 CNS by 120, the Neural Basis of Consciousness. So what we'll do in the 18 classes we have, we'll talk about the scientific study, the scientific exploration of consciousness. We'll talk about mainly the brain basis of consciousness and how the brain connects to the mind, particularly to the conscious mind. How is it that we can have a sensation, that we can have feelings, that we can have subjective feelings, what philosophers call phenomenal states, which are in one way the only way we can truly experience a world when you experience a world, when you feel it or see it or hear it or touch it or it hurts you or pleases you something, then there is something to be pleased or it feels like something to be happy, it feels like something to see blue, it feels like something to hurt, to have a toothache, and that's the main way we experience a world and it's a big puzzle going back to where as long as we can go back and record this history, certainly Aristotle talks about this, Aristotle and Socrates talks about it in Western philosophy and of course it's known as the mind-body problem and science usually has neglected it although there are episodes every 30 years, a bit like a flu, like an epidemic, every 30 years they reoccur and people get terribly interested in the study of consciousness again and since 10 or 12 years we're in such a phase and I think now people have established or beginning to establish a science of consciousness, how is it that certain systems can have these subjective states? How do these subjective states come about? What is their brain basis? Can you build artifacts that have such conscious states? So those are the things we'll talk about, mainly from a new biological point of view, less from a philosophical point of view. This is a very influential article by a philosopher I think in New York, Thomas Nagel, what is it like to be a bat? And he argued that in principle we can never know what is it like to be a bat because we can really never put ourselves in the place of a bat. A bat, let's say, has ultrasound, a bat senses the world, experiences the world in a fundamental different way and folks are using ultrasound and we can never get at that. So rather defeatist pessimistic conclusion, in the limit it would also mean you can't have acting because acting means if I am acting, I'm acting out another character, how can I really feel like the character because I didn't really go through his life experience. Anyhow, but it is a famous article among philosophers. And he points out something that to most neuroscientists were never really thought about until the last 10 years. So the study of the modern tendency to now study consciousness again was very popular in the 30s. It was quite popular at the end of the previous century in 1880, 1819, and was somewhat popular in the 1950s, but this modern research in the interest of consciousness came about due to, well, both the fact that we have now powerful methods to study neurons and to study whole brains, particular function of brain imaging, as well as the interest of figures like Jerry Edelman and Francis Crick. And before then, or even today, still remarkable many neuroscientists don't reflect upon the fact that the animal they're studying or the people they're studying are actually conscious, that ultimately we'd like to describe not just the behavior that people have, they move and see, they move and run and move their eyes and do all sorts of things, but they actually have sensations. Of course, famously, behaviorists in the 30s and 40s totally outlawed any talk about consciousness because it couldn't be operationalized, they claim and it couldn't be measured. But of course, that's really silly. Just because subjectivity is difficult to capture doesn't mean it doesn't exist. Like I said, it's certainly the most central fact of our existence, the fact that we feel and smell and hear and touch. So to neglect that just seems really silly. And as he points out, without consciousness, the mind-body problem isn't all that interesting and right now with consciousness it seems hopeless to some philosophers. So first of all, what is it that we seek to explain? So we seek not so much to explain, I mean specifically focusing on consciousness, not so much behavior. So behavior people are trying to explain and there's no fundamental problem. But there's no fundamental problem to explain how a visual system can sense something and translate that whatever is sensed into some action. I mean, in principle, simple robots are already doing that today. In practice it's immensely complicated because our brains are so complicated and they're very adaptive and we're only beginning to understand the problem. But in principle, it seems no, it doesn't seem intractable. What seems intractable are these problems. First of all, the biggest problem of them all, why is there any feeling at all? Now this sounds a little bit like one of those problems, why is there anything at all that seems like, you know, designed to never have any answer at all. I mean, you know, you can probably all of you have pondered at some point in your life why is there anything in the universe rather than nothing. And so similarly you can ask why is there any feeling at all? Why should, and people, philosophers refer to this as the explanatory chasm, why should a physical system have subjective state or how is it that a physical system like my brain undoubtedly is a physical system, how is it that a physical system can have subjective states? You think about it, think about it for pain, for example. The two topics, philosophers usually focus on as pain and color probably because they're both so vivid. So if you build a robot and, you know, the robot has a sensor at the end of its finger and let's see that the sensor signals, you know, 100 degrees Celsius. Okay, and then the red light flashes on, you know, transistor, you know, a current flows on to the transistor gate, transistor closes, red light flashes on to this danger. Okay, so you would say, well, okay, that's nothing but switching of electrons. I mean, I understand all the physics of that from the temperature increase at the temperature probe all the way to the switching of the electron on the central gate in the CPU and then turning on the lights. I understand that. So clearly it doesn't feel like anything to be a Macintosh computer and have pain, right? That doesn't really make sense. Maybe for Windows machine, but not for Mac. Yet, of course, when we have these states, sometimes, not always, but sometimes when we have these states, we actually have pain. If you put your, you know, if you, you know, I squeeze you or I step on your finger or something, you'll have this state called pain. Not always. There are, you know, lots of disconnects when you have the same physical stimulus, but let's say because you're in a war and you saw a car and you can have this big wound and you don't notice it. So even there, we see that the relationship between physical stimulus and percept can be very, very tricky. We are all at heart naïve realist, at least early on when we grow up. And I said when I was your age, I was like that. I thought, well, there's really no big problem ontologically here, right? There's a world out there. I sense it and there's this one-to-one mapping between what's out there and what's inside my head. And that's it, right? This is called naïve realism. Yes, they're stimuli out there, but usually they're very ambiguous. You can interpret those stimuli in many different ways and sometimes you have a percept and sometimes you don't have a percept or the exact nature of the percept can depend on many, many factors. Now, statistically it seems to work. Otherwise we've never made it out of the ocean, right? Otherwise we'd still be bacteria swimming around single cell organisms. So statistically these things work, but in individual cases, particularly if you go in a lab, you can have this total dissociation inside and pain is one example. But to get back to the basic problem, so why is it that if I squeeze my finger, I not only move my finger away and have all these behavioral dispositions. If I toothpick, I run around like this, I go to the dentist, my tongue plays over the infected tooth all the time. Those are all behavior or behavioral contingencies, but in addition to all that, I have this bad feeling, this awful feeling of pain or pleasure of seeing blue or whatever. And why is it that there's no physical law right now in the universe that explains why a physical system can have subjective stages? It seems totally non-secretary. It seems to be two different levels of explanation. Here's the world of physics and action and reaction and mechanisms and of course, biology is built on top of that and ultimately sociology and all of that, but here somewhere else you have this world of internal sensation and why it's sort of total unclear why there's this relationship between the two and why certain physical systems sometimes in the human brain when they're well rested and not in coma, not in anesthesia, et cetera, can have these subjective states. So that's the big problem of them all. Why is there any feeling at all? Very difficult to get at right now. Then as a corollary, as I mentioned already, many behaviors can occur without feelings. We'll talk quite a bit about them. These are so-called zombie behaviors. Zombie behaviors. Because we'll talk about their interesting things with sleep. There are all sorts of behaviors like that, both in normal conditions, as well as in pathological conditions like sleepwalking and epileptic seizures, et cetera. In us, most of our... the older you get, the more you realize what fraction of your life you do totally on automatic pilot unconsciously. It starts with very simple experiment. We'll talk about involving eye movements where you can show that your visual system you have different types of eye movements. You have six types of eye muscle in each eye. It's an incredible sensitive system, very elaborate, a significant part of the brain that is taken over just by controlling the eye movements. For the most part, you have no idea of this. You can even show that this ocular motor system has access to visual information that you, the conscious you inside sitting, you don't see. The things that your ocular motor system does that you are not aware of. You can show these things provable in a lab. It's a very simple example. When you go running or climbing or biking or driving, all these things you do expertly and maybe you need consciousness in fact you needed consciousness in order to learn these things but once you do them at an expert level consciousness will often interfere with performance of these if you do them really well. Consciousness has always an extra price to be paid which is a couple of hundred milliseconds. Many of these behaviors like talking is one of the best examples. If you really think how you do talking it's totally unclear. There's not, I can tell you there's not Christoph sitting inside my head who says this is the sense I now want to say therefore this is the verb, this is the adjective, this is the tense, now shift it all off to my speech production system. It doesn't happen like that. I just have a vague idea of what I want to say next. In fact, it's not even very explicit. I know that I have to make these three four points I want to go over and the rest just comes pouring out of my mouth. Now to a certain extent it's under my control. I can control reasonably what I say, what I don't say but even that isn't always the case. Famously of course, by Freud on other cases and so here you have a very elaborate system in the language system that is very elaborate over which who's working I don't have any access to. So all this behavior goes hand in hand without any conscious sensation. Vision, take any example like vision or smelling if I open my eyes I see. It seems so trivial that I mean both my parents are academics and when I first told them what I did my Ph.D. and vision they didn't understand. They said what do you mean? You study vision. Where's the big problem? You open your eyes and you see. I don't see any problem there. Well I mean it is true it's so effortlessly because 30 to 40% of my brain is dedicated to vision and it all happens unconsciously. People say okay playing chess now that's a real difficult problem because you have to have these rules and you have to do the combination of the various movements. That's real difficult problem but vision isn't a problem when in fact we know it's precisely the opposite that you can buy for 10 bucks computer software that plays chess probably better than almost any of us yet the machine vision system we have is still very primitive compared even to the visual performance of a single animal like a fly. And so there are many things that go on inside our head. Most of the things that go on inside of our head are unconscious. Some are beyond the pale of consciousness per se. Like you don't have access to language. You don't have access to how you see color or you don't have access how you see motion or stereo. You don't have access how you hear things in terms of morphines. Other things you can have access to like right now I feel the soles of my foot moving right now I'm sort of trancing my attention to the soles of my feet and I can actually feel sort of in my shoe but usually 99.9% of the time I choose my brain chooses not to do that so that you have to make these distinctions. So why is it that all these behaviors can go on without feelings? And in patients you can even see more dramatic examples of it where the conscious system has been destroyed due to a stroke or gunshot or virus yet they can still do certain things all the time while professing they absolutely have no idea how they're doing it. It's just their body is doing it. Those are sort of more extreme cases when you have behaviors without feelings. From a neurological point of view and your scientific point of view that's very interesting because now I can contrast at the new level where's the difference between those behaviors that give rise to consciousness and those behaviors that do not give rise to consciousness. Are different parts of the brain involved? Are those the same parts of the brain but working in a different mode like feet forward versus feet back? Another thing that needs to be explained is the structure of sensation. So sensation people also talk about phenomenal experiences or qualia. It's a work from one quali and many qualia. The qualia are things like color, like pain, like, you know, hearing, hearing, music, the sensation. Now these sensations aren't random. They're highly structured and highly ordered. We know that you might have seen depiction of color spaces, you know two or three-dimensional depiction of color spaces or hearing spaces. These are not random spaces. These are highly structured spaces and more or less on average most humans will tend to see the same thing. Not always. For example, we know now that many women probably have four types of photoreceptors. At least they have the genes for four types of photoreceptors. Two types of red and two types of long and a medium and a short wavelength cone photoreceptors. While many men, of course, at least 10 to 15 percent of men have two cone photoreceptor types. So just between the gender there are significant differences. Yet, you know, on the whole we all experience the same world roughly most of the time. Yeah, and that's a really beautiful part of neuroscience now where we try to relate the individual genetic differences to minute differences in perception. That's something very new only in the last 10 or 20 years. Then we would like to explain that while you're feeling private that's not so difficult to explain. So when I feel something I feel something, I hear something I see something, I can talk to you about it but usually I can only talk about the qualia in relationship to other qualia. It's very difficult to describe the thing in itself. Why is that? And lastly, and also very, very puzzling is how do these sensations how do they acquire meaning? What I mean by that is that these things aren't arbitrary symbols. It's not like in a computer where, you know, again, you can write a computer program that does color, that takes RGB input and then label things using different colors. So, you know, you call something red and you call something green. But these just seem to be abstract symbols and you can exchange them with some other symbols. You can call red green and green red and it doesn't seem to make any difference. Yet for us, these things have meanings. Red is not just a random signal red is associated with the color of blood with sunset and with, you know, the red book of Mao and with, you know, maybe, you know, the red star and revolution and, you know, smell, you know, each smells associated with some memories and with all sorts of things. So there's this rush that, for example, if you ever read a post that he talks about that when you have certain association particular in the olfactory domain you can have this entire very rich rush of memories and yet that sort of tend to be associated with these various sensations, smells and hearing and sides. And so this is highly, again, highly meaningful and the question is how can the brain generate this meaning? How is it that activity of certain neurons can give rise to these meaningful things that I explained that we all experienced as meaningful. So those are the key problems that the neuroscience of consciousness needs to explain. Tall order, isn't it? Okay, now I need to so see, does this wake up? Signal is lost, that's not good. Okay, I need to turn the light off now. What I'm showing you here is a really nifty illusion. It's called motion-induced blindness. And so what you should do just fixate, for example, let me put the cursor on here. It helps, it's not absolutely necessary, but fixate the cursor. Okay, if you keep your eyes still, still as you can and then what do you see? So do you see the circles appearing and disappearing? Usually if the upper two disappear first for most of you or the lower one? That's an asymmetry. After a while I can get all three circles to disappear. So you all see that? If you don't, you should come see me afterwards. I like to use this when I talk to philosophers because for them, they usually look at many people, when you talk about conscience, they talk about very high-level aspects of consciousness, particularly self-consciousness. The fact that I know I'm Christoph, I know I'm thinking and I know that I know, and if I'm really clever, maybe I know that I know that I know. So the self-referential aspects of consciousness that we thought were self-consciousness. Now that's just one aspect of consciousness and it's unclear to what extent animals have it. I mean there's some research using so-called mirror tests where you can show that at least some animals like orangutans and bono mo and chimps and maybe dolphins have at least some aspects of self-awareness relating to body image to at least the side of their image in mirrors. That's just one aspect of consciousness that's probably highest developed in Italian primates and probably in humans. But that's just one aspect. So here what you saw, you have a very vivid percept of yellow spots and sometimes you see him and sometimes he don't. And so here you have a wonderful example that's experimentally much easier to manipulate than self-consciousness because this we can manipulate in a lab, we can change the colors, the orientation, etc. We can then put you in a mag, you can put electrodes in its brain, all of that things you can't do with self-consciousness and you can study why is it that although physically the stimulus is there all the time, the yellow spots never disappear, they're here all the time. Trust me, I'm a scientist. Yet sometimes you see him and sometimes you don't. Where's the difference in the brain? Why is it that sometimes you can see him and when you see him, this by the way when I use the word, just a footnote about language, I mean in the sense of conscious seeing and conscious perceiving. As I mentioned, very often you can show that there are things that go on in your brain or you can even do behavior without seeing. But when you see this, you can see it's yellow, maybe you associate with the yellow van Gogh sunflowers, you associate with yellow, I don't know, yellow bead law, whatever you associate with. And when you don't see it, you don't have any of those associations. I mean you maybe still remember it, but that's much fainter. In fact here you can show you have an aft effect. Even though the disc might be invisible, for example you can show now, even though those yellow discs might disappear, they still evoke an aft effect. In other words, some part of your brain will still register them and do some computation. But those operations, that computation is not made accessible to consciousness. So the great thing about these sort of illusions, they're called perceptual stimuli, perceptual stimuli, because we manipulate, it's always the same stimulus but the percept waxes and wanes. We can use those scientifically to study the footprints of consciousness. Because now we can study the brain in various humans and animals in various techniques and we can say where are the neurons that focus on that fire always to yellow? So I bet you nobody has done that because it's very difficult, but if I bet you you put a recording device in your retina, your retina will always see the yellow. Yet somewhere high up wherever the neurons are that give rise to consciousness, the neurons, if I see them, the neurons will fire. If I don't see the yellow spots, the neurons will not fire. I mean, that's one possibility, the other possibilities. And then, of course, ultimately I'm not just interested in the correlation, I'm interested in causation, otherwise I'm interested in finding that subset of neural mechanisms that if I stimulated would actually give rise to the yellow spots. In other words, I'm interested in finding where the neurons and what type of neurons are in, where do they lie and what other neurons they talk to, et cetera, that actually give rise to this yellow percept. So that's why in our approach, in this book that I've championed together with Francis Crick, I've worked with him for the past 12 years, published our first paper on this in 1980, we continue to work together. He's at the Salk Institute, of course. The approach we championed is that we want to look for the specific neural mechanism that give rise to specific conscious sensations. And that's why right now, purely for tactical reasons, I mean, you don't, as we see right now, you don't win the war by fighting the most difficult battle first. And so likewise, you don't, I think, to approach conscious, which is a very difficult problem. It's not useful right now to think about very highly, or it's less useful to think about very high level things like self-conscious and language or emotions. They're terribly important for humans, no question about it, but they don't make an experimentally amenable system. They don't allow you very well to... I mean, for example, there are no simple illusions of emotions that you can manipulate with this precision on this time scale. That's why vision or faction or some of these sensory modalities are much easier to explore. The neural basis of consciousness for vision or for hearing or for affection is easier to explore than the basis for things like self-conscious, in particular because we have animal models, like a monkey, where the monkey is very, very similar. And everything that we can see about the monkey tells us that the monkey probably sees and smells and hears the world exactly the same way, not exactly, but very similar to the way we do. Certainly, if you train monkeys in tasks like this, for example, you can get a monkey to train. You can get the monkey to train to tell you when, let's say, the upper left yellow spots disappear. He pulls the lever when it disappears and he pulls the lever down when it's present. And then you can ask a typical undergraduate subject, paid undergraduate subject to do it and lo and behold, they do the same. I mean, if you look at this statistic, etc., it's very similar. It's not that surprising since certainly the early parts of the brain of humans and monkeys are very, very similar. They're highly visual creatures. They have two or three types of cones. They have two forward-looking eyes. They have the same type of eye movements. In fact, it would take an expert and there are probably only a few hundred experts on the planet to tell a little cubic millimeter of monkey brain from a cubic millimeter of human brain and look at the... If you just look at the hardware, it's very, very similar. Yes, it's much bigger in a human. In a human, it's more like a 14-inch pizza. That's roughly one... So if you look at cortex, you fold it out, right? Cortex is essentially a sort of two-dimensional technology, a two-plus epsilon-dimensional technology. It's like a sheet. It's a 14-inch pizza, like two to three millimeter thick and you have two of them. You scramble them up and put them in the brain. They put them in the skull. It's more like a peanut butter cookie. It's more like 100 square centimeter. And that sort of mushed up and put in the skull. Now, there are many, many, many answers that people have given over the course of history. And there's no way... We can even begin to capture all of them. It's just no way. It's just too many, too diverse approaches. So, I mean, just to give you the range, I mean, you all know most people on the planet, the vast majority of people on the planet rightly or wrongly believe, of course, that conscience depends on an immaterial soul. So, in the western tradition that comes from... this conception comes from Plato and was taken up by Neo-Platonism in the first and second century and then came from that form into the Catholic Church. And it seemed Augustine and Thomas Aquinas sort of made it sort of part of the central philosophy and it remained there as the central part of western certainly of Christian, the both Protestant and Catholic Churches and of the very offshoots. And also in most other religions there's some form of belief that there's an immaterial soul at the heart at the heart of... there's something immaterial at the heart of consciousness that it has aspects that cannot be adequately described by science. It has free will by definition. I mean, if you don't have free will the entire concept of sin is meaningless. You can only sin if there is a real choice. If I don't have a choice then the concept of sin is meaningless. That means the soul has to be a causal in a sense. In other words, it has to be able to do certain things that don't have any physical priors. That isn't contingent on anything else in the world. Because if it would be contingent on something else in the world then you wouldn't have free will. So that's a key notion of an immaterial world of an immaterial soul that it can do things that are not contingent upon any other physical things in the world possibly outside the world. And of course, many believe, also believe but they don't necessarily have to go together that this immaterial soul is also indestructible and internal and survives death. That's an independent... Typically they go together sociologically they typically go together but they don't necessarily have to go together. Now my point is my position on those things is that I cannot really say anything useful for and against those positions. I myself, as I was raised as a Roman Catholic I'm very familiar with them and I'm quite sympathetic to some of these views but as scientists there isn't anything useful I can say about that as Immanuel Kant says that are filtered through the categories of space and time and causalities I can only say useful things about things that occur sometimes in time, that occur somewhere in space and that have a prior cause otherwise I can't study them using scientific means. So I don't know again as a scientist you can only say I don't know how a soul would survive death if there isn't any physical carrier I don't know how a soul would survive death but otherwise there really isn't too much one can contribute to the debate at this sort of philosophical level. Of course it is true there are many beliefs that people have that are just provable wrong but there are certain things that you cannot really prove. Then there are those among philosophers particularly among contemporary philosophers among contemporary Anglo-Saxon philosophers among contemporary Anglo-Saxon philosophers in the US and in England the first position is totally pooped it is not taken seriously at all anymore. In my opinion like many things in philosophy that is a fashion philosophy is more driven by fashion than anything else because philosophy doesn't have an absolute concept of truth and there is no way to prove a conjecture true or wrong you can only prove a particular philosophy right within a particular philosophical system itself and you know like Marxism for 100 years Marxism certainly in the continent used to be the philosophy number one and now it's not that philosophers suddenly discover that it's all wrong it's just that it's just not a very popular way of looking at the world anymore that's my own personal opinion when it comes to philosophy but certainly of course many philologists outside the Anglo-Saxon content do think and talk a lot about immaterial soul particularly in India in a very different tradition and again I don't want to belittle those beliefs in any way of shape or form I can only assign to study those things that I can measure and there is no doubt I think anybody who thinks about consciousness will agree that no matter your metaphysical predispositions that the consciousness will have a physical carrier will have a physical substrate that we can study this substrate and that we can isolate it in what condition you see yellow and what condition you not see yellow and the fullness of time will explain where are the neurons or what are the neural mechanism that give rise to some self-consciousness that does not to what extent you can then go beyond that to address these more metaphysical questions it's difficult to say right now I tend to stay away from them because those are questions that cannot be answered in today's empirical framework then among this continues among Anglo-Saxon tradition that consciousness cannot be understood by scientific means these are people who are perfectly who are natural philosophers in other words they don't make appeal to metaphysical concepts to extra-natural concepts like soul or God they are strictly natural philosophers but they claim on the basis of I think unconvincing evidence that we cannot we can never understand consciousness what chance will ants have what chance does an ant have of understanding general relativity or sometimes they invoke Goedl's second theorem to argue people like Lukas to argue that a system can never understand itself there are serious limitations of that I find all of this talk very defeatist frankly to me it comes down to saying well gee I don't understand how consciousness can come about so therefore it's going to be forever beyond the ilk of humankind to understand it that's very often what it sounds like just because they fail to understand or their particular philosophical tradition fails to understand it then they make that as a universal and say okay therefore we cannot understand it at all and of course it's self-defeating if I don't try to understand it then of course I will never understand it so I don't find it very useful but there are certainly philosophers who defend that then there are people they're less dominant now in philosophical position certainly in this country but consciousness actually doesn't exist and a little bit Dan Dennard some of you might have heard of him he's sort of one of the big philosophers today believes this it's really difficult to get him to pin down that that consciousness doesn't really exist that there is really no such thing as illusion as the consciousness that it's all a big a big con job that it's a whole bundle of behavioral dispositions and traditional stories that you're being told that you are conscious and sort of you know people like to say that and they behave like they're conscious but there really isn't anything you know this question what is it like to feel it's just a meaningless question there isn't really anything such as consciousness they're sort of you know so they would I guess give you a story you know if you look at these yellow spots well sometimes you can access this information sometimes you can't access this information access so to explain I would say you know in this previous experiment sometimes you were conscious of the yellow spots and sometimes you're not conscious and it's going to be different in the neuronal states they would say well you know it's just all about access sometimes you have access to information sometimes you don't have access to information I don't know I don't find it very convincing I had this correspondence with Dennard about this and I was just coming off a hiking trip in the Sierras and I had to break off my hiking trip because I had toothache and if you ever have a bad toothache I mean nothing in the world can convince you that this pain is not real right I mean that's why I find these arguments just very weak and silly right if you have pain if you have particular toothache pain because it can be long it can be very persistent very vivid okay that it's just the most real thing in the world I mean to claim that this this ache this bad thing in my mouth you know that it wants me to run against the wall that this is just an illusion that you know I'm just linguistically confused it's just a disposition to do this and moan it just strikes me as totally silly I mean anyhow there they are that's some although like I said right now these positions are less are less are less popular among philosophers most or many philosophers at least now take consciousness as a given and seek various explanations for it then there are those people that take consciousness serious but that and that postulate that consciousness is such a fundamental new feature of the universe that we need to invoke new physical new laws that our existing laws just are not sufficient to explain it now this this at first blush strikes me eminently reasonable because as I said you know early on there seems to be this explanatory gap why is systems why physical system that consists out of atoms and molecules and you know in its base you know the for forces and all that why should this system have these subjective states and so for example one approaches by David Chalmers a very smart very I mean very good I really like him philosopher in Arizona he postulates something like that systems in the universe that two aspects to system there's a physical aspect that we know about in physics and biology etc but then there's also this information this phenomenal aspect and it relates to some of the information that that any information bearing system any information processing system has phenomenal aspect including a light switch so this is a very em this is a very how should I say it's a very misty it's almost a mystical point of view because it endows suddenly everything in the universe even that light switch in the wall here with some admittedly very simple form of consciousness I mean Chalmers says it does not feel like a lot to be this light switch here but because there's sort of one bit I don't know two bits are many bits stored there that he just says there is this it's just this double side this dual side of nature that information processing system have this external side that we can deal with with physics and all the natural sciences in addition it has this internal experiential aspects and the task of science is now to be these bridge bridging principles to study bridging principle what sort of systems you know how can you map how can you map how can you map phenomenal experiences like the structure of red and blue and language and all that how can you map that on these physical on these physical states it's not implausible right now it's nobody I mean he just outlines this very crudely he hasn't really there's really no detailed theory there it's difficult to know how to test it and right now he really hasn't he or other people of that ilk who believes something like that haven't given detailed explanation for example would be nice to know in this approach is it really all information processing system or mainly only parallel ones or mainly only serial one maybe you need to be you know have something like a serial like a CPU bottleneck only then you become conscious of whatever's in the bottleneck or you know do you need distributed memory or shared memory or what so people really haven't developed this at all that's one approach towards arguing that consciousness needs new laws the other one is approached most famously by Roger Penrose who's a physicist who worked with or he did all sorts of things he invented Penrose Penrose Tiling and he also did the Penrose Moore inverse in mathematics and he also did with his father he invented the you know the Escher than possible staircase that's actually invented by Roger Penrose and his dad Lionel Penrose he's a very and he worked with Hawkins on the Noherb theorem in black hole cosmology and he also has postulated that in order to explain creativity certainly mathematics and in physics you need to have access to certain non-computable truths and that cannot arise out of he argues and that cannot come about using conventional physics it requires a new form of physics it requires a new form of quantum physics that we don't have yet and he said that also analyzed consciousness although that link is totally vague and if you read his books which are fantastic books the Empress New Mind is one of the best description of Turing machines and computability I've seen Turing has like two pages on the brain it makes this big non-secret to a jump and you also need this new quantum physics in order to understand the brain and there he just totally loses means he's a very smart guy correspondence with him at length he offers no mechanism he knows this except he says well I know I have this deep intuition that we have access to these non-computable truths and I have this deep intuition that this has to relate to consciousness but he doesn't give any mechanism how neurons that are embedded in a medium at 300 degrees Kelvin hardly the ideal medium to give rise to sort of microscopic quantum coherency states and that's what according to him what you need you need to go on over large distances the distance that are relevant in the brain which is sort of centimeters in this 300 degree Kelvin background so it's really the worst possible environment you can have to have these quantum coherence states that sort of form and disappear over fractions of a second no mechanism what's ever there so I don't think that we have no experimental evidence to suggest that you need any sort of exotic physics you can't really let out like many things in science you can't rule it out right now but there's just no evidence for it so therefore what remains right now so maybe you know it's entirely possible in the fullness of time we realize that we're hitting a limit and we need to postulate new laws right now I just don't see those limits and I think so this is what we defend in most people most neuroscientists certainly do this is an emergent property of certain biological systems now by emergent I mean it follows in a non-trivial manner I mean emergent often is used in a fuzzy way in a sort of a you know holistic emergent gestalt like patterns and sort of it's a refuge for fuzzy thinking in this case what I mean it's emergent in the sense that it comes about in a non-trivial manner from laws at a lower level just like you know in biology you know heredity for example emerges in a non-trivial manner from the properties of certain you know nucleic acids and amino acids I mean you know you once you understand the system you understand how it does it but it's non-trivial it's certainly not easy you know you cannot sort of easily predict how that happens or like you know super connectivity that you know Cooper pairs of things like that emerges in a non-trivial manner from the interaction of you know neurons and phonons there's no magic stuff you need there's no new ingredient you need you just have the same old laws of physics and bio-physics and biochemistry in our case we need bio-physics and although if you have a bunch of neurons that are very complex that are adaptive over these time scales then under certain conditions you can get consciousness under certain conditions like I said when I'm well rested and not in coma there are lots of other cases when you have lots of complicated neurons or cells and they don't give rise to consciousness I don't know how many of you guys know but in each of your guts down here they're on the order of 50 to 100 million cells neurons down here it's called the enteric nervous system and you're almost always utterly happily oblivious of this fact right because usually if this nervous system tells you something it's usually bad news you know when you want to vomit you feel nauseated that's usually been messages sort of the only thing that this system tells tells your brain here it's not good news so usually most people don't want to be reminded of it but it's a fact that you have a lot of neurons down there and in 100 million neurons that's sort of you know probably more than your average path to which all of you would ascribe I certainly do ascribe the consciousness so again you have to explain why is it that you know it's a biological system they have neurons there and they have synapse they have some neurons transmitters why you don't get consciousness here but you do get consciousness in a subset here so that's the that's the approach that we take so that's the spectrum of approach like for each one of these hundreds of books you can read on all of these topics so our approach is an eminently pragmatic one I'm not sort of beholding to any one ideology I'm mainly interested in making empirical progress and trying to study the problem and making progress so it's great to have some fundamental debates particularly you know you can have them endless at night over beers and pubs and but that I mean 18 and 20 that's what you should do but at some point you actually want to make progress and then you have to limit yourself to systems that are sort of simpler to study like visual consciousness so we make some assumptions that I think are very common among most of us who look at these problems first of all a working definition now it's a very rough working definition one shouldn't be anal when you define things early on in the pursuit of a scientific topic in hindsight it looks like people always had definition but if you go back and read biographies I mean for some electricity when Ohm and Voltaire and Ampère made there the discovery of the Ohm's Law and Kirchhoff's Law and all those things because the electrons wasn't discovered by Thomson till 18, I don't know 92 or 96 something like that so you couldn't have made a very precise definition if you didn't know about the electron you still made progress Crick and Watson and the deciphering of the double helix and the genetic code went on in the absence of a precise definition of gene and even today it's non-trivial to define what a gene is is it a continuous reason on a nucleic acid can it go over two you know you have editing post-translational editing all those things so right now the working definition we have it seems to require although not always but it seems to very often go hand in hand with attention you need to attend to something like right now I'm attending to you or I'm looking at you but I'm attending to the sound over here and some very brief form of memory how brief is unclear on the odd of a second or two or three shorter sort of on that sort of second those seems to be some of the psychological at the psychological level those seem to be the requirements it's you know there are all these fundamental problems that people like to talk about but they're right now difficult to resolve how do I know my spinal cord isn't conscious but it's just not telling me you know people I've had this debate well I don't know and right now I just don't care it just doesn't seem you know in the fullness of time in the fullness of time we want the consciousometer we want some device that I can point just like in Star Trek I can point at it at something I can read out okay that's conscious at the level of you know whatever 5.2 we don't have that I think there's no reason why we should not have such a consciousometer in the fullness of time but right now we don't have it so there's some problems that are just right now not very useful to worry about like is my spinal cord conscious but it's so briefly conscious only for microsecond that I really can't pick it up well that might be true but I'm just not going to worry about it because I don't know how to test it right now you know it's just like the story of the drunk you look for the key under the light so right now you do experiments on obvious cases when you can study the phenomena so for instance you study people you don't worry too much about people in coma you know an anesthesia when funny things happen you take normal subjects like you well rested you show them stimuli like these so there's no question they're conscious you do the same thing so you try to study the phenomena when most reasonable people can agree it's presence there of course you always worry about those fringe cases but right now they don't make very useful experimental material just because they're sort of much more controversial much more difficult to control also that's why it's so important to work on animals because you know with the ability to do experiments with human it's just very limited you know you don't have access to the brain to the nuance itself you just have access to the large fraction of the brain through functional imaging that's great but that's really still very very crude let's drop the question about functionalism functionalism is a belief right now it's difficult to prove either way functionalism is a belief that comes of course from AI from computer science and artificial intelligence that really the nature of the medium doesn't matter the only thing that matters is the relationship so in principle you could build a computer using co-cans or you could build a computer using you know an adequate or you can do it using CMOS silicon or you can do it using optics it's just a question of how big you want the machine or how expensive and you know those sort of implementation details that's certainly true for computers it's unclear what that's true for the brain is it really true that the only thing that matters for consciousness or for perception is that you have these things called nuance and in principle you can instantiate it in any medium for example in a computer right now we just don't know it could go either ways and it's a purely question of belief right now as far as I'm convinced as far as I'm concerned some people are convinced that in principle once we understand consciousness we can build machines that are conscious I like that idea I'm partly involved in such an approach but we just don't know whether that's true or not it might be that there's something special in the scaling relationship that holds in biology that doesn't hold in silicon maybe we can have this vast amount of parallel information access I don't know you can make reason argument to argue that maybe there is something unique about brains and it's going to be difficult practically or maybe difficult for fundamental conceptual reasons to replicate that in silicon or any other technology we just don't know interesting questions I organized a conference last year on computer conscious how would you know where the computer is conscious you can always say well the computer is just faking it of course the same argument another one of these great arguments you can spend your nights how do I know you're conscious now of course I really don't but on the other end I can say if I step on your toe you're going to behave roughly very similar to what I would and you'll probably have pain like I would and if I look at your brain in a magnet I would find a brain that's very similar to mine you've been raised by a mother and a father so there's a great deal of continuity between me and all of you evolutionary spoken we're very very similar and therefore to argue that only for some magication only I am conscious I'm the only one in the universe who's conscious makes me a very important but on any reasonable matter seems extremely implausible the argument applies a little bit farther a little bit more difficult with monkeys monkeys you know they behave if I stepped on a toe on a monkey the monkey probably would have pain just like I would certainly try to withdraw his foot or run away and you know if you look at the visual system of the monkey it's very similar its behavior as I said under certain conditions is very similar to mine it's a little bit more but you know it doesn't talk of course most importantly they go down sort of the evolutionary ladder and the mouse I think for the record most mammals are conscious what about the octopus well that gets more difficult the evolutionary history is already more distinct they don't have a real cortex they have other neurons but it's not they don't have the same brain organization what about insects like bees they're amazingly complex a million neurons can do very complicated behaviors I don't know because they're the evolutionary structures so far removed from my own you can go one step further and say what about a totally different thing like computers and again the evolutionary history right now is so radical different it's very difficult to answer that question right now in the absence of a fundamental theory of consciousness which may or may not exist if there's going to be a theory that tells us certain system, certain organizational system if they have certain properties will display these phenomenal states if we had such a theory then of course we would know which organism is more conscious for us it seems to be for biological consciousness that what's necessary and sufficient is the brain you need brain activity, you need nothing else you do not need behavior as some people claim it's an important point let me repeat that for biological organisms I'm not talking about machine consciousness for us and bugs and bees and birds and monkeys what you need is brain activity brain activity is all that you need or that's of course terribly important for my life but if you now suddenly paralyze me as happens of course in log in syndrome there are any number of people now unfortunately there's a beautiful beautiful book of a very tragic story the editor of L the fashion magazine in Paris he was 46 or 47 at my age and he had a stroke totally unexpected when he woke up he describes this on the first, the opening page the book is called the butterfly and the diving bell or MIT Press the butterfly and the diving bell he wakes up because he's totally paralyzed and the doctor tapes his eyes shut he can only communicate now with his eyes it's the only thing, it's not infrequent depending on the nature of the stroke depending where exactly it's located that the last thing on top of the brainstem are the nuclei that do the vertical and particularly the vertical eye movements so very often you might get that everything else that the person is called locked in the person has all its sensorium apparatus intact so in principle you can see and hear and touch and smell but he can't move at all he cannot move at all so he has to be artificial respirated etc so it's you know as human condition goes I don't think it gets much worse than that because you're locked in your own body and usually people die of opportunistic infections and so he describes this now he describes the state so then they quickly realize that he was such a locked in patient and he communicated through eye bling through Morse code and later on within a couple of months he learned to regain a little bit of mobility in his neck but mainly it was in his eyes so he dictated this entire little very powerful very compelling story to a secretary I guess about his inner experiences and what you can see he had full vivid in experiences of course he was reduced to living only the mental life since the physical life was impossible for him he describes it quite eloquently good question I don't know I looked into that I don't know so now it's asking a question which is okay so the question was well let me reframe the question if you could never move if you were born without any possibility of moving could you develop consciousness and would now ask are there patients who lost the ability to move very early on just after birth and that's okay so I looked into that briefly I couldn't find any such patients it's possible that those patients would die very quickly in that early age because you know if you have such a traumatic event that you lose all mobility and you're just very young and very fragile and more likely than not you would die so that is actually a good question can you develop consciousness without having ever had behavior that I'm not sure of and if you can never move you never associate what you do when you're a little baby you move your animal you flay you move your hands around you babble all of that that all is necessary in order to prime you stay in order to develop your visual system your motor systems etc if you could never have that I'm not sure you could develop consciousness so that's a very good point but certainly in these login patients or there are people with narcolepsy or there are other people with parasomias with diseases involving sleeping where for example they fall down as you might know when you go to sleep one of the things that happens when you go to sleep into deep sleep, into REM sleep is that there's a central inhibition that acts directly at the level of a motor that shuts off your motor system it shuts off everything except the eyes famously that's why you can get rapid eye movements because again they are relatively high and they're not shut off but everything else is shut off now sometimes you see for example if you have pets at home, dogs at home or when they dream they sort of run I mean in the twitch they sort of chase or cats they sort of chase and stalk so what you can do both there's half million cats when you can take out the nucleus in the brainstem that's responsible for this inhibition then the animal will have e.g. sleep stages but it'll stalk, it'll act out its dream and that's also what we would do and so we would run around and do whatever we do in our dreams and therefore evolution makes sense that we have this inhibition and some people's inhibition also happens due to normal awake behavior so of course that's not normal so they will suddenly collapse these people, it's a bit like a narcoleptic attack they'll suddenly collapse they'll lose all muscle toners except they're fully conscious inside scary thing or there's another rather interesting case of patients of the frozen addicts so-called frozen addicts in the, I think in the 70s up in Mendocino County around Stanford so those were drug addicts who all bought, six of them bought, tainted, or there was some lab in a suburb and they produced this tainted heroin that had a substance called MPTP and this, when they took this they had the high and then what happened over the next three days they lost permanently all motor control the substance in Niagara degenerated this is a toxin, it's specifically attacked in the substance in Niagara so these people were admitted to the hospital in a cataconic state, they were unable to move or what they did, the doctor says they lifted the hand like this and then over a minute the hand gently fell down I'm not going to do it here one of the patients could still open the eyes but it would take them five minutes to open the eyes and then people thought there was some sort of chronic Parkinson's they noticed that this looked very similar to late stage Parkinson's when people are unable to move in late stage Parkinson's and they gave them the same drugs that they gave them precursors of Dopamine they gave them Aldopa and then sort of the patient the frozen addicts quote woke up but so tragically part of the motor control system was permanently destroyed what's interesting from the study of consciousness when they were in these what looked like cataconic states where they didn't move at all they were fully conscious they were trying to communicate to the doctor to tell the doctor that they were awake inside yet they couldn't so all of that to say that you can certainly if as an adult you lose the ability to behave to move about that does not interfere with consciousness it's a different question whether you need behavior at some point in your life or not okay, consciousness is not unique to humans I've said that many times right now it's something that's very difficult to prove but as a gamer it's also difficult to prove you're really conscious and so just by analogy the fact that the behavior is a great continuity in terms of the hardware and also in terms of behavior between us and related species like monkeys so that's what we're going to assume how are we going to approach this in a scientific manner I showed you already of these sorts of phenomena where you can dissociate what's physically present and what you perceive and now you can study systematically and you'll see that you can study the various brain states ultimately what we're looking for what Crick and I have postulated what's sort of now become fairly popular is to look for what we call the NCC the neuronal correlates of consciousness you can hear that quite a bit the NCC, neuronal correlates of consciousness plural correlates many so what we mean we mean is that the neural mechanisms usually we talk about action potential we talk about neurons that fire these blips, these pulses but it doesn't have to be like that but that's the simplest hypothesis we're looking for an explicit correspondent between some neural mechanism and what your conscious of there has to be an explicit one-to-one correspondence because there isn't anything else in other words when you see something when I see the yellow spot for two seconds and this neural mechanism that mediates the yellow has to be on for two seconds and you know when you start when the yellow starts to fail when it becomes weaker and weaker then this neural mechanism has to mimic this fading there has to be an exact one-to-one translation between what I experienced and some neural correlate and we're looking for that and we're not looking for the global correlates we know that your heart has to pump we know you have your brainstem has to pump out various neurotransmitters like acetylcholine has to there's a part of the brain it's called the reticular activating system has to be turned on in order for the brain to be sort of awake all those things have to happen but we care about specific things like the specific mechanism that mediates the yellow or that mediates a sense of pain or that mediates a sense of me now right now knowing I'm Christoph those are the things that we're interested in so this is a cartoon it's a bit dangerous you have the outside world, you have the brain then you have the brain fires away any time you open your eyes we know that because we can put you in a magnet and we can see which parts of the brain are active large parts of the brain are active 30-40% just in response to vision but only some subset of those are actually going to be relevant some subset of neurons and again here we assume it's action potentials but it doesn't have to be like that but that's the most plausible by far the most plausible possibility that some set of these are responsible for generating the specific perceptibility of the dog when I look at this entire scene I have a lot of dogs I happen to actually look at the German Shepherd and if I now for example kill all these neurons by genetic technique or because I zap your brain using a magnetic pulse or by electrical interfering with it then although the same physical stimulus is present I would not perceive the dog or conversely if I activate those neurons for example by putting an electrode in you if you're patient and people do this we do this at UCLA if there's a patient and I put an electrode next to those neurons and I could only activate the technology of those neurons then you should see the dog even though the dog isn't present in the world those sort of experiments have been done so that's what we're interested in and then all the question we want to ask where are such neurons what part of the brain are they how do they look do they have some specific property do they have do they you know if there's some specific mode where they can be active without giving right to consciousness how does it how do these neurons relate to memory how do they relate to planning the endless sort of question what happens in very young children you know are you born with those types of neurons do you have to develop them what about in people with coma what about people you know all those sort of questions we can ask last slide I'm going to finish then so just a preamble so all of this so if you think about this over the next week it's all great fun and you hear a lot of interesting case studies of you know patients with interesting syndromes but fundamentally you always have this and I confess I also have this this problem I say to myself when I lie at night thinking about these well it's all fine and good but why you know I just don't get it how can you know activity in these neurons give rise to things like you know seeing a germ shepherd this to see I mean I know how it can be responded I know why I would run away from a germ shepherd but having this perception of a germ shepherd just seems the weirdest thing how can my brain generate that just and then I found this really interesting quote which was written in the great war but Bateson who was a very famous geneticist in fact he introduced the term genes into all language and he reviewed the book by Thomas Hunt Morgan so he was later on of course famously became the first chairman of biology here at Caltech but the time he was still at the Columbia in New York and Thomas Hunt Morgan in this in a student in the fly room they propagated the flies with a model genetic mechanism and they of course here in this book he amassed evidence to argue that genetic information stored along one dimensional strings I mean in modern language which we now know to be true and he was very much a materialist listen what he has to say here the properties of you know so this is Bateson reviewing Hunt Morgan's book the properties of living things on some way attached to material basis perhaps and some specialty to nuclear chromatin those are the chromosomes we know that's true and yet it's inconceivable inconceivable that particles of chromatin of any other substance however complex possess those powers which must be assigned to our factors of genes that's his spelling the supposition that particles of chromatin this is again chromosomes indistinguishable from each other and indeed almost of course the critical word is almost homogeneous under any known test can by the material nature confer all the properties of life surpasses a range of the most convinced materialism so here's the problem they didn't the problem at the time was and you can make lots of analogy between the problem historically when people thought about the life origin of life and heredity and consciousness and many people at the time were arguing in order to explain what life is you need some special thing we know chemistry we understand chemistry and physics and we know you cannot out of chemistry putting you know molecules together you can't get things that have a will in that personal information that can't be you need something special and so people argue you need sort of there was French philosopher Berreson who argued you need a long vitale you need this vital force you need some special magic in order to turn chemistry into into living beings today we think we know that that's not the case but they still they grapple with this problem how and what is it that they didn't know well almost homogeneous so of course they did not have they did not realize several things they did not realize the amazing specificity of macromolecules they didn't even know the idea that you know you can have things like hemoglobin where every hemoglobin has exactly the same molecular structure and the same molecular weight that wasn't realized at the time yet and then you can store prodigious amount they didn't know about protein chemistry and they didn't realize that you can store prodigious amount of information in in nucleic acids and in string of in polypeptides and so and that's why they could tell us they didn't understand how how this could work out so this is also caveat we have to bear in mind as as my closing comments that the brain is by far the most complex organism in the known universe for its size okay it has on the order of human brain between 10 and 50 billion neurons and each neuron is very very complex and these are not just like in Hopfield network these are not just all either excitator inhibitor neurons there are probably thousand different cell types heterogeneous they're very adaptable at very different time scales and we just have human we just had humans don't have any experience in dealing with these incredible complex organizations so that's why to explain why right now we have great difficulty understanding how the conscious mind can arise out of these networks thanks