Nature Podcast 20 December 2007
Introduction
This is a transcript of the 20th December edition of the weekly Nature Podcast. Audio files for the current show and archive episodes can be accessed from the Nature Podcast index page (http://www.nature.com/nature/podcast), which also contains details on how to subscribe to the Nature Podcast for FREE, and has troubleshooting top-tips. Send us your feedback to podcast@nature.com.
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Adam Rutherford Coming up, have scientists been underestimating the role a single neuron can play in the brain.
Michael Brecht These findings will change our thinking about the somatosensory cortex. We have to think of it as a very precise machine. So, it is really very remarkable that the animal if it tries to it, can sort of detect a single neuron.
Adam Rutherford And Kerri talks to climate change refugee Ursula Rakova, whose islands are gradually disappearing into the sea.
Ursula Rakova It basically breaks my heart because the atoll that has been divided in half is mine. It belongs to my mother and it is mine and like for me having a daughter, the future is uncertain for me.
Adam Rutherford That is from a special report from the climate change conference in Bali.
Adam Rutherford This is the Nature Podcast and I am Adam Rutherford. This week, we start with whales. Since the 19th century we have known that whales were descended from land mammals. In the origin of species, Darwin himself used the phrase 'almost like a whale' to contemporary ridicule to describe the way in which a bear fed on insects under water, but until very recently a big problem was that no transitional cetacean fossils were known. This week in Nature, Hans Thewissen and colleagues at North-Eastern Ohio University's College of Medicine establish a 50-million-year-old stocky, raccoon-sized beast called Indohyus as the missing link between land mammals and their aquatic descendants. Where does it fit into the whale family tree? Here is Hans Thewissen. Nature 450, 1190–1194 (20 December 2007)
J. G. M. Hans Thewissen At about 40 million years ago, whales looked very much like the modern ones. You could clearly recognize them as such. You see Kutchicetus here at about 45 million years ago, we think that it had a flat tail, which was used for locomotion in water, then there was Ambulocetus, which was an animal that probably lived like a crocodile in shallow marine waters and then, Pakicetus that really does not look anything like a whale, it is about 50 million years old and is known from Pakistan.
Adam Rutherford Thewissen and his team have found that Indohyus links those early cetaceans like Pakicetus to ungulates or hoofed animals. The transition from land base to aquatic has been the missing link. Indohyus has been known since the 1990s, but as so often in great discoveries, years of meticulous analysis was crowned with a moment of serendipity that revealed the true significance of the specimen.
J. G. M. Hans Thewissen I think the most exciting moment came when my technician was preparing the skull and he by accident broke the ear off and he was ready to glue it back and he showed it to me and I realized that on the broken surface of this ear you could see that the inside of the bone was very thick, just like a whale and not like any other land mammal.
Adam Rutherford Thewissen's graduate student Lisa Noelle Cooper examined Indohyus's limb bones.
Lisa Noelle Cooper When we look at the bones in Indohyus, in general they look just like a regular terrestrial mammal, a mammal that was walking on land and when we look at the thicknesses of the bones that is when the whole story changes. The bones of Indohyus were actually extremely thick. This is the kind of thing that we see in animals like hippopotamus that live almost entirely in the water. Although they can walk on land, their skeleton has changed that allows them to basically walk on the river bottom. So, what we do with Indohyus is we actually sectioned the bones and then mount them on slides and we grind them down until we can see light through them and what that will show is something like this. Here you can see in a fossil of an animal that was actually living on land that was basically a small deer, you can see that the bone layer is very thin here, but when we look at Indohyus you can see that the bone is actually very thick compared to the inner medullary cavity or the bone marrow and that indicates that Indohyus was in fact aquatic or wading in water.
Adam Rutherford For Lisa, it is a great privilege to be involved in such a significant find.
Lisa Noelle Cooper One of my great passions in life is to study the evolution of cetaceans and whales, dolphins and porpoises and it has been just a thrilling find to be able to understand more of cetacean evolution and the fact that we found that Indohyus was aquatic is a profound and amazing realization that casts the evolution of cetaceans in a whole new light and so, to actually be part of this kind of finding is really gratifying.
Adam Rutherford That is Lisa Cooper. That paper and a short film of the discovery is available on our website www.nature.com/nature
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Adam Rutherford Now, unless you have been living in a cave for the last month, it cannot have escaped your attention that the world's politicians and scientists gathered in Bali last week for the UNFCCC, the United Nations Framework Convention on Climate Change, quite a mouthful. The convention finally drew to a close last Saturday and the official verdict is that it was a success. The idea after all was never to solve this most global of problems in two weeks, but to get nations to agree to a roadmap for the new protocol, a successor for Kyoto, whose second phase of commitment expires in 2012. Kerri Smith sent us this report from a hot and hectic island.
Kerri Smith If I had not known better, I would have guessed I was at a children's birthday party or perhaps some kind of bizarre carnival, but then I realized that the two life-sized snails that appeared outside Bali's International Convention Centre last Wednesday, were not for entertainment. They turned out to be disguised worldwide life fund members drawing attention to the speed or otherwise of the negotiations over climate change taking place under the banner of the UNFCCC, the negotiations driven by the scientific conclusions of the IPCC and by the sea coincidentally. On paper, the conference achieved its aim and in the flesh the meeting was a heady, hectic, and thoroughly enthralling mix of hundreds of nations, peoples, interest groups, and of course the ubiquitous journalists. But the eventual and some might say partial success was a long time coming. Indeed, a snail might have been disappointed with the speed of the talks and in a press conference on Thursday, executive secretary of the UNFCCC, Yvo de Boer looking rather morose opened with a line, "I am very concerned about the pace of things," and by Friday night and tripping over into Saturday morning, the discussions continued. The media schedule was far more frenzied, hourly press conferences and frantic filing from journalists numbering into the 100s. Alas, all this meant that your correspondent was too busy chasing down hallways after Brazilian foreign ministers and representatives of small island nations to get a chance to talk about pace with the snails and I thought that the media centre was unpleasant. Try wearing a full-on padded invertebrate costume in 36 degrees. For the most part, the press briefings were invaluable injections of fact, which given that many of the negotiations themselves are secrets heavily determined the day's news. But if that snail might have might found the tempo a little pedestrian, a gold fish might have felt a certain degree of déjà vu listening to the repeated resurrect from some delegations. An ongoing uncertainty for those of us reporting was whether the Bali roadmap would include a commitment to reduce the machines in the range of 25% to 40% below 1990 levels by 2020. I lost count of the amount of times that Harland Watson and the other US delegates when questioned replied with 'we feel that including numbers in the text prejudges the outcome'. Still this rather infuriating breed of speaker was in a minority, and it was definitely more fun to listen to them then to sit in the media tent, where several rickety mobile air-conditioners were succeeding only in pushing around a lot of very hot air, which thinking about it sounds like some delegation's specialty, but at least they did this figuratively. Outside the pressroom, the advice to the delegates arriving from nearly a 190 countries was to ditch suits in favour of casual boutique shirts, at least for the lower level proceedings so that the air-conditioning did not have to be maxed out to keep everybody from melting. This colourful strategy should be adopted for every conference. What joy to behold Yvo de Boer in a black and yellow jazzy number rather than suffocated by stuffy jackets and tie. Bali's climate has yet to be affected as profoundly by climate change as some places in the world. On Thursday, we spoke to Ursula Rakova a native of the Carteret islands for Nature's new climate change podcast. Her people have been heralded as the first climate change refugees. She described to us how the six atolls north of Papua New Guinea that make up the Carteret's are now seven due to sea level rise and how islanders can no longer grow their staple root crop because the water that bubbles up through the land is too salty. Even though she has done many media interviews, Ursula's voice still cracks when she told us about her islands.
Ursula Rakova It basically breaks my heart because I will be moving away from an island that I was born in and have grown up in and the atoll that has been divided in half is mine, it belongs to my mother and it is mine and like for me having a daughter, the future is uncertain for me.
Kerri Smith It's too late for the people of the Carteret islands to adapt to climate change. They must start evacuating their islands next year, but the hope is that the talks here in Bali will start us on the road to being able to mitigate or prevent its effects elsewhere. It's clear where the major sticking points have been. In his speech on Thursday night, Al Gore or the Gorical as some at Bali have dubbed him was refreshingly honest on this point.
Al Gore Speech
"I am not an official of the United States and I am not bound by the diplomatic niceties. So I am going to speak an inconvenient truth. My own country, the United States, is principally responsible for obstructing progress here in Bali."
Kerri Smith In light of the US' performance and despite their U-turn at the Eleventh Hour, you might be surprised to learn that the US delegations were graced with several awards during the course of the meeting. Again and again, they ranked among the top 3 when the NGO climate action network handed out the tremendously dishonourable fossil of the day awards for those nations who constituted the biggest blockage to progress.
Kerri Smith But perhaps their compromise on Saturday signals the start of a more harmonious period of negotiations and for them, no need to buy a second award cabinet for all those fossils.
Adam Rutherford Kerri Smith at the UNFCCC in Bali and you can hear more news from Bali later this week including the full interview with Ursula Rakova from the sinking Carteret islands on Nature's second climate change pod. Signup and listen for free at www.nature.com/climate/podcast. Now, here is Charlotte Stoddart with three neuroscience papers that focus the brain down to individual neurons.
Charlotte Stoddart The mammalian brain faces a serious resource problem despite the billions of neurons present there are not enough to have one responsible for every single perception, behaviour or memory. To increase its storage capacity, the brain is thought to use overlapping patterns of activity across many interconnected cells instead, but three papers published in Nature this week suggest that this underestimates the part individual nerve cells can play. In one of these papers, Michael Brecht and Arthur Houweling from the Erasmus Medical Centre in the Netherlands show that stimulating a single neuron can influence a rat's behaviour. Their research focuses on the somatosensory cortex, the region of the brain that represents touch. I asked Michael how they managed to stimulate just one neuron given that this region contains about two million of them. Nature advance online publication (19 December 2007)
Michael Brecht We have been able for a long time, sort of, to stimulate single cells or to make intracellular recordings in anesthetized animals, but what the challenge of this particular study was to do this in a vague-behaving animal and we got that to work reasonably well, but the difficulty is that you have to be very close to the cell and that the animal is moving, doing all kinds of behaviours so that is technically a challenging part of the study.
Charlotte Stoddart So, what did you do, how did you manage to overcome these technical difficulties?
Michael Brecht What we did, actually we adopted a technique that had been developed originally to stain neurons and we then reasoned that if one is able to individually label a neuron, we should also be able to individually stimulate a neuron and that is what indeed proved to be possible.
Charlotte Stoddart And, once you had worked out how to stimulate a single neuron in awakened, active rats, how did you then test their response to this stimulation?
Michael Brecht The rats were trained in an apparent conditioning procedure. The actual training is quite simple. You first would start with a strong stimulation current and then, you would reward them, you would do a couple of such pairings of stimulation and reward and then the animals would already expect a reward and would start to lick and we would sort of detect their lick responses and later on only reward them when they would lick after the stimulation. So, they learn it very naturally and in a few days they perform extremely well on this task then.
Charlotte Stoddart So, once you trained your rats and you were then stimulating just a single nerve cell, did the rats respond to every stimulation of that single nerve cell?
Michael Brecht No, no, this is something we have never seen. So, we never saw the animal respond to every stimulus. So, we feel that the signal from a single cell seems to be a weak signal to the animal even when it detects it. So, it is always a case that the response latencies of the animals are pretty long and they never reach sort of 100% response rate. The strongest effects we saw for this sort of cases where the animal may respond in half of the cases to the single cell. So, we do not think that this single neuron provides sort of a detonator, a bang-on signal that is very striking to the animal.
Charlotte Stoddart What did your research tell us about how the brain processes sensory information?
Michael Brecht What we think is that these findings will change our thinking about the somatosensory cortex in a way that as such that we have to think of it as a very precise machine. So, it is really very remarkable that the animal if it tries to it, can sort of, detect a single neuron so it operates at the physically best sensitivity or so, and so what these data tell us is that it is not the case that the cortex just because it contains so many neurons, is in every instance a mass action machine and in every instance it works only this large groups of neurons, what we find is it can under certain circumstance be extremely selective and work extremely precisely.
Charlotte Stoddart And two other papers published in Nature this week reinforce this idea then that individual or small groups of neurons play an important role in information processing in the brain. Karel Svoboda and his team at the Howard Hughes Medical Institute in Virginia excited their neurons using optical stimulation rather than the more usual electrical stimulation. So, Michael, how do these two techniques match up?
Michael Brecht From our own experience we feel that optical stimulation and electrical stimulation seems to activate the brain in quite different ways. So, we do not foresee yet to what extent these techniques will replace each other and to what extent they will be complementary. What is certainly exciting is that the genetic means for optic stimulation techniques are improving at such a fast rate that is certainly an extremely fascinating field. What I think is the strengths of the genetics is that you could tailor your simulation to genetically pre-selected neurons or so, so you could potentially get a lot more cellular specificity and I think that is what many groups are trying. At the same time one has to say we do not fully see yet how far these techniques will go.
Adam Rutherford Michael Brecht ending that report by Charlotte Stoddart. You can find out more about that research and the two related papers by Karel Svoboda online at www.nature.com/nature. Sticking with the brain is this week's Podium. Here is Barbara J. Sahakian, Professor of clinical Neuropsychology at the University of Cambridge School of Clinical Medicine. Nature 450, 1157–1159 (20 December 2007)
Barbara J. Sahakian The personal, social, and economic cause of neuropsychiatric disorders such as schizophrenia, Alzheimer's disease, and brain injuries are staggering. The key focus of my laboratory is to assess the effectiveness of cognitive-enhancing drugs for people suffering with such conditions. It has been estimated that if we had them, treatments cutting severe cognitive impairment in older people by just one person a year would cancel out all predicted increases in long-term care/cause of the aging population. In the process of our research, we also study healthy humans. We explore whether drugs such as methylphenidate also known as Ritalin or Modafinil improve attention, learning, memory, and functions such as planning. There is now considerable evidence that people young and old are using such drugs to try to perform better at university or work and to cope with daily life. Some get them on prescription from their general practitioner; some obtain them via the internet. I complained of jet lag recently at a conference and was offered Modafinil by a US colleague. Another colleague from Oxford University buys it on the web for it adds productivity in important intellectual challenges. These developments raise numerous ethical questions. For example, would you use a relatively safe and effective drug to boost your brain power? Would you be concerned about its prolonged use in children whose brains are still developing? Would you be troubled by drug use in competitive situations such as university entrance exams, would you feel coerced into using drugs or giving them to your children if others around you were using them? Would you be concerned that the use of drugs might increase disparity in society if only the people who could afford them had them? Would you prefer to have guidance from a pharmacist, what do you think it is safe to purchase brain boosters over the internet? The use of brain-boosting chemicals also raises yet more questions. Why do healthy people choose to use drugs when other options are available? For calm and efficient thinking, one can improve work-life balance and relaxation. Sleep, behavioural, and other problems can be addressed through psychological treatments and cognition can be enhanced with education and exercise. Even in psychiatric patients or those with brain injuries, drugs should always be considered as part of a wider treatment and rehabilitation program including psychological and social components. Despite these concerns, we should be encouraging drug companies to develop safer and better cognitive enhances for improving the quality of life for patients, but given the increasing use of these drugs off label and non prescription by healthy people, governmental bodies may have to regulate treatments not only for patients, but also for the wider society.
Adam Rutherford Barbara Sahakian on performance-enhancing drugs. Nature networks our social networking site is hosting a debate on this topic. If you would like to take part, go to www.network.nature.com/groups and join the nature news and opinion group and feedback to us on the podium or the rest of the show by emailing us. The address to write to is podcast@nature.com.
Adam Rutherford Last Sunday was the 90th birthday of Arthur C. Clarke, possibly the most important science fiction writer alive today. You just heard some Strauss from the 1968 film of 2001: A Space Odyssey, Clarke's most famous novel. To wish him a happy birthday and to talk about the significance of his work I have got two of Nature's self-confessed sci-fi geeks with me, biology editor, Henry Gee and news editor, Oliver Morton. Ollie, good SF is a two-way street with fiction being lead by technology of the day and science in turn being influenced by the speculation in the fiction. Clarke managed to have a foot in both camps, did not he?
Oliver Morton Oh, yes. I mean, it is easy to forget now when we think of Arthur Clarke as a science fiction writer, but throughout most of the 1950s he was equally famous if not more so as a science writer, I mean he was very much in the forefront of popularizing the idea of a space age, in fact I think that would be up until 2001 that would be by far what he was best known for.
Adam Rutherford And he is credited with coming up with the idea of geostationary satellite orbits, is not he?
Oliver Morton Yes, I think it was around 1945 that he published a short technical paper pointing out that if you put something up in an orbit which went around the Earth in 24 hours, then you would have something that effectively acted as though it stood on top of a very tall mountain and the idea fascinated him and it later becomes a big theme in his science fiction, especially in the form of an idea of a system where you can link such a satellite directly to the surface of the Earth with a space elevator, which was an idea that he very much made his own, although it was first developed by other engineers.
Adam Rutherford And he had a nice line in maxims too tell us about Clarke's laws.
Oliver Morton Yes, Clarke's laws. I think the best and most famous one is Clarke's third law, which is 'that any sufficient advanced technology is indistinguishable from magic' and it is a very good line. It also speaks quite strongly to the heart of the man, I mean the sense in which technology and magic are indistinguishable and in which a sort of mystical wonder is absolutely congruent with scientific understanding is what Clarke is all about and this sense of the thwarted or slightly off to one side mistake that comes with this incredibly rationalist filter that is what makes his work much more powerful than you might normally expect.
Adam Rutherford Henry, you are the editor of Nature's award-winning SF series, Futures, which Clarke inaugurated in 1999, what was it like working with him?
Henry Gee Well, when we started this series, we wanted to ask a science-fiction writer whom we could guarantee that every reader of Nature would have heard of. So, Clarke was the top of the list and I happened to have his email, but I asked Clarke to write a story and he did it by return much to the fury of his agent, which took some calming down later on.
Adam Rutherford And at the age of 90, do we know, is he still working?
Henry Gee The rumour is he started a novel, but felt too old to finish it. So, he gave the rest of it to Frederick Pohl, who is even older than he is. So, we do not know, but working with Clarke was actually very amusing because we were not quite sure when Futures was coming out and what it would be like. So, he had to supply this story and that was the one time when I actually got to meet him because I managed by luck to get to an exhibition at the national portrait gallery where there were portraits of some extremely famous people along with the people themselves in the gallery and there was Clarke, who has been quite infirm for a while. He was being wheeled around in a wheelchair looking like a terribly old and infirmed chap, but I must say that is only a very clever ruse because he looked at me, clocked immediately to where I was and said, 'when is my article going to be published then?' So, I thought this is the guy I could work with.
Oliver Morton It has got to be said Clarke has been saying that this is his last novel since I think The 'Fountains of Paradise' in the late 1970s.
Henry Gee That is a terrific novel. I am very fond of The 'Fountains of Paradise'.
Adam Rutherford Ollie, what is your favourite Arthur C. Clarke moment?
Oliver Morton I think it is probably some part of 'Rendezvous with Rama', which is a strange and interesting book. In some ways, it hardly has a plot at all and yet it has got this extraordinary image of a world turned inside out to make a spacecraft, maybe a spacecraft turned inside out to make a world and there were moments in that when people are stuck on staircases the size of mount Everest and suddenly the lights come up and they see this world that they are part of, which are really kind of breathtaking and there is a feeling to that book that I think I have responded quite deeply, I mean, there are other great Clarke moments, The end of the nine billion names of god, one by one without any fuss the stars were going out. That is a pretty good way to end a story, but for me it is some of the images in some of the novels really stick with me.
Adam Rutherford Thanks, Henry Gee and Oliver Morton and a big, happy 90th birthday to Arthur C. Clarke from Nature. That is all from this week's show. We are having a break over the holidays. So, look out for our next show on the 10th of January. As ever, we are signing off with Sounds of Science. This week, especially for Christmas we have got a metabolic melody from Tim Karplus and Kevin Ahern. They use it as a teaching tool at Oregon State University. Here is their ditty about E. coli to the tune of 'Rudolph, the Red-Nosed Reindeer'. This is the Nature Podcast and I am Adam Rutherford. Happy Holidays. Thanks for listening. Take it away Rudolph.
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