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Dyslexia Doesn't Work the Way We Thought It Did

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Dyslexia is not just about reading, or even language. It’s about something more fundamental: How much can the brain adapt to what it has just observed? People with dyslexia typically have less brain plasticity than those without dyslexia, two recent studies have found.

Though the studies measured people’s brain activity in two different ways and while performing different tasks, researchers at the Hebrew University of Israel, reporting in eLife, and researchers from MIT, reporting in Neuron, both found that dyslexics’ brains did not adapt as much to repeated stimuli, including spoken words, musical notes, and faces.

Both sets of researchers found that people with dyslexia more quickly forget recent events. This type of memory is called incidental or implicit memory, and includes anything you didn't know you needed to remember when it happened. Because of how quickly their implicit memory fades, dyslexics' brains don't adapt as much after reading or hearing something repeatedly—which is perhaps why it is harder for their brains to process the words they read.

Your brain generally benefits from repetition because it relates a stimulus to what you've already experienced—like a note you have heard before or a face you’ve seen. Researchers can see this by measuring brain response with electroencephalography (EEG), a noninvasive way of measuring electrical activity in the brain by attaching electrodes to your scalp. Measured by EEG, people’s brain responses decrease when they’ve heard a repeated note. The brain gets more efficient with repetition: It knows something about the note already, so it doesn’t have to work as hard to capture all of its details. It’s a bit like when you see an animal and recognize right away that it’s a dog without having to catalogue all of the things that make it a dog. Your brain is efficient at recognizing dogs because you’ve seen them before.

SHORTER MEMORIES AND LESS ADAPTABILITY

In the Hebrew University study, led by Merav Ahissar, researchers gave subjects a musical task: The researchers played two different notes and asked which was higher. Previous research has found that people do better on this task when one of the notes is a repeat of a note they’ve heard recently. But Ahissar found that people with dyslexia did not benefit as much from the repetition. When a tone was repeated only three seconds after the "anchor" tone, they got some benefit, but not after nine seconds had elapsed. And when Ahissar’s team measured dyslexic people’s brain responses with EEG, their brain responses didn’t decrease. Their brains didn’t get any more efficient—they were less adaptable.

The MIT study, led by John Gabrieli, found similar results through a different experiment. Gabrieli used functional magnetic resonance imaging (fMRI) to measure people’s brain activity by measuring changes in blood flow in their brains. Instead of asking people to discriminate between musical notes, Gabrieli's team simply presented people with repeated things, including spoken words, written words, faces, and common objects like tables or chairs. During this task, dyslexic people's neural activity demonstrated less adaptation.

“It was a big surprise for us,” Gabrieli tells mental_floss, “because people with reading disorders don't typically have any problems with faces or objects.” Next, Gabrieli is curious to look into whether the effects of dyslexia on brain plasticity are limited to hearing and vision, or whether they also extend to other senses like touch and smell.

Together, these studies build a better understanding of how dyslexia works, and because the two studies found the same result with different methods, their results are more convincing than a single study alone. But they also raise a new question: Why is dyslexia mainly noticeable in reading if it affects other types of memories as well?

READING IS NEW—AND HARD, FROM THE BRAIN'S PERSPECTIVE

One theory is that reading is simply a difficult task. “We have a long evolutionary history in our brains for recognizing objects, recognizing faces," Gabrieli points out. That's not the case for reading. “There’s hardly a bigger challenge for brain plasticity than learning to read." More evolutionary time has allowed the brain to evolve redundant ways of accomplishing the same thing. Perhaps people with dyslexia are better at compensating for the memory gap for recognizing faces and spoken words because the brain has more alternate pathways for these processes than it does for reading.

Both Ahissar and Gabrieli are most excited that this research opens up new ways of studying—and perhaps someday treating—dyslexia. If dyslexia is a condition of reading and language only, as previously believed, “we cannot study it in animals,” Ahissar tells mental_floss. On the other hand, if it’s a condition of brain plasticity, we can—in fact, plasticity has been extensively studied in animals, and neuroscientists know a lot about it.

Someday, Gabrieli says, it may even be possible to develop drugs that would treat dyslexia by promoting brain plasticity, although researchers would have to be careful both practically and ethically.

“We can’t imagine developing a drug that would enhance language directly—that's too complicated," he notes. "But brain plasticity is something that neuroscientists are making amazing progress on.”

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technology
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
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Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Health
200 Health Experts Call for Ban on Two Antibacterial Chemicals
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In September 2016, the U.S. Food and Drug Administration (FDA) issued a ban on antibacterial soap and body wash. But a large collective of scientists and medical professionals says the agency should have done more to stop the spread of harmful chemicals into our bodies and environment, most notably the antimicrobials triclosan and triclocarban. They published their recommendations in the journal Environmental Health Perspectives.

The 2016 report from the FDA concluded that 19 of the most commonly used antimicrobial ingredients are no more effective than ordinary soap and water, and forbade their use in soap and body wash.

"Customers may think added antimicrobials are a way to reduce infections, but in most products there is no evidence that they do," Ted Schettler, science director of the Science and Environmental Health Network, said in a statement.

Studies have shown that these chemicals may actually do more harm than good. They don't keep us from getting sick, but they can contribute to the development of antibiotic-resistant bacteria, also known as superbugs. Triclosan and triclocarban can also damage our hormones and immune systems.

And while they may no longer be appearing on our bathroom sinks or shower shelves, they're still all around us. They've leached into the environment from years of use. They're also still being added to a staggering array of consumer products, as companies create "antibacterial" clothing, toys, yoga mats, paint, food storage containers, electronics, doorknobs, and countertops.

The authors of the new consensus statement say it's time for that to stop.

"We must develop better alternatives and prevent unneeded exposures to antimicrobial chemicals," Rolf Haden of the University of Arizona said in the statement. Haden researches where mass-produced chemicals wind up in the environment.

The statement notes that many manufacturers have simply replaced the banned chemicals with others. "I was happy that the FDA finally acted to remove these chemicals from soaps," said Arlene Blum, executive director of the Green Science Policy Institute. "But I was dismayed to discover at my local drugstore that most products now contain substitutes that may be worse."

Blum, Haden, Schettler, and their colleagues "urge scientists, governments, chemical and product manufacturers, purchasing organizations, retailers, and consumers" to avoid antimicrobial chemicals outside of medical settings. "Where antimicrobials are necessary," they write, we should "use safer alternatives that are not persistent and pose no risk to humans or ecosystems."

They recommend that manufacturers label any products containing antimicrobial chemicals so that consumers can avoid them, and they call for further research into the impacts of these compounds on us and our planet.

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