- Wires Inserted Into Human Reveal Speech Surprise
- Her Eyes Say Yes, But Her Pheromones Say No
- Plant Siblings Play Nice, Share Their Dirt
- Scientists Make Desktop Black Hole
- Wired.com’s Crazy Flyer Survives with Mental Health Intact — Mostly
Posted: 15 Oct 2009 10:12 AM PDT
A rare set of high-resolution readouts taken directly from the wired-in brains of epileptics has provided an unprecedented look at how the brain processes language.
Though only a glimpse, it was enough to show that part of the brain's language center handles multiple tasks, rather than one.
"If the same part of the brain does different things at different times, that's a thunderously complex level of organization," said Ned Sahin, a University of California, San Diego cognitive scientist.
In a study published Thursday in Science, Sahin's team studied a region known as Broca's center, named for French anatomist Paul Pierre Broca who observed that two people with damage to a certain spot in the front of their brains had lost the ability to speak, but could still think.
Broca's discovery was made in 1865, but subsequent research has been relatively incremental, reinforcing the language-central role of this area but saying little about what goes on inside it. Speech can't be tested in any area other than ourselves, and the standard tool for reading the human brain is fMRI, which averages the activity of millions of neurons at set intervals. It's useful for highlighting regions of the brain that are involved in cognitive tasks, but can't detail what's happening inside those areas.
Sahin's team benefited from a brain-reading technology called intra-cranial electrophysiology, or ICE, in which electrodes are positioned inside the brain itself. It's a medical rather than a research tool, used to precisely measure electrical activity in the brains of epileptics who don't respond to treatment. ICE lets doctors see exactly which parts of a patient's brain may be surgically removed to prevent future seizures. Though it's far too invasive and risky to ever be used for academic research, it gave Sahin's team a chance to watch brains as they processed language.
The patients are "just sitting in a hospital bed, looking at a laptop, and they're jacked in, with wires right into their brain. And we're listening to the brain cells talking," said Sahin. "It's fantastic that we cold get so close to the actual neural data. Compared to fMRI, it's like a close-up, high-speed camera where you can see each beat of a hummingbird's wings, versus taking a picture of the bird flying around a flower.
During the several days that three patients at Massachusetts General Hospital were medically wired, Sahin's team asked them to repeat words verbatim, and translate them to past- and present-tense.
In the space of a quarter-second, a small part of the Broca's area — the only part read by the electrodes — received each word, put the word in a correct tense, and sent it to the brain's speech centers.
This tested only one type of verbal cognition, cautioned Sahin, and the focus was unavoidably narrow, but it was enough to show that Broca's area is involved not only in translating speech, but receiving it. That role was considered specific to part of the brain called Wernicke's area.
More broadly, the findings may represent a general rule for Broca's area, and perhaps other brain regions: Each part plays multiple roles, rather than performing a single task.
"It's very distinct from a model where part A does job A. Instead it's part A doing jobs A, B and C," said Sahin.
In a commentary accompanying the findings, Max Planck Institute cognitive scientists Peter Hagoort and Willem Levelt said that since Broca's original observations, "relatively little progress has been made in understanding the neural infrastructure that supports speech production." The fine-grained Science data "suggests that we are witnessing the 'first go' process at work here," they said.
In further ICE studies of patients, Sahin's team will study other parts of the language process, as well as the role of Broca's area in music and movement. In addition to illuminating the brain's complex choreography, researchers hope the findings will eventually be applied to treating language disorders.
"I'm happy to contribute a piece to the puzzle," said Sahin. "And the puzzle seems to get more complicated each time you put another piece into it."
Image: Ned Sahin
Citations: "Sequential Processing of Lexical, Grammatical, and Phonological Information Within Broca's Area." By Ned T. Sahin, Steven Pinker, Sydney S. Cash, Donald Schomer, Eric Halgren. Science, Vol. 326 No. 5951, October 16, 2009.
"The Speaking Brain." By Peter Hagoort and Willem Levelt. Science, Vol. 326 No. 5951, October 16, 2009.
Posted: 14 Oct 2009 03:35 PM PDT
Honey's sweet smell attracts more flies than does vinegar's sour odor, but the ultimate fruit-fly magnet is eau de nothing.
Ditching pheromones makes male and female fruit flies super-sexy to male flies, even to males of other species, Joel Levine, a neurogeneticist at the University of Toronto at Mississauga, and his colleagues report in the October 15 Nature. The discovery suggests pheromones can be back-off rather than come-hither signals. The finding could lead to a better understanding of the chemical signals that help flies and other animals interpret the world, including how to select a mate and how to distinguish other species.
"It's a very careful paper," says Nicolas Gompel, a neurogeneticist at the Developmental Biology Institute of Marseilles-Luminy in France. "I think it's raising the bar in the field because of the clarity of the analysis."
Typically fruit flies meet each other over rotten fruit. Often several species of fruit flies mill about the same location. Many of the species look very similar,at least to human eyes.
"We geneticists can hardly tell them apart unless we dissect them," Gompel says.
It was a mystery how fruit flies could tell their own species from others. Scientists thought that sight and sound probably played big roles in distinguishing both species and gender. For instance, male fruit flies serenade females during courtship and each species' love song is different. A male fly's "music" and appearance would also probably keep other amorous males from approaching him.
Scientists knew that chemicals called pheromones are important in telling males from females and one species from another, but no one knew how to interpret the message the flies were sending in a mix of 30 or more pheromones.
To decipher the message, Levine and his colleagues used a genetic trick to selectively kill special pheromone-producing cells called oenocytes that are usually part of the flies' abdomens. The team essentially created scentless flies.
Surprisingly, the lack of a come-hither signal was more of an aphrodisiac for male flies than pheromones were. Normal male flies were more attracted to both male and female flies lacking pheromones than to normal females. Males from three other Drosophila species also courted scentless D. melanogaster females, something they would not do in the wild.
The team could then use the scentless flies as a Rosetta stone to help translate the specific messages sent by different pheromones. Adding back a female pheromone thought to be an aphrodisiac, (7Z,11Z)-heptacosadiene or 7,11 HD, to scentless flies didn't make them any more attractive if worn alone. A male pheromone called cis-vaccenyl acetate or cVA, which male flies pass to females in ejaculate to warn other males away, made both normal and scentless females unattractive to males.
But if the perfume blend contained both cVA and 7,11 HD, the female chemical could "counter the chemical chastity belt imposed by cVA," Gompel writes in a commentary appearing in the same issue of Nature.
"Males are only after one thing. They want to mate," Levine says. Even in the face of conflicting signals, the males "would rather hedge their bets and go for it," than go without a mate.
In addition to identifying gender, the researchers found that just one pheromone created a barrier to mating between species. Adding 7,11 HD — which is not made by other Drosophila species — to scentless melanogaster females erected the species barrier that had been torn down by removing the oenocytes. "7,11 HD says, 'she's not one of them,'" Levine says.
These findings indicate that the chemical signals outweigh sight and sound in helping a male choose a mating partner, and that female pheromones may also serve as "slow down" or "back off" messages to keep males from getting too amorous, Levine says.
Females are more discriminating. Given a choice, normal female fruit flies chose males that produce pheromones over unscented males. "She will not go for the guy who has no odors," Levine says. That could mean that male pheromones put females in the mood.
"We expected the chemicals would play a role," Levine says. "What we didn't expect was how much you could account for with only the chemicals. … We had no reason to think that the effects we saw would be so strong."
n the absence of pheromones, flies engage in unnatural courtship behavior. In this movie, two males attempt copulation with each other's heads.
Image: Jean-Christophe Billeter. Video: Jean-Christophe Billeter et al., Nature 2009.
Posted: 14 Oct 2009 03:01 PM PDT
Unlike many human brothers and sisters, plant siblings appear to do their best to get along, sharing resources and avoiding competition.
In a study of more than 3,000 mustard seedlings, scientists discovered that the young plants recognize their siblings — other plants grown from the seeds of the same momma-plant — using chemical cues given off during root growth. And it turns out mustard plants won't compete with their brethren the way they will with strangers: Instead of rapidly growing roots to suck up as much water and minerals as possible, plants who sensed nearby siblings developed a shallower root system and more intertwined leaves.
"It's possible that when kin are grown together, they may balance their nutrient uptake and not be greedy," plant biologist Harsh Bais of the University of Delaware said in a press release. The work will be published in an upcoming issue of Communicative and Integrative Biology.
Two years ago, co-author Susan Dudley of McMaster University in Canada observed a similar pattern in the sea rocket, a common seashore plant that also appears to favor its siblings. But the initial studies of kin recognition have been criticized for failing to control for complicating factors, such as resource depletion caused by competition between the unrelated plants. And until now, the researchers didn't know how plants managed to identify their kin.
As seedlings grow, their developing root system gives off a variety of chemical signals, and the researchers guessed that these secretions might play a role in sibling recognition. To test their theory, the scientists grew wild Arabidopsis thaliana in a sterile liquid containing root extracts from sibling plants, unrelated plants or their own roots. Because each plant was grown in a highly controlled setup, the researchers could be sure any changes in growth were due to differences in the root extracts.
As shown in the time lapse videos below, the seedlings exposed to root secretions from unrelated plants grew significantly longer and more elaborate root systems than those grown in secretions from their siblings. The top video shows unrelated plants, while the bottom one shows siblings.
However, when the scientists blocked root secretions using a chemical called sodium orthovanadate, the differences disappeared, suggesting that the sibling identification system indeed depends on chemicals released by growing roots.
The researchers say their results may have significant implications for farming and agriculture. Although no one knows for sure how sibling recognition would affect crops grown in large monocultures, some researchers think that decreased competition among plants from identical seeds may make monocultures more susceptible to insects and disease.
However, Bais says that the effect of growing a plant with its siblings is likely to be species-dependent, as initial studies have been contradictory. "There is a possibility that the explanation of the trade-offs is not that simple," he wrote in an email. "We have found that plants could resist pathogens better when grown with siblings compared to strangers, so I would take this with caution and not stretch it to all the plant species."
Regardless of how sibling recognition affects agriculture, it may be an important consideration for the home gardener.
"Often we'll put plants in the ground next to each other and when they don't do well, we blame the local garden center where we bought them or we attribute their failure to a pathogen," Bais said in the press release. "But maybe there's more to it than that."
Image: An Arabidopsis plant, Flickr/BlueRidgeKitties.
Posted: 14 Oct 2009 11:51 AM PDT
Two Chinese scientists have successfully made an artificial black hole. Since you're still reading this, it's safe to say that Earth hasn't been sucked into its vortex.
That's because a black hole doesn't technically require a massive, highly concentrated gravitational field that prevents light from escaping, as postulated by Albert Einstein. It just needs to capture light — or, to be more precise, electromagnetic radiation, of which visually perceived light is one form.
The desktop black hole, described in a paper submitted to arXiv on Monday, is made from 60 concentrically arranged layers of circuit board. Each layer is coated in copper and printed with patterns that alternately vibrate or don't vibrate in response to electromagnetic waves.
Together, the patterns completely absorbed microwave radiation coming from any direction, and converted their energy to heat.
Like a near-black hole designed earlier this year and made from photon-absorbing carbon nanotubes, the material could be used in solar energy panels.
Citation: "An electromagnetic black hole made of metamaterials." By Qiang Cheng and Tie Jun Cui. arXiv, October 12, 2009.
Posted: 14 Oct 2009 11:18 AM PDT
Wired.com's Terminal Man appears to have passed the ultimate mental health test — 30 days without leaving an airport terminal except by plane — with his sanity completely intact.
Wired Science conducted a highly unscientific study of Brendan Ross's mental health status (i.e., we gave him several self-administered exams to take before and after the big adventure), and it turns out he's a pretty stable human being.
Despite enduring a month of constant noise, gross public bathrooms and chronic sleep deprivation, Brendan's stress score bumped only 11 points, from 3 to 14 out of a possible 168. According to Psychology World, a website that publishes an online version of the stress test, his second score still puts him well below the reported national average of 50.
Similarly, Brendan's score on a multiple-choice anger test jumped by 50 percent, from 20 to 30 out of a possible 250, but he says he never came close to screaming at a flight attendant or fellow passenger.
"It's not in my nature to snap and start screaming at somebody, I guess," wrote Brendan in a follow-up survey. "There were people who rubbed me the wrong way, sure, but it never came to that. Maybe it was because I knew they'd make good material for the blog, like the 'air marshal' from my last post."
There were a few moments when Brendan felt the fatigue and stress getting to him, however. He says the mood of his fellow passengers greatly influenced his stress level, and he'd find himself getting testy among a crowd of stressed-out passengers waiting for a delayed flight. "Regional attitudes made a difference too," he said. "I was much more irritable in New York than, say, Florida."
Brendan also found sleep deprivation affecting his brain in some unusual ways. For instance, on the second-to-last day of his trek, the Long Beach airport staff arranged for him to take a quick tour of the airport fire station, where he got to ride in a fire engine and shoot the water cannon. But when they invited him to slide down a fire pole, Brendan found himself suddenly unable to control a normally manageable fear of heights.
"Normally, it wouldn't have been a problem, but stepping up to the ledge, in the midst of the fatigue and weariness, the phobia kicked in full-strength, and I couldn't do it," Brendan said. "It was embarrassing — I had to walk back down the stairs. It wasn't the kind of thing that would've happened if I was on a normal sleep schedule, I think."
Wired Science editor Betsy Mason crossed paths with Brendan in New York City's JFK airport just days before the end of his odyssey. Though he seemed fairly lucid, the weeks of sleep deprivation had definitely taken a toll on his comprehension speed, and probably a little bit on his self -awareness as well, as evidenced by his response to "just look normal" in the photo to the right.
And we're not sure if the fact that he started talking about doing another terminal tour with Brazil's Azul Airlines on the day his JetBlue tour ended is a sign that he came through with ease, or a sign that he actually has gone crazy.
Wired's determined flier says the only time he considered giving up was at the very beginning of his trip, and even then the thought crossed his mind only briefly. "The closest I came to giving up was on the second day," he wrote, "when I was looking at a month of doing this. I thought, 'Wow, this may have been a monumentally stupid decision.'"
But Brendan persevered, kindly providing us with a month of blog posts detailing the ins and outs of America's airports. For a first-hand report of air rage, however, it turns out we'd have to find a more irritable traveler.
Images: 1) Brendan rides in a fire truck at the Long Beach airport fire station./Brendan Ross. 2) Brendan at JFK./ Betsy Mason, Wired.com
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