Should I Stay, or Should I go... to Mars?

Sometimes severe head injuries can leave a patient in what is dubbed a persistent vegetative state. But recently, using a brain scanning technique called fMRI, scientists were able to show that some of these people are conscious and capable of communicating with them, but were just not able to move. Now Davinia Fernández-Espejo's has uncovered why - there's a 'disconnect' in the brain which prevents the thalamus - a relay station in the centre of the brain - and the motor cortex - the area of the brain that produces movements - from exchanging information. Graihagh Jackson caught up with her to hear how...

Davinia - So in this paper, we were looking for structural damage in the brain of patients who appear to be in a vegetative state. This is, they don't show any external signs of being aware of themselves, of the environment. But we do know that some of these patients are actually fully conscious. This is a small percentage of them and are just incapable to move. So, the first step we study was to try and identify awareness using these fMRI techniques asking them to imagine they were playing tennis, imagine they were moving their hands. Once we had a patient who we could confirm they were actually aware then we did the second part of the study.

Graihagh - And then my understanding is you also looked at healthy people and mapped what bits of their brain lit up as well.

Davinia - That's right. So, up until now, we were not entirely sure what the differences are between just imagining a movement or actually, physically performing that movement. And that was key in this study because this is the difference between the things that they can or can't do - these patients. So, they can imagine a movement, but they can't actually perform that movement. So we needed to see the difference between these two processes to know what were the areas are key for you to give this step further and actually move. And we found that there is a significant pathway which is the one connecting the thalamus which is the small region, kind of in the deep of your brain and the motor cortex which is the region that ultimately is going to send the signal to your limbs to move. So in a way, these two regions appear to be disconnected so the information can't travel from one to another and that's what's stopping these patients from being able to actually externally move.

Graihagh - That surprises me because you would've thought patient to patient, the structural damage in the brain would be very different, but you think it's down to this one sort of connection.

Davinia - Well, that's a good question. So, in this study, we focused on patients with a very specific type of damage which is traumatic brain injury from a car accident. What we don't know yet is whether this specific damage is going to appear also in patients of different aetiologies, and that will be the next logic step to this study.

Graihagh - What happens in these patients that means that there is that disconnect in the brain?

Davinia - So basically, when we're talking about a car accident, there's speed and sudden deceleration. What happens is that the fibres that are connected from regions of your brain break in the process. So, that ends up leaving regions that can't speak to each other again.

Graihagh - How common is this type of injury?

Davinia - It is very common. They're quite recent, so we only see these patients in the last few years. This is because we are talking about very severe accidents that before all the advances in the medical care wouldn't have survived the accident.

Graihagh - That's really interesting. I mean, I suppose it's great to show that we've had so much progression in this. But equally now, we've got a whole new other caseload of difficult things to solve.

Davinia - That's right. We're getting really good at solving problems in our organs and our body, but the brain is still something we're still kind of trying to understand.

Graihagh - Does that mean then, now that you've identified this blockage, that you can do something about it. Might there be a treatment down the line that could help these patients?

Davinia - Yeah and that's the most exciting thing about this finding. We're still very early in that direction, but I think it's a good first step. So, we can't regrow those fibres that are gone. That can't happen but we can do something to make those connections that are still present to work harder to try to compensate for the damage. There are several ways we can do this. We're still studying what's the best approach, but anything that you can think that could make those fibres that are still there work harder and make these two regions talk to each other could help these patients in the future.

Graihagh - How might you be able to make these connections work harder?

Davinia - So, there are several possibilities. One possibility could be a pharmacological treatment and there's also a number of brain simulation techniques that can help give these regions a little push to try and work a little bit harder.

Graihagh - So, how far away do you think are we from this type of thing? I know you said this is sort of a good first step. How long are we looking at here?

Davinia - Yeah. That's difficult to tell. We're starting to try some of these ideas about how to simulate some of these regions now. So, we're still a few years away from knowing the answers to this.

It's sometimes claimed that men buy fast cars and large camera lenses, amongst other things, to make up for deficiencies in other areas. But this behaviour may not be unique in the animal kingdom: now scientists at Cambridge University have shown that howler monkeys, which are natives of South and Central America, do something similar with the sounds they produce. Connie Orbach went to meet researcher Jacob Dunn to hear how...

Jacob - What we found was that there was a really close relationship between the size of this hyoid bone which a sort of big cup-shaped bone in howler monkeys which they use for resonating sound around, and making a really low frequency call. That closely matched the number of males that they had in each of the species. And so, those species that just had one male usually in a neat group tend to have a very big vocal organ whereas those species that have multiple males tend to have a very small vocal organ. What we also found is that there's a really close relationship between the size of this bone in the throat and the size of their testes. So, species that had a very big vocal organ had very small testes and species that had a very small vocal organ had very big testes.

Connie - So, let me get this right. Loud road (recording), smaller testicles, but big harem. Small roar (recording), bigger testicles. So, it seems the howler monkey just can't have both. But what's it got to do with how many other males there are?

Jacob - We know species that tend to live in groups with just one male. They try and defend groups of females very aggressively and in different species that have more males in the group, there's no longer the need for this male-male shouting competition. But because females will often copulate with several males within the group, so the sort of pressure shifts towards them having to compete for each other after they've copulated with the females. And so, they evolve bigger testicles so that they can produce more or faster sperm.

Connie - Okay, so that makes sense. Now, this hyoid bone must be quite something to have such a big effect. What does it even look like?

Jacob - In humans, it is a very simple little bone. It fits on top of the larynx just under the chin in the throat it's a little horseshoe-shaped bone. But howler monkeys have evolved this different kind of shape to their bone. They've turned it into a sort of bulbous expanded cup-shaped thing which they actually have some soft tissue as well that they blow into, it's a sort of air sac. But it varies hugely from species to species. So, the males have much bigger hyoids than females. But even within the males across the species, there's 10-fold variation from the smaller species to the biggest.

Connie - Is this a model you've got here or is it a real skull?

Jacob - No, this is a cast.

Connie - And this is the hyoid bone.

Jacob - Yup.

Connie - It's a really, really weird-looking bone. It's half a balloon-shaped almost and it seems to be sat kind of right underneath the jaw there. So, why can't they have both? Why do they have to have one or the other?

Jacob - We don't know the answer to that fully yet, but there are two different ways or at least two different ways that this might work and it could be that both of them are working at the same time. One of them is that there is sort of limited energy to be able to invest in different things. The expression of these kinds of traits are costly. There might just not be energy available to do both of those things during development. That will be one mechanism. The other system would be that once you're sort of down, one evolutionary trajectory, there's kind of no point in investing in both. So, as you become a species that has a big hyoid bone which means that you produce a really low frequency call, you become so dominating that your social system becomes that of just one male in the group.

Connie - There's those classic arguments about big cars or flashing their cash is maybe compensating for something else, but do we actually see this in people ever, a trade-off?

Jacob - It has been only once that is as far as I know where they've looked at this kind of trade-off. They found something really interesting actually. They found that the voices of men when played back to women that were judged to be more attractive also had low quality sperm. Which suggests that there might also be this sort of similar kind of trade-off, but it certainly suggests that something might be going on and I wouldn't be surprised if there really is.

(Sounds copyright The Macaulay Library at the Cornell Lab of Ornithology)

What can we learn from exploring Mars and are humans better than robots? Chris Smith asks our panel about the scientific argument for human space travel. We started by considering the case for robots.

Carolin - I think it's a no-brainer. Certainly in the short term, robots are the way to go. We've just heard about some of the hazards that humans face. Even if you can get them to Mars in one piece then the dangers on the surface, the reduced gravity, the radiation. The thing about robots is they're a lot less fussy, they're a lot less fragile, and you don't have to send so much kit with them. So in many ways, they are much more efficient way of exploring. Today, robots can do everything that humans can do. Maybe they don't do it so efficiently. Maybe we just have to be a bit more patient. We'll get our science a bit more slowly, but at the minute, there's no pressing need to be sending humans.

Chris - Sanjeev, you've been involved in the Curiosity Mission which is a pretty big mission. I mean, that's a mini-sized rover that's crawling around on Mars. Would you concur with what Carolin is saying?

Sanjeev - Not at all, I'm afraid. I'm a terrestrial geologist, I'm a geologist who works on Earth, does field work on Earth, and I've moved into the planetary sphere. Whilst Curiosity can do amazing things, it's incredibly slow for me. What we do in days, a human can do in minutes. That's the issue - is that, we've been on Mars for 3 years now, we've got some spectacular discoveries but we can't look around. We can't go this way or that way. We can make rapid decisions. We're not adaptable because of latency effects, et cetera. So, I think a human on Mars could very, very rapidly do this sort of geological characterisation - the geological science that we can do on Earth that even looking 10, 20 years ahead, a robot simply is not capable of doing just because of the human cognitive aptitudes.

Chris - It's just technology though, isn't it? I mean, it's just a question of writing better computer programmes to run these things better.

Sanjeev - Have you tried doing geology? It's very, very hard. The thing is that there's not simple patterns in the geological record. Scientifically, the first thing we're going to do when we get to Mars is actually look at the geological science. We will now understand the geological evolution of Mars. Did life evolve? Finding these things is incredibly difficult. There's a lot of rock on Mars. A rover maybe travels 20 kilometres in its lifetime. I think Curiosity has just done over 10 kilometres. Secondly, there's large areas of Mars which are very, very interesting that it will be very difficult to get robots too.

Chris - Carolin, you're sort of nodding and shaking your head in equal measure.

Carolin - Well, I agree that it would be a nice luxury to send human astronauts to do this job much more efficiently. I just dispute that it's actually required now. I mean, there are two questions being, one is of course, whether we can do all the science with the rovers and the orbiters, and even the stationery spacecrafts such as Phoenix. Yes, they can do it maybe more slowly. But it's a matter of, is getting the science just that much faster relevant for the huge cost it might bring and the huge danger to humans going out there.

Chris - Yeah, I was going to say. I mean, has to - when you're making a decision about doing research, weigh up the pros and cons in terms of what I can get bang for my buck. Sanjeev, what you're sort of suggesting is, "Yeah, let's get some humans on Mars" but the price, you think how much science we could actually do with the same spend both from orbit which is much cheaper and also, maybe even just from here on Earth.

Sanjeev - We can do a lot, but I think nobody is thinking that we're going to do this immediately so the plans are in the next 20 or 30 years for humans to Mars to do science properly. So, I think it's planning stages at the moment.

Chris - Richard, did you want to comment?

Richard - Well, I want to offer a compromise here, something that the European Space Agency and NASA are seriously looking at is to have a mission to Phobos or a mission to the orbits of Mars and then be able to control rovers on the surface. So that way, you eliminate the time delay and you can effectively have them as avatars on the surface.

Chris - When you say time delay, this is the problem that because it's so far to Mars that even at the speed of light, these radio controlled signals, you've got a latency of a delay of many - not just seconds, but minutes, hours.

Richard - Which is why they're building a lot more autonomy into the new rovers like the ExoMars rover which will be the European rover to Mars. But Tim Peake, the British European Space Agency astronaut who's flying to space station in December. He will be doing one of these experiments and actually, operating from the space station, a rover in the Mars yard which is a simulated Mars environment in Stevenage so actually, to simulate that.

Chris - Carolin, what's the price as well because you mentioned eluded to cost, everyone talked about cost but what do we think is actually likely to start costing?

Carolin - I've got absolutely no idea. I mean, just thousands of billions would be my guess. I mean, maybe that's an exaggeration. I just want to come back...

Chris - Ryan is just waving his hand. He's got an idea of the price then. What do you think the price tag is?

Ryan - The lowest estimated cost that I've seen for human Mars missions is on the order of $10 billion or so. So, for comparison with Curiosity which was around 2 billion, a factor of 4 more potentially in the costs for a human mission. Yeah, certainly, I think you can justify that.

Carolin - I just want to go back to Rich's compromise. If you're going to send astronauts all the way to Phobos, you're still exposing them to the same danger. It's still going to not actually cost an awful lot less. If you're going to go away to Phobos, you might as well just go to the surface of Mars. I don't think that's much of a compromise really.

Richard - I think one of the things that this is a compromised option eliminate at least in the short term is the problem of getting to Mars and getting back off again because we talked about sample return. When you talk to NASA scientists about this, no one has managed to get even a coffee cup-size sample of material off Mars. So, unless you're going to go on a one-way trip, which is what Mars1 is proposing, getting back is a real genuine concern.

Chris - I think Sanjeev, because your question and your point is that we want some samples and it's very hard to do this sort of science when you're not on Mars.

Sanjeev - More importantly, you don't just collect samples. As a geologist, you gain context and that's very difficult to do from a distance. And so, I think even doing it from Deimos or Phobos is really difficult. I think what's happening now is really a serious attempt to start thinking about resources on Mars and what you could use as propellant to get back. So I think it's not going to happen instantly, but people are thinking about that. They won't only consider that if they can do it, if the resources have had to be able to provide propellant to get humans back from the surface of Mars.

Chris - Propellant equals rocket fuel.

Sanjeev - Right.

Carolin - I think the key thing though that we're all in agreement is that we need robots at the minute. Whether or not we're going to be sending human astronauts to Mars, they're vital as scouts really to prep - just as precursors, to find where the resources are, the possible landing sites, to assess the climate, the radiation damage. We need to test things like, we were just talking about the launch, the landing technology, the piloting, and even just delivery of equipment, habitat, fuel, food. Everything that we need is all going to be robotic even long before we send the astronauts. So, whether or not you send the astronauts, we still need to develop the robot technology, just as that scouting and that testing ground.

Chris - In other words, we need them anyway so we might as well just solve this problem in the course of solving the next one, don't we? Now, the other question is of course, why do we want to go to Mars? What can we learn about Mars? Interestingly, this year's Christmas lectures at the Royal Institution are all about the future of space travel and space exploration, and they're being delivered by UCL's Kevin Fong.

Kevin - Mars, I think is a large piece of the puzzle when it comes to asking a question of how ubiquitous life is in the universe. We know that 4 billion years ago, conditions on Mars were at least similar to, if not the same as they were on Earth. We know that that was around about the time that life first arose on our planet. And so, if we go to Mars and it proves to be sterile and always has been sterile then it means that Earth is indeed very, very special and it's something particularly special about it that allows life to claw its way and then develop. If we go there and find that there is life now or there has been life on Mars, it probably means that life is ubiquitous in the universe because it suggests that wherever life has a chance, it will claw in at least in some basic form. So, I think it is essential that we explore Mars. I think it has some of the most important answers that we seek in the 21st century.

A mission to Mars is regarded by many as the next giant leap. So let's look back at the legacy of the last one... Connie Orbach has been looking at one of History's defining speeches.

JFK - But why, some say, the Moon? Why choose this as our goal? And they may well ask, why climb the highest mountain? Why, 35 years ago, fly the Atlantic? Why does Rice play Texas? We choose to go to the Moon! ... We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard; because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one we intend to win and the others too.

Connie - In 1962, the then United States President John F. Kennedy gave a historic speech at Rice University, Houston when he announced the USA's commitment to send an American to the moon by the end of the decade. In the 1960s, travel to the moon was just a bigger challenge as the Mars trip seems today. Many of the arguments for and against were the same.

JFK - To be sure, all this costs us all a good deal of money. This year¹s space budget is three times what it was in January 1961, and it is greater than the space budget of the previous eight years combined. That budget now stands at $5,400 million a year--a staggering sum, though somewhat less than we pay for cigarettes and cigars every year.

Connie - Of course, a challenge of this level had more objectives than purely to inspire and the political motives were almost certainly the greatest influence on America's success. The space race became an extension of the Cold War and the Russians had twice beaten the USA. First, with the satellite Sputnik and then with human space flight. Kennedy needed a challenge that he felt he could win to pull the American people together and reaffirm America's status as a leading world power. Today, human space travel is once again on the agenda and the challenge is even bigger. Could it be that we're at the start of yet another space race?

JFK - If this capsule history of our progress teaches us anything, it is that man, in his quest for knowledge and progress, is determined and cannot be deterred. The exploration of space will go ahead, whether we join in it or not, and it is one of the great adventures of all time, and no nation which expects to be the leader of other nations can expect to stay behind in this race for space.