WSU: The Biology of Consciousness with Christof Koch

right so we heard a lot about very beautiful data about observational astronomy and cosmology so now we're turning from the mind of course behind all the data is in a mind the mind of the human observer that peers out at the universe and wonders at how the universe came about so what we're now going to do in the next hour we'll turn that those telescopes those instruments inwards to look at the brain that gives rise to the mind right because ultimately it's uh we believe and all the evidence suggests that it is the brain that that gives rise to experience and including the desire to understand the the world so how can that be so that's the problem of mind most badly construed particularly the problem of consciousness which has been over the last uh 2300 years at least of 2500 years of western inquiries into this primarily a philosophical problem but now increasingly over the last century and a half it's turning into a scientific problem particularly over the last 20 years there have been great advance in as always in physics or in science driven by better instrumentation so we can now look at the brain and peer at it as it does its thing all right so i've divided this lecture into four chapters so one is the problem of consciousness so science uh does many things extraordinary well as you heard this is a somewhat older picture but it's one of the the first picture of the cosmic microwave background radiation and it shows something about the the origin of um our universe um this is the universe 300 000 years after after the initial big bang and we're beginning to understand the the that very early part including something called the inflationary universe quite well although it's a stupendous 13.5 billion years away we have good understanding at the level of chemistry that everything we see certainly everything here you know it consists out of 92 elements and we understand how they interact with the outer valence electrodes that's that's where physics transitions into into into chemistry we unders we understand about the existence of individual atoms and we are also beginning to really get a good picture of um of life we understand a lot of the biochemistry where chemistry transitions into biology we understand um quite a bit about although not everything of course about the evolutionary relationship of all these different creatures on this planet so far unfortunately we only know about life on this planet we understand the evolutionary relationship among all the critters including us we're somewhere hidden behind the behind the backside of that frog this puts us into proper perspective and how all things on this planet are related to each other ultimately going back to a point in time we can't really estimate accurately but somewhere between 3.5 and 4 billion years ago yet nowhere in that description is there anything about consciousness so if you look at the two foundational um theories of physics quantum mechanics and relativity nowhere in there say anything about consciousness if you look at the periodic table or you look at the endless atgc chat in our genes nowhere is there anything about consciousness yet here we find here we find ourselves in a world where we have conscious experience so at this point we have still little ideas how consciousness comes about and philosopher has this expression they see that consciousness is not supervision to physics in other words you can imagine a world and this is what philosophers do they play these mind games they play these counterfactual mind plays you can imagine a world that's fully compatible with everything we know fully compatible with natural law yet where consciousness is absent it's a so-called zombie argument we could perfectly well imagine a world in which we're all zombies in which none of us explains anything which is just dark there's no feelings you know you people move about just like robots move about but without there being any any conscious experience now the the the fact that this is very difficult to address um was already pointed out uh by probably what many people consider the last universal genius gottfried leibniz who of course invented together with newton um differential calculus also invented binary numbers or conceived of binary numbers and he has this beautiful example of a mill in which he so he was wondering about experience how experience comes about so if you just read this moreover we must confess that the perception and what depends on it is inexplicably in terms of mechanical reasons that is through shapes and motions if we imagine as a machine whose structure makes it think sense and have perception we could conceive it at large keeping the same proportion so that one could enter into it as one enters into a mill assuming that when inspecting its interior we only find parts that push one another and we'll never find anything to explain a perception today this this this idea has been popularized by the philosopher um david chalmers and it's called the the heart problem now the uh for me the most fundamental insight that philosophy has contributed to the problem of consciousness the heart of the mind body problem is really the most famous deduction in western thought right expressed by the father sort of of western of modern science a mathematician and philosopher rene descartes and he wrote um he wrote first wrote it in uh in french the poem the japanese donkey sweet translated later on cognito argosam today in modern language we would say i'm conscious therefore i am what he means he's he's looking of course in this uh in this book discourse syllable he's looking at at something that's irrefutable something sort of that at the rock bottom where he can be absolutely certain of anything he says he reasons the only thing i'm absolutely certain of is the fact that i exist because i'm conscious you know i even if i wake up in a hotel room i arrive here in new york city i'm discombobulated because of the jet lag i wake up in the middle of the night it's totally dark i don't see anything but i'm conscious and i i know i'm here i'm something i might be mistaken about who i am i might believe that i'm incredibly attractive to the opposite sex for instance which would be illusory but the fact is that i have this feeling and so this is the one thing that i'm certain of this comes prior to anything i know about physics physics comes secondary to that philosophy it's the only thing of direct acquaintance to and so a direct acquaintance with and so this is the this is the the fact that we know that we can study black holes we can study viruses and we can study brains and science studies all of those objects brains however come we believe different from viruses and different black holes with additional property it feels like something to be in to be a brain at least a healthy brain when you're not in deep sleep or anesthetize or coma etc it feels like something and the question is how do these feelings get inside inside the brain but we believe they're not inside a virus or they're not inside a black hole now many of you will recognize this who sees this as who sees this as blue and black and who sees this as white and yellow well that's of course the right way to see it so you know this divided the planet couple of months ago and went viral um so it you know what's interesting about this illusion there are hundreds of illusions what's interesting and compelling about that is sort of it was naturally found right out there somebody posted a picture of this of a wedding dress of a wedding in scotland to flicker and then was picked up by the media what it shows that you can look at something and see different things and some people see it one way and the other people see it other way and a third group of people can switch but between it has something to do the the the assumption your brain makes implicitly about the background the overall level of lightness in the image but the fact is you see something you're conscious of something and so once again that's a puzzle so that's a puzzle of of of consciousness how does consciousness come into the world what is it specifically talking as a scientist what is it about the physics of highly excitable matter like the brain is it's probably certainly the most complex organ in the known universe and maybe other creatures out there that even have even bigger more complex brains but certainly on this planet the brain seems to be the the mammalian brain particularly the human brain seems to be the most complex organ we know of so somehow associated with with the physics of this highly excitable highly organized system comes conscious experience all right so the challenge is for us a scientist it's a brain that gives rise to sensation it's not the heart so when you say i love you with all my heart that's really metaphorical speaking you really love with your brain you should probably see you i love you with all my brain it just doesn't sound quite as romantic unlike other cultures who did believe it the feelings are in the heart or in the uh or in the liver and and so the challenge is to relate the first person account of what it feels like so this is my brain as i was having a color experience uh you know photoshopped in and these are the part of the brain that are specifically activated when i'm looking at a let's say red rotco right and so the challenge is for science to explain the relationship between that brain that i can observe this is called a third-person property this is what scientists do they observe third-person properties whether you're observing you know the radiate the radio waves coming back from a star from a galaxy whether you're probing a virus or whether you're probing a brain you always see it from the outside but as i said what brain what brains have they also have an inside perspective right there's an outside surface that you can observe the brain you can physically probe it and touch it away and put it in a mri scanner and take bits of out of it and and look at its genes etc but then there's this inside view that you have and only you have an inside view of your brain and you have a day-to-day at night you go away you go to bed that inside view goes away it's switched off right it's extinguished when you're in deep sleep and then in the middle of the night you wake up inside your body inside your sleeping body and you have conscious experience you sleep you meet people you you fly you meet people you haven't seen in decades that maybe that may have passed away you can walk through walls and we call that dreaming and that's another conscious experience so the the challenge is what's the relationship between the third person perspective and the first person perspective this makes a problem a little bit more difficult to study than a than a conventional scientific problem like the you know the the origin and properties of black holes or viruses so when we're talking about consciousness we have to distinguish two different things the tendative and intransitive usage there's content of consciousness which typically what i've talked about what philosophers talk about you know right now your content should be filled with my voice and you know with the images i project but maybe you already drifted off you're you know you're you're on your on your iphone or you you know you have a pain in your foot and you're conscious of pain in the foot or you'll remember something you have to do tomorrow those are all different conscious states so that that's that pertains to the content of consciousness yet then there are so-called states of consciousness right now i don't see anybody asleep because it's a different state of consciousness you're all awake aroused let's see the medical term your brain is aroused as i mentioned already tonight we're all going to go to sleep and that's a different state and sleep is conventionally subdivided into two further sub states called a deep non-rem deep sleep typically not associated with sort of vivid phenomenal dreams and ram that typically comes with comes with these conscious experiences we call dreams then there are other sort of pathological states one is a very useful one brought upon by professionals so called anesthesiologist right because you don't want to experience the discomfort of pain or agony of an operation and then there are other states that come about by gunshot or viral infection or stroke that could be you know the very all the way coma vegetative stage persistent vegetative state unresponsive wakefulness etc it's a very famous case here in the u.s some of you may still remember her terry schiavo but that roughly she was not she was only exceptional in the sense that her case made it to the national media and was litigated up and down the chain ended up in the supreme court the president george w bush got involved at the time but they are probably on the out of 10 000 such patients where they are in a so-called persistent vegetative state so a vegetative state is defined as a the patient has a sleep-wake cycle so the patient will wake up quote move her eyes the eyes are open moves about she shows some a higher level of of motor activity but it's very unspecified it's like this you know it's not purposeful and then the periods where she eyes are closed and she's asleep yet there's no way to um to interact with these patients in a meaningful way so if you shine a light you know you you want them to track or you do this you know a patient will track that or you'll ask or you're asking you know if you feel anything press your hand or something people like terry schaibo are unable to do that so that pertains and there are many many cases like that that pertains to to the basic mechanisms that need to be necessary in order for you to be conscious at all and we know quite a bit about them but but so your brain essentially uh particularly that the top part of your brain the pot the forebrain particularly the cortex the sort of the thin sheet it's like a it's a two to three in a two to three millimeter sheet thing with like a pizza two to three millimeter thick pretty much like a pizza 13 to 14 inch across and then all wrapped up and you have two of them one on the left and one the right that's your cerebral cortex and in order for that cerebral cortex to generate consciousness it has to be aroused so they have to be all factors present your heart has to be a beat your blood supply has to be active you have to get oxygen to the tissue and a whole variety of housing factors no adrenaline serotonin etc have to be sort of made available from the brain stem and if they're not because you had a stroke there or something then you then then you're in coma you're not dead but you may as well be dead because you have no conscious experience it doesn't feel like anything to be you it's just phenomenal nothing blank nada yeah niche so terry schaiber's for as far as we could tell for the last 14 years of her life it wasn't anything to be terry schaibo she was literally not there legally she was there she was alive the person but there wasn't anybody home what is it we can say about this is a sort of the um about consciousness besides sort of these enabling factors that need to be present for you to be conscious at all well we know that conscience is associated with certain types of biological systems what's interesting about it it doesn't come with all biological systems so for instance there are complicated networks in your brain called the immune system in your body called the immune system you have several immune system you have an acquired one an innate one and they do their business silently you don't have any conscious access to them i flew in yesterday from the west coast then you know it's a different immune environment here for my body so my my immune system may right now be fighting off some virus that's you know endemic here in in new york but i don't i have no conscious access to it i don't feel my immune system acting it does whatever it does silently and it may form an antibody to it so when i come back 10 years later it'll still recognize it so that's like a memory but i have no conscious access to that why what what makes the immune system different from the nervous system but even within the nervous system i have you may know there's a secondary brain down here in the gut it's called the enteric nervous system it has action potential and it has neurons etc and it doesn't seem to give rise to consciousness why is that again we don't know we know that consciousness doesn't require behavior we know that i mentioned this already when you dream your brain you of course you most of your dreams will involve motor activity you fly or flap or fight or run or do something now clearly if you would act out your dreams as some people do in so-called parasomnias that's not a good idea and so your brain paralyzes you the essential essential ataxia of pretty much everything of except of course your eye movements um yet you're fully conscious we know this also so patients who for example took tainted heroin so-called mptp patients that went in the state of complete cataconia yet are fully conscious so we know at least in adults you don't need you know right now if i paralyze you you can be fully conscious we know that consciousness doesn't require emotions what i mean by that is that you can look at patients who due to an injury have completely let's say a stroke or a gunshot or an improvised explosive device when you're talking to some veteran so there may be maybe this bomb also blew off their legs so their life has changed forever irrevocably yet if you talk to them they have you know you hear it already in their voice no affect completely flat they can tell you you know they feel fine or what they see what they hear they're clearly they have clearly conscious experience yet they've lost um they've lost because they've lost the underlying neural basis they've sort of they lost the strong emotions so you certainly don't need emotions uh to to have consciousness although there's no question emotions of course enormously enrich our lives that's not the point i'm what the point i'm trying to make you can remove emotions and you still have experience you still have conscious experience you still see red you still have pain you can still fear death um research i won't be talked i won't be talking about but there's a lot of evidence now that you can that attention and consciousness are separate things they used to be confounded because partly because when i attend to something i become conscious of it so if i say please attend to me you will direct your attention to me it's a specific process and we know a lot about its neural spaces but that's separate from from being conscious of although very often they coincide we also know from experiments and from um work of course done in in pre-linguistic children or in patients who are physically can't speak anymore that consciousness doesn't require language not even does it require self-consciousness so self-consciousness is something that's peculiar in particular well developed in us particularly in in adults particularly in the adult literary classes and they like to write endlessly about it it may all actually not always be for the best for them it's hyper developed in us but certainly if you have teenage kids boys they will do something really stupid and you ask them well why did you do that and they say well i don't know it just popped into my mind they have very little self-conscience in general children but but boys it's even later than than girls and and we know that the self-container is really only fully develops you know once you're in the 20s or 30s or maybe even later 40s probably we know that it's due to the late development of the late stage myelinization the the the the insulating properties of of the projection system that go into prefrontal cortex that only happens really fully happens in your third decade of your life and when you're out there so i'm a rock climber and i also bike every day so when you are out there biking and at high speed you know on your on your bicycle on and through traffic you have to be hyper aware right you have to watch your back you have to be aware when you're climbing particularly in the sharp enough rope you have the hyper-aware and you're so focused in fact on the outside you're so conscious of the outside world that that inner critic that voice that totally that always is there with you and and tells you all the bad things about you and you know so like your internalized mom that that uh i mean that voice is gone at this point because you're so intensely engaged with the outside world but you're fully conscious um self-conscious something that's particularly highly developed in in us although other animals also have it but to a lesser extent but it's just one aspect of consciousness so clearly self-conscious is a highly developed aspect of consciousness but it's just one aspect of consciousness when you're out there when you're engaged with a with an engaging book or was a great movie when you're making love as i said when you're climbing etc you're engaged with the world and you have very little self-consciousness at that point so it's it's a late stage evolutionary refinement of consciousness but basic conscience is something much more basic predates self-consciousness we also know from lots and lots of patients that have lost the ability to learn anything and that have lost maybe all their adult memories that they're clearly fully conscious they can be in love in fact there's one very impressive patient like that who had a viral infection two weeks after he married and ten years later he has no he's one of the patient with the densest amnesic memories lesion ever so he has his diary filled with books i'm filled with notes i just woke up for the first time next page i just woke up for the next for the first time over 10 years um but then when he meets his wife he's still in love with it 10 years later it's a great bbc movie he talks this way he embraces him when he sees he says ah you've been gone so long he's very happy with that she leaves come back five minutes later exactly the same thing he's clearly conscious yet he just he what what the tragedy about him is uh he has some inkling something is wrong with him and he's just lost the inability to to make any new memories but he's conscious so through patients like that we know that long-term memory is not really essential for for consciousness and we know through a lot of uh experiments so-called split brain experiment when pace when the surgeon has to cut the fibers that connect the left and the right brain or when you lose one hemisphere entirely that you can still be conscious with with one hemisphere and then we also know through experiment in neurology over the last two century beautiful described by oliver sachs of course is that there's also something very local about consciousness and its content in other words when you lose particular parts of your cerebral cortex because you had a stroke a gunshot or virus or whatever you lose specific content so it may be as specific that you are unable to see color because you had a stroke oliver sacks of course is written beautiful about this page this patient who had a stroke um and then recovered from it but sort of he painted uh you know before he painted in colors and afterwards he painted in very strange colors because he didn't see colors anymore nothing to do with his eyes it's something more central so you have other patients have lost the sense of familiarity that lost a sense of motion etc so there are lots of patients like that who have specific holes in their in their in their in their brain in particular in their cortex and they lose specific content like color emotion or the sense of familiarity so we know bits and bits and pieces of the brain associated with specific type of consciousness now much of what we do we do without being conscious or we do we only become conscious of it after the fact so uh this is called one way to describe this is so called zombie behaviors in fact i the older i get the more i realize that most of the daily pattern of my life and i think of all our lives are formed by by these by unconscious um um actions sort of we're all strangers to to our own mind it may be very simple um it might be so for example when you're you know the the streets here in in downtown york are always filled during the day with hundreds and thousands millions of people shopping and so when you weave your particular when you run right at high speeds through this through this human traffic right you you have to make a very quick adjustment we know this to experiment in fractions of a of a second right in 50 or 100 milliseconds and you're not conscious of that your body executes it effortlessly they're beautiful experiments now right we all spent hours each day on on these devices right and beautiful experiments show that if you were actually conscious of the individual actions of your finger you would slow down greatly and you would make many more mistakes so it's interesting because with typing on on on your devices just like climbing or dancing or learning how to drive or playing tennis all those things are highly trained activity in what we know about them that early on you need to be highly conscious of it right how do i exactly hold the racket right and you have to get people to correct you and you really have to attend to it and this involves cortex but then when you do it again and again and again sort of you you can think of it you download you compile and download sort of code to a different part of your brain typically involving the basal ganglia the counted nucleus and it's executed there without a thought sort of done automatically this highly trainability now like driving or other things we do and at this stage now consciousness can be counterproductive consciousness because now it interferes he said wait a minute how did i do that and then you just do it that's a genius of nike's slogan right just do it do it means don't overthink in this case because it decide but you can only do it do it if it's a highly overtrained activity you couldn't do that for something that you've never done before it's not true that there that psychologically there's a little christoph inside my head that generates okay this is the point i want to make this is now the verb this is the noun this is a conjugation then send it you know from the germ module you know into the english module no i mean usually when you speak how do i know what i say until i listen what i he you know till i listen what what what i actually said right so it's it's your brain that generates this automatically same thing when when when you listen to speech at the other end right you're not sitting there analyzing it at the level of individual sounds right it just makes sense to you so turns out the vast majority of your brain i would guess 90 plus are doing their thing doing their action without you having any conscious access to it when i look at out the world i know i see the world in color we all do unless you're colorblind i see it in color yet we know probably at least half of my new or two-thirds of my neurons process information just intensity-based information yet i don't i don't have access to that i can't sort of turn off my color channel and only see the world in black and white finally what i'm given what we're all given is this final beautiful interface the one that we've conscious access to and all the work is hidden underneath and we have no idea about the work until we did sort of neuroscience and we did computer simulation and trying to understand you know trying to simulate the way the human brain which actually turns out to be very very um very difficult it's only recently that computer can begin to approach that same thing decision we have very little idea why we make decisions and particularly if you ask people you know you do this under controlled lab conditions they're notoriously bad at telling you why they did things we don't really have access in general very well to the reason we make decisions and of course if you've ever been in emotional very trying times like a you know separation a divorce an affair etc you have you you you well know your very powerful feelings of love and hate and disgust and anger etc but you're very little conscious access to the underlying roots you have these feelings you feel them very vividly but it's very difficult to infer the underlying reasons and trying to address them you know which is why it takes years and years and you have to go to a therapist and all of that partly because evolution simply did not give you access to those parts of the brain conscious access to those parts of the brain that generated so the question here for the neuroscientists is a very interesting one where's the difference between all those actions and all those those things that you can do unconsciously and those those aspects of your mental life that you have conscious access to are they in a different located in a different part of the brain is this the conscious part of the brain and this one unconscious or do they operate in different mode maybe there's a conscious mode that's slower and more deliberate and there's an unconscious mode it's faster more automatic more basin people have sort of thought about these ideas a lot but but for me as a neuroscientist you give primarily rise the question where is the difference at the level of the hard way between conscious and unconscious action i worked for many years with francis craig francis crick of course he is a discoverer with with jim watson of the double helical nature of dna then he went on to help decipher the genetic code predicted mrna etc in his last three decades of her life he shifted to the other what he perceived was a great problem in science which is a form of consciousness so we then sort of conceived of this notion of that's been around previously but the focus let's focus now on the ncc we've looked for the last two millennia we've sort of philosophers have have have have investigated or tried to investigate with very limited means available which essentially just language and logic the the palm of mind brain today we can do that by looking at the footprints of consciousness in the brain that's essentially what it is they're called the ncc the neuronal correlates of consciousness so what they are for any one conscious sensation whether you're angry or seeing red or being in love or smelling mom's apple pie those are all different conscious sensation there will be for each one of them some physical or biophysical mechanism in the brain a set of mechanisms that are jointly sufficient to generate that and that unique experience so when you smell mom's apple pie something in the brain has to has to do it and what is the minimal set of something in your brain that generates the smell of mom's apple pie and how does it differ from smelling you know um you know dog urine the dog pee right which smells very differently right is it the same neurons they just change sort of a little bit the activity uh what about a rose or what about seeing you know the best study neural basis is seeing are there different parts of neurons in the different parts of the brain that are responsible for seeing and then what about seeing color with seeing motion with the seeing in depth which is seeing in stereo is there a common mechanism is a common location are they all a common set of neurons do they all have a common set of genes as a common set of synaptic neurotransmitters are they located in a particular part of the brain do they buzz at a particular frequency these are all hypotheses that have been entertained and underlying the ideas of the this ncc the neuronal correlates is that if i by an artificial means either by the electrode of a neurosurgeon or by an outside thing like a con like a magnetic pulse or by a new fancy technology called optogenetics if i induce this neuroma the ncc i should have the the conscious percept and if i somehow inactivate the ncc by revenue removing the neurons or turning them off briefly now that we can do in the lab with pulses of light that the the the conscious percept should go away that's how i know i'm there right so i say well these neurons here doing something particular in this part of the brain whenever they go into that state then i see red and when they go into this state i don't see red so then if i i can show that by demonstrating that if i put these neurons in this state you see that if i remove the neurons you don't see red anymore that's the idea and so now i can systematically walk through different parts of the brain and ask well is this part of the brain responsible for generating let's say vision vision is by far the best studied modality for a number of reasons so for example your eyes you see with your eyes well clearly you know right now you know all the information i get from from from the environment streams through my eyes but of course i can close my eyes and i have a faint echo you know i can imagine so i know where people sit and i know there was a gentleman here and i know where some of you sit and of course tonight as we all know most of our dreams are intensely visual when i when i'm in the dark my eyes are closed so we know from from those sort of observations go back thousands of years that it's not really in the eyes and the the painters of course has always emphasized that we also know that for other reason if you close one eye one eye not both eyes but if you close one eye you know there's this blind spot right there's a spot it's roughly here where the tip of my finger disappears it's a spot where essentially the the cabling of the eye leaves the eye and at that spot there no photoreceptors so in other words at this spot there's nothing nothing converts the rain of incoming photons into into nervous energy so there's a hole there yet i don't see this hole why not well turns out there's an active mechanism in my cortex that compensates for that hole essentially it it interpolates what it sees around it and says well something similar is happening inside i move my eye three to four times a second constantly we all do constantly yet we're not aware of that and suddenly the environment doesn't move right if i if i take my iphone and move it at the same cadence and you look at it you're gonna throw up right because you get these huge shifts well why don't i see them well because my brain edits them out and you can see this yourself so if you look in the bathroom mirror the own eyes move you can perfectly well see my eyes move right but what you'll see if i look my if i look into my into the bathroom where i see my eyes here i see him here i never see him in between in between why not not because they are so fast because you can certainly see my eyes move but because my brain edits out that bit because typically what happens of course if you move we know this image becomes blurred and so the air what the brain does it edits out that sort of 50 millisecond segment snips it out and then splices the movie together so it looks like i look here and i made this instantaneous transition to here which i didn't so it's sort of it's a corn job and a lot of if you look if you look into it a lot of perception is a corn job it's sort of it it does all sorts of editing perceptual editing so uh partly based on my expectation on my experience etc so just like with the with the dress right it's not true sort of naive there's naive realism it says there's a one-to-one mapping between the outside world and the inner world well it's not one-to-one and it's it's a much more active cons it's a construction of a description that your brain does your brain describes the uh the environment on average it does a good job because otherwise we wouldn't have evolved right otherwise would be hit by cars and uh hit by people etc so it's a pretty good it does a pretty good job but through illusions like like like this one or hundreds of other illusions you can show that there's lots of assumption built in assumption and we we have you know we we our perception isn't as good as we think it is all right so the retina probably isn't involved in generating consciousness now what about another part of the brain so you may know there's a part of the brain called the cerebellum okay it's a it's a little brain the cerebellum a little brain at the back of the head ironically in fact it contains more neurons than all the other part of the brain taken together 80 of your neurons you have roughly 86 billion and of those 69 billion in the cerebellum there are real neurons in fact there's among some of the most beautiful one the pukinia cells they have action potential synapses everything you expect of a brain yet when you have a patient like this okay this lady had no cerebellum in fact she never had one she's a rare case of so-called a genesis of the cerebellum she was born without the cerebellum so you can talk to her she's a 20 24 year old lady recently discovered in china when she had some infection was went to the clinic and finally they did these mri scans um she has ataxia she doesn't walk or talk as smoothly as a normal but she talks and she tells you about experience she's married she's a child she can tell you about all of that clearly conscious and we know this from other such patients that you don't need your cerebellum to be conscious which raises the question well it's a it's a real brain and 80 of the neurons in your brain aren't this on this brain but if you lose it you have some trouble you you know you'll never be a ballet dancer or climber yet um doesn't seem to impede your consciousness so clearly consciousness is not associated with that part of the brain of course we want to know why we don't know um then there's the sort of cortex proper so i told you early on this is sort of the that sheet you know that if you unfold it's like a pizza and it's convoluted and you know left and right and we know it's a lot of experiment that's that uh in clinical lesions that that's really this main place where conscience is generated but even there it's not it's even more subtle than that because you can show through the experiment that lots of activity in the brain does not in even cortex does not depend on consciousness per se so this for example was is one such study it's a little bit more complicated study people separately try to dissociate attention and consciousness i mentioned already before that those are two different things so it's a so-called two-by-two design so if you just bear with me for for a moment so on the if you go across in the in the horizontal direction um you manipulate consciousness so what you get people to look at this is an artist tradition what they see so they're looking at a screen at the middle of the screen you see this grating the grading can move either faint the faint draining move to the left or to the right on the on the right you do something in their visual periphery so the physical stimulus is always the same yet you don't see it it's called masking and and psychologists just like magicians have invented lots of tricks to distract you so you are looking at something but don't see it so again but in all four cases the stimulus exactly the central stimulus is always the same it's a it's a very faint grating that moves a little bit to the left or to the right but in the either you see it or because you do this masking the other eye you don't see it or you manipulate attention in one case you ask them to attend to the letters that flash on on the left you see one of them the red m and there are many letters and you have to monitor it always while looking straight ahead you have to monitor the letters to see what the particular target attends or you monitor the central grating and you tell me whether it moves to the left or to the right so that's in this two by two design you separately dissociate the effect of attention from the effect of consciousness and then you're looking at the blood the hemodynamic response the blood response in that particular part of the brain that responds to that central grating and what you can see in in two patients here on on the separate graphs that so on the x-axis you see the time scale is time it's a so it's zero you flash on at zero milliseconds you flash on the the stimulus and then you're looking at the the the changes in the in the blood in inflow into that area and it's sluggish it's it takes seconds um and you can see that it gets modulated by whether or not you're tend but whether or not you see it makes no difference to this to the to the response here so in other words in this part of the brain which is the earliest part of the brain primary visual cortex what matters is not so much whether you see it or not the neurons there fire irrespective of uh whether you see it or not what matters whether you attend to it or not and we know this also so lots of other experiments for instance in patients that are in this persistent relative state i mentioned earlier you can have their pi you can have their primary sensory cortex activated yet the higher areas are inactivated but the primary sensory cortex is activated like here the primary visual cortex and it doesn't give rise to consciousness so it appears to be that the primary sensory areas the areas and cortex that directly receive input from the periphery whether it's visual or auditory or some other sensory they don't give rise to consciousness themselves higher order parts of the brain do so for example this is a picture from below this is so you're looking up at the brain you're looking at sort of at the surface of the cerebral cortex and here you had a bunch of patients where they had electrodes implanted because of epileptic surgery and then the colored areas are regions of the brain so called the fusiform face area that's an area discovered by nancy cambridge at mit that's selective active whenever we see faces so faces of course incredibly important for us right the the you know they're the key element of our social fabric so it turns out we have a highly specialized area in the brain that's dedicated to phase processing and when you fail when you lose that area you may get something known as face blindness protopugnosia here now but that's just observation now you can also do causation because you have an electrode in those place you can stimulate that part of the brain and then you can get the patient for example to look at the doctor's face and what you see but only if you stimulate on the right side of the brain not if you stimulate on the left side of the brain although you have a refusal from face area both right and left but only if you stimulate the right fuser from face area the patient will say oh every time you do that your your face twist your face sort of somehow distorted so it seems we hear we are talking about we have a we're very close to um to the place that gives rise to the conscious perception of a face and it's not in the primary visual area anymore it's a higher area up there's innumerable more research where that comes from um where we can show which part of the brain and this is still controversial right this is not a settled this is far from being a subtle question most people believe all the evidence shows that it's cortex and closely associated satellite structures such as the thalamus that give rise to a specific conscious content which part of cortex generates consciousness is still very controversial is it the front part including frontal cortex is it the back part the parietal inferior occipital temporal part is it the insula those are all different candidates and people are fighting about it but in all cases we what is still true that only certain parts of this excitable system this cortical sheet because that's really what it is it's a two plus epsilon dimensional technology if you want certain activity in some parts of this cortical sheet goes hand in hand with this the thing we call experience we still don't understand why that that activity in that cortical sheet should give rise to consciousness and why not in other parts that superficially at least if i just look at it look very similar what about consciousness in other bulges say non-human animals so here you have a picture of two mammals it's my daughter and her germ shepherd tosca we think well certainly i think it's father but most of us who've been around dogs believe that dogs are conscious they don't have a lot of self-consciousness my dog doesn't sit there and say hmm my dog my tail works in a funny way maybe there's something wrong with me you know or you know in two days it's weekend and then you know we get to spend two days around in the wilderness my dog just is he's a little bit like a buddhist he's in the here now she's in the here now but she can certainly tell you by numeral shoes her tail the position of her ears bark you know a playful bargain angry barker growling but she can tell you just like a child can that doesn't speak yet can tell you about her conscious states and certainly if you look at a piece of dog brain or because we don't experiment on dogs at least we yeah we don't but we experiment on other similar animals like mice when you look at the piece of mouse brain or dog brain or human brain or monkey brain it all looks very similar so here for example you see two pieces of brain in sort of corresponding regions temporal cortex one is a human and the other one is it's a mouse the scale bar is different the human brain is roughly two uh two to three times thicker than a mouse but otherwise it's very similar it's a nissan stain very similar they're very similar neurons not not the same of course similar genes not the same of course similar cells and synapses and circuits and each you know people keep on asking me well what's unique about the human brain well every brain of every species unique it's different from each one we all adapt it to our particular ecological niche we haven't found anything we haven't found anything in the human brain that makes a human brain totally stand out and say well that's what explains it the biggest difference is that our brain is roughly a thousand times bigger than the brain of a mouse we weigh 1500 our brain with three pounds fifty nano gram and mouse is more like a you know point seven gram um a human um um monkey maybe a hundred gram a dog maybe like 60 70 grams so we have a big brain although we don't have the biggest brain of course you know they're whales dolphins elephants that have brains that weigh three or four kilo uh which is a little bit embarrassing for us but never mind so so biology bulges really stretch the great continuity across all these all these animals certainly across all mammals if i give you a little piece of of cortex and ask you from which animal does it come only an expert you know armed with a microscope can say for certain this is a mouse a human or monkey because the stuff is really similar we just have a whole lot more of it so it means we can now of course profitable investigate in these animals that are conscious with with great care because yes they are they are animals they are capable of of suffering in joy and so we have to treat them appropriately with uh with with compassion but if our goal i finally is to understand the brain in particular to minimize human suffering it's caused by by mental diseases we need to do these experiments and then we can do for instance here okay so here you have a mouth it's a little crit you know 20 grams you probably run from it when you see it in your kitchen at home so here you have a mouth that's trained to recognize pictures of me and runs past pictures of other people in the institute that it clearly doesn't care about okay so the point is here you can train a mouse just like you can train a dog or a monkey or you know or your kid you can train people to animals to recognize certain things and so it stops it gets water reward when it you know at a particular picture so now it's not shown because it would intervene so we can swing a microscope over their mouth and what you don't see with a team of six at the ellen institute for brain science we have a team of six neurosurgeons that um that has prepared a transparent window into the skull and now we put a microscope over it and these are so-called transgenic animals so by the wonders of modern molecular biology they they have a gene inside their neurons that make when they when they the neurons fire when they generate electrical pulses just like all neurons do in our brain as well they turn these electrical pulses into flashes of light and i can pick those up i can image the brain in real time as the animal makes a decision should i stop or shall not stop at one particular picture or another so i can query now the mind it's a mind of a mouse which is you know less but it is a mind i can query now the the mind of the mouse and also at the required cellular level that of course i'm blind to in terms of fmri i don't see in them in a functional brain scan and then also what i can do there's this wonderful new technology around called optogenetics as some of you may have heard that allows us now with essentially molecular biology and beams of colored light i can specifically delicately reversibly intensely turn on or off specific nerve cells in the brain with high precision so you can really begin to play sort of the begin to play the sort of if you want the piano of the brain which can turn this neuron and this new and this new and on and those those those neurons off and i can begin to to observe the effect all right because ultimately we have to chase down consciousness to the level of neurons and and not just brain areas not just this area with that area because this area is constituted of 50 million neurons and we know there are probably at least 100 different cell types of neurons types of neurons you know the big ones in small excitatory inhibitory and some project local some project global et cetera et cetera and we need to understand what are the detailed causal mechanisms that give rise to conscious experience because we're now faced with this dilemma so if you fast forward now you you allow the possibility that people like me will discover the the the footprints the neural roots of conscience over the next 10 20 50 100 years whatever and i can but then i'm left with the question why is this particular i didn't mention this structure why is this particular structure important for consciousness why is the cerebellum not important for consciousness why not certain pathways why are they not involved in consciousness why is the cortex when it's sleep in deep sleep why are you not why is it not conscious we know it's not right it's our everyday experience but why is it not there's still neurons there's still fire action potential they fire somewhat differently so it must be the pattern of firing that's somehow responsible and during other cases like epileptic seizures your brain is hyper synchronized it's hyperactive every neuron seems to fire away why doesn't that generate some sort of hyper consciousness it doesn't but why we we need some theoretical understanding if you're confronted with a patient such as this 20 years in a positioned relative state occasionally she utters the same stereotype to one or two words and she has these islands of brain activity left but does it feel like anything to be her not really clear it's very stereotyped for 20 years so maybe it's just sort of you know like a tape recorder stuck there and they own that's the only thing she can say occasionally maybe it doesn't feel like anything we don't know what about um babies when does conscience start in all of us in any of us what about the preterm baby like this one what about the fetus i'm not asking the question when is the fetus first alive but when is the fetus first conscious or when is a child when were you first conscious when wha what was your first conscious experience now you probably can't remember that because of something called infantile amnesia but still you know did you feel at what point did you first feel anything maybe when you exited the mother you know the birth canal of your mom maybe that was a neukai maybe that was your first conscience we don't know we need it we need an explanation we need a measure we need so called conscious omega when you when you get anesthetized we only have very primitive tools right now to tell us is that patient in front of me who can't move because i also paralyzed him is that patient actually conscious or is he or is he hopefully not conscious and not experience the pain and agony in the stress of the operation what about such states as dissociative states all sorts of psychiatric interesting dissociated states what about states like sleepwalking where people can either open they have complex actions seem to be like you know walking driving etc are they conscious what about species that are very very different from us so here you have a squid doesn't have a cortex an octopus has a very different organization but has a complex baby are they conscious what would it be 800 000 neurons 10 times denser than 10 times denser than the brain or our brain do that doesn't feel like something and lastly we are confronted today more and more with creatures that we built that we designed that we programmed and if a patient in a hospital could do any of the things these computers could do there would be no doubt we'd say the patient is conscious so if a patient played chess like deep play like deep blue already played back in the 90s would clearly see the patient is conscious if the patient could do jeopardy like what ibm watson did clearly would say the patient is conscious if the patient could drive like a google self-driving car right or could play video games like deep minds would definitely say the patient is conscious so on what basis can we assert that these things are not conscious certainly by behavior is very complex you know will it the question is will that doesn't feel like something to be this iphone 5. does it feel like something to be an iphone 20 maybe not now but maybe in 20 years but then what is it exactly that that could give rise to conscious experience in things like this right so you can go to movies like her or movies like ex machina they talk about that so ultimately what we need uh we need a theory that takes us from conscious experience to two brains so finally there's a theory let me just give you the and the gist of this um of the theory so there's a theory called um integrated information theory of consciousness iit it's a you can read it all about if you just google iit and you uh the the inventor is somebody called julio tenoni so if you just google i t to noni um it's a it's a it's a principle theory that takes you from basic definition of what consciousness is what any conscious experience is it it exists it's unique it's specific it's specific in a particular way and it's integrated with that with those five axioms based on our own experience it derives a mathematical calculus called iit that finally says that any system that has that makes a difference to itself it's a causal theory so it says any system that has causal effect power on itself and it's defined that using a mathematical um well-defined mathematical theory it may be wrong but it's certainly well defined that says for any system so you take a system like this little piece of electronics or this or my brain and it's a particular state these neurons are on those neurons are off the theory says if the system is comp has complexity as defined by cause effect power being different from zero it can make a difference to itself it will feel like something so it says the universe we live in a universe where if a system has is more than the sum of its path that's a different way of thinking about it if a system exists because it can be defined at a particular spatial temporal level of granularity it makes a difference to itself it it exists and it will have conscious so consciousness associated with it it can measure the theory gives you a number five between it's a positive number zero or positive if it's zero it means it doesn't feel like anything to be to be that system if it's different from zero it says it exists it's irreducible the the quantity of consciousness is so corresponds to the number five the extent to which it is irreducible the more redu the more system is irreducible to its independent part the more it is conscious in this definition the more cos effect power it has on itself the more it is it is conscious it's a so it's a it's a principled analytical theory it also makes empirical predictions so it predicts that for example to measure consciousness you measure the degree of integration and you can do that in a way so one way to do it people are doing it now in clinical studies you put pulses into the brain using a device called tms transcranial magnetic stimulation and you measure the the resulting electrical reverberation over your skull using a multi-channel eg and then you can compute you can give a single number that tells you how integrated it's a response and we can see whenever in page even deep sleep this number is very low on these patients where we have reasons to believe that they're in coma or they have or they're anesthetized in different types of anesthetic this number is very low while in patients that are impaired but otherwise fully conscious like logged in syndrome or in normal people this this number is high so for the first time it gives us a practical measure now more imp most importantly though the theory also makes a number of predictions about which structures in the brain are involved and which are not involved in consciousness because it also makes some predictions about machines and these are fundamentally different from the current functionalist belief the function is believed like philosophers you might know dan dennett and others believe that essentially if you replicate the function of an organism everything then you also get all the properties that's enhancing the turing test right so if you have an entity like ava in the movie x machina or rachel in the movie blade runner or samantha in the movie her that behaves like you you can talk to her and she remembers and she jokes and you know she just acts like any other woman would on on a telephone well then you assume she is conscious right that's a that's a functional definition that's inherent in the standard definition of a turing test this theory says no it's not about functional identity it's about cause effect power so you really have to look at the mechanism underlying the system you can't tell from the outside where the system is conscious so you have to look at the underlying mechanism the physics of the mechanism that gives rise to the experience so you have to look at the physics of the brain or the physics of the of the cpu chip that gives rise to the underlying computational power of the computer in order to say it's it's conscious and certainly this this theory says that a computer simulation of the human brain no matter how fancy would never be conscious in other words you build a perfect simulated replica of a human where you simulate every brain every neuron in the brain is is that we find the real brain is in the computer simulation and you you interface this this computer simulation with with with you know cameras etc and with actuators and you can talk to it and the the the simulation can describe you where you know you show a picture and it says well it's a bottle and it says world science festival on it still if it's a computer simulation there's a difference between the simulated and real it would never be conscious the series has in order to generate contents you actually have to replicate the physics of the brain you could do it in a different medium in principle like you know copper and silicon etc but you would have to replicate you can't just emulate it so finally what i what i hope to have conveyed to you some sense that that today when when it comes to the mind body problem there's lots and lots of beautiful experiments that we can do it's still early days in in the discovery but we know enough already to say you know some of the main facts that much of what goes on in your brain bypasses consciousness that there are certain particular parts of the brain that seem to have a very close a much closer relationship to consciousness to others that this begs for an empirical you know respectful explanation particularly for theory of consciousness in particular this question becomes much more acute now that we're building things that behave more and more like us because at some point we are going to be confronted very practically with the question you know is this thing sentient doesn't feel like anything to be and for that we need a we need a final theory of consciousness that tells us that and with that i thank you for your attention you

Channel: World Science Festival

Views: 12,137

Rating: 4.9037433 out of 5

Keywords: Christof Koch, science of consciousness, Brain Science, free will, Does free will exist?, Free Will, Do humans have free will?, The Illusion of Free Will, Sam Harris, proof free will doesn't exist, types of Free Will, Libet experiment, Does free will require consciousness, New York City, NYC, world science festival

Id: vdHbQjVlrfc

Length: 57min 40sec (3460 seconds)

Published: Thu Jul 30 2020