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A TYPE of beetle renowned for colonising the smouldering remains of forest fires has yielded the secret of how it seeks out its improbable home.

Researchers led by Helmut Schmitz at the University of Bonn in Germany already knew that the fire beetles Melanophila

acuminata have a pair of ear-like organs in their outer skeleton that detect infrared radiation. “The adult beetles are attracted by forest fires from distances of many miles,” says Schmitz. Now they describe in The Journal of

Experimental Biology (DOI: 10.1242/jeb.020164) how the organs work.

The beetles’ infrared-detecting organs are mounted just behind the “hips” of their second pair of legs. Each one contains about 70 spherical sensors called sensillas. Inside the hard outer case of each sensilla is a chamber holding water. This expands when exposed to infrared radiation, exerting pressure on a nerve receptor at the base of the chamber. The greater the pressure, the stronger the infrared radiation.

The team suggest that this insight could help devise new infrared sensors.

Feeling the heat to find a home

HAVE you ever wondered why reading a good book can be almost as moving as events in real life? It may be because you use the same brain region to make sense of both.

Previous studies indicated that the anterior insula and adjacent frontal operculum (brain regions known collectively as the IFO) are activated both when we observe someone experiencing an emotion such as disgust, delight or pain, and when we experience it ourselves. This is believed to be what allows us to empathise with others and understand their

intentions. But what if the emotion is merely imagined, such as when reading about it. Is the IFO active here too?

To find out, Mbemba Jabbi and colleagues at the University of Groningen in the Netherlands focused on the feeling of disgust. They placed quinine, which has a nasty bitter taste, onto the tongues of 12 volunteers while they lay in an MRI scanner. They were also asked to watch a video of someone simulating disgust and read a story about something disgusting.

The team found that the IFO was activated in all three tasks (PLoS One, DOI: 10.1371/journal.pone.0002939). They say that this similarity between first-hand experience and imagination helps to explain why fiction can be so compelling. “This is why books and movies work – they stimulate the area of the brain which is involved in what it really feels like to be disgusted,” says Christian Keysers, a member of Jabbi’s team.

The team suggest that reading about delight or pain also activates the IFO.

For your brain, it’s as good as being there

BASKETBALL pros can use another player’s little finger to predict whether their shot will swoosh through the basket or bounce off the rim.

Neuroscientists led by Salvatore Aglioti of the University of Rome showed 10 Italian league players videos of missed and successful shots, frozen at various stages from before the ball left a player’s hand to the instant before it reached the basket. Coaches, experienced basketball journalists and novice players watched the same footage.

Unsurprisingly, the pros were quickest to call which shots would go in. For video frozen less than half a second in, when the player still cradled the ball, the pros correctly predicted the fate of the shot at a rate well above chance. The others were only able to guess correctly when footage was frozen as the ball left the player’s hand (Nature Neuroscience, DOI: 10.1038/nn.2182).

The pros’ secret may be an ability to mentally play the shot, allowing them to make a call just by looking at the player’s body. When the team measured brain activity, they found that for shots predicted early on,activity in an area controlling the pinkie finger varied in pros according to whether a shot went in or not – indicating this region was involved in the decision. For the others, activity was the same regardless of the shot. Aglioti speculates that pros read the spin imparted on the ball by focusing on the flick of player’s pinkie.

Pros use pinkies to make predictions

PITY the poor male salmon. In the race to become a father, it’s the female who calls the shots. Fluid she releases into the water with her eggs can tip the balance in favour of a particular male by speeding up the rate at which his sperm swim – a strategy thought to help select the best possible mate.

“We were really struck by this result,” says Neil Gemmell at the University of Otago in Dunedin, New Zealand, who looked at the sperm of blue-green chinook salmon. Females of animal species such at crickets, which fertilise their eggs inside their bodies, are already known to exert some control over which sperm get

lucky, but until now it was not obvious how fish which release their eggs and sperm into the water around them could do the same.

Gemmell’s team found that while sperm from one particular male crawled along at 20 micrometres per second in one female’s fluid, they raced four times as fast in another’s (Behavioural Ecology, DOI: 10.1093/beheco/arn089). The difference is crucial, as speed rather than quantity determines which male’s sperm fertilises an egg, Gemmell points out.

Females might be favouring males with a compatible immune system, or a dissimilar genetic make-up to ensure healthier offspring, Gemmell suggests. Variation in the concentration of ions in the fluid such as calcium may be what is affecting sperm motility.

Fussy fish pick a winner from afar

www.newscientist.com 16 August 2008 | NewScientist | 15