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Scientists Find Neurological Basis of Risk-Taking Trait

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How do we calculate the right time to take a risk? And why are some people (and dogs, and fish, and rats) bigger daredevils than others? Scientists working with rats say they’ve traced the answers back to a brain region called the nucleus accumbens. They published their findings this week in the journal Nature.

Animals and risk have a curious relationship. Scientists have tested the risk-taking behaviors of many species (including humans), and nearly all of them, when taken as a whole, are more conservative than they need to be. But within each species, there are individual animals who seem to throw care to the wind, and even the most conservative individuals take risks from time to time. 

“Risky behavior has its moments where it’s valuable,” psychiatrist, bioengineer, and study co-author Karl Deisseroth said in a press statement. “As a species, we wouldn’t have come as far as we have without it.”

A little risk-taking is important to keep a species, and an individual, going. But, Deisseroth notes, a predilection for dangerous choices is a liability. “I’ve seen patients whose aberrantly high-risk-seeking activity resulted in accidents, addictions and social, financial or occupational failures that exposed them to a lot of harm and blame.” 

The researchers were looking at the brain’s reward system, which uses hormones like dopamine to motivate us to seek out or avoid objects or experiences, from an angry boss to a cheeseburger. Inside your reward system, and the reward system of other animals, is a structure called the nucleus accumbens (NA). Your NA contains two categories of dopamine receptor cells called DR1 and DR2.

For this experiment, the researchers focused on DR2 cells. They implanted teeny-tiny optical fibers in the brains of lab rats, then taught the rats to gamble. (Fun fact: this is not the first time rats have learned to play the odds.) 

Each rat was set up with a little game center equipped with a hole. When they felt like playing, the rats could poke their noses into the hole, which would trigger the appearance of two levers. Pulling one lever produced sugar water—the same amount every time, no matter what, like a steady paycheck. The other lever was more like a freelance career. Most of the time, pulling lever 2 yielded a little bit of sugar water, but every so often it would pay off with a much bigger helping. The rats could (and did) play the game 200 times a day. 

As expected, about two-thirds of the rats repeatedly went for the dependable sugar water salary. The other third were bred-in-the-bone freelancers. Even after the researchers switched the levers, the rats kept to their preferences. But just like in the real world, some of the conservative rats occasionally went for the risky lever instead. If their risk paid off that first time, they’d keep taking the risk. If it didn’t, they’d go back to their steady sugar paycheck.

While the rats were gambling the day away, the researchers were watching their DR2 cells. They found that just before the conservative rats chose a level, DR2 activity spiked. When the scientists used the optical fibers to light up the risky rats’ DR2 cells, they became more risk-averse, but only as long as the fibers were lit. As soon as the light went off, they went back to their risky behavior. 

Then the researchers gave the rats small doses of pramipexole, a Parkinson’s disease drug that is notorious for causing impulsive gambling in patients. Sure enough, once the drug was in their system, the salaried rats turned to the high-risk freelance life. 

In other words, high DR2 activity in the nucleus accumbens kept conservative rats conservative. “It looks as though we have found a brain signal that, in most individuals, corresponds to a memory of a failed risky choice,” Deisseroth said. “It seems to represent the memory of that recent unfavorable outcome, manifested later at just the right time when it can, and does, modify an upcoming decision.” 

“Humans and rats have similar brain structures involved,” said Karl Deisseroth, MD, PhD, professor of bioengineering and of psychiatry and behavioral sciences. “And we found that a drug known to increase risk preference in people had the same effect on the rats. So every indication is that these findings are relevant to humans.”

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

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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Opening Ceremony
These $425 Jeans Can Turn Into Jorts
May 19, 2017
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Opening Ceremony

Modular clothing used to consist of something simple, like a reversible jacket. Today, it’s a $425 pair of detachable jeans.

Apparel retailer Opening Ceremony recently debuted a pair of “2 in 1 Y/Project” trousers that look fairly peculiar. The legs are held to the crotch by a pair of loops, creating a disjointed C-3PO effect. Undo the loops and you can now remove the legs entirely, leaving a pair of jean shorts in their wake. The result goes from this:


Opening Ceremony

To this:


Opening Ceremony

The company also offers a slightly different cut with button tabs in black for $460. If these aren’t audacious enough for you, the Y/Project line includes jumpsuits with removable legs and garter-equipped jeans.

[h/t Mashable]