 Can I say what a pleasure and honour it is to give this lecture. Steven Padgett founded the Research Defence Society. A courageous person who has been an inspiration to the many scientists and others who have at times suffered as a result of the criticism of animal research but who on balance have made a'r ysgolwydd yn gwybod i'r ffordd i'r ffordd i'r ffysiolig a'r meddwl. Mae'n ddweud o'r ffordd i'r llwyddoedd o'r llwyddoedd y llwyddoedd yng Nghymru, y ffordd i'r llwyddoedd yn 1926, byddwch chi'n Huxley. Rwy'n gweithio'r ysgolwyddiad. Rwy'n gweithio'r ysgolwyddiad, rwy'n gweithio'r ysgolwyddiad, ond mae'n gweithio'r ystafell yma, ond mae'r mynd i'r hyn o'r ffordd i gaelio'r llwyddoedd. Mae o'r byth yma yn cael bod rhai ymrhusiwn, ac mae'n cwysig o'r ffordd i gyflogio'r hyn o'r gwו a m mientras i'r ffordd i'r ffordd i gaelio'r llwyddoedd. Rwy'n gweithio'r llwyddoedd, rwy'n gweithio'r ffordd, rwy'n gweithio'r olfodol o'r cynandmwm. gyda'r cyfasitio twfynol. Rwy'n meddwl y rhaid i gael gweithredu a'r gweithredu, ma' rhaid i gael gweithredu a'r gweithredu i'r gwneud gweithredu ymddangos chi'n gweithredu ac i'n credu ddim yn ei ddau 4 gyfieithredu yw ddau cyfieithredu y ddweud bod wedi cyfieithredu i'r gweithredu, y ddweud yn ei ddweud yn ei ddweud, yn ei ddweud yn ei ddweud, ond rhaid i'r ddweud eu ddweud confuse four little stories. This is a view of the human brain, this is a photograph of the human brain, some of you will recognize it, it's from Wilder Penn Fields classic studies during preliminary examination before surgery for epilepsy, trying to determine whether removal of the epileptic focus would cause catastrophic effects, particularly for language, and he did it by stimulating the surface of the cortex unrhyw bwysigno'r sŵr eich ffocos cynnym. A oes fel oedd i'chghwil am ddau yn dod o gyfrifatau ac yn byw bwysigio'n gweithio o'r rhannu aelodau i'w gwazio'n cyfrifatau aelodau. Rwy'n credu llawer bod ar�fodd yr oedau'r gyfrifatau yn ddiwedydd mewn ffysigologicaid, ond oedd ddiwedydd, rwy'n cael bod arlayn i'w cwrwm hanes Sounds like it doesn't come with little numbers on it. Wouldn't it be nice if it did because a large part of our task is trying to find out what is done well in the human brain but actually much more interestingly, how it's done. Before I plunge off into nice stories about science let's set it in the context of the clinical need to understand better the nature of the brain and the disorders associated with it. siamhau gwahanol o'r myfyrdd o'r myfyrdd hynad, o'r myfan sydd ymgyrchol. Ymgyrchol panffinol yn teimlo, o ffyrdd ffyrdd yn hyn de deadline. Y ffyrdd yn enw sydd eich myfyrdd yn yr Yn Ysbydd yn 11 oes y na 800 rôl y dylu. Felly, mae'r myfyrdd yn greu, rhai ddechrau sydd y bydd yn credu, a phrydau sydd o'r myfyrdd yn grannu iawn. Yn'r bydd yn leirio, a rydw i'n�ud o'r ddyn nhw'n ddyn nhw, ynghylch yn y Uddi, ac yn ychydig, ychydig yw'r panfennigau, yn 2030. Mae'n meddwl, yn ystod, yn oed yn cael ei gydag i'r byw pethau ond yn gymryd dechrau neu neurologiol ar gyfer y dyfodol, rwy'n meddwl i'r cymryd hyn yn ymddydd. Rwy'n meddwl, rydych chi'n meddwl, ychydig yng ngryf, roedd y tueddau yn y maen nhw yn ymddangos a'n ei gynnal i'r prysgol yn y cyfryd yw. ac yn fawr, mae gen i'n mynd i'r prosesoedd etoedd yn gyffredinol gan eu cyfnodol yn cyfrifio neu psychodlol. Yn gyfnodol, mae'r pethau yn bach i'r ddod. Felly mae'r llun o'r f无 bwysig sydd yn cyfnodol o ran eich bod yn bwysig i'r bwysig i'r ffathogl, i'r bwysig i'r bwysig i'r bwysig i'r bwysig, a ddiwedd fel gyda ni'n wneud bod o'i eu cychwyn i fod yn adegwyr mor cyfwyrdd a'n ein hyg. Rwy'n meddwl yn ychydig y peth o'r problem, rydych chi'n gofio eich hus i'r hyn o'r cyfarches gallu gwahanol. Mae'r unrhyw o fennodau erbyn i'w cyfrifol o'r â'r perthynau ar y galoxi. Rydych chi'n gwybod bod y peth oes yn rhai 10,000 o gwaith o'ch gwaith ar hyn o'r nu'r hyngeithi. ddyn nhw'n gwneud hynny o'r credu ffordd, ac mae'r gwneud hynny ddim yn mynd i'r gwneud hynny o'r gwneud hynny o'r gwneud o'r 1000 miliwn. Mae'r gwneud hynny o'r credu ffordd. Yn ffwrdd, sy'n ddod 10 a 14, sy'n ddod 10 a 15, sy'n ddod, mae'r cyst-di-dwylo yn gweithio o 5 o 9 o'r cyfnod, mae'n ddod yn gweithio i gwylltio o'r cyfrifio ardal yn ddod, We are creating about a million neurons every second. One of the most interesting discoveries of my lifetime in science is that that creation of new connections isn't all happening very early on, as was thought when I was a medical student 50ным y Esperbys. It continues through life. One of the most interesting challenges is to understand how that property of adaptation, of change, of reorganisation, of plasticity plays in both to normal function and in some cases waste to the development of disease. The four topics I'm going to talk about very briefly each are these development of the cerebral cortex the mass folded mantle that seems to be primarily involved in doing the cognitive things the high level things of perception and the consciousness and decision making and the control of high level control and decision making of movement and so on. Language. Huntington's disease is one example of neurodegenerative ac yn ymdeithasol yw unrhyw pleidau genedlaeth genedlaeth. Ychydig, y Cymru sydd wedi ddweud y cerddau allanol o'r gwirio gyda'n mynd i'r gwirio yma, o wneud o'r berdyn nhw'n bwysig o'r blom. Ie, wrth gŵl, mae'r Cymru yn ei gweld yn yma yn ymdill. Well, the cerebral cortex in human beings is vast, but it has grown as it were through evolution gradually. There's been a progressive process and the general organisation and layer to the cerebral hemispheres, the layers of the grey matter of the cortex are very similar in human beings and other mammalian species. This is a picture of a human brain and you'll know that it's divided into lobes of paratal lobe, the occipital lobe, temporal lobe and frontal lobe. The general layout of those areas is similar in all mammals. Moreover, the disposition and function of major areas responsible for sensory processing and control of movement are very similar in their arrangement in mammals. The pre-central gyrus is responsible for the control of movement, connecting directly to motor neurons in the spinal cord. The body is laid out, as you know, from the feet here to the hands and the face, lower down in the gyrus. Running parallel with that is a region in the pre-central gyrus which receives input from the body, from the tissues of the body, from the skin and the deep tissues of the body, laid out in the same topographic arrangement and, to a large extent, interconnected with the motor cortex. There's a visual area at the back, the occipital pole, and an auditory area here at the top of the temporal lobe. Now, that picture could have been drawn by a neurologist at the turn of the last century, 1900. This was broadly known from the effects of damage to the brain in humans, the deficits produced by local damage, focal damage, stroke and so on, in the human brain, before any of the modern research involving microelectros looking at the characteristics of individual neurons and how they function. So this much was known. Moreover, from comparative studies in animals, it's clear that that general pattern of disposition of the sensory motor areas was established right at the beginning of the mammalian line and conserved through the whole of mammalian evolution. So if you look, for instance, at, let's say, a hedgehog as a representative of early insectivores, at the beginning of the placental mammalian line, the disposition of the somatic sensory, the touch areas here, the visual areas here at the back, this is the back, that's the front, and the auditory cortex, the green area, the basic arrangement of those is similar to what one finds in a cat or a sheep or a monkey and in a human being. But although the sizes, of course, are not to scale here, the human cortex is hugely disproportionately large compared with that, let's say, of a hedgehog. But what is clear is that a much larger fraction of the whole surface of the cortex is occupied by those basic sensory processing areas in a hedgehog than in a human being. What's happened during evolution, to a large extent, has been the addition of this extra stuff. What, I suppose, in the 19th century, neurologists would have called association cortex, or even in some cases, silent cortex, as if it was uncommitted in its functions and was somehow perhaps just receiving signals from the committed areas and processing clever ways and perhaps responsible for thoughts and intelligence and those high level things. Of course, we know that in reality the rest of the cortex in higher mammals is filled with a mosaic of committed, computationally committed areas, many of them actually distinctive and recognisable by fine detail of their histology, each probably responsible for processing a particular aspect of an incoming sensory signal or a particular aspect of an outgoing motor command. Well, if the human cortex has evolved progressively and gradually from some kind of early skeletal arrangement, then there is hope that the conservation of the control mechanisms might mean that one can legitimately look at those mechanisms in lower animals, in lower mammals. And that has, of course, driven a great deal of research on the development of the cortex because there is very little that one can do in human beings to look at processes with the precision that modern techniques give in animals. This is a mouse, this is a beautiful video made with optical projection tomography, a method developed in the human genetics unit in Edinburgh, and it shows a mouse embryo at, as you can see, 10 and a half days, post conceptual days. And the embryo has been selectively stained, a monoclonal antibody staining, to reveal two transcription factors, SOC6 and PAC6, which were expressed very early on in the development of the nervous system. And you can see that they're very precisely differentially expressed within the nervous system, defining territories within which gene expression is being regulated differently, already partitioning up the brain into committed regions. The general arrangement, the way in which the cerebral cortex develops its layers, has been studied not only in rodents but in other species, and there's every reason to believe that it's basically similar in human beings. The forebrain starts as a vesicle, the tioncephallic vesicle, the walls of which are made largely from stem cells, from neural precursor stem cells, which are proliferating rapidly, symmetrically proliferating, not yet producing neurons, as the forebrain vesicle grows in size, the tioncephalon grows in size. And suddenly at a critical stage, those stem cells start to produce differentiated post mitotic committed cells, some of which become neurons. They migrate upwards, here are the stem cells here at early ages in the so-called ventricular zone, the wall of the tioncephalon, which will become the forebrain. And then they start to produce neurons, which migrate upwards, and the first of those, the earliest of those neurons, and this is based on relatively recent working in mice and rats, the first of those neurons are not mature type neurons which are going to participate in later circuitry. They're the so-called preplate, they're a transient population, many of them die, and they probably largely play a role in organising the rest of the development. At a certain stage, the stem cells, the same stem cells, probably in many cases, start to produce other classes of neurons, which are genuine cortical neurons, which form a kind of sandwich, they migrate upwards along the processes of the neural precursors, to take their place, splitting the original preplate into two layers, the so-called marginal zone, which becomes layer one of the mature cortex, and then the subplate region below. And gradually these cells accumulate as more and more of them migrate, the later arriving ones moving up towards the top of the cortex, inside out sequence, and that forms the familiar six layers of the neocortex. Again, every reason to believe that that's similar from the crude methods that can or had been applied in human beings until quite recently. But a crucial question, of course, in knowing how a bit of brain works is to know how connections are formed. And for the cerebral cortex, a crucial part of the connectivity is that which brings sensory information in to those distinct specified regions. The somatic sensory cortex, the visual cortex, and the auditory cortex. And it's known that in all mammals, including humans, that general topographic arrangement of those areas is determined by projections from different nuclei within the thalamus, a subcortical structure which has co-evolved with the cerebral cortex, to which the sense organs project. So here's the thalamus hidden down below the cerebral hemispheres, and it consists of a number of nuclei receiving information from the ears, from the somatic sensory surface, in this case the whiskers of this mouse, and from the eyes to different regions of the thalamus. Then each region of the thalamus, there's a relay, a somatic relay, and the thalamic cells then project up to the correct regions of the cortex. So each bit of the cortex, in the marmoset, in the hedgehog, in the human being, each bit of the cortex that's going to become a particular sensory area receives sensory input for a particular area of the thalamus. So how is that achieved? And I'll just describe very briefly some work that Zoltan Molna did in my lab starting many years ago, in which we asked questions about the molecular, the possible molecular control of the process of ingrowth of fibres into the developing cortex from the thalamus. And we chose to approach that initially, not by studying it in the whole embryonic brain, but by trying to produce some in vitro and reduced preparation. And I'm glad to say that part of this research was funded by a foundation which supports research on the replacement of live animals. We were using tissue culture. It must be said of fragments of neural tissue, which of course retrieved from living animals, but the main part of the experiment was done in vitro. What we wanted to do was to see whether we could produce a model of the way in which axons from the thalamus invade the embryonic cortex and then use that to define molecular mechanisms that were controlling that process. So we took samples of very early developing cerebral cortex, usually at around the time of birth in mice or rats, early experiments were in rats, and combined them in tissue culture, in organotypic culture, with small fragments of the thalamus, distinct regions of the thalamus, taken either at birth or before birth. We knew from the living animal that axons are growing into the cerebral cortex from the thalamus a few days before birth, so we could look at the timing, the age, the effect of the age of those different components in the circuitry. Well, we found to our great pleasure that fibres would grow from the thalamus into the cortex in these conditions, and we could label the thalamic block with a cobusine in fluorescent dye, and therefore look at the axons, and here they are, in fluorescence microscopy, growing into the slice of cortex. This is a slice of cortex lying in culture, and growing in a manner that looks very similar to the normal in growth of fibres that you see in the living embryo. But an interesting feature emerged when we combined slices of cortex taken at birth, with thalamic fragments from just before birth, the thalamic fibres grow in, but did not stop growing, and you see here they ascend to the surface, some of them, here's one which has turned through 90 degrees near the surface and is growing off horizontally through the cortex in a way that you never see in vivo, they normally grow in, and then stop at the fourth layer of the cortex, which is the classical receiving area where the neurons have synapses on them from incoming thalamic fibres. So, one of the things that we showed by taking slices of cortex at later and later ages was that the cortex suddenly turns on a signal associated with the developing layer four, what we call a stop signal, at around three days after birth in the rat, which terminates the growth of thalamic axons, causes them generally to bifurcate and then for the growth cones to collapse, they form synapses. Earlier the cortex turns on a growth permissive factor that allows thalamic fibres to invade, they don't invade before a couple of days before birth and begin to invade very shortly afterwards, so we were able to reveal a cascade of factors that seemed to control the growth of the cortex. Well, an obvious question then is, is the specificity of interconnections between different thalamic sensory nuclei and the appropriate receiving area of the cortex, is that somehow predetermined by some kind of molecular tag or key that's appropriate for that connection alone? What's going to be the visual cortex and the kind of chemical tag on it which attracts axons from the visual part of the thalamus? And to look at that question, we did this very simple experiment and we grew a single fragment of thalamus, in this case from the visual part of the thalamus, the part that would receive information from the eyes, in association with two fragments of cortex. One, the occipital cortex, the appropriate bit of cortex to which it should project, and then another bit of irrelevant cortex, the frontal cortex to which it would never connect. What we found to our surprise was that connectivity was indistinguishable. So connections simply depended, the ability to form connections just depended on the proximity of thalamic axons to any bit of cortex available. What mattered then was how the thalamic fibres are guided to the appropriate region and delivered to the appropriate region because they will connect to anything. We looked at that by a technique of labelling that had just been developed and has been very influential in developmental studies. The application of these carbosine and dyes, which you can get in different colours, and these dyes are lipid soluble, they incorporate into the membranes of fixed neurons. So this can be done in fixed tissue, not in living tissue, and they slowly diffuse along the axons and you can use them to trace connectivity even in dead tissue. So here we are looking at a cross section. This is a coronal section through one half of the brain of an E14 rat, gestations about 21 days in the rat. So here is the cerebral wall and at this stage it's just starting to develop neurons. It started a couple of days before in the lateral part here and it's just at this stage just starting the medial part to produce neurons which are moving up to become those early preplate neurons, the transient population. Here's the dorsal thalamus. Those are the neurons which have the task of sending their axons up to the appropriate region of the cortex and it's already a pretty tortuous root. Those cells only arrived a couple of days before from the place where they were born and they don't form distinguishable nuclei at this stage. The techniques that we used involved implanting tiny crystals of carbosine and dyes either into the cerebral wall at different points or into the thalamus at different points to examine the interconnections, whether axons are produced in one direction or the other. In fact, the first projections that you see within the pathway are produced from the cortex, from those very early born transient preplate neurons which are going to die. Here they are presumably doing part of their role in guiding subsequent connections. Here a little crystal has been placed in the surface of the cortex. It has labelled stem cells by diffusion. Here you see the so-called radial glial cells which are neural precursors. Here at the surface are preplate cells which are only migrated into position a few hours before already spinning off axons, growing down in a parallel, nicely organised bundle towards this region, towards what will become the internal capsule between the telencephalon, the subcortical structures. If you put a crystal into the dorsal thalamus at the same time, you find that axons are growing upwards from the dorsal thalamus and if you get the two placements right, if you put into the correct region of the cortex, the one which you're supposed to receive from that thalamic nucleus and the correct region of the thalamus, you get beautiful pictures like this. Here the downward fibres are stained in green and the upward fibres are stained in red and they meet each other and the thalamic fibres then grow over the surface of the cortical fibres guided towards the appropriate region, which they then, after waiting for two or three days, invade and innovate. Well of course we worked for 10 or 15 years on this in rodents and we're really interested in mice, they're super animals, but our real curiosity was to know what happens in humans and we made the broad assumption that things would be similar. We could learn all the lessons from mice, find a few corroborating steps in studies in humans and that would sell up the issue. Well we started to work, and this is work with postdoc still in my lab in Oxford, by strong looking at human embryos. A much harder task than mice of course. We obtain embryos from surgical abortions from the MRC embryo bank here in London and in Newcastle. The quality of the tissue is crucially important in using antibodies to stain selectively to stain different proteins, different gene expression products. Here we are looking, and we can use these techniques to look at embryos as early as four weeks post conception. So here is an embryo at about four weeks post conception. This is a picture of one of the embryos that we studied. The whole embryo is about two and a half millimetres long, and you can see this curious structure at the head end. That's the neural tube, the inward folding neural plate, which is going to become the spinal cord in the brain, which hasn't completely folded yet. You can see here an illustration at this stage. There's still an opening in the neural tube at the head end, and here it is. Well, we've done a great deal of work and much of it I'm very pleased to say does indeed correlate very well with what's happening in mice. These are very preliminary results, but here we are looking at carbosine and dyes revealing axons growing downwards here from the cortex at very early stages. Carnegie Stage at 18, about five weeks post conception, growing downwards towards the internal capsule. Here, in another example, where a small crystal has been placed in the thalamus, just a little later, a bundle of thalamic axons growing upwards towards the cerebral wall. It looks as though a very similar process is going on. We haven't yet examined in detail that handshake process of guidance, but it seems very likely that it's happening. However, one of the visually dominant features of early embryos, which we had never seen in any other species or read about in any other species, was this population of neurons. Here we are looking at the cerebral wall at Carnegie Stage 13. That's around about the 32nd day. It's stained with an antibody for a neuronal marker, so these things that are stained heavily here are neurons. They're in the surface of the cerebral wall in the preplate, that region to which neurons invade from the local ventricular zone, from the stem cells. However, these neurons don't come from the local ventricular zone, and they arrive before there are any neurons being produced locally. They come, we know now, from a region of the ventricular zone which will become future hypothalamus, and they spread out over the whole of the surface of the telencephalon. They're a very curious population of neurons. We call them predecessor neurons. Here's one in more detail. Here's the cell body. The cell body migrates through a long forward process by somatic translocation. This is not an axon. It's a process. They don't produce axons, or where they express neuronal markers, they don't produce axons. They anchor themselves in on the peeled surface here, and then where they make contact through tight junctions with the apical processes of neural stem cells. We think what they're doing is performing transcriptional control of neuroneogenesis in other regions of the brain by communicating through tight junctions with them. Wherever they arrive, local neuronegenesis turns on very shortly afterwards. This has been described in now of the species. We and others now have looked extensively even in monkeys and have not seen neurons of this class, whether it is a unique adaptation for the very large human brain for some reason, we don't know, but an obvious warning here is that lessons learned from animals are not necessarily entirely transferable to humans. Just a moment about language. Language, of course, is one of the most important things we do. It's a defining characteristic of human beings. Again, 19th century neurologists could tell us, well actually not as much as we know about it, but quite a lot of what we know of language now. They already knew that strokes in two regions, of course Broca's classic observations, the effects of lesions in this region, the frontal cortex, close to the face and mouth representation of the primary motor cortex, the region known as Broca's area, which produces anephasia in which the patient is still able to understand what's said to them. They're still able to read, but they can't produce speech. They can't produce organised speech. Huge difficulty in finding words, very, very primitive syntax. They just can't put things together even though they can understand them. On the other hand, lesions here at the junction of the temporal, occipital and parietal lobes of the Venikas area, produces, as it were, the symmetrical condition aphasia of understanding. People with Venikas aphasia can't read, they can't understand what's said to them. They still pour out a sort of language with neologisms which look sort of syntactically constructed even though it's usually nonsensical. So this disjunction between understanding language and expressing language is beautifully demonstrated by not animal research. Animals don't speak and there's no evidence that any species has a fully developed syntactical communication system like human beings. Those observations are entirely derived from very simple clinical observations. And to be absolutely frank, we have not got that much further in understanding how language is done, even though it's so crucially important for understanding what human beings are. We know a little bit about the connectivity. So here between Broca's area, there's strong interconnection with the face, mouth, tongue, larynx area of the Urtiportex. Not surprisingly because it's involved in controlling. It's a kind of premotor control system for speech. Equally, Venikas area has strong inputs from the temporal cortex, from areas involved in the analysis of speech sounds, but also from visual areas. Interestingly, this connectivity, even from a primary visual cortex forward through areas moving upwards towards the parable cortex, can be and has been studied by functional magnetic resonance imaging. Now I'm sure many of you have been wondering when I would raise the value of functional magnetic resonance imaging and some of you might have expected that I would say of course these new neuroimaging techniques are completely displacing research on animals and we'll answer all of the questions. FMRI is incredibly important. A large fraction of neuroscientists make use of it, but there are two key factors that you have to keep in mind if you ask what it could contribute to understanding the brain. One is its relatively poor spatial resolution, a few millimetres at best, and the other is the long time constant of vascular responses on which FMRI is based lasting a few seconds. So although it's useful for knowing, pretty useful for knowing crudely, where things are happening and roughly when they're happening in relation to stimuli, it will never give us the detail of knowledge that one can gain from the study of individual neurons in animals. But I'll show you one example of the way in which it can be used in the study of language mechanisms and their development for instance. And you know we don't have for language the kinds of tools which can be applied so effectively in other areas where animal models are more appropriate. This is a nice study done by Bedney and colleagues a few years ago in which they used three different stimuli. They put people into the scanner and looked at localised activity here and here. The yellow thing in the middle is simply the overlap between the purple bits and the green. Three different stimuli producing activity in this region of occipital and inferior parietal regions. Well what were the three stimuli? We know that the primary visual cortex is at the back here. Well the stimuli were, to begin with, well yes this is the primary visual cortex which responds very well to static patterns just black and white or coloured patterns even when they're stationary. But if you move those patterns either with just straight forward motion like this or even complicated things like transparent motion, you produce activity selectively in this group of areas here shown in blue including this region V5 or MT which seems to be very from animal studies, from monkey studies we know is very very committed to the computation of visual motion. The green area was selectively activated by another form of motion called biological motion. It looks like this, it's this sort of thing. All of you will instantly see, I'm sure, as a moving figure. It's computer generated consisting of a number of dots which are basically doing the same things as these dots, just making local movements. But it's the relationships between the movements which tell you that this is an image of a person moving. Similarly you could distinguish a man and a woman or different animals simply from the pattern of movement of the articulations of the joints. And we are crucially sensitive to that and it's a pretty important biological signal to us, very very useful. It turns out we have an area of our cortex which is committed to it there. So you can imagine that during evolution as the additional cortex has been added, starting with a hedgehog type brain that just has very early simple visual processing. These extra computational bits are added on to do clever things like recognising the analysing motion and even biological motion. Well then what about the purple bit? Is that just another ever more elaborate form of motion which is being analysed? Well the stimulus that generated the response in the purple region of the brain was verbs. Spoken verbs or written verbs. Now not all verbs are verbs of motion of course, but I think probably early verbs, the sort of verbs that would have been used by paleolithic people, probably were largely verbs of motion, no carry, stab, hunt, whatever. So is it so surprising that the system for analysing verbs might have grown out of some kind of sequential chain of evolutionary development associated with the detection of movement? And this area here, it's the right hemisphere, it's true, but this area here on the other side is bang in the middle of Annika's area, the area responsible for analysing and understanding language. There's a similar area on the right but it's less dominant in most right handed people. So that's a kind of just so story based on FMRI, wouldn't it be wonderful to know in the kind of detail that we have about the processing of visual information in this area coming from two decades of exquisite work on monkeys, on the wake monkeys, wouldn't it be wonderful to have that kind of knowledge of what's going on in this area? And we may never have that. Hunting disease briefly. Hunting disease is a neurodegenerative disease. It is interesting and different because it's an autosomal dominant disorder. If you've got the gene, you will get the disorder. It's also distinctive in the region of brain that principally degenerates. Hunting disease is a progressive neurodegenerative disease, although it's usually of quite late onset. It has both cognitive and motor symptoms. The dominant ones are motor, the uncontrollable movements, the career form movements and so on. But there are cognitive symptoms as well. It affects about 1 in 10,000 of the population, at least in western countries. 95% of cases are late onset. That is after having children. That's in some respects very sad because it means that the genetics is transmitted. And it's associated particularly with selective degeneration of the corpushtration, the basal ganglia, structure, subcortical structure closely involved in the control of movement. And here we are looking at a cross section through the brain of a normal human. And here one with hugely enlarged ventricles because of the collapse of the corpushtrate in a person suffering from Huntington's disease. The gene for Huntington's was the first gene identified for an autosomal dominant neurological disorder. It was cloned in 1993. The nature of the gene is fully understood. It's a triplet repeat gene. It has an expanded polyglutamine sequence in it. So it generates a protein that has a long sequence. This means that the genes understood, the protein is very well known. The expression patterns in the human are quite well known. And there is an absolute, at least in these terms, perfect animal model. In fact there are a number of them. I think the most convincing of them was developed in London by Joe Bates. A variety of mice in which the exon of the human mutant gene was inserted into the mouse genome. So it produces mutant human mutant protein, Huntington protein as it's called. And that generates a mouse which dies young, develops motor disorders. Also, as we've shown in some of our work, has cognitive difficulties and a variety of other conditions. It is the most comprehensively compelling mouse model of any neurological or psychiatric condition that I know of. One thing my lab worked on Huntington's for several years, one of the things that we discovered, which was nice because it turned out to have a previously unknown clinical correlation, the mutant gene has associated with it a reduction in neurogenesis in the adult brain. You'll know I'm sure that there are certain small regions of the adult mammalian brain that continue to produce neurons throughout life. Principally the dentate gyrus of the hippocampus, which pushes neurons into the hippocampus, replacing neurons and that probably plays a part in memory processes and actually in the forgetting process it's thought. And there's an anterior stream of neurogenesis which chunks new neurons into the piriform cortex and into the olfactory bulb part of the olfactory system. And it turns out that the mutant gene in the mice we discovered reduces neurogenesis dramatically in both of those sites. So here we are looking at neurogenesis and this is the percentage of cells that are dividing in the dentate gyrus and the piriform cortex in mice carrying the Huntington's gene compared with wild type mice and huge differences in both cases. This is a dramatic reduction. So we thought well if there's a reduction in neurogenesis there were going to be problems with memory and problems with olfaction. But we certainly demonstrated the problems with memory and that correlates well with the cognitive disorders that are detectable in clinical patients. Diagnosed clinical patients because you can genotype before the onset of motor symptoms. But what we predicted was that there would also be problems with the discrimination of smell, the detection of smell. This is a mouse, a mutant mouse double caught in staining for immature neurons in the piriform cortex. Here in the wild type mouse lots of newly born neurons and here in the Huntington's mouse very very few. We tested olfactory discrimination in the mice and it was very poor in olfactory detection and moved into a very small clinical study where we showed that patients diagnosed, genotyped with the Huntington's gene but with no obvious other symptoms had difficulty in discriminating odors and also in detecting odors, the detection threshold. So it's quite likely there's similar defects happening in human patients. Now this is a preamble to a lesson about the value of commitment to the 3Rs frankly. While we were doing this work one of my then graduate students, a Rhodes Scholar and Neurosurgeon from South Africa, Anton van Dellen, wanted to run experiments on improving the quality of the life of laboratory animals. Because after all the normal cage conditions for lab mice like this are really pretty unimpressive. A couple of mice, two or three mice living in a cage and that's it. So what he did was to introduce randomly within cages in the animal house enrichment. Odd things just put into the cage, changed every couple of days to give the mice something to play with. It turned out that the mice that he was doing this with were also involved in the study on Huntington's. We were producing Huntington's mice from heterozygous parents. So some of the offspring were carrying the genes, some were not, some were wild type. We didn't know which were which till we broke the code at the end of the various studies that we were doing. So this was a nice unplanned double blind experiment. Because some of the Huntington's disease mice and we didn't know which ones that were mutant were being exposed to the enriched environment and others were not. I learned when we carried out the normal kinds of diagnostic testing that we did on the mice we found a separation between the two when we broke the code. So here for instance, and this was confirmed in every test cognitive and otherwise that we looked at with these mice. Here's a simple test in which the mice are put onto a wooden rod and they walk out to the end of the rod. There's bedding and so on underneath. They play around with the rod and then eventually when they get a bit tired they fall off. At least they do if they're suffering any motor disorder. Wild type mice can stay there for a long time. So we had a test of their co-ordination ability and here we are looking at the non-enriched, the normal mutant mice and this is the percentage of the group of mice that were failing this rod test as a function of age. And here even from about 60 days on some of them are already failing. 100, 120 days all of them are failing that very simple test. They're in really bad shape by the stage. But here matched randomly unicated group with enrichment very few of them had detectable symptoms even up to 160 days. So this is equivalent if you like to translate it in simplistic terms to human beings I mean equivalent of delaying the onset of the motor disorder by many, many years. And this is in a noticeable dominant condition which had previously thought to be just absolutely autonomous and inevitable and progress. There's nothing that one could do about it. It also rescues the degenerative changes in the stratum. In the mouse the stratum collapses but here we are looking at at Huntington's the mutant mice living in an enriched environment not statistically distinguishable from wild type mice but if they're non-enriched here there's a significant collapse even at this quite early stage in the volume of the corpus stratum. So enrichment slows down to a large extent prevents for some considerable time the degeneration of the stratum. Well the nice thing about discovery and by the way that has now been demonstrated in virtually all other neurodegenerative conditions in animal models that enrichment of the environment delays the progress of the disease. What we realised was that enrichment now provided us with a tool to separate trivial consequences from the mutation from things that might be critical in pathogenesis because for any particular molecular change, anatomical change, behavioural change we could ask is this change modified by enriching the environment because we know, we knew that enriching the environment significantly delayed the progress of the disease. And the perhaps the most interesting work that came out of that was a study by Tara Spars, now in Edinburgh, now a Chancellor's fellow in Edinburgh as part of her defil in my group. Looking at the expression of a growth factor an important neuronal growth factor, BDNF, brain derived neurotrophic factor in different parts of the brain. And what you found was that in mutant mice using quantitative western blotting in mutant mice there's a significant reduction in the amount of BDNF specifically in the corpus stratum. That's interesting because BDNF is a growth factor to support and sustain neurons. So was it possible that a reduction in BDNF expression or availability in the striatum was causing the degeneration and therefore the disease? One wouldn't know without a control, although control is enrichment because enrichment delays the disease. The question is does it also delay the decrease in BDNF expression and it does. So there's a precise correlation between those. So what we suggested on the basis of this and a large amount of other work was a hypothesis for the pathogenesis and frankly the pathogenesis of the disease was not and even now it's not fully understood. But our suggestion was that BDNF produced by cortical neurons and we knew that expression even in the mutant mice was normal in the cortex. It's transported along corticostriatal neurons particularly from frontal cortex into the striatum and that transport is interfered with by the mutant Huntington protein. There's other parallel evidence that protein is involved in this particular transport so this isn't so stupid and I just have an entirely irrational idea. So the mutant protein might reduce the amount of BDNF reaching the striatum therefore causing degenerative change and hence precipitating the cascade of symptoms. Well there it's at, the last line of our paper said this might offer a new approach to therapy but yes agonists of the receptor for BDNF don't cross the blood-brain barrier. I mean there are big problems with BDNF agonists. However the FDA has very recently given approval for a clinical trial, an early clinical trial to a group in the University of California in Davis directed by Jan Nolta who proposed to use genetically modified mesonchymal stem cells derived from donors from human donors from bone marrow genetically transformed so that they over express BDNF directly injected into the striatum, into the corpus striatum of patients and genotact patients. And the basis of this which is convinced the FDA is the fact that such stem cells, mesonchymal stem cells harvested from bone marrow transformed genetically and then injected into the mouse model of hunting disease delays virtually prevents the onset of symptoms in a way very similar to environmental enrichment. So their plan and here we are looking at a section of the striatum staying for neurons, the blue cells are neurons, the green cells are mesonchymal stem cells over expressing BDNF. So the clinical trial moves in this case to humans with cerebral injection into the striatum of the modified stem cells in the hope that this will alleviate the condition. Keeping our fingers crossed would be very nice to think that a discovery stimulated entirely by fundamental research questions might eventually lead to translation of that sort. Finally unbriefly stroke, stroke of very common condition and very debilitating and very expensive caused of course by the occlusion of blood supply or region of the brain or by hemorrhage. Here for instance these are scans that show the blue penumbra of subsequent bleeding around an area of initial stroke and a lot of changes that go on around a stroke in which associated cortex dies far beyond the region that's been immediately impacted by the ischemia or by the bleeding associated with the stroke. The drug companies of course have been very interested in whether one might prevent in some way the additional damage in the neurotoxic damage in the region around a stroke. This has been a graveyard frankly for pre-clinical studies as many of you will know. Here just a few of the papers Trouble with Animal Models do stroke models, model stroke and so on and the reason is 500 neuroprotective treatment strategies, drug strategies have been developed with very encouraging pre-clinical results but as this fairly recent paper concluded only aspirin and intravenous thrombolysis have any certain clinical values. A catastrophic failure of the transition between pre-clinical and clinical seized with glee by some of our opponents of course as being typical of the failures of pre-clinical work on animals its non-transferability to humans. Just to quote though from the same article exactly the same article in a review of Animal Studies published in seven leading journals of high impact about one third of the studies, pre-clinical studies did translate at the level of human randomized trials and a tenth of the interventions were subsequently approved for use in humans. Glass half full, a glass one tenth full or 90% empty, I don't know but it seems to me that 100% isn't bad when one recognizes the difficulty of transfer from animal studies to humans. In fact is that we wouldn't need animal pre-clinical studies if we had the ability to do everything to develop and to test a new drug on humans but an alternative way of putting that is that human studies are essential to discover whether therapies that appear to be effective in animals can be transferred to humans and are safe. There's an essential interplay between the two. What has come out largely of the analysis and the agonizing about the failures of the pre-clinical studies is actually a lot more scrutiny in the design of pre-clinical animal studies even with suggestions such as this recent paper that they should be subject to very similar designs, protocols, controls, management as clinical studies with different study sites being involved in pre-designed animal studies with much more scrutiny about numbers and power and statistical design than there should be a steering committee very similar to that for a clinical trial and so on that pre-clinical CROs might be responsible for this kind of study. There's certainly a lot of re-examination of the validity of animal research at every level because of criticism of inadequate numbers, inadequate power calculations, inadequate comparability and in some cases poor experimental design. I think that's something we have to accept and do better. It is not a reason for saying that animal research can never work and should be abandoned because abandoning this crucial phase and the development of new treatments would be catastrophic for the patients for instance helped by the 10% of drug studies that do transfer right through directly to clinical benefits. So finally to conclude, what can we learn from all of this apart from lessons about those individual areas of research? What I've tried to do is to give a picture of balance. Balance of the value of studies on animals when there is no alternative, when the work simply cannot be done on humans and where the animal model is appropriate for understanding human beings, which is not always. The great difficulty I think is and it's not unique but certainly true in this area is the continuing polarisation within this debate about the importance of animals. Opponents to animal research often certainly employing exaggerated and sometimes factually incorrect arguments but equally the supporters on our side often equally exaggerating the benefits exaggerating the difficulty of conducting parallel studies or equivalent studies in human beings and so on. Avoiding that kind of polarisation by admitting the difficulties in some cases as well as the advantage in others I think is absolutely crucial. Just to give you an example of the one of the most problematical issues which is selective quotation drawing on the opinions and evidence of others. What did Darwin think about animal experimentation? Well, he said this. You ask about my opinion on vivisection I quite agree that it is justifiable for real investigations on physiology. But he also said this. It is a subject which makes me sick with horror so I will not say another word about it else I shall not sleep tonight. Interestingly, he said both things in the same letter. This is the full text of a letter to Ray Lancaster. But not the mere damnable and detestable curiosity. So he was making a distinction between valuable research and useful investigations of physiology perhaps applicable with just tinkering for no benefit at all. So I want you to be very careful with quotation. So I want to raise just some questions which I think we all need to address. Do we really have adequate ways of assessing the validity of the animal models we use? It seems to be crucial if particularly if they are part of a preclinical study. Is there more scope for developing alternatives? The kinds of technical advances being made in human study are making things possible in humans now that we are not in the past and we must recognise that. Those of us who have been committed to animal work will not deny it. Yes, and is there sufficient funding available for the areas of new opportunity? On the other hand, is medical progress being impeded by excessive bureaucratic regulation and by excessive I mean not demonstrably valuable in terms of maintaining ethical standards or the correctness of procedure? I think those of us who deal with the problem of applying for animal licences are not that I do any more but those of those whom I know still who deal with it. Do wonder from time to time whether the benefits that are gained by the enormous amount of bureaucracy associated with the process are matched by benefits to the animals and benefits in terms of the value of the research. And how effective is the evaluation of evidence from animal research before it transfers into clinical trials? Particularly, of course, how justified is the use of primates? How justified is genetic modification? And especially, how justified are we in using techniques that are almost bound to cause suffering? So with those thoughts, I'd like you to think about the brain. It's no crucial issue because of those dilemmas that I raised right at the start. It's a wonderfully exciting area of science. It's incredibly important clinically because of the magnitude of the problems that need to be solved. But at the heart of that whole, those driving forces towards science on the brain, there is the conundrum, there is the organ that makes us think, that makes us know and that makes us suffer. Thank you.