What if we could leave our body and have a new one? | Henrik Ehrsson | TEDxGöteborg

when I was a kid I had this strange idea I thought maybe God has made a mistake maybe when he was supposed to put my soul in my body there was a mixup so he put my soul in my brother's body and my brother's soul in my body and now we're living our lives in the wrong bodies how do I know that this is my body how can I be sure so the young man I got interested in science and brain science in particular how does the brain creates the conscious human mind it's quite fascinating when you think about it the brain one and a half kilo clump that you can sort of hold between your hands a hundred billion neurons brain cells that communicate with analog electrical signals and yet everything you will ever experience sing or feel come from that piece of biological tissue how is this possible so I started to become a brain scientist in Sweden and then I went to London to learn more about advanced brain imaging technologies but I never forgot this questions I had as a child how do I know that this is my body why does it feel like my sense of self is located inside this body and I experience the world from this perspective well some of you might say what's kind of strange questing' is that of course the self is in the body where could a self otherwise be it's not like the self is leaving the body from time to time well that's not entirely true so when I was a medical student I was doing my clinical rotations I was a psychiatry and emergency ward and I was interviewing a young man around 25 he was suffering from schizophrenia and I was taking was interviewing him he was quite calm at the moment at a time we are sitting in a small room and there was also an experienced all the nurses in the room and when I was talking to him suddenly he got quiet just fro stop talking another nurse stood up I remember she walks over she takes the guy and starts to shake him like this and I go what's good what's happening here what's going on and she said you know from time to time you started shaking to get his self back into his body because his self sort of floats away he has out-of-body experiences I was very curious what's going on here so he started to talk talking again I asked him what did you experience what happened and he said well I was just sitting and then I saw you were talking to this other guy and then I saw the nurse came up and started to shake that guy so he had this experience that his self had left his body moved to another corner of the room and there he was looking at himself from this new perspective like he was looking at now the person and I thought what's going on what's going on in this this guy's brain what is happening in my brain now when I have sort of a normal in body experience so I decided I want to do experiments I want to understand this more but in science if you're going to study a system how the brain gives us the sense of a bodily self we need to have a way to preserve that system so how do we take a normal test person bring him or her to the lab and change that person's sense of only self well we use something called a perceptual illusions is a Mind Tricks that allows us to study how the brain interprets sensory information so this is one illusion we discovered in my lab a couple of years ago so you the test person you're sitting in front of a table and you put your hand on the table and there's a screen that occludes the hands you can't see it then the scientist is using two small paintbrushes and is stroking your hand and a portion of empty space like this in the beginning is really boring I mean nothing happens you sit there someone is stroking your hand but then after 15 20 seconds in most cases something strange happens you can see that in the participants face their eyes open the mouth open they start to giggle suddenly they start to sense touch where they see the paintbrush moving in empty space and they lose awareness of the real hand and it's not experience that we have in invisible hand straight in front of their eyes and invisible hand that senses the touch of the paintbrush so here we have created some kind of out-of-body experience for the hand we have pulled out the sense of the hand from the real hand to empty space and so this tells us that that's the brain this is a very dynamic process it's like it's the brain can interpret and change it the experience or your own body it also suggests that might be something very important about how the brain interprets what you what you see what you feel now people not making this up this is your note people just not being imaginative here you really feel this invisible hand and we can test that by attacking the hand with a hammer or a chop object and then we can see if people respond with a fear reaction just like if we attack the real body and we can measure that because people sort of sweat and we can measure the increase in moisture of the skin by putting two electrodes on the skin and we can see that there that they react in the same way like when we set in the real hand and it turns out that the solution or base very precise rules like scientific rules you could say so you have to apply the strokes in the same directions different directions there's no illusion you have to apply the touches simultaneously if there is a delay to asynchronously then there's no illusion and it only works inspect within space close to the test person within reaching distance so what we think is going on here is that the brain is integrating putting together what you see and what you feel into one coherent representation of your body so we call this multi-sensory integration so the brain takes puts together what you see what you feel and information for the muscle stamp and create creates a coherent representation that this is my body but can we take this further so now we did an experiment with a hand can we use the same principles to create an illusion that someone the real body and experience like an out-of-body experience so we try that in another illusion experiment that we design and now you're the test person you're sitting on the share and now you wear head mount in this place it's two screens in front of your eyes and they're connected two cameras that we put two meter behind you so you see yourself to the back and then I touch the test person's chest and then I move my hand towards the cameras so synchronizing the touches like this so now something very strange happen if you're the test person you start to experience that you're outside your real body that you're sitting a couple of meters behind yourself and and you're looking at yourself you know it's you but it doesn't feel like you anymore it feels like another another person but you have to do that you have to apply these touches simultaneously if it's out of sync it doesn't work so this is a breakdown of the illusion there's a tactile stimulation of the person's chest there's a visual stimulation towards the cameras if it's synchronous you feel the illusion you're outside your body it's asynchronous you don't have illusion and again we can test this by attacking the person with a hammer like that and now you we are attacking the sort of conscious sense of self bodily self that is now sitting two meters behind your real body and and people react with with fear fear response if we attack the person's real body then the person don't care it's not scary because the self is not in the body anymore so but can you take this further can we give people a sort of body swap illusions we took the self out from the real body can now give the mind in you body would that work so we have done experiments like that so now we put the cameras on the head of a mannequin pointing down and you wear the head mount to this place and when you look down you see the mannequins body the first-person point of view and that's important it doesn't work if you look at the mannequin like you look at another person and then we do this synchronized stroking so we we touch the mannequin and body at the same time same direction corresponding body parts and now boom you just feel that the manic is bodies you this is your new body it doesn't matter if you're a man or a woman or the kiss me is color of your skin if you have clothes on I just feel as mannequin is you and it works with any human body just think about for him think about that for a moment so your brain are willing to accept any human body as your own as your own body but it has to look like a human it has to have a human body plan it doesn't work with things that doesn't resemble human like a large lobster for example or a table or a block of wood but if we obey the basic rules of the board illusions in terms of time space and humanoid body shape then it works with very large bodies for me two giants or very small little lilliputs so we have done experiments where you feel that you are like a 30 centimeter little doll like a Barbie's friend can and then you we do the synchronized stroking on the little doll and your real body and you wear the helmet to this place now you feel that you are that little that little doll and it's a very vivid illusion and now you're living in the world of giants you see these gag antique hands and people look like Giants you know this can't be happening this can't be true but just feels real it's please like it's your body innocent has profound effects on how you experience the world around you so what's going on in the brain so this is a brain this is the front this is the back this is the top of the brain and here we're taking a brain inflated it so we can see the surface a little bit better back here in the brain we have the visual cortex information from our eyes reaches the part of the brain helps us see and then up here we have the Sumatra sensory cortex information from muscles the skin and joints touch sense of touch which is that part of the brain and then we have these areas in the brains integration zones the frontal and parietal Association cortex and these areas they can receive visual information and somatosensory information and integrate these signals and create a coherent representation of that this is my hand now when you stand sense that yourself is located in a particular place we think that there's another part of the brain that is important in the so called temporal Association cortex and in this part of the brain last year there was Nobel Prize awarded for the discovery of so-called play cells these are cells that keep track where a rat is located in the little cage it's like the brains GPS and we think that in humans this area keeps track where your sense itself is located in the world so how do we test this this is a hypothesis right how do we can go on and actually do experiments well we use this fantastic thing called brain imaging technology brain imaging techniques so here using functional magnetic resonance imaging so it's like a big tunnel you go into that tunnel only your legs are sticking out and we can create images of the brain activity in healthy people by strong magnetic fields and radio waves so we can register brain activity at the resolution of two by two by two millimeter cubic voxels the ceiling reflects changes in the oxygen level of the blood because in brain cells work they use of Europe of oxygen so now when you went into that tunnel you the test person are going into the tunnel and you wear the head-mounted displays what you see is the scanner room from the perspective of a stranger that's lying in the corner of the scanner room and you see that strain you're being stroked and you feel touches on your own body at the same time at corresponding place right so now we're scanning the outer board illusion and the bodies for pollution so you don't feel that you in the scanner anymore you're feeling like you're lying on the floor on the scanner room and that you have a new body a strange body and the scanner is collecting data all the time and now we can teleport your sense of self between two locations in the corner of the scanner room the right corner in the left corner several ten seconds during one corner and then you're sapped teleported through to this corner back and forth all the time during this out the board illusion what time is collecting brain data so first we for which areas that give you sense that a stranger's body is your own body and we found increases in activity in these frontal and parietal Association cortices that integrates what you see in what you feel it gives you sense of of ownership of the body and then we had looked for activity that reflected the sense of self location the sense of where you located in space and we found that this particular part of the medial temporal cortex where placed cells for finding rats activity that reflected the conscious sense where yourself is located what have you learned well we have learned that when we have a normal in body experience there's two systems in the brain that are working in concert working together there's one system that is saying hey this is your body and by integrating what you see what you feel and there is another system that keeps track where your sense itself is located in the world with respect to environmental landmarks in the environment that says you're located exactly here and if these two systems are working properly interpreting the information properly you have a normal in body experience but it is if the brain is not working properly Kevin if you experience an outer body experience for example we have a brain disorder or you haven't slept well or you're tired and and these things are not working properly then you can have an outer body experience because the information is not integrated integrated properly so so how can we use this how can we use this to improve human health and make our everyday life easier I think that there are a number of important applications now first of all it can give us give us a new understanding of what is going wrong in major psychiatric and neurological disorders where there is a disturbed sense of self and an embodied perception for example in schizophrenia there are 50 million people in the world that are suffering from schizophrenia and disturbances in the sense of self is part of the core symptoms and we don't know what is causing it so we can now do new experiments to try to understand better what might be go wrong with the sense of self in schizophrenia maybe to develop better diagnostic tools or therapeutic tools but we can also use a knowledge about how the brain creates the sense for building itself to project the sense of the self into artificial devices and I think that we are almost on a virtual scientific revolution where scientists mind scientists brain scientists engineers and robotic people can work together to use to use this for for ended up in a number of different applications for example to create a new generation of artificial limbs for amputees that feels exactly like real limbs so that amputees can feel a whole again and also may be used a persists more intuitively because it feels like black black and real ocular Braca real Han for example in the case of over of an upper arm amputee we can also improve today's applications in virtual reality and projected sense of self into computer-generated avatars so that in virtual reality you have a full-blown illusion bodies for pollution that the simulated avatar really is your new body and I can increase the realism and immersion in in today's application in games for example or we can project the sense of self into advanced humanoid robots so that you get the illusion that you are now the humanoid robot or the when you see a field through the body of the robot and and when you move the robots make the same movement that to be very helpful for example if an engineer is supposed to control a humanoid robot in rescuers work say they're going to fix a nuclear power plant it could be see if you just teleport your sense of self into that robot and you can react very quickly very intuitively very fast so I think we have a lot to learn from from from science and brain science and technology to improve people's health and make our lives easier thank you very much for listening you

Channel: TEDx Talks

Views: 35,040

Rating: 4.9022899 out of 5

Keywords: TEDxTalks, English, Sweden, Science (hard), Cognitive science, Science

Id: ZEhXX47PRvw

Length: 17min 53sec (1073 seconds)

Published: Mon Mar 28 2016