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A woman who has been extensively studied because she was thought to be unable to experience fear has been successfully terrified in an experiment in which she inhaled carbon dioxide. The woman, known as SM, has a rare genetic condition called Urbach-Wiethe disease, which has left a part of her brain called the amygdala severely damaged. This primitive brain structure is thought to be important for generating fear responses; SM had not shown fear since childhood, either in real-life threat situations, or in response to the scary films, spiders, snakes, etc., presented to her by previous researchers. Inhaling high levels of carbon dioxide is one way of provoking fear, as this builds up rapidly in the body when a person can’t breathe and so is detected as a suffocation threat. The researchers in this recent experiment

had previously shown that the amygdala directly detects carbon dioxide, causing fear in mice. So when they tested SM, two other patients with the condition, and 12 healthy participants by having them inhale 35% carbon dioxide (850 times that in normal air), they only expected to see fear responses in the healthy participants. But they saw almost the exact opposite. All three ‘fearless’ patients showed all the signs of panic and reported intense fear – a new experience for them! Conversely, only a few healthy participants experienced panic. The study, published in Nature Neuroscience, proves the amygdala is not essential for causing fear responses and suggests the true picture is more complicated. Other brain regions involved in bodily awareness – the brainstem and insular cortex – are now thought to be essential for the internal threat system.


Astronomers at the Harvard-Smithsonian Centre for Astrophysics (CfA) announced in February that the nearest Earth-like planet could be a stone’s throw away (in astronomical terms): orbiting a red dwarf star just 13 light years away. NASA’s Kepler space telescope spots planets outside our solar system by watching for a momentary fall in a star’s brightness as a planet passes in front of it. Most of Kepler’s targets are fairly large Sunlike stars, but red dwarfs are dimmer and smaller, so an Earth-sized planet produces a bigger brightness dip, making it easier to see. These stars are also cooler, so a planet must be closer to it to be in the habitable ‘Goldilocks’ zone where liquid water is possible. A smaller, faster orbit also makes it more likely the planet will pass directly between us and the star when we are watching.

Simon Makin is an ex-post-doc researcher in auditory perception turned journalist. G U R U • I S S U E 1 1 • A P R I L / M AY 2 0 1 3 • PA G E 2 0

The astronomers first re-analysed all the red dwarfs in the Kepler catalog of 158,000 stars, and found most of them smaller and cooler than previously thought. This discovery led them to conclude that the planets seen ‘transiting’ in front of them were also smaller in size to cause the observed dips in brightness. They then identified 95 candidate planets orbiting red dwarfs, and calculated from this that around 90% of red dwarfs should host planets between half and four times Earth’s size. Statistically, around 15% of red dwarfs should actually host Earth-like planets – meaning around 4.5 billion such planets should be littered throughout the galaxy. That’s a lot of places to look for life. This paper was submitted to the Astrophysical Journal, although a more recent paper has reduced the estimate to habitable planets being 6.5-7 light years away from earth, using updated definitions of ‘Goldilocks’ zones.

(Fear) Flick • Ian.Kobylanski, (Planet) Flickr • jenschapter3


Guru Magazine Issue 11: They're watching you.  

A unique FREE bi-monthly mag for the thinking person. Entertainment, news and science - but there aren't any lab goggles in sight. Inside t...

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