Watch videos with subtitles in your language, upload your videos, create your own subtitles! Click here to learn more on "how to Dotsub"

TEDxBuenosAires - Mariano Sigman - 04/08/10

0 (0 Likes / 0 Dislikes)
I would like to talk about something I belive is very mysterious, and at the same time, very basic and close; that is how does consciousness arises from a group of cells, axons, cables a lot of flesh and other stuff in the brain. Personally, I have always been driven into this story, and I have been investigating it for a while now I believe it is extremely relevant to investigate an area we are barely able to define. Consciousness may seem a limited territory, a territory more suitable for philosophy, or intuition and I want to show you, actually it is the purpose of my lecture to show you that we can approach the matter from an empirical perspective, that we can approach it by means of scientific experiments: we can make science out of consciousness. So I will begin with an experiment, and I want you all to participate I will ask you to look closely at the center of this image and to raise your hands when the color dots on the side of the picture disappear be careful that sometimes you have 1, 2, 3, 4 dots I want all of you to raise your hands, because all of them have to disapear. There are exactly 1370 people in the room, I counted the exact number of hands... This serves us as a paradigmatic experiment, for it allows us to divide the objective reality, which is out there, from our own subjective reality, which is inside each and every one of the 1300 heads inside the room. The dots never left the picture, but they disappeared from your consciousness disjoining objective from subjective reality will allow us to begin experimenting with consciousness. We will now try another game... there is an image in the screen that occasionally blinks and each time it blinks there is something that changes... I will now ask you to raise your hand once more if you are able to see what has changed in the picture you should not be able to see it, so stay calm... the ones that do see it stay calm as well, we will discuss it later... very few hands...oh, now there are some more, good as I only have 18 minutes, and I can not let 18 minutes go by while your try to discover what has changed I will ask you to focus on the rail in the middle of the screen...I am not touching anything and now there is no way not to see it, in fact, there is no way that change does not penetrate our consciousness we went from being unable to see what was changing out there in the middle of the screen to see it no matter what.... we now have no way of not seeing it and this experiment involves a very important lesson for us, which is, that we are only able to perceive whatever permeates our consciousness, and still we belive it to be the entire world arround us but the truth is that, from all that affects our senses only a very small fragment is able to penetrate our consciousness notice that something that was changing in the middle of the screen was completely invisible to most of the people in the room. When working in the lab, this experiment results in a more specific outcome In the experiment I will show you now the objective is to determine the change in the brain path when a stimulus accesses our counsciousness, in respect to when it does not the experiment I will show you now is a prototype of the simpler version of the original experiment and at the same time, maybe the most powerful... what I will show you now is a person that sees a number, this number only lingers for an extremely brief period of time, and at the same time there are distractions just like I distracted you while your where looking at the rail in the previous experiment and because of that, sometimes the person is able to see the number which means the number penetrates his consciousness, and sometimes the person does not see it, which means the number lingers in a subliminal region of the brain we wish to investigate what you are going to see on the top of the screen is the path of the unconscious trace in those cases where the stimulus remains subliminal, and on the bottom of the screen you will see the path of the conscious stimulus if you take a look a the time frame, you will see this film has been slown down...this all happens approximately in the fraction of a second, about 200 or 300 miliseconds you will see, you can already see actually, how the back of the brain is activated that is where the visual region is located, it is not very important, but it means the stimulus is visual, and that therefore the visual region of the brain is activating what is important about this image is that, as I told you before, this is a stimulus that is not going to penetrate the consciousness, notice the top of the screen... we can now see something Sigmund Freud intuited a long time ago which is that the unconscious stimulus leaves a visible trail in the brain, even when it does not have access to the report after a long time, we are now able to see that trail, and therefore we are able to find the unconscious stimulus and not only that, for we can also measure the behavioral effects, the imapct a subliminal stimulus can have on our behaviour. If I flashed a number before your eyes for a very small amount of time, so small you would not be able to see it and ask you all if the number I showed you was smaller or bigger than 10 the right thing to do would be to say you don´t is not what most people do though, but it would be the right thing to do because one can not express an opinion about something he hasn´t seen now, if you were to answer my question, that answer would be typically correct, not always, but it would be more likely to be correct that if you were just guessing the importance of this experiment is that it shows us that decisions can be conditioned in this case we are conditioning it in an appropiate manner, but we can condition it in any way we want from the unconscious, by the means of a stimulus we don´t even know existed in the first place. Let´s carry on with the film, what you are going to see now is that both paths split there is a moment where one would want to see the brain path of the impact a stimulus has on our consciousness, and I make a halt here, 300 miliseconds afterwards -which is relatively late- and we can see that the conscious stimulus sizes the entire brain for an instant and this is a suitable metaphor, a good image of what we have today, of what represents the physiological base of our consciousness. The different aspects of a stimulus are gathered at the same time in our consciousness; the visual aspect, in which the stimulus presented itself, as well as the auditive aspect, and so on what I mean by this is that when one sees the number 7, something says 7, and 7 means something it has a language, a memory, and all of these representations are gathered in a specific point in time by our consciousness, and we can see on the screen how that occurs and what I have shown you until now is that a number of stimuli can affect us and still be invisible in regard to our consciousness what I want to show you now is the opposite effect, this will work very well for those of you who are close to the screen who can see this is moving? almost everyone, good it works for everyone... well, it´s still, I promise... you will be able to see the image are moving it yorselves actually you can see that if you move your eyes it moves faster what you are doing right now is creating movement, the movement you are seeing is being created by your own consciousness there is no movement on the screen, your consciousness is making it up. This one is my favourite because it´s a hybrid between art and science, in this two paintings by Akiyoshi Kitaoka, a japanese scietist and artist, you can see the sunflowers spinning, and notice that the sunflower you are directly looking at is always still this shows I´m not cheating, because each one of you is looking at a different flower and I have no idea which one it is and as for the flowers that are moving, notice that the more you move your eyes the faster they spin you realize you are playing with consciousness, -besides this is free and legal, I mean, there is no problem with this game, no one could go to jail beacuse of it- but you realize you are playing, we are playing with consciousness and we can turn this into an experiment. There is a moment every day when we all experiment with our consciousness some experiment a little more, and others a little less, but we all do it and in this moment, when we are lying in bed and we close our eyes, our consciousness suddenly shuts down the stimuli arround us keep coming; someone is talking to us, something is ringing, but we are not listening, our counsciousness has shut down and after a while our consciousness begins to function again, but in a much more bizzare state in a way that is stranger, and above all, a state which is disjoined from our senses, like in the image I just showed you you are filled with the most vivid and interesting images and your eyes are still is your own consciousness, your memory that is making this images up and therefore building reality in that particular moment according to certain memory patterns...but what I find the most interesting is that during the dream not only our consciousness is disjoined from our senses, but also from the muscules, from the movement, the action and this is in a way the essence of the dream, because dreaming is about being able to experience any kind adventure the most risky and intrepid adventures like flying without jeopardizing the body...the body is inmune, and in a way intact because it is completely disjoined from consciousness and this happens in a way we can understand pretty well by blocking the modulator which connects the dialogue between the brain and the muscle and every once in a while, in about 5% of the people... it has happened to me and we must be about 70 or 80 people in this room who have experienced it you wake up abruptly without being able to establish a proper connection between the brain and the muscle and when you try to move you discover you can´t, because you can´t lead your muscles when you try to speak to the person next to you to explain the situation you´re in you discover you can´t, because there is no voice without muscle and then you try to move desesperately, to let the other one know what is going on... but still you can´t because literally, without the muscle we are trapped, regardless the awareness of the mind there is no way of expressing and comunicating with the outer world. This phenomenon called sleep paralysis only lasts for a short period of time never more than 2 seconds, and then becomes a funny anecdote but in certain clinical cases, like with pacients in a vegetative state this situation is permanent this patients can be, and actually are unable to communicate with the outer world for the length of their lives. Vegetative patients are patients who have cycles; they have day and night, they are awake and asleep, they have certain reflective movements but none of the movements they can perform can lead us to assume any kind of intention any kind of agency...none of the movements they can perform reflect any kind of coherent communication with the outer world and in those situations there is no way one can assume the existence of consciousness in that being and actually, for a long time clincal medicine assumed that these patients had no consciousness and some time ago, Tristan Beckenstein and I decided to take a second look at these theory due to a certain intuitive hunch that maybe these patients had a trail of consciousness that couldn´t be percieved in the usual ways and the strategy we used in order to solve this problem was to find the minimum unit of behaviour for which consciousness was needed. These patients probably can´t do mathematical equations, nor talk they probably can´t do many things for which consciousness is necessary, but maybe they can do one the most simple of them all, and that would be enough for us to know they have consciousness and we found the answer to this question in an experiment by Larry Squire, a neurobiologist from San Diego who carried out a most elaborate version of an experiment by Pavlov in which there was a tone symphony; a binary simphony made out of two tones, acute tones and grave tones and after one of the tones, for instance the acute one there was a deliberate annoyance, which was some sort of blowing in the eye and the objective was to see if the people participating in the experiment were able to learn this connection and to make the experiment a bit more complex, Squire did the same thing I did with you before which is distracting the audience while they were watching the film and this made the experiment much more difficult and Squire found that more o less half of the pople were able to learn the connection in the sense half of them made an ocular response exactly before the blow and when they left the experiment, Squire interviewed them and found that exactly the same people that were able to consciously report the rules of the game, the ones who consciusly understood what the experiment was about, were the only ones who had learned and that was a gold mine for us, because it established the exact relation we were looking for; a connection between something we could measure like the eye, because those patients can move their eyes and what we wanted to know, that was if they actually had consciousness, we could relate something measureable with what we wanted to know and we started measuring that, and we saw lots of patients that weren´t learning and I can remember the moment vividly, like one of the few moments in every scientist´s life where one feels the huge vertigo of a discovery. In that time I was living in Paris and Tristan flew from Cambridge, where he had analysed a patient and we analyzed her in my house in Château Rouge, in the north of Paris and we saw she was learning as much as the most vigorous patients with full consciousness did and in that point we understood we had made an enormous discovery. We kept investigating, I resturned to Argentina and Diego Shalom joined the project we continued with this experiment for many years and after 35 patients we saw that actually 3 of them, which were not many of them, but were not few either arround 10% of the amount of patients diagnosed as not having any consciousness at all had in fact a clear trace of consciousness, and with that we knew they had the capacity for coherent thought but we couldn´t tell what they were thinking and that came afterwards, after an experiment by Adrian Owen in Cambridge an experiment which shared many of the subjects we had used for our own experiment and that was based in a similar strategy, but differed in its measurement of the brain activity in the patients Owen selected people who were able to tell what was happening to them and told them to think about two different things: on the one hand, to imagine themselves playing Tennis, like Federer or Nalbandian (not Coria) and on the other hand, to imagine themselves walking arround their house and those exercises generated different patterns of brain activity. On the left of the screen you can see the pattern of brain activity of a person who is playing Tennis and on the right you can see the pattern of brain activity of a person imagining to be walking arround their house. These patterns are different because they involve distinct functions, located in different parts of the brain. The details are irrelevant... the important thing is that they are different and therefore they can allow us to know what the person is looking at by looking at his brain activity, and again this isn´t the most interesting case because that person can simply tell us what he is looking at. But when one is working with a pacient whose ability to think is unclear a patient we can´t be sure what he is thinking about, and we see that the pattern of brain activity is exactly the same than the regular patient when we tell him: imagine you are playing Tennis, he generates a pattern that is coherent with this or when we tell him: imagine you are walking arround your house, and he generates that I think we are able to asume, without any doubt, that he has the capacity to imagine and therefore, that he has a consciousness. We saw that our patients were able to learn using this criterion which is why we are able to use this experiment as a communicational device. If I can´t communicate with you I can tell you: every time you want to say yes imagine you are playing Tennis and every time you want to say no imagine you are walking arround your house. I can ask questions, look at the pattern, and use the code that has become a language to communicate with someone for whom this device is the only window he has in order to access knowledge, in order to communicate with the outer world. Owen´s group showed that they could in fact communicate with one patient who answered a number of questions using this device, this code. The last thing I want to tell you before I finish is that we can use these same ideas for understanding certain kinds of thought which can not be expressed in terms of language to understand one of the most amazing worlds we are sorrounded by: the world of smaller kids. The way in which newborn babies think, after a week, after a few moths... and I will tell you an example, that is the example of language, the one we have studied the most and the one we know the most about. What you can see in the image on the bottom left is the network used by adults to respond to language. This is a very complex network we can understand in great detail all you need to know is that in the typical sequence, the sensory cortex listening to language is activated in the middle of the auditive cortex, and this in turn sends an activation to a region in the front left known as Broca´s area, which you can see in this picture. This region is necessary for the production and articulation of language and we know that because patients that have lesions in this area are able to understand language but they are unable produce it: they are aphasic. A few years ago in Paris, the 3 of us, Sislene, Stan Dehane and I where wondering if babies only 3 months old, babies who were still a long way from producing their first words -for babies only begin talking arround their first year, which would mean they would still have to cuadruplicate their lifetime in order to start talking- we were wondering if these babies already possessed some sort of structure permissive of language and we discovered that their language network was exactly the same; we saw that babies were responding to language in the exact same way as adults by activating, first, the auditive cortex, and afterwards, by directing that activity to Broca´s area. We were also able to see that Broca´s area was specific of language, because when we played the same sounds in the opposite direction the auditive cortex would respond, but Broca´s area wouldn´t. And what we found was the first demonstration of an idea that had appeared a while back a theoretical idea, an idea that had been approached intuitively that was that language wasn´t learnt from scratch, that language was not learnt from zero but that there was a scaffolding in every human being just like Chomsky thought, a scaffolding prepared to respond from within all of an auditive range to those sounds which corresponded to language. The brain is somehow set to respond to the combination of sounds which make up the different languages. Personally, I wanted to tell you that this discovery, which ended up having a very simple conclusion, became extremely relevant when my son Milo was born a while after. Milo is the 5 months old baby you are now seeing on the screen, on this picture he was about 3 months. When Milo was 3 months and he tried to grab something, he did a tremendous effort to attain something that was extremely simple for us doing something as simple as closing his hand required all of his effort, all of his attention, his entire consciousness. I was able to see that effort and seeing him, playing with him, and being able to share what he was doing was the most entertaining thing in the world for me back then, and it still is. With this I was also discovering something else; that even when I couldn´t see it, or hear it when I was talking to him, I could tell Milo was, in his own rudimentary way, very simply and silently also producing language, also talking to me. Thank you very much.

Video Details

Duration: 18 minutes and 43 seconds
Country: Argentina
Language: Spanish (Spain)
Producer: TEDxBuenosAires
Views: 125
Posted by: wesleyoliveira on Apr 11, 2011

Mariano Sigman estudia la máquina que construye la realidad. Investiga cómo emergen de una mezcla casi infinita de células y cables (axones y neuronas) el pensamiento, la memoria, los sueños, las emociones y la conciencia. Experimenta con ilusiones visuales y busca en trazas de la actividad neuronal los motivos de la toma de decisiones, del lenguaje y del pensamiento consciente e inconsciente.

Caption and Translate

    Sign In/Register for Dotsub to translate this video.