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People in a vegetative state may feel pain
THIS WEEK
What if people in a coma feel pain… interpret it as unpleasant. Using PET scans, previous studies have detected activation in the sensory-discriminative network in people with UWS but their findings were consistent with a lack of subjective awareness, the hallmark of the condition. Now Markl and her colleagues have found evidence of activation
IT IS a nightmare situation. A person diagnosed as being in a vegetative state has an operation without anaesthetic because they cannot feel pain. Except, maybe they can. Alexandra Markl at the Schön clinic in Bad Aibling, Germany, and colleagues studied people with unresponsive wakefulness syndrome (UWS) – also known as vegetative state – and identified activity in brain areas involved in the emotional aspects of pain. People with UWS can make reflex movements but can’t show subjective awareness. There are two distinct neural networks that work together to create the sensation of pain. The more basic of the two – the sensory-discriminative network – identifies the presence of an unpleasant stimulus. It is the affective network that attaches emotions and subjective feelings to the experience. Crucially, without the activity of the emotional network, your brain detects pain but won’t
Vanishing world may be roasted down to its core NOW you see it, now you don’t. A disappearing exoplanet is helping us understand how some rocky worlds meet fiery ends, and may even give us a glimpse of what lies deep inside rocky planets like Earth. Known as KIC 12557548b, the planet was discovered last year using NASA’s Kepler space telescope. This eye in the sky looks for dips in starlight as a planet passes in front of its host star. The more light is 14 | NewScientist | 23 February 2013
reuters
Julia Sklar
blocked, the larger the planet. KIC 12557548b is very small and orbits so close to its star that its year lasts just 16 hours. What’s more, the dimming it causes varies wildly. This could be because the planet is surrounded by a gigantic, everchanging cloud of material that stretches into a long tail. Eugene Chiang of the University of California, Berkeley, who was part of the team that found the planet last year, thinks the surface is being evaporated away by the intense heat of its star. Chiang and colleague Daniel Perez-Becker have now come up with a model of how rocky planets evaporate, based in part on Kepler
to people with diagnoses such as UWS,” says Donald Weaver at Dalhousie University in Halifax, Nova Scotia, Canada, who was not involved in the work. But it will encourage future study, he says. Changing a diagnosis depends on whether neurologists are ready to accept alternative ways of diagnosing disorders of consciousness, says Boris Kotchoubey at the Institute of Medical Psychology and Behavioural Neurobiology in Tübingen, Germany, who worked on the study. Nonetheless, Kotchoubey is confident that the way people with UWS are cared for will change, even if their diagnoses remain the same. “I know that many doctors working with such patients have been instructed to treat their patients as if they can understand them and perceive at least something in the environment, perhaps pain, pleasure, or emotion,” he says. But not all people are treated this way. Prior to the study, one of the people in Markl’s study was given no anaesthesia before a tracheotomy, which involves an incision in the neck to allow breathing without using the nose or mouth. As people with UWS are clinically considered unable to understand pain, doctors do not –Safer to give pain relief– have to give an anaesthetic. n
in the affective or emotional network too (Brain and Behavior, doi.org/kfs). Her team gave moderately painful electric shocks to 30 people with UWS, while scanning their brains using fMRI. Sixteen people had some kind of brain activation – seven only in the sensory network but nine in the affective network as well. These results question whether some diagnoses should change from UWS to minimally conscious, which is characterised by some level of awareness. “I don’t think this paper alone will change the clinical approach
data (arxiv.org/abs/1302.2147). Their model says that if KIC 12557548b was once about as big as Mercury, it should now be the size of Earth’s moon, which would make it the smallest known exoplanet. The current record holder is a newly announced planet slightly larger than the moon. They also found that small, rocky worlds close to their star should take roughly 10 billion years to vaporise completely, and that the rate of this
“Eventually enough of the planet is vaporised that its gravity weakens, making it easier for mass to escape”
process changes over time. “If you start with a Mercury-sized object, it can sit there very happily for billions of years, very slowly bubbling away,” says Chiang. Eventually enough of the planet is vaporised that its gravity weakens, making it easier for material to escape and speeding up its destruction. KIC 12557548b may already be stripped down to its naked iron core. That means it should be possible to study the surrounding cloud and work out its composition, giving us a first look at the innards of a rocky world, says Ignas Snellen of the University of Leiden in the Netherlands. Jacob Aron n
What if people in a coma feel pain… interpret it as unpleasant. Using PET scans, previous studies have detected activation in the sensory-discriminative network in people with UWS but their findings were consistent with a lack of subjective awareness, the hallmark of the condition. Now Markl and her colleagues have found evidence of activation
IT IS a nightmare situation. A person diagnosed as being in a vegetative state has an operation without anaesthetic because they cannot feel pain. Except, maybe they can. Alexandra Markl at the Schön clinic in Bad Aibling, Germany, and colleagues studied people with unresponsive wakefulness syndrome (UWS) – also known as vegetative state – and identified activity in brain areas involved in the emotional aspects of pain. People with UWS can make reflex movements but can’t show subjective awareness. There are two distinct neural networks that work together to create the sensation of pain. The more basic of the two – the sensory-discriminative network – identifies the presence of an unpleasant stimulus. It is the affective network that attaches emotions and subjective feelings to the experience. Crucially, without the activity of the emotional network, your brain detects pain but won’t
Vanishing world may be roasted down to its core NOW you see it, now you don’t. A disappearing exoplanet is helping us understand how some rocky worlds meet fiery ends, and may even give us a glimpse of what lies deep inside rocky planets like Earth. Known as KIC 12557548b, the planet was discovered last year using NASA’s Kepler space telescope. This eye in the sky looks for dips in starlight as a planet passes in front of its host star. The more light is 14 | NewScientist | 23 February 2013
reuters
Julia Sklar
blocked, the larger the planet. KIC 12557548b is very small and orbits so close to its star that its year lasts just 16 hours. What’s more, the dimming it causes varies wildly. This could be because the planet is surrounded by a gigantic, everchanging cloud of material that stretches into a long tail. Eugene Chiang of the University of California, Berkeley, who was part of the team that found the planet last year, thinks the surface is being evaporated away by the intense heat of its star. Chiang and colleague Daniel Perez-Becker have now come up with a model of how rocky planets evaporate, based in part on Kepler
to people with diagnoses such as UWS,” says Donald Weaver at Dalhousie University in Halifax, Nova Scotia, Canada, who was not involved in the work. But it will encourage future study, he says. Changing a diagnosis depends on whether neurologists are ready to accept alternative ways of diagnosing disorders of consciousness, says Boris Kotchoubey at the Institute of Medical Psychology and Behavioural Neurobiology in Tübingen, Germany, who worked on the study. Nonetheless, Kotchoubey is confident that the way people with UWS are cared for will change, even if their diagnoses remain the same. “I know that many doctors working with such patients have been instructed to treat their patients as if they can understand them and perceive at least something in the environment, perhaps pain, pleasure, or emotion,” he says. But not all people are treated this way. Prior to the study, one of the people in Markl’s study was given no anaesthesia before a tracheotomy, which involves an incision in the neck to allow breathing without using the nose or mouth. As people with UWS are clinically considered unable to understand pain, doctors do not –Safer to give pain relief– have to give an anaesthetic. n
in the affective or emotional network too (Brain and Behavior, doi.org/kfs). Her team gave moderately painful electric shocks to 30 people with UWS, while scanning their brains using fMRI. Sixteen people had some kind of brain activation – seven only in the sensory network but nine in the affective network as well. These results question whether some diagnoses should change from UWS to minimally conscious, which is characterised by some level of awareness. “I don’t think this paper alone will change the clinical approach
data (arxiv.org/abs/1302.2147). Their model says that if KIC 12557548b was once about as big as Mercury, it should now be the size of Earth’s moon, which would make it the smallest known exoplanet. The current record holder is a newly announced planet slightly larger than the moon. They also found that small, rocky worlds close to their star should take roughly 10 billion years to vaporise completely, and that the rate of this
“Eventually enough of the planet is vaporised that its gravity weakens, making it easier for mass to escape”
process changes over time. “If you start with a Mercury-sized object, it can sit there very happily for billions of years, very slowly bubbling away,” says Chiang. Eventually enough of the planet is vaporised that its gravity weakens, making it easier for material to escape and speeding up its destruction. KIC 12557548b may already be stripped down to its naked iron core. That means it should be possible to study the surrounding cloud and work out its composition, giving us a first look at the innards of a rocky world, says Ignas Snellen of the University of Leiden in the Netherlands. Jacob Aron n