Feeling dopey? Refresh your “circadian eye” with a burst of orange light.

Light is a powerful wake-up call, enhancing alertness and activity. Its effect is controlled by a group of photoreceptor cells in the eyeball that make the light-sensing pigment melanopsin. These cells, which work separately to the rods and cones needed for vision, are thought to help reset animals’ body clocks – or circadian rhythms. Studies with people who are blind suggest this also happens in humans, although the evidence isn’t conclusive.

To find out how melanopsin wakes up the brain, at the University of Liege, Belgium, and his team gave 16 people a 10-minute blast of blue or orange light while they performed a memory test in an fMRI scanner. They were then blindfolded for 70 minutes, before being retested under a green light.

People initially exposed to orange light had greater brain activity in several regions related to alertness and cognition when they were retested, compared with those pre-exposed to blue light.

Light switch

Vandewalle thinks that melanopsin is acting as a kind of switch, sending different signals to the brain depending on its state. Orange light, which has the longer wavelength, is known to make the pigment more light-sensitive, but blue light has the opposite effect. Green light lies somewhere in the middle. The findings suggest that pre-exposure to orange light pushes the balance towards the more light-sensitive form of melanopsin, enhancing the response in the brain.

“We knew that light had a non-visual impact on cognitive brain responses but the photoreceptors involved were not definitely established” says Vandewalle. “Our findings constitute compelling evidence in favour of a cognitive role for melanopsin,” he says, adding that more thought should be given to the impact of different colours of light in environments such as schools.

from the University of Oxford’s Nuffield Laboratory of Ophthalmology says the findings are intriguing but he points out that several previous studies have suggested that blue light enhances alertness and is more effective at resetting circadian rhythms. “More work is clearly needed to understand the differences between these results,” he says.

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Listen up Fido! The brains of humans and dogs respond in the same way to vocal sounds like laughter and barking. The finding suggests that the voice processing area of the brain evolved only once, at least 100 million years ago.

Attila Andics of the MTA-ELTE Comparative Ethology Research Group in Hungary and his colleagues trained 11 dogs to lie motionless in a functional magnetic resonance imaging (fMRI) scanner. They recorded patterns of brain activity in the animals as they listened to nearly 200 human and dog noises, from whining and crying to barking and laughing. They also performed the same experiment on 22 humans.

Most animals have to be sedated for brain scans, to stop them moving. This limits what the scans can tell us. But recently, better training methods have meant it has become possible to train dogs to lie still long enough to scan them while awake. Andics is the first to compare humans and dogs in the same experiment.

The scans revealed that human and dog brains both lit up in similar areas in response to the sounds. As might be expected, dogs responded more strongly to dog sounds, and humans responded more to human sounds.

Bark to me

“Dogs and humans share a similar social environment,” says Andics. “Our findings suggest that they also use similar brain mechanisms to process social information.” That might help explain why humans and dogs communicate with each other so readily.

Andics also proposes that the results indicate a single evolutionary origin for the voice processing area of the brain, potentially dating it back to at least 100 million years ago – the last time humans and dogs shared an ancestor.

But there is an alternative explanation, says of Arizona State University in Tempe. “The brain is a highly plastic organ, and the dogs’ responses could just be the result of a lifetime listening to human voices,” he says. “It doesn’t necessarily point to an evolutionary similarity, except to show that there are similar ‘continents’ in human and canine brains that might do similar things.”

“Similar brain activity does not necessarily mean that dogs and humans, or even individuals within each species, experience sounds and vocalisations in the exact same way,” says of Oregon State University in Corvallis. “We should take care to recognise and value the unique perceptual and emotional worlds of each species, just as much as we have come to value the similarities.”

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Perception of our own bodies can be easily manipulated using tricks such as the rubber hand illusion, which fools people into thinking a rubber hand is their own. Reflecting someone’s limb in a mirror has also been used to treat phantom limb pain.

Now and his colleagues at the University of LĂźbeck in Germany have shown that a similar mirror illusion can fool people into feeling relief from an itch, even when they scratch the wrong place.

The team injected the right forearms of 26 male volunteers with itch-inducing chemical histamine. Because the injection creates a red spot, they painted a corresponding dot on the opposite arm so both looked identical.

One of the researchers then scratched each arm in turn. Unsurprisingly, scratching the itchy arm produced relief, while scratching the other one did not.

Sweet relief

Next, they placed a large vertical mirror in front of the itchy arm, blocking off the subject’s view of their right arm and reflecting back the non-itchy one in its place . They asked the volunteers to look only at the reflected limb in the mirror, whilst a member of the team again scratched each arm.

This time the participants felt relief when the unaffected, reflected arm was scratched.

Although the effect was relatively weak – the relief from mirror scratching is about a quarter of that from scratching the real itch – the study shows that visual signals to the brain can override messages from the body if there is a mismatch between them.

at Liverpool John Moores University, UK, thinks the finding could lead to treatments for chronic itching – a debilitating but poorly understood condition in which patients will often scratch their skin until it bleeds. “This paper adds important insights into the complex mechanisms underlying itch – an often ignored sensory channel, but one that can have devastating consequences on quality of life for patients,” he says.

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In 2010, the University of California, Berkeley, and Stanford University when they asked students to take DNA tests so they could analyse their own data as part of a course. Because DNA contains a wealth of personal information, there was that students might have opted to take the test without making a properly informed decision.

Since then, the use of relatively simple tests that sequence snapshots of DNA across the genome has become an increasingly common teaching aid on university courses. With the cost of whole-genome sequencing plummeting, it is likely that this more in-depth analysis will soon make an appearance in the classroom, making the concerns even more pertinent.

One school that already uses the more advanced approach is the Icahn School of Medicine at Mount Sinai in New York City. To find out what people needed to help them make a decision, Saskia Sanderson, a health psychologist at the school followed 19 students as they decided whether or not to have their genomes sequenced as part of an advanced genetics course.

She says that what they found most helpful was a short course discussing the technique and the issues involved, rather than simply being given time and encouraged to talk it over with friends and family.

“Genetic counsellors” were available but only two students went to see them, of whom one said they only went for the experience.

Before the introductory course, only nine students felt they were prepared to make an informed choice. This rose to 16 by the end of the course, with all of them feeling this way by the start of their advanced genetics module, suggesting it was the content of the introductory course – not just time passing – that helped them decide.

“One of the most surprising findings was that all the students opted to analyse their own genomes in the end,” says Sanderson. “We thought that as they learned more about the many limitations and risks of whole genome sequencing, they might lose interest and not be as keen to get the data as they initially were.”

Still, offering something as expensive as whole genome sequencing for free might have swayed the students’ choices, she says.

While students may feel they can make informed decisions, , a bioethics specialist at George Washington University in Washington DC, says there are other questions to consider. “Are universities checking to make sure that students have a support network at home to help them cope with bad news?” she says. “And are the students really prepared to assess a risk that might not become important to them until long after the course is over?”

Journal reference: Genome Medicine,