There have been many attempts to create a virtual brain, by simulating massive networks of neurons. But brains aren’t just piles of neurons. They also do things. They perceive. They reason. They solve tasks. Enter Spaun – the first brain simulation that actually shows simple behaviour, from recognising and copying a number, to solving simple reasoning problems.
It simulates 2.5 million virtual neurons, including the electricity that course through them, and the signalling chemicals that pass between them. It’s almost as accurate as the average humans at 8 separate tasks and, rather delightfully, reproduces many of our strange quirks – like the tendency to remember items at the start and end of a list.
I’ve written about Spaun for Nature News. Head over there for more
The good news: the blogs are back online, and speeds are back to normal. Thanks for your patience.
The bad news: the comment system has now changed so that you can only comment after you have created an account and signed in. This overwrites my old comment policy of being able to comment freely once your first comment is approved.
For the record, I found out about this change on Monday and I’m not happy about it. If you feel the same, just bear with me – I’ll have an update in a week or so. Or feel free to voice your views by… erm… registering and leaving a comment, or sending me an email.
In the meantime, plenty of cool science coming up…
For tens of thousands of years, humans have created sculptures by carving pieces from a solid block. They have chipped away at stone, metal, wood and ceramics, creating art by subtracting material. Now, a group of scientists from Harvard University have figured out how to do the same thing with DNA.
First, Yonggang Ke builds a solid block of DNA from individual Lego-like bricks. Each one is a single strand of the famous double helix that folds into a U-shape, designed to interlock with four neighbours. You can see what happens in the diagram below, which visualises the strands as two-hole Lego bricks. Together, hundreds of them can anneal into a solid block. And because each brick has a unique sequences, it only sticks to certain neighbours, and occupies a set position in the block.
This means that Ke can create different shapes by leaving out specific bricks from the full set, like a sculptor removing bits of stone from a block. Starting with a thousand-brick block, he carved out 102 different shapes, with complex features like cavities, tunnels, and embossed symbols. Each one is just 25 nanometres wide in any direction, roughly the size of the smallest viruses.
You may have noticed that Discover has had a redesign. This has been accompanied by a migration to new servers, which means that the site is currently loading slowly, if at all, and that comments aren’t working yet.
Apologies for the inconvenience. If you have any complaints, please leave a comme… never mind.
A very hungry caterpillar munches on a cabbage leaf and sets off an alarm. The plant releases chemicals into the air, signalling that it is under attack. This alarm is intercepted by a wasp, which stings the caterpillar and implants it with eggs. When they hatch, the larval wasps devour their host from the inside, eventually bursting out to spin cocoons and transform into adults. The cabbage (and those around it) are saved, and the wasp—known as a parasitoid because of its fatal body-snatching habits—raises the next generation.
But that’s not the whole story.
Some parasitic wasps are “hyperparasitoids”—they target other parasitoid wasps. And they also track the cabbage’s alarm chemicals, so they can find infected caterpillars. When they do, they lay their eggs on any wasp grubs or pupae that they find. Their young devour the young of the other would-be parasites, in a tiered stack of body-snatching. It’s like a cross between the films Alien and Inception.
Here’s the 13th piece from my BBC column
There’s an old saying among people who work in public health: Tobacco is the only legal product that, when used as intended, will kill you. Decades of research have thoroughly documented the health problems that result from inhaling tobacco smoke – more than a dozen different types of cancer, heart disease, stroke, emphysema and other respiratory diseases, among others. Are these risks an inevitable part of smoking? Or is there a way of creating safe cigarettes without any of these hazards?
“I think it’s very unlikely,” says Stephen Hecht from the University of Minnesota Cancer Center, who studies tobacco carcinogens – substances that cause cancer. Tobacco smoke is a complex cocktail of at least 4,000 chemicals including at least 70 known carcinogens. No one has made a “cigarette that is significantly decreased in all of these [chemicals] and is still something people would want to smoke, even though the industry has worked on this for around 50 years,” says Hecht. “There’s no indication that it’s possible.”
But neurons don’t always need synapses to communicate—some in the antennae of a fly can influence one another without any direct connections. The electric field produced by one can silence its neighbour, like two individuals standing side by side and whispering “Sssssshhhh” at each other.
This phenomenon, known as ephaptic coupling, has been discussed for a long time but it’s always been a bit obscure and arcane. There are very few examples of it, and none where this indirect silencing actually affects an animal’s behaviour. Su has changed that – his study shows that ephaptic coupling affects a fly’s or mosquito’s sense of smell. That knowledge might be useful for protecting crops from hungry insects, or people from disease-carrying ones.
I’ve written about this story for The Scientist, so head over there for more details.
Image by Martin Hauser
If you want to find an ocean animal that kills with speed, don’t look to sharks, swordfishes, or barracuda. Instead, try to find a mantis shrimp. These pugilistic relatives of crabs and lobsters attack other animals by rapidly unfurling a pair of arms held under their heads. One group of them—the smashers—have arms that end in heavily reinforced clubs, which can lash out with a top speed of 23 metres per second (50 miles per hour), and hit like a rifle bullet. These powerful hammers can shatter aquarium glass and crab shells alike.
Most research on mantis shrimps focuses on smashers, but these pugilists are in the minority. The majority are “spearers”, whose arms end in a row of fiendish spikes, rather than hard clubs. While the smashers actively search for prey to beat into submission, the spearers are ambush-hunters. They hide in burrows and wait to impale passing victims. They’re Loki to the smashers’ Thor.
Given their differing lifestyles, you might expect the spearers to be faster than the smashers. They rely on quick strikes to kill their prey, and they target fast victims like fish and shrimp rather than the tank-like, slow-moving crabs favoured by smashers. But surprisingly, Maya DeVries from the University of California, Berkeley, found that the fastest spearer strikes at just a quarter of the speed of the fastest smasher.