Tag: fMRI

The signature of the bluffing brain

By Ed Yong | November 1, 2010 3:00 pm

Poker

The best poker players are masters of deception. They’re good at manipulating the actions of other players, while masking their own so that their lies become undetectable. But even the best deceivers have tells, and Meghana Bhatt from Baylor University has found some fascinating ones. By scanning the brains and studying the behaviour of volunteers playing a simple bargaining game, she has found different patterns of brain activity that correspond to different playing styles. These “neural signatures” separate the players who are adept at strategic deception from those who play more straightforwardly.

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Scientists discover gene and part of brain that make people gullible

By Ed Yong | April 1, 2010 7:10 am

Supra_credulusScientists have discovered the part of the brain that makes people gullible, it was claimed today. The findings could have massive implications for treating the growing number of people who fall wide-eyed for sensationalist media reports.

Professor Cristoph Morris, who led the research, said that a part of the brain called the inferior supra-credulus was unsually active in people with a tendency to believe horoscopes and papers invoking fancy brain scans. “This correlation is so strong that we can speculate about a causal link with a high degree of certainty,” he concluded.

Morris made his discovery using a brain-scanning technique called fluorescence magnetic resonance imaging (fMRI), which can read people’s thoughts with an incredible degree of accuracy, just slightly better than chance. His results are published in the Journal of Evolutionary Psychoimagery.

When Morris studied individual neurons within the supra-credulus, he found that gullibility was associated with the activity of a single gene called WTF1. The less active it was, the more feckless people were. This fits with existing evidence, for faulty versions of WTF1 have already been linked to a higher risk of being Rickrolled and buying the Daily Mail. “You could say that gullibility is in your genes,” said Morris. “You’d be shatteringly wrong, but that wouldn’t matter to gullible people.”

The researchers described their discovery as “the holy grail of behavioural neurogenetics”. Morris explains, “It’s a real breakthrough. It means that we can fire a magic bullet right into the heart of sensationalist media stories. We can develop vaccines that stop people from buying things on the grounds that the packaging has a smiling farmer on it or that they’re endorsed by the cretin who may or may not have lost Big Brother.”

Morris has been collaborating with nutritionist Patricia Marber to develop just such as vaccine. Together, the duo found that they could completely stop the activity of neurons in the supra-credulus by smashing them with a giant hammer.

“We think that the iron in the hammers is somehow suppressing WTF1 in a way that stops nerve signalling in the supra-credulus,” explains Marber. “We might need some clinical trials to check that the hammers are effective and to work out any side effects, but you go right ahead and write your headline.  Say something about Thor. Everyone likes Thor.”

“It’s not like the people who need the treatment will question it,” she added.

The fMRI scans also revealed that the supra-credulus was more active in the brains of women than in men.  Evolutionary psychologist Stephan Koogin, who also worked on the study, thinks he knows why.

“Picture, if you will, a group of Pleistocene-Americans. The men are out hunting for mammoths and bears, and they can’t afford to be fooled by fake tracks. The women stayed at home picking berries or something, and they needed to tell each other far-fetched stories to keep each other entertained, because berries are really boring. Sounds reasonable, doesn’t it? Assuming all of this is true, and who’s to say it isn’t, I’m right.”
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Will vs. Grace – are people honest because they resist temptation or because they don't feel it?

By Ed Yong | July 14, 2009 9:40 am

Blogging on Peer-Reviewed ResearchIn a world where the temptation to lie, deceive and cheat is both strong and profitable, what compels some people to choose the straight and narrow path? According to a new brain-scanning study, honest moral decisions depend more on the absence of temptation in the first place than on people wilfully resisting these lures.

Joshua Greene and Joseph Paxton and Harvard University came to this conclusion by using a technique called functional magnetic resonance imaging (fMRI) to study the brain activity of people who were given a chance to lie. The volunteers were trying to predict the outcomes of coin-flips for money and they could walk away with more cash by lying about their accuracy.

The task allowed Greene and Paxton to test two competing (and wonderfully named) explanations for honest behaviour. The first -the “Will” hypothesis – suggests that we behave morally by exerting control over the desire to cheat. The second – the “Grace” hypothesis – says that honesty is more a passive process than an active one, fuelled by an absence of temptation rather than the presence of willpower. It follows on from a growing body of psychological studies, which suggest that much of our behaviour is governed by unconscious, automatic processes.

Many studies (and several awful popular science articles) have tried to place brain-scanning technology in the role of fancy lie detectors but in almost all of these cases, people are told to lie rather than doing so spontaneously. Greene and Paxton were much more interested in what happens in a person’s brain when they make the choice to lie.

They recruited 35 people and asked them to predict the result of computerised coin-flips while sitting in an fMRI scanner. They were paid in proportion to their accuracy. In some ‘No-Opportunity trials’, they had to make their predictions beforehand, giving them no room for cheating. In other ‘Opportunity trials’, they simply had say whether they had guessed correctly after the fact, opening the door to dishonesty.

To cover up the somewhat transparent nature of the experiment, Greene and Paxton fibbed themselves. They told the recruits that they were taking part in a study of psychic ability, where the idea was that people were more clairvoyant if their predictions were private and motivated by money. Under this ruse, the very nature of the “study” meant that people had the opportunity to lie, but were expected not to.

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How wearing a cast affects sense of touch and brain activity

By Ed Yong | April 23, 2009 12:00 pm

Blogging on Peer-Reviewed ResearchHaving your arm in a cast can be a real pain but immobilising your hand in plaster has consequences beyond itchiness, cramps and a growing collection of signatures. Silke Lissek from Bergmannsheil University found that just a few weeks in a cast can desensitise the trapped hand’s sense of touch, and lower neural activity in the part of the brain that receives signals from it. The uninjured hand, however, rises to the occasion and picks up the sensory slack by becoming more sensitive than before.

Lissek recruited 31 right-handed people, each of whom had one fractured arm encased in a cast, and compared them to 36 uninjured people. She measured the sensitivity of their fingertips by touching them with a pair of needles that were brought increasingly close together, and noting the distance at which the two needles felt like just one.

She found that the uninjured recruits had equally sensitive fingers on both hands, but for the cast-wearers, the fingers of the injured hand had become less receptive (no matter which arm was plastered). The threshold distance at which they perceived two needles rather than one was further than the same distance for the uninjured recruits. The healthy hand, however, became more sensitive and could tell the needles apart even if they were closer together than normal.

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MORE ABOUT: cast, fMRI, somatosensory, touch

Pre-emptive blood flow raises big questions about fMRI

By Ed Yong | January 21, 2009 2:00 pm

Blogging on Peer-Reviewed ResearchThe blood that flows into our heads is obviously important for it provides nutrients and oxygen to that most energetically demanding of organs – the brain. But for neuroscientists, blood flow in the brain has a special significance; many have used it to measure brain activity using a technique called functional magnetic resonance imaging, or fMRI.

This scanning technology has become a common feature of modern neuroscience studies, where it’s used to follow firing neurons and to identify parts of the brain that are active during common mental tasks. Its use rests on the assumption that the flow of blood (“haemodynamics” to those in the know) is a decent enough stand-in for the firing of neurons – the latter creates a shortage of nutrients and oxygen that is corrected by the former.

But Yevgeniy Sirotin and Aniruddha Das from Columbia University have found that this assumption might not be entirely valid. They used a new technique to independently measure and compare nerve activity and blood flow in the brains of live monkeys. Sure enough, they found a blood flow pattern that reliably matched the activity of the animals’ neurons.

But they also spotted something that no one has seen before – a second haemodynamic signal, of equal strength to the first, that didn’t correspond to any local brain activity. This second signal was not a sign of parts of the brain that are active, but those that may need to be active in the near future. It seems that if the brain expects a task in the future, it can anticipate which of its regions will be needed and flush them with blood in preparation.

Monkeysee.jpg

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The smell of danger – shocks help people discriminate between similar odours

By Ed Yong | March 29, 2008 12:28 pm

Blogging on Peer-Reviewed ResearchBad experiences can be powerful learning aids for our sense of smell. A new study reveals that electric shocks can make people more sensitive to the differences between very similar chemicals that previously smelled identical.

Nose.jpg
Every day, thousands of different molecules waft past our nose. Many of these are uncannily similar and some are more important to others. Wen Li from Northwestern University wanted to see how people learn to distinguish the critical smells from the unimportant ones.

Smell the difference

Working in the lab of smell guru, Jay Gottfried, Li attempted to train 12 volunteers to smell the difference between a pair of enantiomers – molecules that are mirror-images of each other but are otherwise identical. The two chemicals were versions of 2-butanol and both had a grassy tang. At first, Li asked volunteers to sniff the odd one out between three bottles, two that contained one molecule and a third that contained its mirror-image. On average they scored 33%, no more accurate than complete guesswork.

Their scores more than doubled when Li gave the volunteers an electric shock whenever they were exposed to one enantiomer, but not the other. Li didn’t provide any shocking impetus for a second pair of mirror-image molecules and accordingly, this control pair remained indistinguishable throughout the experiment.

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The machine that identifies images from brain activity alone

By Ed Yong | March 5, 2008 1:01 pm

Blogging on Peer-Reviewed ResearchModern brain-scanning technology allows us to measure a person’s brain activity on the fly and visualise the various parts of their brain as they switch on and off. But imagine being able to literally see what someone else is thinking – to be able to convert measurements of brain activity into actual images.
Tank.jpgIt’s a scene reminiscent of the ‘operators’ in The Matrix, but this technology may soon stray from the realm of science-fiction into that of science-fact. Kendrick Kay and colleagues from the University of California, Berkeley have created a decoder that can accurately work out the one image from a large set that an observer is looking at, based solely on a scan of their brain activity.
The machine is still a while away from being a full-blown brain-reader. Rather than reconstructing what the onlooker is viewing from scratch, it can only select the most likely fit from a set of possible images. Even so, it’s no small feat, especially since the set of possible pictures is both very large and completely new to the viewer. And while previous similar studies used very simple images like gratings, Kay’s decoder has the ability to recognise actual photos.

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