Consciousness: Neuroscience, Perception and Hallucination – Professor Anil Seth

It's a pleasure to be here again it's been a couple of years, we started with two, two of the three mysteries about our place in the universe have already been sold, while the first one is literally about our place in the universe, we are not in its center. Copernicus showed We have been orbiting the Sun for hundreds of years and now we know we are somewhere, a speck in the abyss and the western spiral arm of a galaxy between God knows how many and then Darwin came along, of course, in the 19th century. . century and revealed that we are not so special among all other animals, or related to all other living creatures, we are just a twig, a branch of a beautifully rich and elaborate evolutionary tree and a third mystery and if you like the third way We still often think of ourselves as special, unique, apart from the rest of the universe, it is

consciousness

, so we all know what

consciousness

is, it is what disappears when you fall into a dreamless sleep, we will have general anesthesia, we all We will die and that is what is coming.

When you wake up again or are resurrected and it is the presence of whatever kind of subjective experience you are having, we are all conscious, now we are all having a conscious experience, it is something that really cannot be an illusion. You still think about the fact that we are conscious now here and now, but how does this happen, how does the material fill the warm, moist neurons and glia and all the things that are inside the skull, how does that generate this in a universe of conscious experience. like one of these completely intractable mysteries but it happens somehow it happens somehow inside each of our brains this combined activity of many billions of neurons last count one has about 80 billion neurons and a thousand times as many connections between neurons somehow this incredibly complex biological machine is giving rise to conscious experience, how does this happen?

Even the possibility of an explanation that can take you from mechanism to conscious experience has been considered something perhaps beyond the reach of science and this is a very old concern about the relationship between the mind. and matter or consciousness and matter is the difference between the inner world and the outer world between the subjective and the objective between the mind and the brain probably the most influential way of expressing this confusion dates back to René Descartes who caused a lot of mischief in the philosophy of mind by dividing the world into two types of things there are res Kaja tans the matter of mind and the matter and sorry, the matter of mind the matter of conscious experience and there are res X stanza the matter of matter things that metal chair boards are made of and brains and bodies are also made of and once you've split the world and the universe in two like this into two fundamentally different modes of existence, it's very, very difficult to know how. unite them again and thus consciousness. although in reality it is rather the central phenomenon of mental life and in the birth of psychology in the birth of

neuroscience

consciousness was taken as the central topic of study despite the fact that during most of the 20th century research on consciousness was considered quite disrespectful and when I started my university studies in the 90s and I was basically told not to do it and in fact I was told not to do it several times because it is not something that can be studied scientifically, although we know that depends on the brain and the brain. clear and measurable forms perhaps the most pessimistic statement about the study of consciousness was in the International Dictionary of Psychology, this is from 1989, so it was quite a long time ago, but it is still in the memory of Stewart Sutherland, who compiled this dictionary.

He was actually the founding

professor

of psychology at the University of Sussex, where I work, and the goals of consciousness were these: consciousness is a fascinating but elusive phenomenon, it is impossible to specify what it is, what it does or why it has evolved, no. Nothing worth reading has been written about it in the psychology dictionary. That's absolutely true, that's right, and that's where we were about thirty years ago, of course, a lot of sensible things worth reading have been written about consciousness before and after, and a good place to start is with the philosopher David Chalmers, who you can think of. for today's purposes as a kind of modern incarnation of René Descartes because he raises this problem of the difference between the separation of mind and matter from Kaja Townsend Rezac's stanza in a way that really focuses on consciousness rather than in the mind or mental processes.

In general, he is known for coining the term the hard problem and that is how he describes what the hard problem is. I just read the part I highlighted where it says that it is widely accepted that experience arises from a physical basis, but we have no good explanation of why and how this arises, why physical processing should give rise to a rich life. interior, it seems objectively unreasonable for it to be so, and yet it does, this is the hard problem, as Chalmers put it in 1995. Expand a little on what you mean by that by comparing it to a couple of other ways of looking at the problem and We're not going to solve the hard problem today, we're going to sneak up on it and see if it dissolves. have to be solved, so the usual way of presenting the difficult problem is to contrast it with what are called the easy problems of consciousness and the easy problems of consciousness are the problems of the rest of

neuroscience

and psychology, these are the problems of how the brain works.

How does this machine inside my skull take in sensory information? I process it in various ways to allow my body to move. To guide my behavior. To lead me to say several things. How does

perception

work? How does the action work? How does the brain work as a mechanism? Of course, not all of these extremely difficult problems are easy, which is why we have neuroscientists to try to solve them at least a little, but the intuition that Chalmers is trying to expel is that even if we reach the end of this journey and solve the easy problems to have a satisfactory explanation of how brains work as machines, we wouldn't have touched the hard problem at all, there would still be this mystery of why there should be such a thing as being an organism with a brain, why, in other words, why doesn't everything happen in darkness, that's the type of intuition of course, I think it's a really dangerous intuition because we have no idea what it would be like to solve the easy problems and what things would still seem mysterious to us or not, I'll give you an example of that in a second , so rather than simply contrasting these issues, I propose to open up the way I think about consciousness and the way I try to investigate it in the laboratory. and with colleagues it is what I call the real problem of consciousness and this says that yes, conscious experiences exist, there is no escaping it, it really is there, people even now will try to tell you yes, you know you are wrong if you think that Your Conscious experiences exist and depend on ways that we can examine in the brain and the challenge is to explain the properties of conscious experiences in terms of things that happen inside the brain and the body, questions like why does a visual experience appear the way it does?

What does it do and why is that different from an emotion? What does it mean to be a self? Why is the experience of being a self different from the experience of listening to music? For example, things like that and the idea is that if you can get closer to this great mystery. Instead of thinking it was a big mystery and trying to solve it with some special source that results in Sliven relating mechanisms to consciousness, you can simply explain the properties that we tend to attribute and that we tend to associate with consciousness in terms of things. and brains and bodies and then see how much mystery remains.

This isn't a new approach, of course, in fact, a lot of people do this all the time, but it's a good way to formalize it and frame it, it's not an easy problem because we're talking. As for conscious experiences, we are not just talking about what brains do, as long as biological machines, and it is not the difficult problem either because we are not trying to find the only special source that makes consciousness magical from a mere mechanism. Now there's sort of a precedent for this, it's not a precise analogy, but I think it's informative anyway, and that's how in the history of science we've come to understand that the basis of life now was not that long ago. time as the leading biochemists and biologists of the time considered The problem of life was as intractable as some of us today think of the problem of consciousness, that is, he worried that, no matter how complicated the explanation given, could give about the mechanisms of living systems, something would still be missing.

He would still need a special fountain, a spark of life, and an L&B towel that would make the difference between the living and the non-living. No explanation in terms of mechanisms would be sufficient, and of course we no longer think that way now. is the philosophy of vitalism that mechanisms would be insufficient for life now, of course, vitalism is quite faded and we don't understand everything about living systems, of course we don't, but this sense that life is in principle , inexplicable in terms of mechanisms has definitely disappeared and One of the strategies that led it to disappear was the idea that life is not just one thing, if you assume that life is a big scary mystery, then you will tend to look for a big solution sometime. very dramatic explanation and that's not really the case for life now that we think about life, it's made up of many different characteristics, but not all living systems share most things, that's why we have metabolism, we have reproduction, we have homeostasis of the body and all these are properties of life. systems and they can all be explained individually by things that happen inside organisms, but collectively they explain a difference between things that are alive and things that are not and then of course you have gray areas like viruses etc., droplets of oil and all that. so maybe the same strategy can work for consciousness, that's the kind of perspective I'm going to explore today: consciousness is not just one thing and if we stop treating it as a big scary mystery in search of a big dramatic solution, then We might make more progress than we think and so how well does the study of consciousness work over the last twenty-four thirty years?

Practically since Stuart Sutherland wrote his rather scathing comments in the dictionary of psychology, has the standard method been to look up the rather scathing comments? called neural correlates of consciousness, this is a figure I stole from Christof Koch, who is still one of the leading researchers and scientists of consciousness. He now he is based in Seattle and he pioneered this approach called what we now call NCC. look for the neural correlates of consciousness now carrot caricature it here is a talk with a brain he is looking at the world in the world there is a dog and he is having an experience of the dog he is seeing a dog he has a visual experience of a dog now the idea is that there will be something in your brain, the NCC for this particular conscious experience, there will be something, whether it be a pattern of activity or a particular group of neurons, whatever, that when that is present there will be the conscious experience of dog and when it is absent there won't be, so it's the idea that there is a minimal neural mechanism that is altogether sufficient for the presence of any single conscious

perception

that is the NCC and this is a really good idea because it gives you something to do, you know?

Basically, you can try to identify these NCCs by many methods, use classical methods of things like you, try to have situations that match as closely as possible, other than in one case someone has an experience of something, in another case it is not classical. This is something like a binocular rivalry where you have two different images in different eyes, so the sensory information is always the same, but the conscious experience tends to swing back and forth so that you can then see well what the correlate is. neuronal of that turn or that change. what dominates conscious experience at any given moment, that has been the dominant method and it has been dominant because you can do something, but it is also limited and it is limited because we know the correlations and not the explanations, the fact that correlates with why neither means that X causes Y nor does it mean that you understand anything about what the relationship means and why it becomes new.

There are all these amazing examples of false correlation. I think things like the divorce rate in Minnesota correlate with the price of cheese. In mid-century France, things are very, very statistically significant, but of course they have no meaning, so correlations and not explanations, so the idea to challenge for neuroscientists interested in consciousness is how we get from correlation toexplanation. It's one thing to say yes, your prefrontal cortex. It lights up when you are conscious of seeing a dog. Let's say that another thing is to explain well what that tells me about why the dog's experience is the way it is and not any other way, and I think that the closer you get to the explanation, the less mysterious consciousness becomes.

It comes back as a phenomenon in the universe, but you have to do this anyway. I mean, this is just part of what, even if there is some mystery left in the end, this is the business of science, so with that introduction, let's try and take the same strategy that biologists took with respect to life and apply it to consciousness, and one way to do it is to divide consciousness into different different objectives what are the types what are the properties of consciousness data that the science of consciousness should try to explain and a very rough way to do it is into three different things and We are going to talk about all of these three today there is a conscious level.

The conscious level is the difference between being completely unconscious and being awake conscious as you are now. It covers something, it's basically how conscious you are on a scale from not at all to a lot, so there is conscious content when you are conscious. you are aware of something right now the sound of my voice the atmosphere in this room the feeling of this seat behind you the content is what explains the content of any specific conscious scene and then part of almost every conscious experience there are some interesting possible ones exceptions, but almost all the time part of what you're experiencing is the experience of being yourself, of being a self within this within the world around you, so how do we explain the specific experience of being a person and I think that for me?

Anyway, this is where I find it most interesting because it gets to the heart of what we really want to understand, what it's like, what it means to be a self to be an individual, but we'll end there. Let's start with perhaps the most basic question, which is the conscious level, why that makes the difference between being unconscious and being conscious. The first thing to say about this is that the conscious level, this supposed scale of how conscious you are, is not the same. Just like how awake you are, we can call how awake you are, we can call that level of physiological arousal, so this graph that you will find represented in several different ways in many different articles contrasts the conscious level with wakefulness, now you can see most of the time they correlate so when you are in a coma or under general anesthesia you are both not awake and conscious and then you can sleep deeply, light sleep, drowsiness: conscious wakefulness now where you are awake and conscious, but critically you can leave.

From this diagonal in both directions, when you are dreaming, you are having conscious experiences of a different character. Now there are all kinds of interesting differences between dream experience and non-dream experience, but you are conscious and by definition you are not awake, you are asleep. you are dreaming and on the other side you have conditions that are more pathological unfortunately conditions like the vegetative state epilepsy absence of seizures in these conditions you are awake but there is no one at home you lack conscious experience that is why conditions like the vegetative state The states that follow to a really serious brain injury are very difficult to die.

It is very difficult to know what to do with them because patients still perform sleep-wake cycles, but do not respond to any verbal commands. There is no behavioral sign that anyone is home. Not at all, the clinical definition of the vegetative state is that there is no conscious experience even though there is still the presence of wakefulness, so simply knowing that these off-diagonal states exist is enough to tell us that the basis of the Being conscious is not the same, it is not coextensive with the basis of physiological arousal, so what makes the difference? What is it in the brain that holds an indication of how conscious we are?

Is it the number of neurons that are involved in anything? The brain is not making a beautiful example of that is simply considering the cerebellum. The cerebellum is often called the little brain. The mini brain that hangs from the back of the cortex. Here, the cerebellum. I'm always amazed when I remember it. -Quarters of all the neurons in your brain said before, you have about eighty billion neurons in your brain and most of them three quarters are in the cerebellum, only a quarter is in the rest of the brain in the cortex now, if you have damage to your cerebellum or a birth without one as happens in some rare cases you will have several problems you will have problems with the coordination of your body also your thinking but she will not lose consciousness you can do without a cerebellum and you will be conscious, then it is not just a crude property of the number of neurons, is it about some particular region?

Well this is a more complicated question, there are certainly parts of the brain that if damaged you will lose consciousness irreversibly and forever, there are regions deep within the brain stem. that act like this, if you have very extensive damage throughout your cortex, this can also happen, but in most cases it is where those regions have been identified, it is almost as if that is like on/off switches instead of where consciousness occurs. If something happens somewhere in particular, I mean you know that if you unplug the plug from your computer or the TV, of course it turns off, but that doesn't mean that the plug is what generates the image on your TV. screen and then it's neural activity maybe it's how active the brain is maybe it's some kind of crude signature of the conscious level.

This is also not true when you lose consciousness while sleeping or even in some pathological stage your brain does not. It doesn't shut down, activity levels change a little bit depending on what's going on, certainly while you're sleeping your brain is just as active most of the time as it is during normal wakefulness, so it's not just that there isn't a crude measure of neural activity is sufficient, but I will simply go through a long litany and history of different things that people have tried. I'm going to skip ahead more or less to today and tell you about a property of brain activity that seems to correlate specifically with how conscious you are and this is This was discovered using a method called TMS and EEG, so this is our lab. in Sussex for a few years now and, for example, as you probably know, it's just a way of recording the electrical activity of the brain with sensors that you have.

We're embedded in this TMS cap because though, how many people know what TMS is and are just trying to get some codes? This is transcranial magnetic stimulation. This is basically a big magnet and you use a pedal, you press it and then it injects. a very, very strong pulse of activity in the brain, like below this eight-bit figure, so you can stimulate the brain in this way. What this method allows you to do is basically stimulate the brain and use EEG to record the echo, it's a bit like hitting the brain with an electric hammer and then listening to what happens, so this combined method is called TMS EEG and About 15 years ago a colleague of mine at March Alamos emini, who is now in Milan, did a really amazing experiment that was published science at the time and he used this, he pioneered this method and he used this method to really see how he sees the echo in the dream and had to wake up, so when people are unconscious compared to conscious, now suppose we are looking.

I'll distinguish wakefulness from consciousness again in a minute, but the simplest contrast you can make is weight versus sleep, so what he found was that the pattern of response to this TMS pulse is very different when you're awake from work than when you're awake. when you're asleep and I can show you this in a couple of movies, this all slows down dramatically, you can see the milliseconds at the top, so when you stimulate when you're asleep you get a response for the brain to respond. stimulation but the activity remains very very local where the stimulation occurred, it doesn't spread very far around the brain, it goes back and forth but goes away reasonably soon, however when you are awake and you can see it starting again, now there is a immediate response, but then the echo changes in complicated patterns in space and time and lasts much longer and what this tells us is that the awake brain, the conscious brain, are the different parts of the brain that talk to each other in a way much more complicated. and intricate ways that happen in the sleeping brain why different parts of the brain are still active individually but do not communicate in the same way.

After many experiments like this, the group of evil masters just came up with a simple way to put number two, how complicated this echo is and they did it in a very simple way. Basically you can imagine if you treated the response as a photo over time and then asked how compressible that photo is in the same way that if you have and when you email a photo it compresses it to the shortest file size that you need to regenerate the photo, then you're saying how complicated, how much information do I need to describe the complexity of that pattern and you. put a number on that and that's the number here they call it the disturbance complexity index the offender's index of the complexity of a disturbed with the PCI index is basically the first order beginning of a principled consciousness meter and that is very exciting development because if there is something that catalyzes progress in science it is the ability to measure things and when we do the other example in the history of science where this is very clear is in temperature and heat, so it was the development of thermometers which was not easy which was plagued with controversy at the time and catalyzed the understanding in physics that heat is not a substance that flows in and out of things, it is the average molecular kinetic energy of the molecules within whatever you're measuring, so we can measure something maybe we can get here we can make progress but as you can see this, this PCI index discriminates very well different levels of consciousness here is a group of healthy subjects everyone is up here here are people under anesthesia anesthesia with ketamine in this case and they are all below when he applied the measure to patients with various disorders of consciousness after brain damage and organized them in order so that it correlated very well with their diagnosis, so that people in vegetative who are awake but not conscious fell the highest threshold for people in the so-called minimally conscious state above locked-in syndrome where people are fully conscious, they are just completely paralyzed, it is normal, so this specifically reflects the level conscious now because it works in patients in a vegetative state.

There are a couple of exceptions, such as this person here has been diagnosed in the clinic as being in a vegetative state, but shows a pci level that suggests this person could in fact be conscious, so this method is already being used in some neurology clinics to determine if the diagnosis may have been incorrect or who is recovering and who else might want to take a closer look now. You don't actually need this complicated TMS EEG device to do this type of work in Sussex. doing something similar by just looking at spontaneous brain activity, so we just record an EEG of people when they're awake, in this case when they're asleep, and we're just asking how complex the brain activity is, essentially, how random is it, how spatiotemporal contrast versus activity and we can put a number on it, so it's the same approach, we basically represent all this complicated activity of strings of ones and zeros and ask how complex that array of ones and zeros is, how compressible it is. we get a number and then we use that number as an indication of the conscious level and somehow it works too.

We have here that awake rest is higher than light sedation, which is higher than general anesthesia. We can also do the same with deeply placed electrodes. in the brain, so this was in a collaboration and it was work done by a former PhD student, Michael Shortener, our and in this case, these are from patients who had electrodes implanted deep in the brain, they are patients with severe epilepsy, so what? This often happens in people who are having brain surgery for epilepsy. They are implanted with electrodes so that the neurosurgeons can determine where the epilepsy is, where the epileptic focus is and what part of the brain to cut, but they generally have these electrodes for long enough so that you can do experiments while they are well, they are basically mapping the epileptic focus and again the same thing, we have electrodes deep in the brain and we can calculate thecomplexity and again is greater for awake rest. they are all different regions frontal parietal temporal occipital higher for awake rest than especially for early non-REM sleep, which is when you're not dreaming.

What's interesting about this data set is that REM sleep when you're dreaming is basically exactly the same as waking rest, so now this again distinguishes wakefulness from how conscious you are, so Brett in terms of this measure, when you're dreaming, your brain looks the same as it does when you're awake, obviously it's not exactly the same, but through this lens it's the same way, our most recent adventures using this technique were done in collaboration with Robin Cart Harris, he works here in London, at Imperial, and Robyn has pioneered the resurgence of the neuroscientific study of psychedelics, which was banned in neuroscience for a long time for unfortunate reasons given its clinical potential, but very little is still known about what happens in the brain with psychedelics, so as a first exploratory study, we thought we would apply the same type of measures.

Do we see changes in this conscious level index when people are basically tripping and the answer is yes, we do, so it's three different psychedelics, psilocybin, LSD and ketamine, people argue about whether it's a psychedelic or not, but certainly in low doses it has psychedelic effects and in all cases we see this increase in this level of complexity for most people most of the time, so the brain becomes more random if it likes to have freer activity under the psychedelics and it was a fun experience for us because we had never encountered it. It's interesting because there hasn't been any other situation where we've seen this measure increase from the waking baseline.

We tried several things by getting people to watch movies or engage in complicated thinking. Nothing made it go up other than this, so this is It's interesting that this doesn't hold true, we can show that you can go beyond the baseline of awake rest and of course when the media got it, they misinterpreted it for complete, since yes, we found evidence of a higher state of consciousness, as if that were some kind of real thing no, we just found evidence that the brain is more random and its dynamics go in the opposite direction to sleep, that is Different from saying yes, there is a higher state of consciousness and of course that was when the Daily Mail picked it up. having this sidebar about the dangers of LSD to make sure people didn't do anything in the city so these measures are practically useful, but why they work.

This is where we return to the need to move from a correlation to an explanation. Why something like the complexity of brain activity or its response to stimulation? Why should that explain the difference between conscious and non-conscious? There are a couple of theoretical perspectives that talk about this and they are quite influential in the science of consciousness. now and in fact they were the reason why when I finished my PhD I moved to San Diego for a few years motivated and inspired by these ideas and so I stated the obvious, the first observation is very, very simple in e2 that all conscious experience that you have is different from any other conscious experience you have had or will ever have is enormously informative in that way you can have a huge variety of different conscious experiences, each one of them is different, even the experience of pure darkness is informative in this in this sense because it's different from any other experience you're having, that's technically what information means, it's how many alternatives are ruled out if something is the case, if you have a die, you roll it and you get a number. that rules out five alternative possibilities, every experience you have rules out a huge number of possible alternative experiences, very, very informative, which is quite useful for the organism and the second thing is that every experience you have is not only informative, but it is also highly integrated.

I like this side of our illusion just to give you the impression that we don't perceive colors and shapes separately. We do not have fragments of conscious experiences floating around independently. As far as we know, we experience a unified consciousness. It seems that everything is united. every conscious experience has these properties at the level of phenomenology at the level of what experiences are informative and integrated and that sounds a little trivial, right, it was like that, so the nice thing about putting things that way is that you can start to say well what types of mechanisms, what types of systems also have this property of being integrated and informative, so you can imagine systems like the one here, where there are many small independent subsystems, which can be very informative because they can all come into contact. different states. but there is no integration, so you can't have it, so from this point of view the brain, the cerebral basis of consciousness, will not be a bunch of independent things.

It sounds obvious, but it's also good if you have an imaginary system, whatever it is that is closely connected to everything else. completely interconnected web now here everything is integrated but you will have very little or no information there is very little potential for a system like this to go into many different states everything is too close together so it is only in systems in this kind of confusing middle ground of the that people generally talk as if they are in the realm of complex systems where things are connected in some way to each other, so that there is a kind of global unity of what is happening, but the connections are loose and not entirely rigorous, so these systems like this, this is just a cartoon, of course, it can end, it can also be very informative, so how do we capture this middle ground and put a number on it long before we put a number on it?

This already explains some of the observations about the basis of the brain. of consciousness that I mentioned earlier, so the cortex is highly involved in conscious experience, if you have damage to your visual cortex, you will lose it or your visual experience will be affected, so it is certainly involved and this is a cut through from part of the human visual cortex. brain that is actually a monkey brain and here you can see this incredibly complicated network. This is a first approach to the anatomy of the visual system. It doesn't have many independent elements and it's also not completely connected.

Maybe you're somewhere in this middle ground. whereas the cerebellum, which as I mentioned before doesn't seem to be involved in consciousness at all, actually behaves if you look at its anatomy, it actually looks a little bit like this. The sarabande is often called this type of crystal structure, it is a bunch of independent semi-circuits that interact with each other seem to be deliberately functionally isolated from each other, so we can already understand why the cerebellum is not associated with consciousness and the axis of the course because the cerebellum is not the right type of organization to support this balance of integration and differentiation that characterizes conscious experience and we can get a little more sophisticated in this we can start to think about instead of just looking at it and saying yes, no, that It's simple and that's complex, we can try to put a number.

I'm doing it again like Massa Meanie was doing with his PCI index and there are several ways and we've been working on various ways to do this for years. Now there are different measures of integrated information and causal density and I will ask questions about these equations. later, so make sure you remember them and understand them fully, but that's why this field is quite exciting because we can refine these more specific measures of exactly how we operationalize this idea of ​​complexity and then see it in practice. which ones work and which ones don't and there we focus on the basis of the conscious level and there are many interesting implications for this work in addition to its basic scientific and philosophical importance.

I mentioned earlier that there are patients in a vegetative state and these techniques are already being used to identify residual consciousness in patients who have been previously diagnosed as unconscious with an evil masseuse and another colleague of ours, Tim Bain. Recently, we wrote a recent play that came out a few months ago, a couple of months ago. ago and in January we applied this way of thinking through what we call islands of consciousness and what is interesting about this, what we find interesting about this, there are now things that used to be purely within the realm of the philosophical thought experiment that are now becoming a material reality and people don't really think about them as seriously as they should be, so if you can, take this line of thinking and say a system that is complex enough in specific ways. that we are talking about, if that exists even if you are isolated from the rest of the world, perhaps it is the basis for some kind of conscious experience and I am not saying that your phone is conscious or that your refrigerator is conscious or that the Internet is conscious, but at least things made of neurons and there are now some examples of exactly this kind of thing happening so this is destiny if you like it's related to the famous brain in a vat X the real philosophical brain is how you know that you are not. a brain in a vat, but the premise is that this brain is not connected at this moment to any internal or external stimuli.

Could it be conscious? Could something be happening in this brain though? it's not connected to anything and there are some strange examples of this type of work now moving from the flossing chair to the laboratory. This was an article that really scared me when I read it about a year ago in the wild and it was describing an advance in neuroneurosurgery medicine and one problem with people who suffer brain damage is you know the brain dies pretty quickly when it lacks oxygen. and that's why your strokes are so debilitating and why brain death is death, so what?

What these people did was they said, I wonder if we can have a technology that can revive brains a little bit if they've been deprived of oxygen, so he designed this weird Heath Robinson type machine that looks crazy and you put a brain in it and you fill it up. with all these fluids and everything and they wanted to see if this brain could regain activity, so they went to a slaughterhouse and they took brains out of pigs that had just been thrown in the trash and I've been dead for a few hours, that's it and they took the brains out. brains, they put them on this, they turned on the pump and they started to see things, they started to see that the cellular activity in the brain had restarted, there was synaptic activity, this brain revived. to some extent, and this is incredibly, it's an impressive feat of medicine, but also quite disturbing because well, maybe that brain is now having experiences and if so, which the authors were remarkably aware of, I want to give it a lot credit because they were very aware of the ethical minefield they were opening up here, so they deliberately made sure to apply some sort of neural blocking agent, basically an anesthetic, to the brain just to make sure that there was no organized neural activity and therefore, There wasn't because they prevented it, but it's easy to imagine someone doing it without doing that and then we're faced with the question of oh oh, what do we do?

It is a case in which ethics needs to get ahead of science because science moves quickly towards another. example and this was something that was personally very significant to me. I was chatting to a neurosurgeon in Edinburgh a couple of years ago and he told me about an operation that usually happens very rarely in children because their brains are more plastic and recovery is much slower. better for children with very, very, very severe epilepsy, in this case I mean that the epileptic seizures can be dozens, 20 or 50 a day and, as a last resort, what surgeons have done for a while is completely remove the diseased hemisphere, this is called hemispherectomy. you can just cut out the hots, usually the right hemisphere that is involved in these types of seizures, you can surprisingly eliminate it if you do it early enough, the results are usually quite good, children lose a little bit of motor synchronization and quite the opposite. side of the body to recover and I can do it very well.

I had always wondered what they put when they take out the hemisphere. Turns out they use ping pong balls to throw, yes they are light, they don't crash, I mean why not? ping-pong balls, but now there is a new operation called Hennis ferrata and this is different because now you leave the hemisphere and you get better results that way because you are disturbing if you like the blood flow balance, you are disturbing things less if you leave the hemisphere inside so that it is totally disconnected, but it remains inside the skull and connected to the vascular system, so it is not a living part of the brain completely disconnected from everything that is inside along with the part ofbrain that is preserved this could be an island of consciousness this could be an island of consciousness that we don't know about and the third context and this is probably the most worrying of all these cases, how many people know about cortical organoids, so this is again a rapidly developing technology is developed for very good medical reasons when people are developing drugs that tend not to date, you know, tests on animals and tend not to work when you test them on humans, it's a classic thing, so What people have started to do is develop mini brains from human stem cells, they are called organoids, so they are organoids that can be anything, they can be heart-lung, they are basically lab-grown models of human organs that can be used for medical research and this has been going on for a while, but now people are developing mini brains, brain orgonites, cortical organoids, they're not really mini brains because they don't have all the complexity of not just shrinking, but they're three dimensional organized structures with types differentiated neurons in them and their shell activity. and these things can now be cultivated, they can be cultivated, you know, they can be ground by the thousand, they are being ground by the thousand and again the question arises: is there some kind of threshold where there is something that feels like being? a cortical organoid again, there is no answer, yes, but we can imagine some of these measures being useful in limiting that question, but I really mentioned it as the case where ethics again must get ahead of science and why a scientific understanding . consciousness is not just about the philosophical exercise, it's really important, that's why they like to move on to talking about conscious content, the second of these large-scale properties of consciousness, how do we explain what we are aware of here and now?

We are aware and let's start very simply with the vision. We tend to focus on the vision. It is easy to study. Visual experiences dominate much of our lives, but I always want to qualify this. Because we have other senses as well, we just don't tend to see them, but we'll start with vision and I think it clarifies a couple of important points very well. The first is that what we perceive visually is, in a sense, both. less and more than there is in the world and this is very obvious if we take something as simple as color to know that there is this entire electromagnetic spectrum of light and what we call the visible part of the spectrum is only a small part.

Cut out a thin slice of this reality and everything we experience visually is built from this small slice of what's really happening in the world, but it's not just a filter down to that thin slice of reality, we generate colors from it. and we have sensitivity. only for three specific wavelengths, but from that we generate all the colors that we could potentially perceive. Colors do not exist in the world. We have known it since Newton, our brain produces colors of the universe. I think it was Suzanne who said. Color is where the brain is in the universe and I think the same applies to everything we experience, like to anticipate where I'm going, that applies to everything, so we generate color from colorless electromagnetic signals.

I want to show you a demonstration of how The color constructed is this is called the lilac hunter illusion. If you focus your eyes on the black cross, try not to blink, try not to move your eyes, and I want you to raise your hand if you start to see something strange happening. Is it okay if someone isn't watching? a green disk spins, I think most, but if you move your eyes and blink the magenta patches will come back, but if you focus again they should all disappear and be replaced by a single moving green disk, does that happen?

Okay, great, there's no green disk, there's nothing green happening at all, what's happening and it's really compelling, so there's actually three separate things happening. The first is something we call Troxler fading, so these patches will have indistinct boundaries and if there is something with an indistinct boundary and the periphery of your vision tends to fade out and be filled in by what's around it, that's Troxler, the second fade is apparent motion, so when things disappear and reappear in adjacent slices in close spatial proximity, we perceive or infer motion between them, this is why there is no film. works, we infer motion between rapidly presented static frames and a third thing that's happening is the opposing color we see, so these magenta patches our brains adapt to them so that when they disappear, what we perceive as motion is replaced by the opposite in color space. magenta and the opposite in color space: magenta is green, there is actually a fourth thing happening here that I just mentioned before, that colors do not exist in the world, it turns out that magenta exists even less than other colors, the magenta is yes If you get magenta, you get it by mixing red and blue light, that's how you get something that looks magenta and the green electromagnetic spectrum is in the middle of blue.

You know that these wavelengths are not blue, green and red, but what we call blue. and red are on each side, what we call green, so when the brain turns blue and red it expects green because green is in the middle and it doesn't catch it, so it invents something and what it invents is magenta, which It means that the green that you are seeing is not actually green, okay, I hope that is completely clear and the idea that I want to continue with to explain this phenomenon and, in fact, all of our experiences, all of our conscious contents, is the idea that the brain is a prediction machine and here is the basic thought, this is a thought that goes back thousands of years, prominent in cat and others and in Helmholtz in the 19th century, but the idea is that you imagine that You are a brain and you are locked inside this. bone cavity of the skull you do not have direct access to the things of the world, whatever they are, what they really consist of, all you get as a brain are noisy and ambiguous sensory signals that are not colored, have no shapes or smells, they are just signals These signals do not come with labels that I am from a cat or I am from a coffee cup or even that I am from the eyes or the ears they are just signals and the brain is trying to figure out what is there. out there based on this ambiguous flood of incoming energy and perception from this point of view has to be a process of inference, the process of best guessing in which the brain combines this ambiguous sensory input with expectations or prior knowledge about the shape. in that the world is to form its best guess of what is out there and that is what we consciously perceive.

It is not a window into the eyes, it is not a transparent window to an externally existing mind. An independent reality. What we perceive is the brain's best guess. of the causes of the sensory signals you encounter and again there are a couple of fairly easy and familiar demonstrations to give an idea of ​​this. What I really want to communicate is much deeper than these rather superficial examples that I can show in a presentation. is how many people have seen this before Idul from the checkerboard, not all, some of you, so if you look at this image here and just look at the two patches a and B they should now look like different shades of gray, right, everyone you will see that yes. well of course they are exactly the same shade of grey, otherwise I wouldn't waste time showing it to you, they don't look like it, but they really are the same shade of grey, if I can prove it by putting the same picture here. and I've joined the patches with bars of the same gray color and you can see that there is no division, there is no discontinuity, it really is the same shade of gray, if you think I'm cheating by putting a different image up there.

Well, I'll just move this bar and you can see that it works here as well. It has the same shade of gray, but if I remove the bar it looks different. So what's happening here is that the brain has wired into its visual perception mechanisms that objects in shadow appear darker than they are and so the brain is compensating for that. , that's why we perceive this patch to be clearer than it really is and that is an example of prior expectations. really shaping what we consciously perceive here is another example. I don't know how many of you would have seen this before.

If they have, I apologize, but if you look at this for a moment, it should look like a lot of maybe black and white spots once you don't have much other than that, but of course it's not just that if you fill it out you'll see that it's a photo of a woman in a hat kissing a horse, you know why that photo is so there is a structure, there are objects, people, actions, behavior, something is happening in this image and if you look at it for a moment, I don't have time to leave it on first forever, but try to immerse yourself in this image for a second and If I re-image the path and drain the colors, you should still be able to see the echoes of that image in this black and white pattern, this is called image mole or two-tone image and once you have seen it.

It is very difficult to unseat it and the notable thing here is that the sensory information has not changed. All this changes. Your brain guesses better about the causes of that information and that changes what you see, so now you see at least the shadows of a horse and a person. where before there was just meaningless confusion so how do we make sense of all this in the brain? Well, this view of perception as an inference about what's out there really changes the way we think about the perception that develops in the brain. Strawman The classic way of thinking about perception is how things seem, it seems as if there is a real world out there in which we receive information through our senses and as this information filters deeper and deeper in the brain, we read it so early. stages the visual cortex can read things like edges and outlines and maybe colors and then later stages things like objects or parts of objects and then in higher stages and places like in the temporal cortex here this is a monkey brain so this is a The monkey you have reads things like faces and people and actions, so there's an almost hierarchical development from the outside in the brain that just reads what's in the world in this outside-up or bottom-up direction, which It seemed like a reasonable way. and in fact, we know that the visual system is organized this way, that there are pathways that flow deeper and deeper into the brain, but there are also many connections that go in the other direction that go from inside the brain backwards. to sensory surfaces, and in fact, there are more of these connections flowing in a top-down or inside-out direction than there are coming to the brain from the world, which is a little disconcerting if you think that perception is this The process of reading the world is more of a process of writing the world, so the way of thinking about perception in terms of prediction machines is very different from the classical view rather than perception depending on sensory signals reaching the brain from the bottom up or from the outside in what we know.

Perceiving depends just as much, if not more, if not quite well, not entirely, but more on predictions, perceptual predictions that flow in the opposite direction, from top to bottom or from inside to outside, which is why we do not perceive passively. our world, we actively generate them all the time. A sort of formal mathematical basis for thinking about perception in this way, which is Bayesian inference. Bayes Thomas Bayes was a 17th century priest who formalized how to reason with probabilities and the idea that this is what the brain does when it perceives, so the basic concept. here you go, you know some sensory data, which is a problem.

I won't look at the math in particular, this is a probability distribution, so things are happening here, but there is some prior belief, this prior belief could be things like this. a dog and this sensory data could be something like mmm animal in the distance and then the brain's best guess of what's happening is basically a multiplication of these together, so you get what you call the posterior belief, it's the best assumption of the causes of this sensory sensation. data given to your brain expectations about what is happening these expectations can be very very simple like light comes from all things in the darkest shadow you don't know where your brain has these expectations it just does everything that can be expectations that you You consciously feel like you can walk out of here expecting to run into a friend and tell them how boring and horrible this talk has been and then know that expectations will shape what you perceive when you meet someone who may look a little like your friend, but in fact It is not and what is happening in the brain is this canoe.

I maintain anyway this continuous process of inference about what is causing the sensory signals and the mechanism by which the brain does it. This goeswith a little more detail. This is the most detailed slide. and I'm not going to break it all down is that one way the brain does this kind of mathematical reasoning with probabilities is if it is continually trying to reduce the prediction error, so the idea here is that the brain's predictions about what is happening really flow into this. top down direction from inside out and then sensory signals coming from outside in bottom up direction what we used to think of as the input, you know, maybe transmitting information about the world actually these signals just transmit errors, transmit a difference between what the brain expects and what it gets at each level of processing within the brain's perception, in this case it becomes a process in which the brain continually updates its predictions to try to minimize prediction error, so ideally we perceive more accurately, if you will, when there is no sensory information. not at all because we have predicted it perfectly this really changes I want to emphasize it for me it was a kind of very radical rethinking it is so natural for us to think that the sensory signals that come in convey information about what is there in some sense that it is still true, still There is information about it, but we don't read that information to form our perceptions.

These signals are used to calibrate and update predictions and it is the predictions that are the basis of what we perceive. This is still a theory, it is not. something I want you to assume is completely uncontroversial fat, but it's a very compelling way to think about perception. I also wanted to point out that this theory of how the brain perceives perception, as you will notice, is not a theory about consciousness. I'm not saying this is where the magic happens. What it is, although it is a form, is a theory that explains the mapping between mechanisms and what we perceive by speaking in a language of predictions that go in one direction in prediction errors.

I can start writing. say things about why certain experiences are the way they are and not otherwise, why the visual world is organized into objects, for example, while the sense of emotion is not different kinds of predictions and some kind of evidence is accumulating. for this. ideas now, this is a pretty old experiment we did a few years ago and it just tests a simple hypothesis that if all of this is true, then you should consciously perceive more accurately and more quickly the things you expect rather than the things you don't expect. So we should see what we expect rather than the other way around and we tried this and a very simple experiment where people came in and in one eye they had a sort of continuous massive changing oblongs of colors that started out high contrast and faded out. and in the other eye there was an image of a house or a face and if you put yourself in this situation, you will start seeing only the oblongs and then at some point, the image, whether it be the house or the face, will break through and the You see, and what we were interested in was whether that advancement would occur more quickly if you expected to see a face and the image was a face compared to if we are expecting to see a house and the images of a face, so our predictions become confident because If the theory of predictive coding is correct, then we should do it.

If we're expecting a face, when we get sensory data from a face, that prediction should be verified more quickly and we should see things more quickly and that's actually what happens, that's just a piece of data that says that's what happens, We see the things we expect more quickly and more accurately than the things we don't expect, so you could say to summarize this. these kinds of experiments that instead of saying something like I'll believe it when I see it, it's actually probably more accurate to say I'll see it when I believe it, which has a lot of implications for media now, all of these are very important.

There are many simple experiments like that, all pointing more or less in the same direction, not universally, but we are still a long way from explaining something like the richness of the perceptual world in which we live. I mean, it's not just about seeing a face that we see. experience these rich multimodal scenes full of landscapes, objects, characters and all kinds of things. Can we take history and really explain something about the rich phenomenology of everyday perception? I just wanted to mention here a nice conference between this way of thinking. and a concept I encountered years ago in art history called viewer participation.

This is a classic concept in 20th century art history popularized by Ernst Gombrich and the most important part was the idea of ​​thinking about how people experience works of art and it. says Gombrich in 1960, that it is the power of expectation, rather than the power of conceptual knowledge, that shapes what we see in life no less than in art, so that the viewer shares this idea that what we experience is brought into an image by the observer, that is what viewers share. we, creatively, the brain creatively complete an image to generate our perceptual experience, to me that has a lot of resonance with this idea of ​​top-down predictions, interpreting, giving shape and structure to otherwise meaningless sensory signals, gone because I said there is no innocent eye that cannot perceive what cannot be classified again very resonant with these new ideas and it always occurs to my mom when I look at things like impressionist works of art because in impressionist paintings like this what the artist has managed to do is a kind of reverse engineering of a completely visual system for painting.

It is not the result of perceptual inference but its raw materials. In impressionism you're painting the variations of brightness that serve as raw material upon which the brain can do its interpretive work, which is why we project a landscape into and upon it's kind of quite incoherent, well, there's code from a distance, but you know when you get close to a painting like this you can't see that there is no detail in it, it just provides the source upon which the inference does its work, so to me this is a really important clue that yes, it is the Viewer participation is this top-down element of perception that is really responsible for giving our everyday experience the texture and phenomenology that it has, and of course this can go a little wrong if the balance between predictions and errors of prediction changes, so if your prediction is a little off in some way, you can see things that maybe are there, you might see, you might see faces in the clouds, we can all see faces and clouds.

There's a general term for this called pareidolia, which means stitching patterns on things and this is because faces for humans and many other primates are incredibly important stimuli in the world, so we have very strong prior expectations of seeing faces everywhere to be able to see faces or at least echoes of faces where there are none. faces there is a brilliant twitter account called face picks which I highly recommend you follow. There are so many things around the world that look like strange faces and you can collect them now, so if this line of thinking has legs, maybe we could simulate what

hallucination

s are like, maybe we could generate simulated

hallucination

s and therefore understand the basis brain of hallucinatory perception, which in this way of thinking is not fundamentally different from normal perception, it is like when the balance has shifted a little, it is not something fundamentally different.

We did this a few years ago with the Kessler uzuki case from my lab and what we did was take these neural networks that today are just computer algorithms that actually simulate the bottom-up pathway through a visual system and they are very , very good at classifying images you show, the image search used on the phone works this way, you show an image to the network this way, it will tell you which image is off or what is in the image, it's like reading the information of the image in the bottom up direction, but what we can do is basically run it backwards and this was first done by Google, they called it deep sleep and we took the same idea and did it a little bit more differently and We said, well, let's fix the top. level and we basically say dog, there is dog and then for every image we show it it updates the image instead of guessing what's in the image until the prediction error goes away so it basically says update the image so it fulfill your dog prediction.

So what we did was we took a panoramic video of the Sussex campus to make it a 360 degree video and then for each frame we applied this algorithm so that the algorithm is a towering dog for each frame and then we make a kind of movie and People put on a virtual reality headset and look around and have a very strange experience. This is like it's a lot more powerful if you actually use the screen to be able to look around, but there are too many dogs here, it's usually not like that. They look like this and what's intriguing here is that these are not just dogs photoshopped into an image right there, but rather they are organically emerging from the scene and this may not be the case.

People try to say well, what really is a model? Perhaps it has some affinity with things like psychedelic hallucinations rather than psychotic hallucinations and is the clue to what happens in the brain when we have experiences of this type, but the most important thing is that it is clear that this is what happens all the time We just don't notice it when the balance is normal, but if you tip the scale one way or another, strange things start to happen, so this way of thinking tells us that you know that hallucination is a type of uncontrolled perception. in which our best guesses are not held back by things in the world and, in the same way, we can think of normal perception in the here and now as a kind of hallucination, but a controlled hallucination in which the best guesses of the brain maintain control of the world by treating sensory information as a kind of prediction error signal what we perceive all the time is a hallucination but it is a control for this nation this does not mean that things do not exist sometimes they misunderstand me and people You say so it's all a hallucination go jump in front of a bus I don't like it is the way the bus appears in our conscious experience, which is a controlled hallucination.

Buses have solidity and extension that don't depend on the existence of my brain, which is why you shouldn't jump in front of one now. I'm going to order. I want to end this section by just hinting at how far we can take this story because I've shown you that we've gone from very limited experiments and small color demonstrations to faces in natural scenes and paintings that we're working on. In the lab, the line I'm trying to follow is that this applies to everything, not just the specific contents of what we experience but, for example, the perception of time.

Time is a very disconcerting phenomenon. I could continue with that during another lecture. you know what it is why it flows it's baffling to physicists as it is to philosophers as it is to neuroscientists but we experience time we experience worship we experience in the moment of them now we don't have time sensors inside our heads how do we do this? We have a circadian clock that causes us jetlag but we don't have some kind of stopwatch in our heads to measure time and if we did that wouldn't solve the problem anyway it would be like saying I hear because I have a bit of a band in my head that plays music How do we perceive time?

So Warrick Roseboom, who also works with us at Sussex, has long been promoting the idea that time is the brain's best guess about the rate of change of perceptual information in The scene in which a lot of things happen is prominent, while we tend to experience the duration being longer, so we tested this idea. What we did was we took a lot of videos of this - a cow in the field next to our lab, but we also took videos of busy city scenes and all kinds of different scenes that humans rated and actually rated the busiest scenes. like they lasted longer than the unoccupied scenes and showed all kinds of other biases that people show and then we retrained a neural network like ours.

We use the hallucination machine to detect things that happen in navigation and then we use that network to generate an estimate of the duration and it matches the human data very well, so now we can start to understand time as a kind of inference about what is happening in our perceptual world that we construct is from our senses and it is not just the moment there are also changes now change again this seems like a funny thing right, things change what they do not change and if things change in the world then surely yes we arelooking now we will see, we will experience them as changing, it seems reasonable to assume that and this, of course, is also not true just like time, just like color, just like the nurse dog or the canals, change is something that the brain first of all it's your best guess of what's going on in the world so sometimes things can change and we don't experience them as changes so this I don't know if you've seen before if you've noticed but all the The bottom of this image has changed color while talking from that color to that color.

Probably no one noticed that color change, no, so this begs the question: what did you do? Some people say well, what's weird because I didn't notice the change, so I was still noticing this color or this color at the end. The resolution of that question is no. You were perceiving that color at the end but you did not perceive the change. Change is a separable aspect of your perception, change in perception is not the same as the perception of change. There are people with certain types of brain injury who cannot perceive change, so they perceive the world in static snapshots, but actually experience the loss of that part. from your experience, whereas here you just didn't, you didn't even notice that you weren't receiving changes, you just didn't perceive the change and perhaps the most fundamental thing is something that we are seeing right now, we have the impression that what we perceive is real Yes, I perceive these openings, you exist, but I perceive you as if you existed in the world and not as inferences that my brain makes.

I perceive colors as properties of the world. Norah constructs with my brain, why is this? Why do we perceive that things really exist and this is what they are? I think that's actually why people think that consciousness is such an intractable problem because we perceive the contents of our experience as real properties of the world and it all becomes very, very mysterious, but this is also an aspect of perception. that builds the brain. Sometimes we don't experience things as real. If you stare at the Sun, have an image of laughter on your retina, and you don't experience that as a real part of the world, it's a glitch. vision and you experience it that way, many other examples like that, there are some psychiatric conditions like depersonalization and derealization, people don't hallucinate, but they experience their worlds and themselves as lacking reality, so we are starting to experience early games with this.

The idea is also a video in progress, but what we can do here is Alberto Mariela from the lab and we again take a panoramic video in the lab and then people come into the lab and sit exactly where we took the video. and it was a headset with a camera on the front and so you look at the real world through the camera, but then at a certain point we changed the input to the pre-recorded video and if you do it smart enough, people don't do it . Notice that what you are experiencing now is not real, but you experience it as real, so we can use this intervention to begin to analyze how far we can take things before people lose the perception that it is real, which is something really fun to do.

We mess with people this way, so that's the end of the content section. The take home message is that what we consciously perceive is the brain's best guess about the causes of its sensory input and now, in the last 15 minutes, and then I'll finish with the questions. I will talk about the self and when I talk about the self, the main point here is that the self is not what you think it is. I'm not sure what you think it is, but it's probably not what you think. I think there's a natural way of thinking about the self.

This is the sort of straw man version of the self. There's a world out there with things that provide sensations. There's a self that's the doll. All of this wonderful information that the self reads. It forms a perception. of the world there we go and then it performs some action and we get new sensory information the self is the type of perceiver the self is the one who makes the perception now I don't think that's right at all I think the self is also a perception it's not what Is perceiving oneself a perception? A consequence is another type of controlled hallucination.

It is another type of controlled hallucination. It is another type of brain-based hallucination. A clue to this is that there are actually many different ways in which we experience being ourselves. There is the experience of being a body and being oneself. having this particular object in the world that is my body and this is not my body there is the experience of having a first-person perspective of seeing the world from a particular point of view there is the experience of trying to do things being the cause of the actions that do not have free will, people often say that there is a narrative self, the experience of being a person continues over time, for months, perhaps for years, and there is a social self, the experience of being you is refracted partly through the minds of others, so I experienced being me, the experience of me is partly defined by what I think you all are thinking about me and all these aspects of yourself that can be separated and I'm not going to go through them, but they may find, for example, a neurological or psychiatric condition or an experimental manipulation that can independently manipulate all of these different aspects, which suggests that this thing that we experience as being a unified self is a construct because it can break down in many ways. different.

I will give you an example which is the body. I, so we experience part of the universe as if it were my body, our body, and the rest is not, we somehow make this distinction, it's called body ownership experience and the idea here is that again the brain is doing its best conjecture about what the body is and what it is not and there is a very well known demonstration of this and I am sure many of you have seen this before but I am going to show you again how many people have seen a rubber hand illusion experiment .

Not everyone is fine, so this is the rubber hand illusion experiment. It's very easy to do. You can do it at home. All you need. I'm sure everyone has a rubber hand at home. So if you take someone, you put their real hands on them. so they can't see it behind a partition, they focus their attention on this fake hand and then experiments the guy in green here takes brushes and simultaneously strokes the real hand and the fake hand while people focus their attention on the fake one. hand now imagine being this person's brain what is happening you are this person's brain you see something that looks more or less like a hand and you experience touch because you are touched and you see this fake hand being touched so it is a good evidence for the brain to make a better guess, well, you know, it doesn't really seem like it's not my hand, but whatever, yeah, I'm getting all this evidence that I'm going to come to the conclusion that somehow It's in my hand and it's "It's a very, very strange experience and a way to test it.

You know you can measure smart things like skin conductance and all kinds of things, but the most fun way to test it that will be demonstrated here is do that and so you can." I can't say without any clever statistics that this guy has assimilated to the fake hands on his body in some way. We love this experiment so much that we did the world's largest rubber hand study last year in Sussex with 500,400-something people we did in the rubber hand illusion which hilariously involved post-operative bleeding. Had to spend about three days with a nail file filing these rubber hands because they were too shiny when we can find them where we ordered them and then we ran all the psychology.

The first year in this experiment, the reason for this is that we wanted to understand individual variability because, actually, analyzing this this illusion works much better for some people than for others, what is the difference that makes that difference and it turns out that the story The standard rubber hand approach is about integrating sensory signals from different modalities, touch and vision may not actually be what is happening. All this graph shows is that it really matters how hypnotizable you are, so we also measured the hypnotizability of each of the students. your response to the imaginative suggestion is the more modern way of saying it and it turns out that if you are highly hypnotizable you experience the illusion very strongly, it is almost as if the experimental context encourages you to have the necessary bonds to have that experience and if you are not hypnotizable you don't have it much there's always a difference between when you stroke the hand, the fake rubber hands synchronously where it works and asynchronously where it doesn't work, but the actual experience that people report depends entirely on how hypnotizable they are, so that It was just another one, so that's part of the top down, if you are very hypnotizable, you will impose top down suggestions more strongly, you can do it.

We've also been doing other versions of this for a while, this is the so-called body swap illusion, here there are two people wearing headphones and our cameras in the front again look at each other and we swap feet so this person see herself through her eyes from her perspective and vice versa and then we have them shake hands and when they shake hands you get this kind of critical stimulation of the multisensory system that again the brain makes a different best guess like oh , I actually have to be there and you get something like an out-of-body experience that you see for yourself. you feel like you are seeing yourself from an outside perspective.

I think I'll skip that and I think this speaks to a more general invocation because for millennia people have been reporting things like out-of-body experiences and interpreting them as evidence that the soul must have an immaterial basis because we can experience ourselves floating free of the material body, so it cannot depend on the material body, which of course is totally wrong to think hmm, we will talk, do questions and answers at the end. but you, you, you, so people have these experiences, so the first things that people have are the experiences that they say they are having, but having an ounce of bodily experience is not evidence that the soul is immaterial, it's just evidence that there are certain conditions under which the brain makes a very unusual best guess about where the first-person perspective is, so I'm coming to the end now and I'm going to jump very quickly to this last part, which is that we experience our bodies not only as objects in the world, we also experience them from within.

This is called interreception. There is a large part of the brain that is processing and controlling signals that come from the deep physiological interior of the brain. After all, after supporting us. Alive, this also helps us understand other aspects of conscious Salford, for example, we can think of emotions as also types of perceptions based on exactly the same principles, but emotions are now perceptions from inside the body, so they are only a visual experience as a prediction about visual signals, emotions, we can think of as the brain's best guesses about changes in interceptive signals coming from inside the body, which basically tell the brain how well it is doing its job of keeping up with life and, if you think about it a little, rather, it has a subjective meaning, people, this is not up to date, this is only when people report different emotions in their body, we all notice that we tend, for example, to feel anxiety often on our fingertips or somewhere and pride in our heads of course, so Anyway, movement is a very embodied type of experience and it turns out that it probably depends on the perception of these internal body signals and also begins to hint at why emotions are different from, say, visual experiences.

Metaphorically, emotions can have forms of pain, they can be acute. they have a dull level of anxiety but they are not literally sharp or dull they have no shape in the same way that the table here has a shape why not well the vision is trying to discover what is distally in the world for what shape is a It is a useful way to summarize sensory data, but body data reflects how well control is going, how well I'm doing at staying alive, so emotions are structured that way, we tend to feel good or bad in various ways. degrees instead of round or square, but it's the same basic principle.

I'm going to skip it and yes, this just means that our experience in the body is very different from experiences in the world, but they can be understood in the same way as predictions, but predictions that have different functions and this is again what I mean. from the beginning in moving from correlation to explanation and if you take this line of thought - it's a kind of maximum and I this is and I've been thinking about this line where you come - it's that the experience of being a self is so intimately linked to our nature as living organisms that for a long time peopleYou tend to think of the brain as a kind of computer that the body carries from one meeting to the next, and you've tried.

In a way, separating the body from the mind and consciousness and in Descartes and using it again is quite responsible for this part of us is driven by the need to make ourselves special and not similar to other animals, of course, we are very similar to other animals, but if this, if the perception mechanisms of any type of Ellucian perception are loosely rooted in the regulation of the body, that is why we have perception in the first place, everything we perceive can be traced back to the origin of these mechanisms of prediction that are ultimately oriented toward the regulation of the body, so that we cannot understand our experiences of self and world except in light of our nature as a living organism, so that we perceive the world we pass through and for the fact that we are living organisms, and this is a conclusion that I don't really hope to approach you, but I'm glad I did.

It is a very satisfactory way of recognizing the importance of what differentiates us from machines, from computers, from robots, something fundamentally different, without saying that only living beings can do it. be conscious maybe maybe I don't know but we can only understand our own human consciousness in the light of our nature as flesh machines like beast machines so let me summarize and then I'll stop this is the kind of content and I united so that what we perceive is not an object a direct reading of a mind-dependent reality is a best guess based on the brain a controlled hallucination this applies also to the experience of what in the world our body is an element I don't have time for the same argument, but it basically applies to all other aspects of the self as well, but self-perceptions aren't about figuring out what's there, they're about control and regulation, so what character, the way we experience being self, is fundamentally different from the way we experience being the world, but it is not the self that perceives the self, it is a type of perception, so what What we should remember from this section is that instead of I think, therefore I am, I predict, therefore I am, I am the child of your set of a whole collection of predictive perceptions related to oneself, so let me, I have five minutes.

I'll recite a couple of implications and stop at one implication from all of this. If perception is a matter of construction, we all have different conscious experiences. our own personalized personalized universe because we will all have different, to some extent, prior expectations about what is happening. Remember to get dressed. How many people see it as blue and black? How many people see it as white and gold? Yeah, that's pretty good. split right so this is a fun example of how given the same image we see different realities, the actual dress by the way is blue and black so those of you who think it's white and gold are actually wrong , but we will see it differently and I think this has a lot of interesting social implications, if we really perceive things as real, it makes it more difficult to understand it.

Other people may have different experiences and if you can't recognize the potential that other people may see things differently then it's harder to talk to them and therefore it's a bit like the echo chambers of social media. , but you actually delve into basic levels of how we perceive and experience the immediate worlds around us, the second implication is that we can now begin to shed new light on many psychiatric and neurological disorders that are very cruel to psychiatry and, until recently , it is mainly about treating the symptoms rather than understanding the The mechanisms that we can give painkillers equivalents of painkillers make people feel positive or negative, but we cannot give the equivalent of an antibiotic for a psychiatric disorder, but if we start to understanding things like schizophrenia, Tourette syndrome, anxiety psychosis at a mechanistic level of perceptual predictions.

Being altered in specific ways that open the way to a proper mechanistic understanding of psychiatric conditions and a new era for psychiatry, the next implication is that we think that if we can think about the conscious worlds of other creatures, it is easy to assume again that maybe other animals to the extent that they are conscious have some kind of diminished version of how humans experience the world because we would like to put ourselves at the center of everything, but think about what the experience of being a self for an octopus could be like. octopus has about 500 million neurons very, very, very intelligent very intelligent creatures, but most of its neurons are in its arms, which are relatively autonomous, so it is not clear that an octopus would need or have any sense of where It's his body in space, so what would it be like to be an octopus that you wouldn't have? a clear experience of being a specific body and I think that then feeds back into the way we experience ourselves, it's just a point, a small region in a vast space of possible minds and ultimately this whole idea that the experience and conscious perception are based on physiology and our I think nature as living organisms means that consciousness probably has more to do with life than with intelligence.

We tend to associate consciousness with intelligence again because of this pernicious anthropocentrism that we all have, that we are special and we think we are special. We are intelligent and we are aware, so the two must go together, which is why I think people in artificial intelligence always talk about when systems become intelligent enough, at some point the lights will turn on and they will be aware of why the People make that statement it's not entirely clear to me being intelligent allows you to be conscious in different ways because we can mentally travel in time. I can experience not only sadness and disappointment but also regret and anticipate regrets.

You have to be smart to experience these kinds of horrible things. things, but they are just different ways of experiencing things, consciousness rule mechanisms have to do with being alive, not being intelligent, so this has implications for things like AI. What would it take to build a conscious machine? Maybe you have to build a living machine first. or at least the machine that cares about its own persistence in time so close to ending we have solved consciousness what time it is how we solve consciousness not in the sense that we have found some special source that crosses this chasm between the subjective and the objective there is.

I haven't given you any kind of magic ingredient that will solve the difficult problem. I'm agnostic about whether that will continue to be a problem, but instead we've crept up, maybe we need a special font, maybe it still exists. some already know about the Eureka moment and we will look back on it and think that yes, that's what happens, that's what makes the difference, well, maybe there isn't a hard problem, maybe certain clever philosophers will finally be convinced that we are wrong . There is nothing to explain about being conscious, but I prefer to admit that conscious experiences exist and what we have been doing is focusing on explaining, predicting and controlling the properties of subjective experience in terms of mechanisms in the brain and body and that In general, it is what science does now in physics, science has not told us why our universe exists in the first place, we do not really know what is out there, but it is a successful science because we can explain many phenomena, we can predict what what is going to happen. and we can control things if we can do so with respect to the biological basis of conscious experience, we have done what a scientific research program can reasonably be expected to do, we may think that it is not enough, but that is again because we could think that they are somehow special, so what I would suggest is that instead of solving the hard problem, this approach dissolves it and, as we progressively understand why experiences are the way they are and not otherwise, this great mystery of the existence of consciousness will no longer be resolved.

Be so mysterious and I leave you with what then arises what David Chalmers has called the metaproblem of consciousness. Why do we think there is a difficult problem of consciousness? Why does it seem so mysterious if we can understand the intuitions that guide us? and to think that there is something so inexplicable about the relationship between mechanism and phenomenology, then I think we will be on the way to dissolving, if not solving, the difficult problem, so I will end there and this, so again I point to the book, in reality is me. I just discovered it today, it has a publication date of February 4th, so I need to finish it, not this February 4th, the next one every 4th, there is a TED talk, there are other ways you can follow things for me, it is like a three and a half hour interview.

With Sam Harris, if you really want to torture yourself, you can listen to him and just be grateful for the help of many people in the Sussex lab. You've done a lot of the work I presented and I'll leave it at that. and thank you for your attention and we have about 20 minutes for questions, yes, yes, so I'm going to try and I was asked to repeat the question to the rest of the audience today, which everyone can ask in general about the following experiences of surgery. So what do we really know about how these changes in the body can actually alter a sense of self?

There are many different things that happen in the body, especially in the intestinal area, there is the microbiome that each of us had and that we were populated by. a distinctive set of microorganisms and there is interoception that is related, which I already mentioned, that many of the signals travel through the vagus nerve. Yes, there are many groups working on this. Ours in Sussex is one of those made by Hugo Critchley and Sarah Garfinkel. most of the interoceptive work that the experimental level other groups in Zurich do a lot of things and now in Aarhus in Denmark and there is so much evidence that the body and changes in the body affect our mental states much more directly and profoundly that we have recognized it previously, so I've actually written some things before about how we can understand things like the condition called depersonalization, which is when things that feel unreal like a disruption in interoceptive prediction and there are other people talking about similar things for anxiety.

Also for depression, the challenge in all of this is that it is really very difficult to manipulate and measure the signals within the body, because when most people focus on vision, I can show them that they have very tight control over what they do. I show them visually and in a way. which I just don't have when everything is closed it's tied up inside the body so it's very difficult to do but that doesn't mean nothing is happening in fact there are now only glimpses of research programs looking at the microbiome that had . A chat with a leader of a microbiome program in Canada last year and I hadn't really even thought about interoception, which I thought was a little crazy because presumably it would be a mechanism by which the microbiome could influence the brain, so What these kinds of things are just starting and I'm sure you know there's a word, there's a lot of evidence for vagus nerve stimulation as a treatment for things like depression and others, but this is all very ad-hoc, you know. that works and again the vagal nerve.

The vagus nerve is targeted because it's accessible, it's relatively easy to stimulate the vagus nerve compared to what you do in other ways inside the body, but it's actually an emerging frontier, even beyond our kind of specific term. field for him, people call him. computational psychosomatic s-- ok, let's see, we'll go there yeah, yeah, fascinating talk, thank you very much, moving on to the last question. I'm just curious if you have studied or are planning an area, they are two separate areas. things in an area and a population in an area, I recently read a study or a report that says people are born blind.

Well, there is not a single known case of someone who was born blind and then developed schizophrenia and much of what you presented was based on vision. So I'm curious if the same model you're presenting works. Do you think it would work as well as people who are born blind or just use senses like touch and that kind of thing and then the other population? I'm very interested in long-term meditators and people who struggle and sometimes say they achieve a loss of sense of reality or a loss of sense of body, but they still function anyway.

I'm just curious if that is included in your research. Okay, so the first question was about this interesting article that comes out of the Philco Let's group at Yale that points out a fad that we don't know about.I was aware until I read it. At least I haven't read the full article yet, but it does indeed seem to be the case that people who are born blind are somehow immunized and insulated from schizophrenia, let me take that first one, okay look, I don't know what they're going to call it. , says about this, it's intriguing and what comes to mind so often explains that you get afflicted as a combination of two things, a z' hallucination and delusions, so false perceptions and false beliefs, and the idea is that If you have consistent false perceptions, then ultimately your brain needs to explain these false perceptions and that induces delusions, so I can make sense of false perceptions if I have strange beliefs about the CIA controlling me or something, So it could be that the development we call the etiological pathological trajectory of schizophrenia almost always passes through vision because it is such a dominant sense that false perceptions are first formed through vision and then transcribed into false beliefs.

I'm not, actually I am, but this doesn't make sense because actually the most prominent symptom in psychosis is auditory hallucinations, so maybe you could tell a different story. that, in fact, blind people have better hearing systems, so they are less susceptible to hearing. I don't know, but it's a really fascinating perspective. The second question was about meditators, super interesting again. There's been a lot of neuroscience crossover between the mindfulness meditation community and a neuroscience community. I've attended a few neuroscience meditation retreats over the years and it's wonderful, you know, it's clear its clinical and lifestyle benefits, It's a wonderfully interesting manipulation because long-term meditators actually report substantial changes in how they experience especially themselves, you know the body that you can have feelings of ego dissolution in meditation, a lot of meditative practice is really about training attention. , so you are learning to pay attention to recognize your thoughts as thoughts and your perceptions as beings. perceptions and I think this is so you can imagine now the beginnings of a cognitive neuroscience of meditation here where we really understand that meditation allows you to have this little separation so that you realize that what you perceive is not how things really are. and that also applies to yourself and that's of course where the benefit of meditation comes from, that you're not stuck in the reflective cycle of thoughts and perceptions, so yeah, I think there's brain imaging stuff. , there are new monks like the mature Ricard, who is the one who has been the Dalai Lama's French translator, put himself as a guinea pig, has done, I don't know, tens of thousands of hours of meditation in the Himalayas and You'll put yourself in a brain scanner and in one minute it manipulates your level of mindfulness. mindfulness and we see what's happening in the brain, that's pretty much yes, it's happening, but it's kind of the opposite of hypnosis, by the way, that's another way of thinking about meditation, so in the In hypnosis you receive a suggestion to experience something and you are not aware that you are following that suggestion, so it is like a lack of attention to your own perceptions and thoughts, whereas meditation is the opposite and in fact, if you observe Across populations, you will find that mindfulness traits correlate with hypnotizability traits, so people who do score high on meditation scales score lower on hypnotizability scales, so I I was wondering if going high relates to Michael Graziano's attentional schema theory that consciousness is how we represent attention to ourselves and also how we tend to see consciousness in ourselves and others. as we say seeing faces in clouds, okay, so this is a question about another researcher named Michael Graziano who has a theory of consciousness called attention schema theory, which I'm not going to answer at length because it requires explaining in detail what it is. that theory. which I don't want to do here, but basically I don't really like it and the reason the basic idea is that consciousness somehow happens because we build a model of how our attention works, it's a model of what we pay attention to. at some point it probably has something to do with it, it can explain a lot about the relationship between attention and conscious awareness, but I think there's still this little confidence trick that emerges and that's where the magic is and I don't do it.

I don't like it that way, I prefer to think more in terms of what I hope I have been doing to explain the specific phenomenological character of different types of conscious experiences. Attention plays a role in all of them, but I don't think it is the magic solution to exploit them. That makes a difference. We are talking about the implications for psychiatry. I'm particularly interested in anxiety and depression, when you could say something about that, yeah, well, there's, you know, I'm not a psychiatrist, I don't have a medical degree. The training that my co-director has at the center is the chair of psychiatry there, so this was really the motivation, the practical motivation, to get into this and find better approaches within psychiatric psychopaths as we talk about when it comes of anxiety and depression, there are some very interesting ideas that again link these phenomena with interoception with aberrant ways in which we perceive and control the body, so there is a theory, an idea about depression that needs to be tested and find out how. try it, but the idea is that when we start to develop depressive symptoms, when the brain comes to a kind of inference that it is not controlling its body very well, it is a kind of failure of what we call physiological allostatic regulation, that there is this type The conclusion the brain reaches is that no matter what it does, its physiological regulation goes wrong and that is why you often see a trajectory from a kind of chronic fatigue to depression.

You can explain that trajectory in the same way, it's just an idea. that there are many others, but they all seem to involve a physiological dysregulation like second CDs, okay, yes, I am serious, but yes, I mean, meditation is very useful, I do not repeat, it is not a panacea, but training your attention to the interceptive processes you can begin. To know, you disassociate yourself from the immediate experience of depressive symptoms to a certain extent and the anxiety that people have thought about anxiety is a discrepancy between what your body is telling you and where you want it to be, so this idea of that anxiety is a kind of interoceptive prediction error we know that there are many connections between the body and anxiety that if you present certain stimuli in different phases of the cardiac cycle you get different effects on um, like the fear that you feel when faced with a stimulus that induces fear and this is mediated by anxiety as well, so there are all kinds of clues that these intercept processes are very involved, but there is no kind of innovative approach that takes advantage of this, it is still difficult to solve for the reasons that were mentioned previously. very difficult to manipulate and measure at this level thank you fascinating my question is about the implications for psychotherapy in general, especially with psychotherapy that focuses so much on the self and so-called self-enhancement and self-training, I'm really interested in whether all your research questions can reframe the type of questions asked of clients and patients in general, that much of psychotherapy is based on hypothetical theories of the past, but not necessarily on body-based physiological discrepancies, maybe yes, so The question was about whether these kinds of ideas inform and perhaps improve psychotherapy and I hope so, I'm not a psychotherapist, but certainly by offering some potential more mechanistic descriptions of these processes, maybe they can fill in some of the kind of things that otherwise relatively vague associates and suggestions that come up in psychotherapy, of course, it works as practice and cognitive behavioral therapy and things like that, yes, it works, but we sort of dig deeper and understand a little bit more about why these things work and why they might work. different for different people I also think that's one of the key things that I think every body involved in psychotherapy or psychiatric medicine knows that people are different and that you can't have one treatment for everyone and if we start to understand the true basis mechanistic of why people feel what they feel, that could also help personalize these types of treatments, maybe you know that you can even have a very, very cool beard, you might find that some things work for people who are highly hypnotizable , other things work for people who are highly practiced meditators, it could be like that, but yes, I think there is a lot of promise.

What always scares me is this kind of too fast approach to science. Enlighten them to say that science has proven it. that this job called it or these things and kind of overconfidence and trying to use a little bit of blunt authority that says like science says this, so believe it, here's a picture of a brain and yeah, I don't like that picture of brain stuff, okay, women in the red sweater and quick questions, the experiments on the level of consciousness and any complexes that you see in different activities, etc., have you ever had a chance to test where people are when they sing or when they are dancing when they do something like that because it just links to the interception question.

I wonder if it would be fascinating to know whether those kinds of things where you integrate the body really lead to a higher level of consciousness or not, and we Obviously I've linked to the comments that were just made about psychotherapy and so on, yeah, so I ask about singing, dancing, if they somehow affect these measures of the conscious level, which I think I didn't really want to describe as a higher level of consciousness. but as a measure that reflects this, there's this scale of dancing, definitely not, I mean, if you can get someone to dance while they're perfectly still so their head doesn't move so we can imagine, then that's fine, but that's usually not very feasible, so part of The problem is the experimental limitations in acquiring the data.

I think it would be very interesting to do it, but you typically can't do brain imaging in these highly mobile situations, you just don't get it, you don't get clean data, I think. It would be nice to see that there are people that you know can get into mode using EEG headsets and stuff, but as soon as people start moving their muscles, the signal from any muscle just overwhelms the stuff it's getting from the brain and it's really, really complicated. Okay, so my question is, well, a relatively recent development in the study of consciousness, specifically, is the Templeton Research Award, which compares information integration theory with global workspace theory. .

Now it seems to me that you know that you are drawing some ideas. of integration information theory, but it's not specifically, you know you're not a big proponent of that if I understand correctly, but more generally, I just want to know your opinion on the Templeton research grant, okay and Yes, one thing would be the results. Okay, I'll try to answer this very quickly, so this is a question about a new initiative by this group called the Templeton Foundation and what they are doing is investing tens of millions of dollars in research groups with the goal of the idea being that we have too many theories of consciousness, we need to narrow the field, so let's get different groups talking to each other and propose an experiment that regulates, to some extent, disambiguating competing theories, so I've been involved in advising. on this initiative for a while and I think it's good, the problem that I have with it, I think the problem that you will find is that all the theories, there are many theories out there and they are all theories of different things, they all say that the theories of consciousness, but they are all, they all define consciousness slightly differently and make different initial assumptions and they are not equal in their ability Amin to do experimental testing, so you have to say it bluntly, because you will get their apples. and oranges is very difficult: it won't do what they want, but it will be useful because even getting people who are loyal to different types of theories to agree that a particular experiment will be informative for their theory that it will count a little against or for it is a very useful exercise.

I'm going to go to another workshop to come to Compaq. Predictive processing against integrated information theory. My problem is predictive processing. It is not a theory of consciousness, it is a theory. of how the brain works that is useful for consciousness, so it cannot be disambiguated from a theorywhich claims to find a special kind of place, so I think it's kind of flawed but useful, so all these things are going to fail, but they're going to fail in interesting ways and that's okay, that's what we all do well, thank you , regarding what you said about the brain being a prediction machine, it reminds me of the multiple draft model postulated or at least written by Daniel Dennett in which He says that there are several parallel processes in the brain that represent various perceptions and when They reach a certain threshold, it becomes a conscious experience, whatever that means, and I was wondering if there is any evidence or neurological evidence of such internal feedback loops in the brain. that that reinforces those processes, yes, so this is a reference to the philosopher Daniel Dennett, who is one of my long-term inspirations and mentors.

He had a theory since dawn. He wrote a book in 1990 called Consciousness. I explained to him what the best title in the world is because of course it's not and people call it consciousness explained and part of that is this idea of ​​multiple drafts, multiple drafts is actually a theory of the self in which we have everything these types of partial narratives and none unique. sensor where everything comes together where the self resides and, you know, I'm very sympathetic to that, well, I think the theory struggles because it's not really a theory of perceptual experience and it's very difficult to pin down Daniel on whether he thinks or not.

Perceptual experience is something we must explain. He'll say yes, yes, perceptual experience exists, but they're not what you think, which I think is great, but in terms of evidence, it's actually evidence that Dennett would like to overlap considerably with evidence of what which we have also called global workspace theory, so there is not a single place but a network of regions where when something has access to that network that is the moment when consciousness occurs. I haven't talked about this theory today, but it is very popular. theory because again it's pretty testable, you can see if you see this big network of activity when you're aware of something and you do it in some cases, but there's some evidence that that lines up very well with the multiple draft theory, but I think the theory itself doesn't work for me anyway, it does what I would like a theory of consciousness to do, but having said that Daniel Dennett is always right, that's fine, thank you all very much for your patience and attention.