Exam season is around the corner, so this week the Naked Scientists take a walk down memory lane to find out what's going on upstairs when you learn and remember things, and investigate if it's possible to boost your brain power. Plus, in the news, prosthetic fingers that can actually feel, the sacred art of origami gets a DNA update and Kat asks whether giant pandas really just don't fancy getting frisky.
In this episode
00:53 - Abnormal embryos can form healthily
Abnormal embryos can form healthily
with Professor Magdalena Zernica-Goetz, The University of Cambridge
Professor Magdalena Zernica-Goetz got personal with her science after a test during her pregnancy left her worried for the health of her baby. The Chorionic Villus Sampling, or CVS test is offered to pregnant women whose babies are at a high risk of having a genetic condition like Down's Syndrome. It is done in the early stages of pregnancy and cells from the placenta are analysed for abnormalities as a proxy for problems in the embryo. However, until now there has been very little understanding of what the results of this test might actually mean. Magdalena explained to Naked Scientist Connie Orbach how she has been on a mission to find answers for mothers-to-be everywhere...
Magdalena - I was not a very young mother so I decided to do a pregnancy test that you can do for the very first time when you are three months pregnant and, to our total surprise and trauma, we found out that as many as 25% in the placenta which was holding my baby Simon and me together were aneuploidy with specific genetic abnormality, this was a trisomy of the chromosome number 2. This means we have an additional copy of the chromosome number 2 which is one of our major chromosomes so many, many genes lie on that chromosome. So this was the result but, obviously, this does not mean that the baby will have the same abnormality but nevertheless, it's extremely worrying when you find out that a quarter of your placenta might be abnormal and you wonder to what extent you should worry about your baby's abnormality.
Connie - So just before we go on, I think I need to find out what happened during your pregnancy?
Magdalena - I had another test a month later. It was quite stressful but this test was normal so I was relieved and, indeed, Simon was born a few years ago normal. But I imagined that scientists not only use logic in their lives but emotions and this emotional stress and logic together made me very determined to redirect my research and find a way that we can experimentally address that situation, in the mouse of course, because it's not possible with human embryos, but whatever we find on mouse embryos is very likely to be true for human embryo development, as this stage of development it looks extremely similar. So we maked so-called chimeras. We put some normal cells together with abnormal cells and we film development in the first instance and what we found, which was absolutely incredible so it was the happiest news we had at the time, is that those abnormal cells were preferentially eliminated by programmed cells death. So it means that they really died at the part of the embryo that will make a foetus.
Connie - So watching the development of this embryo that you had created, which was part abnormal, part normal, you saw that actually, the abnormal cells were selectively dying?
Magdalena - That's right, exactly.
Georgia - Did you take these mice to birth?
Magdalena - So the next step was to identify the dream answer to the question, how many normal cells we have to have at that stage (the first few days of our life) for the embryo to be normal. So we tried to establish it by making embryos in which we have one to one ratios, so one abnormal, one normal or we had ⅔ of abnormal cells and ⅓ of normal cells. So a very small proportion of normal cells and we found that even in those cases, some of those embryos entirely corrected themselves and were born as normal mice so, even in the cases where there were just a few normal cells at this stage of their lives, they were still able to populate those cells that were abnormal and dying.
Connie - So your case of 25%, and yes this is still a mouse model, but your case of 25% was actually a really small proportion of the number of abnormalities that you could have to still survive and have a perfectly healthy baby?
Magdalena - That's right, so even if it was that it was 25% or 50% of my cells that will give rise to Simon were abnormal, they would be eliminated.
Connie - What does this mean about this test that people are doing? Should they still bother doing the test or is this an unnecessary worry for people?
Magdalena - It depends what one does this test for. So, for example, if the whole population of cells tested by CVS would show abnormalities then, obviously, that's a very worrying sign. If the test shows that there is no abnormality, then it's fantastic news because there is nothing to worry about. So, essentially, our results add to the reflection on what this test really means and how careful we have to be in interpreting the results of that test. But also, what this particular paper shows is that we try to now reveal the mechanism by which those cells are eliminated and by which normal cells take over and repair the gap which was generated. So this is an extremely intriguing and extremely important scientific problem of how the cells compete against each other and how they substitute for each other when there are some cells that die and we try to understand the process by which it happens.
Connie - In terms of your own experience and what brought you here, how does this feel that you've now kind of solved this mystery that caused such a bad time in your life?
Magdalena - Well I think it's extremely reassuring that such a traumatic event in my own life can bring some good news and, at the end of the day, help other mothers to be, and how they feel about their pregnancy even if they receive bad news as I received, a long time ago.
06:40 - Prosthetics that can feel
Prosthetics that can feel
with Dr Calogero Oddo, The University of Pisa
If you have to have your hand amputated, the current generation of prostheses can only go so far to replace what you've lost. They can restore some of the aesthetic and motor properties of the body part, but still missing is a sense of fine touch that can tell, for example, whether something is rough or smooth. And this is critical for manipulating objects correctly. But now we're a step closer to restoring this missing modality thanks to a bionic finger that uses piezoresistive sensors (sensors that respond to pressure) to detect surface textures and turn them into nerve signals that an amputee's brain can understand. Calogero Oddo is its creator, and he spoke about it to Chris Smith.....
Calogero - The natural skin has receptors internally that are the transducers (the physical interaction of our hand with external walls). They transform into a sequence of neural signals that are then conveyed to the nerves and then arrive through the nerves up to the brain and they represent the tactile information to our brains so we can percept.
Chris - What is the material that you're working with that is capable of discerning textural features or how rough a surface is? What are you making these things from?
Calogero - The system is multi-layered. So we have this rubber that covers the sensor. The sensors are made of silicon which is like glass, which has inside piezoresistors that transform mechanical information, so they turn this information into electrical signals. Then these are acquired by embedded electronics that convert this information into digital, and then there is an artificial neuron model that keeps the continuous wave forms that are required from the artificial sensors and transforms into the spikes that are those on/off events to stimulate the nerves.
Chris - How do you teach your computer programme what each surface feels like and then, how do you marry the recognition of that surface and its output of spikes into the nervous system so that it's putting them into the right pattern of spikes, which is what would happen in an intact individual, someone with a normal hand?
Calogero - This is done by a technique that is minimally invasive to record from the nerves of the intact subjects when they touch naturally the surfaces. We are learning how the natural code is arranged in correspondence to a particular experiences and then we try to emulate.
Chris - So, in essence, what you do is you're recording what sort of patterns of nerve activity a person gets when they run their natural skin over the same surface and then when your new detectors experience that same surface contour, you just generate the same nerve output of spikes and that's what you're going to put into the nervous system?
Calogero - Yes, this is exactly what we are doing. The nice thing is that our finger is not specialised to the surfaces that we test in this experiment but, in principle, if we test other surfaces it is able to generalise. So it is able to reconvert the other surface into different senses of the spikes that the brain can interpret and recognise.
Chris - How do you get the signals from your bionic finger back into the nervous system of the amputee in the first place?
Calogero - There was an implanted interface that allowed the stimulus to be delivered to the nerve. What we do is insert into the nerves electrodes (like wires) to electrically connect the nerve.
Chris - If you actually do the experiment and you take the output from your system and you apply it to the nervous system of an individual, does it really feel to a normal human that that surface is the one that they should be feeling?
Calogero - This was declared by Dennis, one of the amputee subjects that tested the technology. He said exactly this "not 100% but it makes sense to his brain". Meaning that he was able to interpret the stimulus and to imagine the stimulus in pictures.
11:31 - The great fly gender divide
The great fly gender divide
with Dr Jenny Regan, University College London
On average, if you're male, your life expectancy is likely to be shorter than if you're female, and some diseases seem to affect one sex more commonly than the other. So can the humble fly tell us why? Jenny Regan explained to Chris Smith why she thinks it can...
Jenny - In researching aging, something that really sticks out is that females live longer than males. In addition to this, when we did some manipulations that could extend lifespan, there are some manipulations that extend female lifespan very well but don't do anything for males. Specifically, the one that we were interested in is putting animals on a diet. This can really extend the lifespan of females but males derive much less benefit from being on a diet than females do.
Chris - So how did you pursue that?
Jenny - We used the fruit fly (drosophila). What we actually started out doing was switching sex in various tissues. To do this we took advantage of something that is particular to drosophila biology, which is that each cell individually specifies it's own sex. So we could harness this particular feature to switch sex just in specific cell types or specific tissues around the fly and we wanted to see if having a female organ in a male fly would be able to let the males get this lifespan extension that the females get in response to diet.
Chris - So what organ did you do this sex switching on?
Jenny - We looked at the liver analogue, we looked in blood, we looked in brain, and finally we looked at the gut and when we feminised the male gut and put these flies on a diet, what we saw was that the males then responded to being on a diet and their lifespan was extended.
Chris - If one studies the natural history of ageing in these flies (males versus females) and you look specifically at the gut, are there clear differences in what happens in the males and what happens in females as they age in that organ?
Jenny - Yes there is, and this is something that we did in parallel. We started to look at the guts of ageing males and ageing females and when we started out we expected that we might see males had worse guts than females because males are shorter lived than females but, actually, what we found was that male guts are really well preserved as they age and this is in real contrast to females. And when we looked at females over ageing, we saw a real spectacular decline. So we saw wounds appearing in the gut and we saw small tumours appearing in the gut as well.
Chris - Can you explain why, therefore, on the basis of your observations you see this difference between how long males live and how long females live and why calorie restriction makes a difference?
Jenny - When we looked at female guts, females who had been on a diet actually had better guts than females who had been fed a full compliment of food, and so those restricted diet females had fewer small tumours and few wounds in their guts so it looked like they were really better off from being on a diet. So, we started to understand that perhaps this difference that people observed for the last few decades, might be explained by the fact that the guts respond very differently, i.e. the males don't really get much of a benefit from being on a diet, whereas the females do.
Chris - What is it about the female biology that means that their gut benefits in this way that the males don't?
Jenny - Well the females, they're really egg machines, especially towards the earlier part of their lifespan they're laying hundreds of eggs a day, so it's really important for them to be able to get as much nutrition from food as possible. And some related studies recently have shown that females can grow their guts spectacularly when they're required to do so by the demands of egg production so it seems that females have more of a reason to have active stem cells in their gut. It also is true that females, when their guts are challenged by an infection, their guts responds much more than males in the sense that they repair their gut faster or they switch on stem cells to actively divide more than males do and we think this is probably the root of the difference we see in the male.
Chris - It's not that their gut lets them down, it's something else that's making them age and die prematurely compared with the females, and if you sorted out the guts in the females, they would live even longer?
Jenny - Yes, absolutely. For females, the gut and the deterioration of the gut is really important, but for the males it looks like something else is important and we think that this could be they don't respond as well to microbial challenge. So this could be something which is more of an issue for males than it is for females.
16:20 - Myth: Giant pandas have no sex drive
Myth: Giant pandas have no sex drive
with Dr Kat Arney, The Naked Scientists
It's mythconception time, and as spring - and maybe love - is in the air, Kat Arney has been finding out if giant pandas just don't fancy it.
Kat - Easter, or rather springtime, has been associated with fertility in human culture for many thousands of years. It's not for nothing that we have Easter bunnies and eggs, and the arrival of longer, warmer days is guaranteed to get the sap rising. But while bunnies are often said to have no problems in the reproductive department, giant pandas are allegedly terrible at romance - which apparently explains their poor track record at producing baby pandas.
But a new study from US-based conservation researchers working at the Chengdu Giant Panda Breeding centre in China suggests that this might not be true: pandas do enjoy getting frisky, but only if they actually fancy the other panda in the partnership.
Thanks to poaching and destruction of their natural habitat, giant pandas are an endangered species, with just a couple of thousand left in the wild. The only hope to save the pandas is to breed them in captivity, but although the Chinese breeding centre does manage to churn out super-cute baby pandas on a fairly regular basis, this hasn't been quite the roaring success that researchers might have hoped. And panda pairs in zoos seem to be extremely reluctant to get down to it - as witnessed by the rollercoaster of excitement and disappointment around Tian Tian, Edinburgh zoo's female panda and her possible pregnancies.
When breeding giant pandas in captivity, conservationists tend to try and pair up animals with the lowest levels of genetic similarity or relatedness, to try and avoid inbreeding. But researcher Meghan Martin-Wintle noticed that if a female panda at the Chengdu centre was given the choice of two males, one of which with 'good' different genes and one with more similar genes, she tended to ignore the genetically ideal male and lavish her affections on the other one.
And if she was encouraged to breed with the genetically preferable male, they either didn't manage to get it on, or she didn't manage to get pregnant. But if she was allowed to get up close and personal with the panda she fancied the most, the female was twice as likely to give birth to a cub. And if the attraction was mutual, there was an impressive 80 per cent chance that love would be in the air, with an equally high success rate in producing cubs.
There are other factors at play here too, including whether the pandas had been hand-reared by humans, along with their age and size - it turns out that being a larger, older male gives you a better chance of becoming a panda dad.
So it seems that the pandas and their sex lives have been unfairly maligned by the media. It turns out that they're just like the rest of us: if you want to get frisky, it helps if you fancy the other party - or panda.
19:16 - DNA origami!
with Kerstin Goepfrich, The University of Cambridge
Origami, the ancient art of paper folding, is popular all over the world as a way of relaxing or expressing creativity. But a new type of origami which is making waves in science celebrates its 10th anniversary this year - Georgia Mills has the story...
Georgia - Scientists in Cambridge are currently using origami to make structures which could change the face of drug delivery. There's just one twist - it's not paper they're using...
Kerstin - We are assembling DNA into arbitrary two and three dimensional shapes on the nanoscale. So we are literally building with the building blocks of nature, so to speak.
Georgia - That's Kerstin Goepfrich who's working on this technique at the Cavendish Lab in Cambridge and she kindly agreed to show me around. But first, I wanted to know why anyone would want to use DNA to build with...
Kerstin - What makes DNA a good building structure is, first of all, it's availability. It's safe to use, you get it everywhere; it's very cheap and it's very easy to process; it's quite stable and we can programme it's assembly and that's, of course, the big plus. You can programme assembly with near atomic precision. So how do you fold a piece of DNA?
Let me take out a piece of velcro tape actually, because I really like to use that for illustration. So imagine, you had a long piece of velcro tape which is basically a long single strand of DNA - it's very floppy. But now, imagine you had a short piece of DNA (a short piece of velcro tape) which matches the long one at one side and say at a distant end. By doing that, you can pull the long piece together and now you've got something like a loop just made from velcro tape. Now with many short pieces of velcro tape you could, essentially, fold the long piece up into any shape and here this is a bit, broken, but you will see you can make a flower or a clove by attaching a few pieces of velcro tape together and this is exactly how DNA origami works. You take a long single strand of DNA and fold it up using short pieces, which we call staples.
Georgia - The four letters that form DNA (A, T, G and C), they like to stick to one another. G always stick to C and A always sticks to T, and these are known as the base pairs. So if you use this knowledge, you can design sections of the DNA strand that will always like to stick to one another and this would make the DNA automatically fold up on itself which can be used to build any structure you like. So, if I wanted to fold some DNA into the origami classic shape of a crane, how would I go about it?
Kerstin - Today you just go online, you download a programme which is actually available for free and this programme is just a 3D drawing software so you literally draw the shape you want. So, you can literally draw a single strand of DNA and then it appears in the 3D view...
Georgia - Once Kirsten has drawn the right shape, she sends off the specifications to a company who then synthesise the DNA with the right pattern of base pairs needed. They then send it back to her in a small white box which can then be processed in the lab...
Kirsten - This is the DNA room and, as you can see, it's not very exciting. There are lots of fridges and freezers, which we use to store the DNA, and I will go to one of those now and I'll show you the little box in which the DNA comes...
Let me see... here. And in every single one of the wells here we've got one DNA sequence and now we can take a pipette and we would use this pipette to mix all the difference sequences together, essentially...
Georgia - This is like no pipette I've ever seen.
Kirsten - Oh, this has 12 tips so that you don't have to do them one by one, we just get 12 at the same time.
Georgia - You're so busy here you need 12 in 1 pipettes?
Kirsten - Yes. We don't have a pipetting robot yet! So, once we've mixed all the bits and pieces of DNA together, we put them in a small tube like this one here and then we put them into this machine, which looks fancy, but all it is an oven. It's called a 'thermocycler' but it just heats the DNA up, cools it down slowly and then as it cools down it forms the predesigned shape.
Georgia - Why does heating it up and cooling it down help the individual strands form into whatever shape you've made?
Kirsten - You just give it a bit of energy so that when the DNA is already coiled up a bit it can straighten out and by cooling it down, you allow the DNA double helices to form.
Georgia - After seeing the lab I was satisfied I knew roughly how to make a DNA crane. What I wasn't clear on was why anyone would want to do this...
Kirsten - This is a great example of how something which might seem like art and a scientist playing around can be transformed into something real and into something which does have applications in the real world. So, it is simply a way of assembling atoms with near atomic precision and, in my lab, we're using DNA origami to make small channels or pipes which can punch holes into membranes and into the envelope which surrounds the cell, and we are doing that because 50% of the drugs that we currently use target channels in cells. So just imagine what you could do if you could could create artificial channels exactly the way you want them.
Georgia - So it will be a way of drug delivery?
Kirsten - It could be a way of drug delivery. It could be a way of simply understanding the process which is really fundamental in biology, namely the way cells communicate.
Georgia - As well as potential medical applications, the technique has also be used to build tiny basic computers and also nanoscale rulers. And, while paper origami is hundreds of years old, DNA origami celebrates it's tenth birthday this year. So new possibilities for applications are still being dreamt up and, as far as Kirsten is concerned, the sky's the limit.
Kirsten - I think one day origami might even save a life which is what paper origami artist Robert Lange once said. One day I hope the same may be true for DNA origami in a way.
Music from Jukedeck - create your own at
25:54 - How to make a memory
How to make a memory
with Dr Dean Burnett, The University of Cardiff
What is actually happening in the brain when we make a new memory? Dr Dean Burnett is a neuroscientist from the University of Cardiff and he's here to give Kat Arney the lowdown. He started by explaining how memories first form...
Dean - Let's say someone's just written down their phone number or your number phone for you on a piece of paper and it's an Inspector Gadget situation and it's going to self-destruct in ten seconds so you've got to try and remember it from recall only. So, the number itself when you first experience it will enter your short term memory, which is like part of your brain which is actively processing information at any one time. People have a misconception that short term memory is like a few minutes, few hours. No, it's actually 30 seconds to a minute, maximum. It's very short - anything more than that is technically a long term memory. It's supported by activity in the frontal cortex, the frontal lobes...
Kat - That's the front bit of your brain, right? The bit at the front of the head?
Dean - Yes. The bit at the front straight on - it looks like a pair of Ds back to back. It's very active, it's very ongoing, it's processing information all the time. It's not for storage so I liken it to writing your name in a sparkler - the information's there briefly but then things happen it fades. Information is coming in all the time so the space is needed for other things so you've got maybe a minute to get it into the long term memory.
Kat - Kind of like taking a photo of that word written with the sparkler. You have to find some way of capturing it and keeping it for longer. What happens next then?
Dean - Exactly. The phone number, if that's what we're talking about, enters your short term memory and it's like a chunk of information - chunking is what it's called. We can remember up to four chunks at any one time in our short term memory. Now we need to attach a significance to that and make it salient enough that it becomes important enough to be laid down in the long term memory by the hippocampus. So the information feeds through into the hippocampus which is sort of the central hub of the memory system.
Kat - Just give us a quick description of the hippocampus. If I picture my brain, my head, where's the hippocampus and what does that do?
Dean - Where is it? It's in the temporal lobe which, if you think of the brain as a boxing glove, it's the thumb. So it's like the inside of the thumb toward the centre near the...
Kat - Right in the middle...
Dean - It's an older area and it's right next to the olfactory area too which is one theory as to why smell is such evocative of memory.
Kat - Ah, yes..
Dean - And it's shaped a bit like a seahorse in cross section. Hence the name hippocampus - it's not about a holiday camp for large mammals. It is like the processing centre of all long term memory. Sensory information is fed into it and the hippocampus takes this and binds all the important stuff and forms new memories by connecting neurocells together in a certain way to form synaptic connections, and each of these is what represents a memory.
Kat - So memory is basically nerve cells (nerve connections), that are just knitted together as the hippocampus decides 'okay we need to remember this, this is a phone number we need to remember', and it will knit together neighbouring nerve cells and that's your memory?
Dean - That's generally the accepted wisdom at the moment in that there's a certain combination of connections forms a memory, in the way that certain patterns in ink on paper form a word. So that's what we think memories are at the moment, and these are being constantly made by the hippocampus all the time because, obviously, we are constantly experiencing things.
Kat - So say we've got as far as my phone number, it's gone into my hippocampus. How then does it become something I can remember? I can still remember my parent's phone number from the house I grew up in. Is that 'it's just still there' or is that then stored in a different way, those very, very long term memories?
Dean - There still there essentially. The very first one, you could argue, is still there but every time it's retrieved or reactivated they might be forming a new memory for the incident itself where that memory is retrieved.
Kat - It's kind of writing on top again? It's kind of colouring it in a bit firmer?
Dean - Yes, or forming new connections with it. Every time you use that number you are experiencing it in a different way. So you're telling someone you want to call you - someone you've taken a fancy too - and you say well my number is this. Then that memory is going to be a lot more vivid so it's connected to that as well. So it's constantly being shored up and reinforced all the time if it's a common memory.
Kat - Could my brain get full? Say, there's lots of people I fancy and I collect all their phone numbers, is my brain going to get full of them?
Dean - Logically, eventually it would but, as far as we know, no-one's lived long enough yet for that to happen. It's actually got a fantastic storage capacity the human brain has. We don't know what it is yet but it's way beyond our current scope to really calculate it so... Yes it could, but don't worry about it is the general jist.
Kat - And then, that's all the information that's in there. So when I want to retrieve a memory - what's happening? Are those nerve cells just firing in the pattern that it originally went in?
Dean - Sort of, yes, unless it's been modified since. That's another thing about human memory, if you remember things in a different context it can constantly tweak your memories and adjust them and that's arguably a failing of biological memory, it's not essentially rigid. So when you're in a certain situation where you need to retrieve some memory like in your frontal cortex is doing all the conscious thinking again. It will think 'what happened there then', and then the patterns of connections is triggered and the link between what you think about now and the memory you need is activated and the more connections there are to that memory, then the more likely and the more able you are to retrieve it.
Kat - And very, very briefly. We've talked about remembering things like phone numbers or you can imagine a fact for an exam, is there a fundamental difference between remembering those kind of things and then, for example, I can remember the birth of my friends child?
Dean - Yes. It's believed the brain does categorise these in certain different ways or at least we think of them in different ways. One of them is semantic memory - that's memory for just information. So knowing pythagoras' theorem, knowing your niece's birthday - that is semantic information. It's just information you have access to, whereas the memory for learning pythagoras' theorem or memory of the birth itself, that would be an episodic memory, which is memories of actual events from your life themselves in which the information is contained, and that's constantly ongoing.
32:46 - Why not sleep on it?
Why not sleep on it?
with Dr Matt Jones, The University of Bristol
How we form memories is a complicated system as many different things can disturb the process, from drug use to emotional state. But there's one thing that we now know is critically important for memory, and that is sleep. Connie Orbach went to meet Dr Matt Jones in Bristol to find out more...
Connie - It sounds quite other worldly doesn't it? Well actually, this is the sound of our brain's orchestra. It's the patterns of activity of different parts of our brains as we sleep, whirring away, organising, filing, sorting our memories and it was recorded by Dr Matt Jones' team at the University of Bristol...
Matt - Well, it's funny stuff sleep because we tend to equate it, of course, with rest but, in fact, parts of the brain are more active during sleep than they are during wakefulness. In particular, a part of the brain called the hippocampus, which is a central hub for integrating learning and memory, becomes very active during certain phases of sleep. As you probably know, human sleep is subdivided into non-REM (non-rapid eye movement) sleep, sometimes called slow wave sleep and REM (rapid eye movement) sleep, and these different phases are associated with different types (patterns) of hippocampal activity. Now the hippocampus is activated during wakefulness, so neurons in the hippocampus, for example, code information about new places that we visit and is then reactivated during subsequent sleep when those neurons that encoded new memories come to life again. So you replay your waking experience whilst you're offline during sleep and it's this process which is thought to support the strengthening of memories, the sourcing of memories: kind of sorting the wheat from the chaff - which things we need to remember, which things are less important and can, therefore, afford to forget.
Connie - Wow. So parts of the hippocampus are being activated specifically by location as we're moving around and then, as we sleep, we're literally replaying that in exactly the same order of brain cell activation, as it was in the day?
Matt - That's right. We're replaying those patterns of activity that encoded new memories during the day but we're doing it at a different time scale. So, in fact, the patterns of activity that are replayed during sleep are replayed on a compressed time scale (about 10 times faster than they were during wakefulness), and that short time scale activity is thought to be important for driving changes in the strength of connections between brain cells that cooperatively encode these memories. Now we know it's important for memory function because, if you disrupt that replay activity, then you slow formation of memories.
Connie - So is that all that's happening at this level of hippocampus play cells or is there more than that?
Matt - So, no neuron and not brain structure is an island and the hippocampus has to share all this information it's laying down memory with other parts of the brain. For example, certain parts of our environment might be particularly rewarding. So, if you wander down a new corridor and stumble upon a big pile of chocolates and think woohoo!, then dopamine signalling in the midbrain, for example, is activated and that dopamine signaling is also replayed during subsequent sleep in a way that coordinates with the hippocampus. That might, for example, enable the brain selectively strengthen particularly important memories about chocolate. Similarly, we know that over time as memories mature, then they're integrated into other parts of the brain beyond the hippocampus into the neocortex, for example. So the neocortex is important for storing memories long term and that integration of memories across the hippocampal system and the neocortical system is supported by coordinated activity during sleep. We suspect that the way the brain deals with this is to brain waves or neural oscillations as a kind of clocking mechanism to coordinate activity. The brainwaves are acting almost like the conductor of an orchestra so the hippocampus, when we're asleep, doesn't necessarily know when to do its stuff and the neocortex is being told when to do its stuff by external stimuli. So instead, we have this internal conductor mechanism (these slow waves), which modulate the time of the hippocampal activity and the timing of the cortical activity and, therefore, bring the two into line allowing the hippocampus to tune in to the neocortex and vise versa.
Connie - In the day, we're processing information and our brain cells in the hippocampus are firing, dependent on specific things that are happening. At night, we're then recoding that at a quicker pace to give us a strong memory and that's happening whilst we're asleep. But on top of all of that are our hippocampus needs to go talking to other parts of the brain to link all of these bits of information and, in order for it to know when to do that, we've got these huge ripples of brainwave activity which are giving it a second by second, like a conductor coordination, telling it where to go.
Matt - That's exactly right... yes.
Connie - Wow! That sounds incredibly complicated but amazing. It sounds really awe inspiring, I think, is probably where I want to go with that.
Awe inspiring indeed. I just can't get over the complicated patterns of activity that are happening through our brains all the time. It's so much more than I can even... take in. Maybe I should be giving sleep a bit more credit.
38:39 - Sleep, memory and schizophrenia
Sleep, memory and schizophrenia
with Dr Ullrich Bartsch, The University of Bristol
We've heard how sleep plays a pivotal role in making our memories strong and resilient but, well it is a little complicated! And if something's that complicated then there are many ways for it to go wrong. Many people don't realise but one of the most debilitating symptoms of schizophrenia is actually the mental impairments particularly memory loss, so has this got something to do with sleep? Connie Orbach met Dr Ullrich Bartsch at Bristol Univeristy's sleep lab to find out...
Ullrich - We've got an MRI scanner over there and the facility for experimental rooms and meeting rooms.
Connie - A sleep lab is exactly what you might imagine. It's a bit like a hospital - there's a bed, a bathroom and well... then there's all types of kit to monitor you muscle tone, your brainwaves, eye movement and infrared cameras to watch you while you sleep. So maybe a bit more creepy than a hospital. And next door to this room is where Ullrich Bartsch and his colleagues will sit for hours on end, night after night, measuring their patients quality of sleep by the different patterns of brainwaves detected.
When we sleep, we cycle through different stages. First very deep, slow wave sleep... Next we move into lighter sleep, characterised by bursts of spikes called sleep spindles and finally... REM sleep - smaller faster waves. Okay, but I know what you're thinking... What on earth's all this got to do with memory and schizophrenia?
Ullrich - Sleep has been shown in the past 10 or 20 years to be important for memory consolidation and one of the biggest problems in mental health, particularly in schizophrenia, is the treatment of cognitive deficits. And one intriguing fact that has long been anecdotally reported is that schizophrenia patients will initially start losing their regular sleep pattern before their psychosis kicks in. That is mainly the loss of one particular oscillation that occurs during sleep and these are these spindle oscillations that I've mentioned earlier.
Connie - Schizophrenics show less of one particular type of sleep wave - the spindle. And as Matt said, patterns of brain wave are important for memory but how do we show that's really what's behind their forgetfulness. Well, that brings us back to the sleep lab... Ullrich takes healthy people and pre-symptom schizophrenics and gives them a simple movement task. Thinking I had an opportunity for a fun test, I decided to give it a go myself. I had to type out a five digit sequence as fast as possible over and over again... 14132, 14132, 14132, 14132, 14132... You get it. I did this twelve times with a break between each trial. Over the twelve tests people improved but the real kicker is that after a nights rest when they do the task again, they have improved a lot more.
Ulrich - In the motor task, I think you can reach up to 30-40% improvement.
Connie - But what about schizophrenics? Well interesting, when they sleep, they don't improve at all.
Ulrich - So the spindles, that I've mentioned earlier are, in fact, correlated with the amount of improvement that you show the next morning after you've slept over learning a motor task.
Connie - So the more spindles you have the better your improvement - is that right?
Ullrich - Yes, that's correct.
Connie - If I remember correctly, you were saying that in schizophrenia that schizophrenics have less of these spindles during sleep and so what does that mean when you get schizophrenics to do this task?
Ullrich - So they, first of all, perform much worse on the motor sequencing task. So their initial learning is already lower, so they would have difficulties with motor coordination but also, if they would sleep for a night and wake up the next morning and be tested again, they would not have improved in that particular task.
Connie - Not have improved at all?
Ullrich - They wouldn't have improved at all. Of course, there are some participants who do better than others but on average, if you take a relatively large group of schizophrenic patients, they would show little or no improvement. The idea is that because they have less spindles, they cannot process the information that they've taken up during a day as well as during sleep and they can, therefore, not strengthen these memories during sleep and then cannot show improvement in the task the next morning.
Connie - Now we know that what can we do? Can we just get them to sleep more? Instead of eight hours of sleep at night, why don't we get them to do ten hours sleep a night?
Ullrich - Unfortunately, it's not that easy because you need the right type of sleep. So, as we said, there are different stages and stages and sleep spindles are particularly characteristic of that particular sleep stage. In the case of schizophrenics, there are other things that we could do, so we could make the sleep more continuous. Most schizophrenics will have fragmented sleep but also we could try and bring back some of the missing oscillation, if you will, so there might be a way of using pharmacology. The right pharmacology (the right sleeping pills) to bring back the right oscillations during sleep. Another promising concept for enhancing oscillations during sleep is actually electrical stimulation or magnetic stimulation. A recent technology has emerged where people can use magnetic pulses, which is called transcranial magnetic stimulation, to actually induce activity patterns of brainwaves in brains of healthy people but also it's beginning to be used in clinical populations.
Connie - Clearly sleep and memory are intrinsically combined, impossible to separate but what about the rest of us. I asked our sleep expert for a few tips.
Ullrich - If you have to take in a lot of information and you have to remember it the next day, it's probably good to have either have individual naps in between in the afternoon, so that will definitely help your brain to pack the influx of information nicely.
Connie - Individual naps between study; Who knew that students had it right all along!
Ullrich - Yes, they were doing the right thing and especially the young brains need even more sleep than the older brains.
Connie - I'll tell my boss and start petitioning to get beds put in at work.
Ullrich - Yes, well if only. I would be happy to sign a letter if you need some support.
45:13 - Can you train your brain?
Can you train your brain?
with Dr Adam Hampshire, Imperial College London
Unless you have been under a rock for the past few years you may have notice an increasing obsession with Apps that promise to "train your brain" with a series of different task. These Apps usually come with a price tag but are they worth shelling out for? Dr Adam Hampshire from Imperial College London joined Georgia Mills to explain what these apps aim to do...
Adam - Researchers have been working on a variety of approaches to cognitive training that are being applied in these sorts of apps. Now one of the most popular areas of research focuses on trying to increase what psychologists refer to as working memory capacity. This is essentially how much information a person can actively hold and process in mind. So the idea there is that through exercises capacity could be increase, rather like if you slop more RAM into your computer. Now there are simple and complex variants on this theme, for example, one might be asked to hold sequences of numbers, images, or spatial locations in mind across some delay. So, I make say to you, for example, repeat the sequence 1893574. In more complex working memory training, there may be distracting stimuli or multiple different tasks that a person has to try and perform at the same time. Now, as you practice and get good at the task, you get better at it and the difficulty level is increased. So the idea is it's a little bit like going to the gym and upping the level.
Georgia - I've had a go at a couple of these games myself and they're quite fun but is there any evidence that they actually do anything?
Adam - Well, that's actually a very controversial question. So a major problem is that there are many poorly validated products out there on the market. Now the aim with that type of training is exercise and improve core working memory capacity but, of course, anyone can practice and get good at a specific task - that's just learning. If it's going to be useful, the training really needs to lead general improvements that extend beyond the training task itself and for the most part, the products that are out there and are available haven't really been validated properly in that latter respect. I've got a bit of a unique perspective on this question actually, because I've been involved in research that show positive and null findings.
For example, a few years back I was involved in one study in which we tried to cognitively train around about 11,000 individuals using the type of training that was being made commercially available and we found participants got good at the train task but they showed no generalised improvements whatsoever. However, subsequently, when we we tracked and trained older adults using the same tests, we found that there were generalised improvements and this data was published just last year. So to my mind, that study's actually some of the best evidence to date that cognitive training can sometimes have generalised benefits. A sort of take home message there really is that certain forms of cognitive training may help certain populations but that said, training in young healthy adults, it might just not work. But, on the other hand, it may perhaps be possible to try and slow memory decline in older adults. That area is really very active in research at the moment.
Georgia - So to sum up, these games for someone like me, I might do a sudoku every single day - I'm going to get super, super good at sudoku but my memory and my maths and things like that - I'm not going to see an improvement, but you have found this kind of improvement in some select proportions of the population. So, should be spending my time just playing a fun computer game instead?
Adam - Well that's actually quite an interesting question in itself. So I've run a number of studies where I've just screened large scale cohorts from the general population and, funnily enough, I found that individuals who say they do brain training, presumably with commercial packages, show no advantage whatsoever. Individuals who say they play normal computer games tend to be a little bit better in terms of their working memory and reasoning ability. So, of course, that's just a large scale cross section cohort study. We can't infer cause and effect relationships from that type of data but it's quite interesting. It all goes against the zeitgeist that brain training is good and other computer games are perhaps somehow bad. I think it's a promising area of research at any rate.
50:07 - Can two planets share the same orbit?
Can two planets share the same orbit?
Graihagh Jackson put this question to Dr Stuart Higgins from the University of Cambridge...
Stuart - In theory... yes.
Graihagh - Well, now that we've got that straight. Only joking. Astronomers actually have a special name for these things.
Stuart - Astronomers call such systems where two objects are orbiting around each other with a common centre between them - binary systems. You might have recently about a binary system of two black holes whose fingerprint was discovered in gravitational waves, measured by the LIGO experiment. In that case, the two black holes were spiralling into each other, merging but could it be possible for a less destructive scenario to occur with two planets.
Well, first of all it's actually worth noting that when the Moon orbits the Earth, it's not just the Moon moving. The mass of the Moon has enough gravitational pull to also influence the motion of the Earth. However, if you imagine drawing a line between the centre of the Moon and the centre of the Earth, the point on that line about which the Moon and Earth are rotating is located deep inside the Earth, very close to the centre in fact. So, while the Moon does cause the Earth to wobble about a bit, because the Earth is so much bigger than the Moon, it's essentially as though the Moon is just moving around the Earth.
Whereas, when we think of a binary system, say between two more equally matched objects. If you were to draw an imaginary line between these, the point on that line about which they were rotating wouldn't be inside either of the objects, they're both rotating round a point of empty space. And a classic example of this is Pluto and its moon, Charon. Because they have roughly similar masses (Charon is about 12% the mass of Pluto), the impact it has on Pluto's orbit is much greater than say the Moon's orbit on the Earth. This means that Pluto and Sharon slowly rotate around a point in space. It looks a bit like an adult swinging a child around in the playground. The adult's feet remain at the centre of the rotation but, as they lean back, their head is also rotating around their feet as is the child.
Graihagh - Okay. Spinning children till their sick is one thing but I wanted to know is have we ever actually seen the rocky equivalent out there in the universe?
Stuart - Well, in 2012, astrophysicists using the KEPLER space telescope observed something even more complicated than that. A pair of planets orbit round a pair a stars. Imagine two suns orbiting orbiting closely around each other and then two planets at different distances orbiting around those rotating suns. If you were standing on the surface of one of those planets and looked up at the sky, you would see two suns like the famous fictional planet of Dantooine from Star Wars.
Graihagh - Science fiction turns to science fact. Great, I love it when that happens but that's only one example. Is there any other evidence that hint at these binary planets. Well according to Stuart, we should be thanking our lucky stars...
Stuart - In 2014, scientists from the California Institute of Technology developed a computer simulation that binary systems of two earth-like planets are also possible.
Graihagh - There you have it Jonathan. In theory yes but we're yet to find too many examples. So, watch this space. A big thank you to Stuart Higgins who helped us out with this one. Next time on question of the week we're hot on the trail of Lebohang's predicament.