- Email: [email protected]
Even silent videos excite auditory brain
IN BRIEF
bettmann/corbis
DUST fountains from craters on the moon might be where astronauts have their wishes granted. Such plumes could aid the search for water and other resources. The first signs of flying lunar dust came during the Apollo 17 mission. Astronaut Gene Cernan saw an extended glow in the sky which may have resulted from light scattering off the stuff. It’s thought that the solar wind is involved in lofting dust, but the conditions that lead to such events are not fully understood. Now a team led by William Farrell of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, has modelled how dust could be thrown up at the moon’s poles, where the solar wind blows horizontally over crater rims. On reaching the rim, electrons and ions in the wind spread apart because of their different masses. The team’s computer simulations show that clouds of electrons will form in the leeward side in the crater. This should create repulsive electrostatic forces on the surface, stirring up dust (Journal of Geophysical Research, DOI: 10.1029/2009JE003464). If enough material were thrown up, a probe could collect and analyse it for signs of frozen water and minerals from hard-to-reach areas below. “Why go down to prospect for gold if the surface is throwing gold up for you?” says Farrell.
16 | NewScientist | 8 May 2010
Cancer cells turned on by making the right connections IN CERTAIN social circles, it’s not what you know, but who you know that counts. The same seems to be true of the gene switches that turn on cancer cells. One way cells turn genes on and off is via small RNA molecules. In cancer, the usual pattern of microRNA production is disrupted. But as some miRNAs regulate many different genes, and each gene is affected by many different miRNAs, their exact role in cancer is tough to pin down. Carlo Croce, a cancer researcher at Ohio State University in
Columbus, and his colleagues created a diagram of interacting miRNAs for normal body cells by connecting them according to which genes they target and the function of those genes, in a way similar to analyses of human social networks. Most miRNAs have limited effects, but it turns out that a few extend their influence in many directions – just as a few people in a social network seem to “know everybody”. When the researchers compared these networks for ordinary cells and for cells from
51 forms of cancer, they found that all the miRNAs of ordinary cells were connected in a single network. In contrast, the cancer cells often had subsets of miRNAs that were not connected to the rest of the network – rogue groups that had broken free. What’s more, the highly connected “hub” miRNAs were often different for cancer cells (Genome Research, DOI: 10.1101/gr.098046.109). These unique hubs might represent key points of attack in cancer therapies, says Croce. ed alcock/eyevine
Want a drink? Try the dust fountain
Melting icebergs boost sea-level rise WHEN an ice cube melts in a glass, the overall water level does not change as the ice melts into the rest of the liquid. Doesn’t that mean that melting icebergs shouldn’t contribute to sea-level rise? Not quite. Most sea-level rise comes from water and ice moving from land into the ocean, but the melting of floating ice causes a small amount of sea-level rise, too. Icebergs are made of fresh water, which is less dense than salty seawater. So while the amount of seawater displaced by the iceberg is equal to its weight, the melted fresh water will take up a slightly larger volume than the displaced salt water. This results in a small increase in the water level. Andrew Shepherd and colleagues at the University of Leeds, UK, used iceberg surveys to analyse the amount of ice floating on the world’s oceans. Taking into account melting ice shelves, melting Arctic sea ice and the increase of Antarctic sea ice – which removes water from the oceans – they estimate that about 746 cubic kilometres of ice are melting each year, overall (Geophysical Research Letters, DOI: 10.1029/2010GL042496).
Even silent videos excite auditory brain IS A sound only a sound if someone hears it? Apparently not. Silent videos that merely imply sound – such as of someone playing a musical instrument – still get processed by auditory regions of the brain. Kaspar Meyer at the University of Southern California in Los Angeles and colleagues showed eight volunteers nine silent video clips that implied sound, including people playing violins, a dog howling and chainsaws cutting into trees. As they watched, their brains were scanned using functional MRI. Each type of implied sound created
a unique pattern of brain activity in the “early auditory cortices” – regions thought to be devoted to the initial processing of sounds. After noting these patterns in a several of the volunteers, the researchers were able to predict which type of video other volunteers had watched, just from the activity in the auditory cortices (Nature Neuroscience, DOI: 10.1038/nn.2533). The volunteers also reported imagining the sounds as they watched the videos. The results broaden the role of regions previously thought only to be involved in initial sensory processing.
bettmann/corbis
DUST fountains from craters on the moon might be where astronauts have their wishes granted. Such plumes could aid the search for water and other resources. The first signs of flying lunar dust came during the Apollo 17 mission. Astronaut Gene Cernan saw an extended glow in the sky which may have resulted from light scattering off the stuff. It’s thought that the solar wind is involved in lofting dust, but the conditions that lead to such events are not fully understood. Now a team led by William Farrell of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, has modelled how dust could be thrown up at the moon’s poles, where the solar wind blows horizontally over crater rims. On reaching the rim, electrons and ions in the wind spread apart because of their different masses. The team’s computer simulations show that clouds of electrons will form in the leeward side in the crater. This should create repulsive electrostatic forces on the surface, stirring up dust (Journal of Geophysical Research, DOI: 10.1029/2009JE003464). If enough material were thrown up, a probe could collect and analyse it for signs of frozen water and minerals from hard-to-reach areas below. “Why go down to prospect for gold if the surface is throwing gold up for you?” says Farrell.
16 | NewScientist | 8 May 2010
Cancer cells turned on by making the right connections IN CERTAIN social circles, it’s not what you know, but who you know that counts. The same seems to be true of the gene switches that turn on cancer cells. One way cells turn genes on and off is via small RNA molecules. In cancer, the usual pattern of microRNA production is disrupted. But as some miRNAs regulate many different genes, and each gene is affected by many different miRNAs, their exact role in cancer is tough to pin down. Carlo Croce, a cancer researcher at Ohio State University in
Columbus, and his colleagues created a diagram of interacting miRNAs for normal body cells by connecting them according to which genes they target and the function of those genes, in a way similar to analyses of human social networks. Most miRNAs have limited effects, but it turns out that a few extend their influence in many directions – just as a few people in a social network seem to “know everybody”. When the researchers compared these networks for ordinary cells and for cells from
51 forms of cancer, they found that all the miRNAs of ordinary cells were connected in a single network. In contrast, the cancer cells often had subsets of miRNAs that were not connected to the rest of the network – rogue groups that had broken free. What’s more, the highly connected “hub” miRNAs were often different for cancer cells (Genome Research, DOI: 10.1101/gr.098046.109). These unique hubs might represent key points of attack in cancer therapies, says Croce. ed alcock/eyevine
Want a drink? Try the dust fountain
Melting icebergs boost sea-level rise WHEN an ice cube melts in a glass, the overall water level does not change as the ice melts into the rest of the liquid. Doesn’t that mean that melting icebergs shouldn’t contribute to sea-level rise? Not quite. Most sea-level rise comes from water and ice moving from land into the ocean, but the melting of floating ice causes a small amount of sea-level rise, too. Icebergs are made of fresh water, which is less dense than salty seawater. So while the amount of seawater displaced by the iceberg is equal to its weight, the melted fresh water will take up a slightly larger volume than the displaced salt water. This results in a small increase in the water level. Andrew Shepherd and colleagues at the University of Leeds, UK, used iceberg surveys to analyse the amount of ice floating on the world’s oceans. Taking into account melting ice shelves, melting Arctic sea ice and the increase of Antarctic sea ice – which removes water from the oceans – they estimate that about 746 cubic kilometres of ice are melting each year, overall (Geophysical Research Letters, DOI: 10.1029/2010GL042496).
Even silent videos excite auditory brain IS A sound only a sound if someone hears it? Apparently not. Silent videos that merely imply sound – such as of someone playing a musical instrument – still get processed by auditory regions of the brain. Kaspar Meyer at the University of Southern California in Los Angeles and colleagues showed eight volunteers nine silent video clips that implied sound, including people playing violins, a dog howling and chainsaws cutting into trees. As they watched, their brains were scanned using functional MRI. Each type of implied sound created
a unique pattern of brain activity in the “early auditory cortices” – regions thought to be devoted to the initial processing of sounds. After noting these patterns in a several of the volunteers, the researchers were able to predict which type of video other volunteers had watched, just from the activity in the auditory cortices (Nature Neuroscience, DOI: 10.1038/nn.2533). The volunteers also reported imagining the sounds as they watched the videos. The results broaden the role of regions previously thought only to be involved in initial sensory processing.