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Thrill-seekers' brains feel no fear
in Brief
Max Dereta/getty
DO YOU have a friend who loves bungee jumping, and insists it never scares them? Their bravado may have a biological basis: the bodies and brains of some thrill-seekers react less to threat than others. A team led by Lilianne MujicaParodi at Stony Brook University in New York, recruited 30 first-time skydivers and used fMRI imaging to observe whether their brain circuits involved in risk assessment were well-regulated. A well-regulated circuit is one that reacts to a threat and then returns to a normal state once the threat has gone. To test this, a loud, unpleasant noise was made as the skydivers lay in the scanner. They were also shown a series of faces – some aggressive, some less so – to test their threat perception. And on the day of the jump, the team measured stress hormones before and after. They found that people with better regulation were better at recognising threat in angry faces. They also showed larger increases in stress hormones. Poor regulation was linked with poorer threat recognition and smaller hormone rises (NeuroImage, doi.org/v6c). “It really has to do with the reckless and the brave,” says Bruce McEwen at Rockefeller University, New York. “The reckless seem to have a brain that doesn’t react as it should to alert them to danger.”
20 | NewScientist | 11 October 2014
Stellar explosion captures cosmic map of Cigar Galaxy IT WAS caught in a flash. The flare from a recent supernova has been used to map out a distant galaxy in 3D. Astronomers rushed to their telescopes in January when 2014J, the closest supernova in 27 years, burst into view. Now Arlin Crotts of Columbia University, New York, is watching the light from this stellar explosion echo around host galaxy M82, also known as the Cigar Galaxy (arxiv.org/ abs/1409.8671). We normally associate echoes with sound, but other waves echo
too. For example, radar is based on radio wave echoes. Light from supernovae moves out in all directions and bounces off dust in the surrounding area. A map of the dust in M82, 11.4 million light years away, was created by measuring how long it took for these light echoes to reach Earth. Normally, light echoes are viewed using historical images, but Crotts has used the Hubble Space Telescope to watch them as they appear in the sky. “You have this really detailed 3D map, all the way over in some
distant galaxy where there is really no other way to make such a map,” he says. It can be difficult to see light echoes because most supernovae are far away, but 2014J is the second-closest ever, after the 1987 supernova in the Large Magellanic Cloud. “It was always expected that M82 would be a good target for searching for light echoes,” says Stephen Fossey of University College London, who first spotted the supernova. “This kind of work is certainly important for probing the dust environment.” Mark Conlin/Getty
Thrill-seekers’ brains feel no fear
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Birds’ eye for colour coordination NOW here’s a clever design trick. Birds actively match the colour of their nests to their surroundings to blend in. To test if birds choose to camouflage their nests or whether they are well-camouflaged simply because of the colour of available building tools, like twigs and leaves, Ida Bailey and her team at the University of St Andrews, UK, performed a spot of redecorating. They wallpapered the cages of 21 male zebra finches (Taeniopygia guttata) with a new colour – blue, pink or yellow – and offered the birds nesting materials in two colours, one that matched the wallpaper, and one that contrasted with it. All of the birds built their nests predominantly with material that matched their wallpaper (The Auk: Ornithological Advances, doi.org/ v5d). Bailey says their experiment is the first to show that birds carefully choose the colour of their nest materials. But all of the birds also included a small amount of the nonmatching colour, which Bailey says may provide “disruptive camouflage”, breaking up the outline of the nest to help conceal it from predators.
Clever clams help algae harvest light LITTLE and large they may be. But giant clams have evolved a unique trick for redirecting sunlight to their microscopic algal tenants. In many species of giant clam, photosynthetic algae live in the clam’s fleshy mantle, which is exposed to the sea and sunlight through the flaps of its shell (pictured). In exchange for their home, the algae secrete glycerol, which feeds the clam. Now Alison Sweeney of the University of Pennsylvania in Philadelphia and her team have discovered that the clam uses
specialised cells, called iridocytes, to give these algae the perfect amount of light to photosynthesise. The algae grow in pillars that extend about 2 millimetres deep into the clam mantle, meaning that most of the cells don’t come into direct contact with sunlight. But Sweeney found that the iridocytes fan sunlight out into a cone of optimal intensity light that illuminates the entire 300-cell pillars (Interface, doi.org/v6d). Sweeney and colleagues hope to artificially mimic the arrangement for growing algal biofuels.
Max Dereta/getty
DO YOU have a friend who loves bungee jumping, and insists it never scares them? Their bravado may have a biological basis: the bodies and brains of some thrill-seekers react less to threat than others. A team led by Lilianne MujicaParodi at Stony Brook University in New York, recruited 30 first-time skydivers and used fMRI imaging to observe whether their brain circuits involved in risk assessment were well-regulated. A well-regulated circuit is one that reacts to a threat and then returns to a normal state once the threat has gone. To test this, a loud, unpleasant noise was made as the skydivers lay in the scanner. They were also shown a series of faces – some aggressive, some less so – to test their threat perception. And on the day of the jump, the team measured stress hormones before and after. They found that people with better regulation were better at recognising threat in angry faces. They also showed larger increases in stress hormones. Poor regulation was linked with poorer threat recognition and smaller hormone rises (NeuroImage, doi.org/v6c). “It really has to do with the reckless and the brave,” says Bruce McEwen at Rockefeller University, New York. “The reckless seem to have a brain that doesn’t react as it should to alert them to danger.”
20 | NewScientist | 11 October 2014
Stellar explosion captures cosmic map of Cigar Galaxy IT WAS caught in a flash. The flare from a recent supernova has been used to map out a distant galaxy in 3D. Astronomers rushed to their telescopes in January when 2014J, the closest supernova in 27 years, burst into view. Now Arlin Crotts of Columbia University, New York, is watching the light from this stellar explosion echo around host galaxy M82, also known as the Cigar Galaxy (arxiv.org/ abs/1409.8671). We normally associate echoes with sound, but other waves echo
too. For example, radar is based on radio wave echoes. Light from supernovae moves out in all directions and bounces off dust in the surrounding area. A map of the dust in M82, 11.4 million light years away, was created by measuring how long it took for these light echoes to reach Earth. Normally, light echoes are viewed using historical images, but Crotts has used the Hubble Space Telescope to watch them as they appear in the sky. “You have this really detailed 3D map, all the way over in some
distant galaxy where there is really no other way to make such a map,” he says. It can be difficult to see light echoes because most supernovae are far away, but 2014J is the second-closest ever, after the 1987 supernova in the Large Magellanic Cloud. “It was always expected that M82 would be a good target for searching for light echoes,” says Stephen Fossey of University College London, who first spotted the supernova. “This kind of work is certainly important for probing the dust environment.” Mark Conlin/Getty
Thrill-seekers’ brains feel no fear
For new stories every day, visit newscientist.com/news
Birds’ eye for colour coordination NOW here’s a clever design trick. Birds actively match the colour of their nests to their surroundings to blend in. To test if birds choose to camouflage their nests or whether they are well-camouflaged simply because of the colour of available building tools, like twigs and leaves, Ida Bailey and her team at the University of St Andrews, UK, performed a spot of redecorating. They wallpapered the cages of 21 male zebra finches (Taeniopygia guttata) with a new colour – blue, pink or yellow – and offered the birds nesting materials in two colours, one that matched the wallpaper, and one that contrasted with it. All of the birds built their nests predominantly with material that matched their wallpaper (The Auk: Ornithological Advances, doi.org/ v5d). Bailey says their experiment is the first to show that birds carefully choose the colour of their nest materials. But all of the birds also included a small amount of the nonmatching colour, which Bailey says may provide “disruptive camouflage”, breaking up the outline of the nest to help conceal it from predators.
Clever clams help algae harvest light LITTLE and large they may be. But giant clams have evolved a unique trick for redirecting sunlight to their microscopic algal tenants. In many species of giant clam, photosynthetic algae live in the clam’s fleshy mantle, which is exposed to the sea and sunlight through the flaps of its shell (pictured). In exchange for their home, the algae secrete glycerol, which feeds the clam. Now Alison Sweeney of the University of Pennsylvania in Philadelphia and her team have discovered that the clam uses
specialised cells, called iridocytes, to give these algae the perfect amount of light to photosynthesise. The algae grow in pillars that extend about 2 millimetres deep into the clam mantle, meaning that most of the cells don’t come into direct contact with sunlight. But Sweeney found that the iridocytes fan sunlight out into a cone of optimal intensity light that illuminates the entire 300-cell pillars (Interface, doi.org/v6d). Sweeney and colleagues hope to artificially mimic the arrangement for growing algal biofuels.