English medical journal The BMJ.

Researchers at the University of Cambridge measured more than 400 wineglasses from the past three centuries to gauge whether glass size affects how much we drink. They dug deep into the history of parties past, perusing both the collections of the Ashmolean Museum of Art and Archaeology at the University of Oxford and the Royal Household's assemblage of glassware (a new set is commissioned for each monarch). They also scoured a vintage catalog, a modern department store, and eBay for examples.

After measuring these cups, researchers concluded that the average wineglass in 1700 held just 2.2 fluid ounces. For comparison's sake, that's the size of a double shot at a bar. Glasses today hold an average of 15.2 fluid ounces, even though a standard single serving size of wine is just 5 ounces.

BMJ infographic detailing increases in wine glass size from 1700 to 2017
BMJ Publishing group Ltd.

Advances in technology and manufacturing are partly to blame for this increase, as is the wine industry. Marketing campaigns promoted the beverage as it increasingly became more affordable and available for purchase, which in turn prompted aficionados to opt for larger pours. Perhaps not surprisingly, this bigger-is-better mindset was also compounded by American drinking habits: Extra-large wineglasses became popular in the U.S. in the 1990s, prompting overseas manufacturers to follow suit.

Wine consumption in both England and America has risen dramatically since the 1960s [PDF]. Cambridge researchers noted that their study doesn't necessarily prove that the rise of super-sized glassware has led to this increase. But their findings do fit a larger trend: previous studies have found that larger plate size can increase food consumption. This might be because they skew our sense of perception, making us think we're consuming less than we actually are. And in the case of wine, in particular, oversized glasses could also heighten our sensory enjoyment, as they might release more of the drink's aroma.

“We cannot infer that the increase in glass size and the rise in wine consumption in England are causally linked,” the study's authors wrote. “Nor can we infer that reducing glass size would cut drinking. Our observation of increasing size does, however, draw attention to wine glass size as an area to investigate further in the context of population health.”

[h/t Live Science]

Researchers Pore Over the Physics Behind the Layered Latte

The layered latte isn't the most widely known espresso drink on coffee-shop menus, but it is a scientific curiosity. Instead of a traditional latte, where steamed milk is poured into a shot (or several) of espresso, the layered latte is made by pouring the espresso into a glass of hot milk. The result is an Instagram-friendly drink that features a gradient of milky coffee colors from pure white on the bottom to dark brown on the top. The effect is odd enough that Princeton University researchers decided to explore the fluid dynamics that make it happen, as The New York Times reports.

In a new study in Nature Communications, Princeton engineering professor Howard Stone and his team explore just what creates the distinct horizontal layers pattern of layered latte. To find out, they injected warm, dyed water into a tank filled with warm salt water, mimicking the process of pouring low-density espresso into higher-density steamed milk.

Four different images of a latte forming layers over time
Xue et al., Nature Communications (2017)

According to the study, the layered look of the latte forms over the course of minutes, and can last for "tens of minutes, or even several hours" if the drink isn't stirred. When the espresso-like dyed water was injected into the salt brine, the downward jet of the dyed water floated up to the top of the tank, because the buoyant force of the low-density liquid encountering the higher-density brine forced it upward. The layers become more visible when the hot drink cools down.

The New York Times explains it succinctly:

When the liquids try to mix, layered patterns form as gradients in temperature cause a portion of the liquid to heat up, become lighter and rise, while another, denser portion sinks. This gives rise to convection cells that trap mixtures of similar densities within layers.

This structure can withstand gentle movement, such as a light stirring or sipping, and can stay stable for as long as a day or more. The layers don't disappear until the liquids cool down to room temperature.

But before you go trying to experiment with layering your own lattes, know that it can be trickier than the study—which refers to the process as "haphazardly pouring espresso into a glass of warm milk"—makes it sound. You may need to experiment several times with the speed and height of your pour and the ratio of espresso to milk before you get the look just right.

[h/t The New York Times]


More from mental floss studios