1 00:00:04,640 --> 00:00:08,280 Speaker 1: How do your billions of tiny brain cells with their 2 00:00:08,320 --> 00:00:14,159 Speaker 1: electrical spikes build consciousness? And why is your laptop, with 3 00:00:14,240 --> 00:00:19,280 Speaker 1: its billions of parts and tiny electrical signals, presumably not conscious? 4 00:00:19,920 --> 00:00:23,600 Speaker 1: Could other large systems like a city be conscious? And 5 00:00:23,640 --> 00:00:25,840 Speaker 1: what does any of this have to do with ant 6 00:00:25,880 --> 00:00:30,080 Speaker 1: hills or bluebirds or your memory of your first kiss? 7 00:00:33,920 --> 00:00:37,000 Speaker 1: Welcome to Inner Cosmos with me David Eagleman. I'm a 8 00:00:37,000 --> 00:00:40,920 Speaker 1: neuroscientist and an author at Stanford University, and I've spent 9 00:00:40,960 --> 00:00:45,200 Speaker 1: my whole career studying the intersection between how the brain 10 00:00:45,280 --> 00:00:49,479 Speaker 1: works and how we experience life. And there's hardly a 11 00:00:49,479 --> 00:00:55,920 Speaker 1: better example of this intersection than consciousness. Your feeling of 12 00:00:55,960 --> 00:01:00,240 Speaker 1: being aware of your surroundings and your own existence, your 13 00:01:00,280 --> 00:01:05,880 Speaker 1: ability to experience and feel things. This somehow emerges from 14 00:01:05,920 --> 00:01:10,480 Speaker 1: the activity of our brains, and it is our experience 15 00:01:10,520 --> 00:01:14,880 Speaker 1: of life. So today we're going to dive deep into 16 00:01:14,959 --> 00:01:20,000 Speaker 1: a big question, possibly the central question of neurobiology. What 17 00:01:20,640 --> 00:01:24,679 Speaker 1: is consciousness. We'll talk about how we can define it, 18 00:01:24,920 --> 00:01:28,040 Speaker 1: why it's a challenge for our science to capture it, 19 00:01:28,560 --> 00:01:32,399 Speaker 1: and whether other things could be conscious. So think back 20 00:01:32,440 --> 00:01:36,600 Speaker 1: to your first kiss. The memory of it pops back 21 00:01:36,640 --> 00:01:40,360 Speaker 1: into your head in an instant, But where was that 22 00:01:40,600 --> 00:01:45,160 Speaker 1: image before you became conscious of it, that feeling, the 23 00:01:45,319 --> 00:01:48,320 Speaker 1: name of the person, How is it represented in your 24 00:01:48,360 --> 00:01:52,800 Speaker 1: brain before and after I ask you to think about it. 25 00:01:53,040 --> 00:01:56,760 Speaker 1: What's the difference between those two states? In other words, 26 00:01:56,800 --> 00:02:04,560 Speaker 1: what events in the brain constitute awareness or consciousness. I 27 00:02:04,640 --> 00:02:07,640 Speaker 1: made an earlier episode about all the things going on 28 00:02:07,720 --> 00:02:12,440 Speaker 1: in your head unconsciously without any access or awareness on 29 00:02:12,480 --> 00:02:16,720 Speaker 1: your part, and the upshot there was that at any moment, 30 00:02:16,880 --> 00:02:20,320 Speaker 1: there's an enormous amount of activity going on in your brain, 31 00:02:21,040 --> 00:02:25,639 Speaker 1: one hundred billion cells having little electrical spikes tens or 32 00:02:25,720 --> 00:02:29,680 Speaker 1: hundreds of times per second, and you are not consciously 33 00:02:29,720 --> 00:02:33,000 Speaker 1: aware of almost any of that activity in your brain. 34 00:02:33,760 --> 00:02:38,280 Speaker 1: But a tiny, tiny bit of that activity is conscious. 35 00:02:39,720 --> 00:02:42,560 Speaker 1: And so for this episode we're turning to that tiny 36 00:02:42,680 --> 00:02:46,280 Speaker 1: tiny bit and the question of what is different about 37 00:02:46,720 --> 00:02:49,680 Speaker 1: that activity than all the other activity in your brain, 38 00:02:50,160 --> 00:02:52,560 Speaker 1: and why it's such a challenge for us to figure 39 00:02:52,560 --> 00:02:56,840 Speaker 1: out how to translate that activity in your brain into 40 00:02:57,000 --> 00:03:03,240 Speaker 1: your private, colorful experience of the world. The explanation of 41 00:03:03,320 --> 00:03:08,280 Speaker 1: consciousness is one of the major unsolved problems of modern neuroscience, 42 00:03:08,400 --> 00:03:13,520 Speaker 1: and possibly the most important. So first, what is consciousness. 43 00:03:13,760 --> 00:03:17,160 Speaker 1: Defining it is the first step to the problem. So 44 00:03:17,280 --> 00:03:19,440 Speaker 1: there are lots of ways to try to wrap our 45 00:03:19,560 --> 00:03:22,040 Speaker 1: arms around it. But the definition that I think will 46 00:03:22,040 --> 00:03:26,800 Speaker 1: get us started the fastest is to say consciousness is 47 00:03:26,840 --> 00:03:29,480 Speaker 1: the thing that flickers to life when you wake up 48 00:03:29,520 --> 00:03:32,920 Speaker 1: in the morning. I mean, think about how wacky this is. 49 00:03:33,000 --> 00:03:36,200 Speaker 1: You have the same brain the moment before you wake 50 00:03:36,280 --> 00:03:39,400 Speaker 1: up in the moment after, but something just changed a 51 00:03:39,440 --> 00:03:42,200 Speaker 1: little bit about the activity, the way the signals are 52 00:03:42,240 --> 00:03:46,600 Speaker 1: moving around, and suddenly you're conscious. Whereas a moment ago 53 00:03:47,040 --> 00:03:49,680 Speaker 1: you were just lying there like a sack of potatoes. 54 00:03:50,120 --> 00:03:52,920 Speaker 1: You had the same brain, but you weren't aware of anything. 55 00:03:53,680 --> 00:03:57,000 Speaker 1: But now your brain cells start to run a slightly 56 00:03:57,040 --> 00:04:01,920 Speaker 1: different algorithm, and suddenly you're aware of your existence, of 57 00:04:01,960 --> 00:04:06,800 Speaker 1: your name, of your history, and your bedroom and the 58 00:04:06,840 --> 00:04:09,920 Speaker 1: smell of coffee and the feel of your sheets and 59 00:04:10,000 --> 00:04:11,040 Speaker 1: the details of. 60 00:04:11,000 --> 00:04:11,960 Speaker 2: The room around you. 61 00:04:12,200 --> 00:04:17,680 Speaker 1: Now, weirdly, what you're experiencing is a private experience. It's 62 00:04:17,680 --> 00:04:22,480 Speaker 1: what we call a subjective experience. It's not objective, which 63 00:04:22,480 --> 00:04:26,480 Speaker 1: is something we can measure and agree on a shared reality. Instead, 64 00:04:26,600 --> 00:04:30,520 Speaker 1: only you are experiencing it. So if there's someone else 65 00:04:30,560 --> 00:04:32,680 Speaker 1: in the bedroom when you wake up and that person 66 00:04:32,800 --> 00:04:36,120 Speaker 1: is looking around, there are different things going on in 67 00:04:36,160 --> 00:04:42,119 Speaker 1: that head, different thoughts, different feelings, a different subjective experience. Okay, 68 00:04:42,160 --> 00:04:45,359 Speaker 1: so imagine you're there and you roll over and you 69 00:04:45,400 --> 00:04:47,559 Speaker 1: look at a painting on your wall and you see 70 00:04:47,560 --> 00:04:53,240 Speaker 1: the colors. Now, what's happening inside your brain is that 71 00:04:53,360 --> 00:04:57,680 Speaker 1: different wavelengths of light are bouncing off the painting and 72 00:04:57,680 --> 00:05:02,600 Speaker 1: they're activating particular color photoreceptors in the back of your eyes, 73 00:05:04,480 --> 00:05:07,640 Speaker 1: which sends signals back to your brain through the optic nerve, 74 00:05:08,200 --> 00:05:12,440 Speaker 1: and in the brain, cells in the visual cortex start activating. 75 00:05:13,040 --> 00:05:15,960 Speaker 1: And if you had a magical microscope by which you 76 00:05:16,000 --> 00:05:18,560 Speaker 1: could view what was happening in the brain, you'd see 77 00:05:18,560 --> 00:05:22,359 Speaker 1: that you have a vast pattern of cells in the 78 00:05:22,400 --> 00:05:25,480 Speaker 1: back of the brain that activate when you look at 79 00:05:25,720 --> 00:05:29,200 Speaker 1: one painting color, and a different pattern of cells that 80 00:05:29,240 --> 00:05:32,320 Speaker 1: activate when you look at a different color. But the 81 00:05:32,440 --> 00:05:36,280 Speaker 1: question is why do you perceive the red in the 82 00:05:36,279 --> 00:05:41,240 Speaker 1: painting as red? There's just a particular wavelength of light 83 00:05:41,440 --> 00:05:45,360 Speaker 1: associated with your private subjective experience of seeing red. 84 00:05:45,760 --> 00:05:48,120 Speaker 2: But the redness is something made. 85 00:05:47,920 --> 00:05:50,479 Speaker 1: Up by the brain and could just as easily be 86 00:05:50,600 --> 00:05:54,039 Speaker 1: perceived by you as blue or green or anything else. 87 00:05:54,920 --> 00:05:58,680 Speaker 1: So why does this particular pattern of cells equally a 88 00:05:58,760 --> 00:06:03,920 Speaker 1: particular color. These are called qualia. Qualia are the features 89 00:06:03,960 --> 00:06:08,120 Speaker 1: of our experience, the internal experiences that are associated with 90 00:06:08,440 --> 00:06:12,359 Speaker 1: conscious states. The redness of red in this case, or 91 00:06:12,440 --> 00:06:16,520 Speaker 1: the sweetness of sugar, or the pain of a headache, 92 00:06:16,760 --> 00:06:21,000 Speaker 1: these are called qualia. Now, these are irreducible, which means 93 00:06:21,000 --> 00:06:24,960 Speaker 1: they can't be described in terms of something else. And 94 00:06:25,000 --> 00:06:28,040 Speaker 1: by the way, they're also ineffable, which means they can't 95 00:06:28,080 --> 00:06:32,120 Speaker 1: be fully explained or described in words like if I 96 00:06:32,200 --> 00:06:35,080 Speaker 1: ask you, what does an avocado taste like, how are 97 00:06:35,120 --> 00:06:37,000 Speaker 1: you going to answer that. Let's say that I tell 98 00:06:37,040 --> 00:06:39,480 Speaker 1: you I've never eaten an avocado, and I really want 99 00:06:39,560 --> 00:06:42,039 Speaker 1: you to tell me what that experience is. It's not 100 00:06:42,200 --> 00:06:45,719 Speaker 1: something that you can directly transmit to me, because it's 101 00:06:45,839 --> 00:06:50,000 Speaker 1: an experience that's private to you and generally cannot be 102 00:06:50,120 --> 00:06:54,200 Speaker 1: reduced to words. The last piece of the foundation that 103 00:06:54,240 --> 00:06:56,800 Speaker 1: we need is that when you look in the brain, 104 00:06:57,680 --> 00:07:00,640 Speaker 1: it's all just neural signals going on, and all those 105 00:07:00,680 --> 00:07:03,719 Speaker 1: signals look exactly the same. So if I opened up 106 00:07:03,760 --> 00:07:06,600 Speaker 1: a little window somewhere in the skull and showed you 107 00:07:06,680 --> 00:07:09,240 Speaker 1: just a little bit of brain tissue. And I used 108 00:07:09,320 --> 00:07:12,160 Speaker 1: that magical microscope so you can see all the spikes 109 00:07:12,240 --> 00:07:12,960 Speaker 1: zipping around. 110 00:07:13,240 --> 00:07:14,440 Speaker 2: And I said to you, hey. 111 00:07:14,440 --> 00:07:17,720 Speaker 1: Are we looking at the visual cortex here, or the 112 00:07:18,160 --> 00:07:21,840 Speaker 1: auditory or the somatosensory or some other part. You wouldn't 113 00:07:21,840 --> 00:07:24,000 Speaker 1: be able to tell me. I wouldn't be able to 114 00:07:24,000 --> 00:07:26,840 Speaker 1: tell you because it's all the same stuff going on 115 00:07:26,920 --> 00:07:30,280 Speaker 1: in there. It all looks the same. There aren't spikes 116 00:07:30,280 --> 00:07:33,160 Speaker 1: that equate to consciousness and other spikes that are running 117 00:07:33,160 --> 00:07:37,320 Speaker 1: around unconsciously. It's all cells and spikes, and they all 118 00:07:37,360 --> 00:07:42,160 Speaker 1: look alike. So why do some patterns of signals mean 119 00:07:42,200 --> 00:07:46,680 Speaker 1: the color red and others mean the smell of apple pie, 120 00:07:46,800 --> 00:07:50,360 Speaker 1: and others mean the pain of a paper cut. It's 121 00:07:50,400 --> 00:07:52,960 Speaker 1: all just signals and networks of cells. It's all the 122 00:07:53,040 --> 00:07:56,600 Speaker 1: same stuff running around. And so this is really the 123 00:07:56,640 --> 00:07:59,600 Speaker 1: heart of the mystery. The brain is made up of 124 00:07:59,760 --> 00:08:03,120 Speaker 1: lots of cells, eighty six billion neurons and about as 125 00:08:03,160 --> 00:08:06,600 Speaker 1: many glial cells. But they're just cells. And the brain, 126 00:08:06,640 --> 00:08:09,240 Speaker 1: as far as we can tell, is just a giant 127 00:08:09,640 --> 00:08:14,240 Speaker 1: machine that's made out of biological wetwear. It's an enormous 128 00:08:14,280 --> 00:08:18,760 Speaker 1: and quite alien computational device. But every cell in the 129 00:08:18,800 --> 00:08:23,120 Speaker 1: brain is driven by the activity of other cells, and 130 00:08:23,200 --> 00:08:26,040 Speaker 1: so no matter how complex the whole system is, it 131 00:08:26,040 --> 00:08:29,560 Speaker 1: appears to be fundamentally a machine in which each sequence 132 00:08:29,600 --> 00:08:33,120 Speaker 1: of actions is leading to the next sequence. It doesn't 133 00:08:33,320 --> 00:08:37,160 Speaker 1: appear that there's some extra bit in the brain that's 134 00:08:37,200 --> 00:08:40,560 Speaker 1: not just about the physical stuff. And so somehow we 135 00:08:40,600 --> 00:08:44,079 Speaker 1: need to look for consciousness in the physical stuff. And 136 00:08:44,160 --> 00:08:48,760 Speaker 1: we know that consciousness depends on the details in the brain, 137 00:08:49,520 --> 00:08:53,400 Speaker 1: because even very small damage to your brain can change 138 00:08:53,760 --> 00:08:57,920 Speaker 1: your consciousness. For example, if your brain is badly damaged, 139 00:08:57,960 --> 00:09:01,520 Speaker 1: you can end up in a coma without consciousness. Your 140 00:09:01,520 --> 00:09:04,760 Speaker 1: brain changes and your consciousness changes. But this happens in 141 00:09:04,840 --> 00:09:06,199 Speaker 1: much more subtle ways. 142 00:09:06,240 --> 00:09:06,720 Speaker 2: Every day. 143 00:09:06,960 --> 00:09:12,000 Speaker 1: When you ingest alcohol, the little ethanol molecules interact with 144 00:09:12,080 --> 00:09:16,480 Speaker 1: your cells and your consciousness changes. Same with drugs, same 145 00:09:16,520 --> 00:09:20,400 Speaker 1: with fatigue, same with low blood sugar. Or if you've 146 00:09:20,400 --> 00:09:23,200 Speaker 1: ever known someone who had a stroke, or got a 147 00:09:23,280 --> 00:09:27,760 Speaker 1: brain tumor, or had a traumatic brain injury, their consciousness 148 00:09:27,800 --> 00:09:32,080 Speaker 1: can change pretty drastically. So we know that consciousness is 149 00:09:32,200 --> 00:09:35,720 Speaker 1: intimately tied to the details of what's going on in 150 00:09:35,760 --> 00:09:39,760 Speaker 1: the brain. Now, the French philosopher Renee Descartes thought that 151 00:09:40,160 --> 00:09:43,760 Speaker 1: the physical and the mental were separate. Essentially, there's a 152 00:09:44,080 --> 00:09:48,360 Speaker 1: separate soul, and that was maybe a reasonable starting guess, 153 00:09:48,400 --> 00:09:52,800 Speaker 1: but centuries of neurology have taught us otherwise. When the 154 00:09:52,880 --> 00:09:58,000 Speaker 1: brain changes, your consciousness changes. You are your brain. You 155 00:09:58,320 --> 00:10:01,040 Speaker 1: can get a surgery and replace your heart entirely with 156 00:10:01,080 --> 00:10:03,800 Speaker 1: an artificial heart, and you're really no different. You can 157 00:10:03,840 --> 00:10:06,840 Speaker 1: get a kidney removed, and you're really no different. But 158 00:10:07,000 --> 00:10:10,600 Speaker 1: even a very tiny change in the brain makes a 159 00:10:10,760 --> 00:10:15,360 Speaker 1: giant difference to your conscious experience. Now, the amazing thing 160 00:10:15,440 --> 00:10:18,600 Speaker 1: is that modern biology knows a lot about what is 161 00:10:18,679 --> 00:10:21,720 Speaker 1: happening inside the human body, all the way down to 162 00:10:22,360 --> 00:10:25,720 Speaker 1: cells and the contents of cells, to the genome and 163 00:10:25,760 --> 00:10:28,439 Speaker 1: the molecules that make up the proteins and so on. 164 00:10:29,000 --> 00:10:33,320 Speaker 1: But where are you in that picture? Why are you 165 00:10:33,400 --> 00:10:37,479 Speaker 1: someone who cares about your life and listens to podcasts 166 00:10:37,520 --> 00:10:41,800 Speaker 1: and has desires and fears and aspirations and tastes and 167 00:10:41,840 --> 00:10:44,880 Speaker 1: so on. One of my mentors, the late Francis Krik, 168 00:10:44,960 --> 00:10:48,240 Speaker 1: had a chalkboard in his office and it was busy 169 00:10:48,280 --> 00:10:51,120 Speaker 1: with lots of scribbles, but there was one word right 170 00:10:51,160 --> 00:10:54,920 Speaker 1: in the center, and that was meaning. And what he 171 00:10:55,000 --> 00:10:58,000 Speaker 1: was reaching for with that was why in the world 172 00:10:58,040 --> 00:11:01,280 Speaker 1: does any stimulus mean mean something to us? Why do 173 00:11:01,360 --> 00:11:04,480 Speaker 1: you care about anything? How do you run a bunch 174 00:11:04,520 --> 00:11:09,040 Speaker 1: of activity through cells and get meaning? This is really 175 00:11:09,120 --> 00:11:12,440 Speaker 1: the question of consciousness, and it's a difficult problem for 176 00:11:12,520 --> 00:11:17,160 Speaker 1: neuroscience to tackle. In part, it's because the language we 177 00:11:17,280 --> 00:11:20,760 Speaker 1: have in science doesn't tell us how to translate from 178 00:11:20,800 --> 00:11:25,920 Speaker 1: the realm of the physical to the realm of subjective experience. 179 00:11:26,160 --> 00:11:29,800 Speaker 1: I can't write down an equation that captures the activity 180 00:11:29,800 --> 00:11:31,520 Speaker 1: in a bunch of cells and then I say, okay, look, 181 00:11:31,600 --> 00:11:34,000 Speaker 1: just do a double integral here and add something and 182 00:11:34,040 --> 00:11:37,760 Speaker 1: carry the five. And that is the feeling of rain 183 00:11:37,880 --> 00:11:40,880 Speaker 1: on a hot day, or the feeling of silk between 184 00:11:40,920 --> 00:11:45,720 Speaker 1: your fingertips, or the sound of a saxophone and a stairwell. 185 00:11:46,160 --> 00:11:49,240 Speaker 1: So science doesn't seem to have the language, at least 186 00:11:49,320 --> 00:12:09,440 Speaker 1: not yet, to translate from the objective to the subjective. Really, 187 00:12:09,480 --> 00:12:13,080 Speaker 1: the easiest way to see what's weird about consciousness is 188 00:12:13,120 --> 00:12:18,040 Speaker 1: to think about other big, complex systems that presumably don't 189 00:12:18,040 --> 00:12:21,560 Speaker 1: have consciousness. So imagine I were to hand you one 190 00:12:21,640 --> 00:12:25,200 Speaker 1: hundred billion tinker toys. You remember those old toys with 191 00:12:25,240 --> 00:12:28,040 Speaker 1: metal rods and connectors, and you can build pulleys and 192 00:12:28,080 --> 00:12:28,600 Speaker 1: levers and. 193 00:12:28,600 --> 00:12:29,520 Speaker 2: Any kind of structure. 194 00:12:29,840 --> 00:12:33,120 Speaker 1: Now, these tinker toys that I hand you are physical 195 00:12:33,200 --> 00:12:36,400 Speaker 1: things that can interact. So you push this one and 196 00:12:36,440 --> 00:12:38,760 Speaker 1: that pulls this and shifts that, and pulls this one 197 00:12:38,800 --> 00:12:42,120 Speaker 1: down and moves that one sideways. Each piece interacts with 198 00:12:42,160 --> 00:12:45,120 Speaker 1: the other pieces around it, just like the brain. So 199 00:12:45,240 --> 00:12:49,360 Speaker 1: the question is, can you build a tinker toy structure 200 00:12:49,800 --> 00:12:53,880 Speaker 1: that is large enough, sophisticated enough that the whole thing 201 00:12:54,000 --> 00:12:58,320 Speaker 1: becomes conscious? At what point do you say, Okay, I'm 202 00:12:58,360 --> 00:13:00,520 Speaker 1: going to add this one more piece and can here 203 00:13:00,960 --> 00:13:05,320 Speaker 1: and now it's enjoying the beauty of a flower, or 204 00:13:05,440 --> 00:13:09,960 Speaker 1: now it's perceiving the color indigo blue, or now it's 205 00:13:10,040 --> 00:13:15,319 Speaker 1: experiencing the smell of sunscreen on the beach. Or consider this, 206 00:13:15,760 --> 00:13:19,719 Speaker 1: What is the difference between your brain and your laptop. 207 00:13:19,880 --> 00:13:22,120 Speaker 1: As I said at the beginning, your brain is shuttling 208 00:13:22,160 --> 00:13:26,400 Speaker 1: signals all around, and so is your laptop. But presumably 209 00:13:26,960 --> 00:13:31,400 Speaker 1: your computer doesn't feel anything. It's just running algorithms. When 210 00:13:31,480 --> 00:13:35,160 Speaker 1: you launch a funny YouTube video, it might make you laugh, 211 00:13:35,600 --> 00:13:40,239 Speaker 1: but your computer doesn't feel amused or thrilled or surprised 212 00:13:40,360 --> 00:13:44,800 Speaker 1: or mirthful. It's just moving around voltages through billions of gates. 213 00:13:45,440 --> 00:13:49,640 Speaker 1: So what is the difference between you and it? Why 214 00:13:49,679 --> 00:13:54,440 Speaker 1: do electrical signals in the computer equal logical operations or 215 00:13:54,440 --> 00:13:59,040 Speaker 1: pixel colors, while electrical signals zapping around in your brain 216 00:13:59,600 --> 00:14:03,080 Speaker 1: equate to the sweetness of sugar or the sting of 217 00:14:03,240 --> 00:14:06,839 Speaker 1: wabi or the feeling of love. Why do we have 218 00:14:06,920 --> 00:14:12,680 Speaker 1: this internal theater instead of running like tinker toys or laptops. Now, 219 00:14:12,679 --> 00:14:15,160 Speaker 1: one thing to note is we're tackling this question is 220 00:14:15,200 --> 00:14:19,320 Speaker 1: that consciousness seems to have evolved because it is useful. 221 00:14:19,680 --> 00:14:23,520 Speaker 1: Consciousness is like a high level operating system. So back 222 00:14:23,520 --> 00:14:27,400 Speaker 1: in the day, you'd program computers directly with punch cards 223 00:14:27,480 --> 00:14:32,720 Speaker 1: or in machine language, But eventually we developed user interfaces 224 00:14:32,840 --> 00:14:37,080 Speaker 1: like Windows, which hid all of the complex operations of 225 00:14:37,080 --> 00:14:40,000 Speaker 1: the computer and allowed us to just deal with the 226 00:14:40,080 --> 00:14:43,120 Speaker 1: stuff we needed at the highest level. I just want 227 00:14:43,160 --> 00:14:45,400 Speaker 1: to move this thing over here, and send this email 228 00:14:45,440 --> 00:14:49,720 Speaker 1: and drop this picture, And that's essentially what consciousness seems 229 00:14:49,760 --> 00:14:51,800 Speaker 1: to be. It's a way for us to just have 230 00:14:51,880 --> 00:14:55,280 Speaker 1: the highest level picture of what's going on, Like let's 231 00:14:55,320 --> 00:14:57,880 Speaker 1: go get some breakfast and go for a walk. Without 232 00:14:58,080 --> 00:15:01,280 Speaker 1: needing to deal with all the billion details of how 233 00:15:01,320 --> 00:15:03,880 Speaker 1: your muscles are contracting and how you're getting oxygen to 234 00:15:03,880 --> 00:15:06,840 Speaker 1: the right places and which chemicals need to be expressed. 235 00:15:07,440 --> 00:15:12,760 Speaker 1: We just get the windows without all the machine code. Okay, 236 00:15:12,800 --> 00:15:15,240 Speaker 1: So let's return to the central question. How do you 237 00:15:15,480 --> 00:15:19,240 Speaker 1: build consciousness out of cells? In other words, how do 238 00:15:19,320 --> 00:15:23,800 Speaker 1: you get some magical high level property from simple low 239 00:15:23,880 --> 00:15:27,800 Speaker 1: level parts. Now that sounds impossible, but the first thing 240 00:15:27,800 --> 00:15:31,800 Speaker 1: to understand is the concept of an emergent property. To 241 00:15:31,960 --> 00:15:35,360 Speaker 1: understand consciousness, we may need to think not in terms 242 00:15:35,360 --> 00:15:38,280 Speaker 1: of the pieces and parts of the brain, but instead 243 00:15:38,320 --> 00:15:41,400 Speaker 1: in terms of how they all interact with each other. 244 00:15:42,200 --> 00:15:44,760 Speaker 1: So if we want to understand how simple parts can 245 00:15:44,760 --> 00:15:47,880 Speaker 1: give rise to something bigger than themselves, just think of 246 00:15:47,920 --> 00:15:51,880 Speaker 1: something like an ant hill, look at something like leafcutter. 247 00:15:52,000 --> 00:15:52,400 Speaker 2: Ants. 248 00:15:53,560 --> 00:15:57,040 Speaker 1: They've got millions of members in a colony, and they 249 00:15:57,080 --> 00:16:00,640 Speaker 1: act like farmers. They actually cultivate their own food. Different 250 00:16:00,840 --> 00:16:05,280 Speaker 1: ants have different roles. Some leave the nest to find 251 00:16:05,760 --> 00:16:08,880 Speaker 1: fresh vegetation, and when they find it, they chew off 252 00:16:08,960 --> 00:16:12,280 Speaker 1: large pieces that they carry back to the nest. But 253 00:16:12,320 --> 00:16:15,880 Speaker 1: they don't eat the leaves instead. What happens is these 254 00:16:16,120 --> 00:16:19,160 Speaker 1: smaller worker ants take the pieces of leaves and they 255 00:16:19,200 --> 00:16:22,200 Speaker 1: chew them into smaller pieces, and they use this as 256 00:16:22,440 --> 00:16:28,920 Speaker 1: fertilizer to grow fungus in large underground gardens. So the 257 00:16:28,960 --> 00:16:33,280 Speaker 1: ants feed the fungus, and the fungus blossoms into small 258 00:16:33,400 --> 00:16:36,960 Speaker 1: fruiting bodies which the ants later eat. So they use 259 00:16:37,000 --> 00:16:42,680 Speaker 1: this incredible farming strategy to build enormous nests underground that 260 00:16:42,840 --> 00:16:46,880 Speaker 1: extend sometimes hundreds of square meters. So, just like humans, 261 00:16:46,920 --> 00:16:51,600 Speaker 1: the leafcutter ants have built and perfected an agricultural civilization. 262 00:16:52,520 --> 00:16:53,760 Speaker 2: But here's the important point. 263 00:16:53,840 --> 00:16:58,600 Speaker 1: Although the colony is like a superorganism that accomplishes these 264 00:16:58,640 --> 00:17:04,200 Speaker 1: extraordinary feats, each ant individually behaves just like a simple 265 00:17:04,200 --> 00:17:08,600 Speaker 1: little robot. It just follows its local rules. The queen 266 00:17:08,840 --> 00:17:13,560 Speaker 1: isn't giving commands and coordinating behavior. Instead, each ant just 267 00:17:13,680 --> 00:17:18,000 Speaker 1: reacts to local chemical signals from other ants, or from 268 00:17:18,280 --> 00:17:21,000 Speaker 1: larvae or intruders, or food. 269 00:17:20,760 --> 00:17:21,800 Speaker 2: Or waste or leaves. 270 00:17:22,080 --> 00:17:26,800 Speaker 1: Each ant is just a simple autonomous unit whose reactions 271 00:17:26,840 --> 00:17:31,640 Speaker 1: depend only on its local environment and its genetically encoded rules. 272 00:17:32,440 --> 00:17:37,919 Speaker 1: So even though there's no centralized decision making, the colony 273 00:17:38,119 --> 00:17:44,000 Speaker 1: exhibits very sophisticated behavior. Each ant communicates locally with no 274 00:17:44,200 --> 00:17:47,040 Speaker 1: sense of the bigger picture. But what emerges at the 275 00:17:47,160 --> 00:17:53,840 Speaker 1: level of the colony is an agricultural civilization. So the 276 00:17:53,880 --> 00:17:57,320 Speaker 1: important lesson here is that the complex behavior of the 277 00:17:57,359 --> 00:18:03,399 Speaker 1: colony doesn't arise from complexity in the individuals. Each ant 278 00:18:03,480 --> 00:18:05,840 Speaker 1: doesn't know that it's part of something bigger. It's just 279 00:18:05,960 --> 00:18:10,240 Speaker 1: running its small, simple programs. But when enough ants come together, 280 00:18:10,920 --> 00:18:16,440 Speaker 1: a super organism emerges with collective properties that are more 281 00:18:16,480 --> 00:18:21,080 Speaker 1: sophisticated than its basic parts, and this phenomenon is known 282 00:18:21,119 --> 00:18:25,480 Speaker 1: as emergence. This is what happens when simple units interact 283 00:18:25,520 --> 00:18:29,840 Speaker 1: in the right ways and something larger emerges. The key 284 00:18:29,880 --> 00:18:34,200 Speaker 1: thing is the interaction between lots of ants, and this 285 00:18:34,320 --> 00:18:37,840 Speaker 1: is what's going on with the brain. A neuron is 286 00:18:37,920 --> 00:18:40,160 Speaker 1: just a type of cell. It's just like the other 287 00:18:40,320 --> 00:18:43,919 Speaker 1: cells in your body, but with some specializations that allow 288 00:18:43,960 --> 00:18:49,680 Speaker 1: it to extend processes and propagate these electrical signals. But 289 00:18:49,880 --> 00:18:53,040 Speaker 1: like an ant, an individual brain cell is just running 290 00:18:53,080 --> 00:18:56,560 Speaker 1: its local programs its whole life. It just carries these 291 00:18:56,600 --> 00:19:00,879 Speaker 1: electrical signals along its membrane. It spits out neuro transmitters 292 00:19:01,040 --> 00:19:03,480 Speaker 1: it gets spat on by other cells. 293 00:19:03,840 --> 00:19:04,960 Speaker 2: That's it. 294 00:19:04,960 --> 00:19:09,320 Speaker 1: It lives its life in darkness, embedded in other cells. 295 00:19:09,400 --> 00:19:13,320 Speaker 1: It doesn't know if it's involved in moving your eyes 296 00:19:13,440 --> 00:19:16,199 Speaker 1: to read a Tony Morrison novel, or it's involved in 297 00:19:16,280 --> 00:19:19,600 Speaker 1: moving your hands over the piano keyboard to play Mozart. 298 00:19:20,000 --> 00:19:23,440 Speaker 1: It doesn't know about you. So here's what's so weird. 299 00:19:23,480 --> 00:19:28,760 Speaker 1: Although your goals and intentions and abilities are completely dependent 300 00:19:28,960 --> 00:19:32,520 Speaker 1: on the existence of these little neurons, they live on 301 00:19:32,600 --> 00:19:36,600 Speaker 1: a smaller scale with no awareness of the thing they 302 00:19:36,640 --> 00:19:40,840 Speaker 1: have come together to build you. But get enough of 303 00:19:40,880 --> 00:19:44,479 Speaker 1: these basic brain cells together interacting the right way, and 304 00:19:44,560 --> 00:19:48,000 Speaker 1: the mind emerges. And I'll talk more about this notion 305 00:19:48,080 --> 00:19:51,720 Speaker 1: of emergent properties in other episodes, because the concept is 306 00:19:51,760 --> 00:19:57,400 Speaker 1: so fundamental. Everywhere you look you find systems with emergent properties. 307 00:19:57,840 --> 00:20:01,080 Speaker 1: Take an airplane. If you take any single hunk of 308 00:20:01,160 --> 00:20:04,560 Speaker 1: metal on the airplane, not a single one of these 309 00:20:04,640 --> 00:20:08,400 Speaker 1: pieces has the property of flight. But when you arrange 310 00:20:08,440 --> 00:20:13,240 Speaker 1: all the pieces in the right way, flight emerges. Or 311 00:20:13,560 --> 00:20:17,240 Speaker 1: imagine a bunch of metal poles. None has the property 312 00:20:17,480 --> 00:20:21,840 Speaker 1: of constraining the behavior of a lion, but arrange several 313 00:20:21,840 --> 00:20:24,320 Speaker 1: of these poles in the shape of a cage and 314 00:20:24,440 --> 00:20:30,400 Speaker 1: the property of lion constraining emerges. And somehow you get 315 00:20:30,400 --> 00:20:32,879 Speaker 1: a bunch of simple cells together and you wire them 316 00:20:32,960 --> 00:20:37,919 Speaker 1: up in the right way, and consciousness emerges. So the 317 00:20:37,960 --> 00:20:41,400 Speaker 1: pieces in parts of a system can be individually simple, 318 00:20:41,720 --> 00:20:44,919 Speaker 1: but what emerges at a higher level is all about 319 00:20:45,000 --> 00:20:49,879 Speaker 1: their interaction. So the mind seems to emerge from the 320 00:20:49,920 --> 00:20:52,800 Speaker 1: interaction of the billions of pieces and parts of the brain. 321 00:20:53,200 --> 00:20:56,639 Speaker 1: But this leads to a wacky question. Can a mind 322 00:20:56,880 --> 00:21:01,520 Speaker 1: emerge from anything with lots of inter acting parts? For example, 323 00:21:01,840 --> 00:21:05,800 Speaker 1: could a city be conscious? After all, a city is 324 00:21:05,840 --> 00:21:09,320 Speaker 1: built on the interactions between elements. Think of all the 325 00:21:09,440 --> 00:21:12,680 Speaker 1: signals moving through a city. You've got telephone wires and 326 00:21:12,760 --> 00:21:17,040 Speaker 1: fiber optic lines and sewers carrying waste, and every handshake 327 00:21:17,119 --> 00:21:20,240 Speaker 1: between humans, and every traffic light and so on. This 328 00:21:20,480 --> 00:21:24,080 Speaker 1: scale of interaction in a city is on par with 329 00:21:24,119 --> 00:21:26,560 Speaker 1: the human brain. Now, it would be very hard to 330 00:21:26,680 --> 00:21:29,680 Speaker 1: know if a city were conscious, because it doesn't have 331 00:21:30,200 --> 00:21:32,520 Speaker 1: ears and a mouth, and so how could it tell us? 332 00:21:32,560 --> 00:21:36,439 Speaker 1: How could we ask it? To answer a question like 333 00:21:36,520 --> 00:21:42,000 Speaker 1: this requires a deeper question. For a network to experience consciousness, 334 00:21:42,080 --> 00:21:45,160 Speaker 1: does it need more than just a number of parts, 335 00:21:45,240 --> 00:21:50,320 Speaker 1: but beyond that a very particular structure to the interactions, 336 00:21:51,040 --> 00:21:53,000 Speaker 1: and that leads us to what we have in terms 337 00:21:53,040 --> 00:21:57,320 Speaker 1: of scientific theories of consciousness. By the way, just a 338 00:21:57,400 --> 00:22:00,439 Speaker 1: side note before we get into the scientific theories. For 339 00:22:00,520 --> 00:22:03,320 Speaker 1: the purposes of this episode, we'll assume that everyone is 340 00:22:03,359 --> 00:22:06,840 Speaker 1: having the same type of conscious experience. What's interesting is 341 00:22:06,880 --> 00:22:10,000 Speaker 1: that we don't really have any idea how to measure consciousness, 342 00:22:10,000 --> 00:22:13,080 Speaker 1: so we don't really know if other people are conscious. 343 00:22:13,600 --> 00:22:18,240 Speaker 1: And there's a branch of philosophy called sollipsism, which suggests 344 00:22:18,280 --> 00:22:20,879 Speaker 1: that you are the only conscious person in the world 345 00:22:21,160 --> 00:22:24,760 Speaker 1: and everyone else is not conscious. They're just moving zeros 346 00:22:24,760 --> 00:22:27,159 Speaker 1: and ones around and saying the right things and acting 347 00:22:27,160 --> 00:22:29,960 Speaker 1: in the right way. But let's not go there. I 348 00:22:29,960 --> 00:22:32,800 Speaker 1: think it's a reasonable assumption to take on board the 349 00:22:32,880 --> 00:22:37,600 Speaker 1: notion that everyone around you is conscious and having private 350 00:22:37,800 --> 00:22:42,040 Speaker 1: internal experiences just like you are. So one way you 351 00:22:42,040 --> 00:22:46,880 Speaker 1: could go about studying consciousness scientifically is by saying, when 352 00:22:46,920 --> 00:22:51,119 Speaker 1: you are seeing the color orange, what are the neurons 353 00:22:51,119 --> 00:22:54,879 Speaker 1: that are lighting up? And when you're tasting cinnamon, which 354 00:22:54,960 --> 00:22:57,480 Speaker 1: neurons are popping off? Or when you're conscious of a 355 00:22:57,640 --> 00:23:01,280 Speaker 1: face or conscious of a touch or a sound, What 356 00:23:01,400 --> 00:23:04,919 Speaker 1: precisely can we measure in the brain. Now, this is 357 00:23:04,960 --> 00:23:08,520 Speaker 1: an endeavor that was emphasized by scientists like Francis Krik 358 00:23:08,560 --> 00:23:12,000 Speaker 1: and Christoph Coch. They said, hey, as the first step here, 359 00:23:12,359 --> 00:23:17,280 Speaker 1: let's try to find the neural correlates of consciousness, as in, 360 00:23:17,359 --> 00:23:19,959 Speaker 1: when you are conscious of something, what is lighting up 361 00:23:19,960 --> 00:23:22,720 Speaker 1: in your brain. One way you can study this is 362 00:23:22,720 --> 00:23:27,080 Speaker 1: by looking at something like binocular rivalry. So I'll explain 363 00:23:27,119 --> 00:23:29,240 Speaker 1: what that is. Let's say that your two eyes are 364 00:23:29,240 --> 00:23:33,120 Speaker 1: seeing very different images. In your left eye, I show 365 00:23:33,160 --> 00:23:35,800 Speaker 1: you a picture of a shoe, and in your right eye, 366 00:23:35,840 --> 00:23:38,080 Speaker 1: I show you a picture of a house, and there's 367 00:23:38,080 --> 00:23:40,879 Speaker 1: a piece of cardboard in between your eyes, so that 368 00:23:41,040 --> 00:23:44,320 Speaker 1: each eye is just seeing one thing, the shoe. 369 00:23:44,160 --> 00:23:44,760 Speaker 2: Or the house. 370 00:23:45,520 --> 00:23:48,679 Speaker 1: Your conscious experience is not of seeing them both at 371 00:23:48,680 --> 00:23:53,040 Speaker 1: the same time or a fusion. Instead, you see one 372 00:23:53,680 --> 00:23:56,679 Speaker 1: and then after a few seconds it switches and you 373 00:23:56,680 --> 00:23:59,199 Speaker 1: see the other. You see the shoe, and then you 374 00:23:59,200 --> 00:24:01,639 Speaker 1: see the house, and then it's back to the shoe, 375 00:24:02,080 --> 00:24:05,040 Speaker 1: and it switches every few seconds. And it's not because 376 00:24:05,040 --> 00:24:07,920 Speaker 1: you're moving your eyes around or something. It just happens 377 00:24:08,000 --> 00:24:10,879 Speaker 1: as your brain lands on one percept or lands on 378 00:24:10,920 --> 00:24:14,560 Speaker 1: the other. So if I ask you about your conscious experience, 379 00:24:15,000 --> 00:24:18,000 Speaker 1: you are seeing either the shoe or you're seeing the 380 00:24:18,040 --> 00:24:21,520 Speaker 1: house at any given moment. So you can use experiments 381 00:24:21,640 --> 00:24:25,040 Speaker 1: like this to then look for the correlates of consciousness. 382 00:24:25,080 --> 00:24:27,920 Speaker 1: You can map which areas of the brain are firing 383 00:24:27,960 --> 00:24:31,159 Speaker 1: when you're conscious of the shoe versus the house. We 384 00:24:31,240 --> 00:24:34,000 Speaker 1: can look for what is different about the patterns of 385 00:24:34,040 --> 00:24:37,320 Speaker 1: neural activity in the moments when you're perceiving the shoe 386 00:24:37,760 --> 00:24:40,200 Speaker 1: versus when you're perceiving the house. The key thing is 387 00:24:40,240 --> 00:24:43,360 Speaker 1: that I'm not changing anything in the outside world. The 388 00:24:43,440 --> 00:24:47,680 Speaker 1: only thing that's changing is your internal experiences. So the 389 00:24:47,800 --> 00:24:51,760 Speaker 1: question is what is the difference going on inside the brain. Now, 390 00:24:51,800 --> 00:24:55,520 Speaker 1: this sort of study has been an ongoing endeavor, but 391 00:24:55,720 --> 00:24:58,919 Speaker 1: part of the challenge with these types of experiments is 392 00:24:58,920 --> 00:25:02,119 Speaker 1: that we don't have great techniques to measure the activity 393 00:25:02,560 --> 00:25:05,760 Speaker 1: in billions of individual cells. All we have are things 394 00:25:05,880 --> 00:25:11,320 Speaker 1: like fMRI functional magnetic resonance imaging, which allows us to 395 00:25:11,400 --> 00:25:14,479 Speaker 1: measure great, big chunks of activity in the brain at 396 00:25:14,480 --> 00:25:17,879 Speaker 1: any moment. So we can see big blobs of activity, 397 00:25:17,920 --> 00:25:21,440 Speaker 1: but we can't narrow down with a high degree of specificity. 398 00:25:22,119 --> 00:25:25,399 Speaker 1: As technology gets better, we can see a pathway to 399 00:25:25,520 --> 00:25:46,159 Speaker 1: eventually answering these kinds of questions with greater specificity. So 400 00:25:46,720 --> 00:25:50,280 Speaker 1: those types of experiments are ongoing and they're fascinating, but 401 00:25:50,359 --> 00:25:55,879 Speaker 1: they're only attempting to answer the easy problem of consciousness. 402 00:25:56,040 --> 00:25:59,280 Speaker 1: What am I referring to when I say the easy problem? 403 00:25:59,440 --> 00:26:04,080 Speaker 1: Some years ago, the philosopher David Chalmers divided the scientific 404 00:26:04,160 --> 00:26:09,080 Speaker 1: exploration of consciousness into two categories. There's the easy problem 405 00:26:09,200 --> 00:26:13,000 Speaker 1: and the hard problem. The easy problem is to find 406 00:26:13,320 --> 00:26:18,080 Speaker 1: neural signals that correlate with consciousness, as in this region 407 00:26:18,200 --> 00:26:21,720 Speaker 1: is active when you're conscious of something. But the hard 408 00:26:21,800 --> 00:26:26,199 Speaker 1: problem of consciousness is explaining why the physical stuff of 409 00:26:26,240 --> 00:26:31,480 Speaker 1: the brain gives rise to subjective experience. It's a hard 410 00:26:31,520 --> 00:26:35,760 Speaker 1: problem because it's not clear how physical stuff gives rise 411 00:26:35,840 --> 00:26:38,240 Speaker 1: to a private internal life. 412 00:26:39,119 --> 00:26:40,280 Speaker 2: That's the hard problem. 413 00:26:40,680 --> 00:26:43,119 Speaker 1: Now we don't know the answer to this, but we 414 00:26:43,160 --> 00:26:47,119 Speaker 1: can make progress by being very clear about the different challenges. 415 00:26:48,080 --> 00:26:52,560 Speaker 1: One of them is something called the binding problem. For example, 416 00:26:52,600 --> 00:26:54,760 Speaker 1: imagine that you look at your window and you see 417 00:26:54,800 --> 00:27:00,280 Speaker 1: a beautiful blue bird fly past. Different signals from the 418 00:27:00,280 --> 00:27:03,720 Speaker 1: bird are processed by different regions of your brain. So 419 00:27:03,920 --> 00:27:07,520 Speaker 1: part of your brain is detecting the motion. This is 420 00:27:07,560 --> 00:27:10,879 Speaker 1: the dorsal stream. Part of your brain is recognizing the 421 00:27:10,960 --> 00:27:14,040 Speaker 1: shape of the bird. That's the ventral stream. Part of 422 00:27:14,080 --> 00:27:17,119 Speaker 1: your brain is registering the blue color. This is a 423 00:27:17,160 --> 00:27:20,760 Speaker 1: network called visual area four. Part of your brain is 424 00:27:20,840 --> 00:27:23,760 Speaker 1: listening to the sound of the bird chirping. 425 00:27:23,800 --> 00:27:25,520 Speaker 2: This is your auditory system. 426 00:27:26,200 --> 00:27:29,640 Speaker 1: The features of the bird are getting represented in totally 427 00:27:29,680 --> 00:27:34,800 Speaker 1: different territories of your brain. And yet somehow your brain 428 00:27:34,920 --> 00:27:38,040 Speaker 1: is able to put all of this information together so 429 00:27:38,080 --> 00:27:42,360 Speaker 1: that you see a single unified bird. You don't see 430 00:27:42,400 --> 00:27:46,600 Speaker 1: the blue bleeding off, the moving object, and the sound 431 00:27:46,680 --> 00:27:50,480 Speaker 1: coming from somewhere else. It all seems like one thing, 432 00:27:50,880 --> 00:27:55,040 Speaker 1: even though it's processed in a bunch of different parts. Now, 433 00:27:55,280 --> 00:27:59,399 Speaker 1: how do all these processing streams get combined. How do 434 00:27:59,440 --> 00:28:02,760 Speaker 1: our brains take the disparate pieces of information that we 435 00:28:02,920 --> 00:28:07,040 Speaker 1: receive from our senses and combine them into a single, 436 00:28:07,200 --> 00:28:11,520 Speaker 1: coherent experience of the world. That is the binding problem. 437 00:28:11,920 --> 00:28:14,720 Speaker 1: All these little pieces of the blue bird somehow get 438 00:28:15,080 --> 00:28:20,320 Speaker 1: bound together. What's the solution? We don't know. One theory 439 00:28:20,359 --> 00:28:24,359 Speaker 1: is that the brain uses timing information to integrate things. 440 00:28:24,440 --> 00:28:27,679 Speaker 1: This means that different pieces of information are bound together 441 00:28:27,840 --> 00:28:30,320 Speaker 1: by the fact that they're all popping off in the 442 00:28:30,320 --> 00:28:33,680 Speaker 1: brain at the same time. For example, when you see 443 00:28:33,680 --> 00:28:37,960 Speaker 1: the moving blue bird, the signals representing motion and the 444 00:28:37,960 --> 00:28:42,560 Speaker 1: signals representing birdness and blueness, and the signals identifying the sound, 445 00:28:43,160 --> 00:28:46,840 Speaker 1: they're all synchronized. Like imagine that you're at a stadium 446 00:28:46,840 --> 00:28:50,240 Speaker 1: full of people and you clap your hands every three seconds, 447 00:28:50,600 --> 00:28:53,800 Speaker 1: and scattered in the crowd are others who clap their 448 00:28:53,840 --> 00:28:56,400 Speaker 1: hands every three seconds at exactly the same time that 449 00:28:56,440 --> 00:28:56,720 Speaker 1: you do. 450 00:28:57,520 --> 00:28:58,880 Speaker 2: The idea is that you'd come. 451 00:28:58,760 --> 00:29:00,840 Speaker 1: To be able to pick out these folks out of 452 00:29:00,880 --> 00:29:05,120 Speaker 1: this giant crowd because you'd realize your synchrony with them. 453 00:29:05,640 --> 00:29:10,160 Speaker 1: And that's the general idea with this temporal binding theory. 454 00:29:11,080 --> 00:29:13,440 Speaker 1: And there are various other ways that people think about 455 00:29:13,760 --> 00:29:17,240 Speaker 1: how the binding problem gets solved. One is called global 456 00:29:17,280 --> 00:29:21,280 Speaker 1: workspace theory. This was proposed by my colleague Bernard Bars, 457 00:29:21,600 --> 00:29:24,360 Speaker 1: and the idea is you've got all these disparate elements, 458 00:29:24,800 --> 00:29:29,040 Speaker 1: but things come together in what Bars calls the global workspace, 459 00:29:29,480 --> 00:29:32,840 Speaker 1: and that's when you get consciousness. In other words, consciousness 460 00:29:32,880 --> 00:29:37,160 Speaker 1: arises from the global sharing of information within the brain. 461 00:29:37,720 --> 00:29:42,320 Speaker 1: Different brain modules are performing their specialized functions, but their 462 00:29:42,360 --> 00:29:46,400 Speaker 1: output is integrated and made available to the entire brain 463 00:29:47,040 --> 00:29:51,280 Speaker 1: via this hypothetical global workspace where the information gets combined 464 00:29:51,960 --> 00:29:56,320 Speaker 1: and different processes compete for attention to enter it. When 465 00:29:56,360 --> 00:30:00,640 Speaker 1: information gets into the global workspace, it becomes available to 466 00:30:00,760 --> 00:30:05,000 Speaker 1: conscious awareness and you become aware of it. So in 467 00:30:05,040 --> 00:30:08,240 Speaker 1: this view, consciousness emerges from the integration of all these 468 00:30:08,240 --> 00:30:13,880 Speaker 1: diverse sensory and cognitive bits into a single, unified representation, 469 00:30:14,360 --> 00:30:17,680 Speaker 1: let's say, of the bluebird. Another theory proposed by my 470 00:30:17,800 --> 00:30:22,560 Speaker 1: colleague Julio Tononi is called integrated information theory. So he's 471 00:30:22,600 --> 00:30:27,480 Speaker 1: proposed a quantitative definition of consciousness. It's not just about 472 00:30:27,520 --> 00:30:31,280 Speaker 1: the pieces and parts interacting. Instead, in this framework, there 473 00:30:31,280 --> 00:30:35,800 Speaker 1: has to be a particular organization that's underlying this interaction. 474 00:30:36,840 --> 00:30:42,480 Speaker 1: So to study consciousness in the laboratory, Tononi uses transcranial 475 00:30:42,520 --> 00:30:46,600 Speaker 1: magnetic stimulation TMS to compare the activity in the brain 476 00:30:47,040 --> 00:30:49,880 Speaker 1: when it's awake and when it's in deep sleep, when 477 00:30:49,920 --> 00:30:54,000 Speaker 1: your consciousness is not there. So by introducing a burst 478 00:30:54,000 --> 00:30:57,480 Speaker 1: of electrical current into the cortex, he and his team 479 00:30:57,560 --> 00:31:01,000 Speaker 1: can then track how the activity spreads, and what he 480 00:31:01,080 --> 00:31:04,320 Speaker 1: finds is that when his subject is awake and consciously aware, 481 00:31:04,560 --> 00:31:08,800 Speaker 1: you find these long lasting ripples moving to different cortical areas, 482 00:31:09,360 --> 00:31:14,400 Speaker 1: and this unmasks this widespread connectivity across the network. But 483 00:31:14,600 --> 00:31:18,360 Speaker 1: in contrast, when a person is in deep sleep, that 484 00:31:18,560 --> 00:31:22,600 Speaker 1: same pulse stimulates only a very local area and the 485 00:31:22,640 --> 00:31:27,320 Speaker 1: activity dies down quickly, So the network has lost its connectivity, 486 00:31:27,480 --> 00:31:29,560 Speaker 1: and you find the same result. When a person is 487 00:31:29,640 --> 00:31:33,360 Speaker 1: in a coma, the activity spreads very little, but as 488 00:31:33,400 --> 00:31:37,440 Speaker 1: a person emerges from a coma over weeks into consciousness, 489 00:31:37,720 --> 00:31:42,440 Speaker 1: the activity spreads more and more widely. So Toanoni believes 490 00:31:42,480 --> 00:31:44,960 Speaker 1: this is because when we are awake and conscious, there's 491 00:31:45,080 --> 00:31:50,760 Speaker 1: widespread communication between different cortical areas, but in contrast, when 492 00:31:50,800 --> 00:31:54,600 Speaker 1: you're asleep or in a coma, you lose this communication 493 00:31:54,680 --> 00:31:58,480 Speaker 1: across areas. So in his framework, Toinoni suggests that a 494 00:31:58,760 --> 00:32:04,680 Speaker 1: conscious system requires a perfect balance of enough complexity to 495 00:32:04,760 --> 00:32:09,560 Speaker 1: represent very different states. This is called differentiation. Can I 496 00:32:09,600 --> 00:32:11,880 Speaker 1: distinguish black from white, and hot from cold and so on, 497 00:32:12,640 --> 00:32:16,840 Speaker 1: and enough connectivity to have distant parts of the network 498 00:32:16,880 --> 00:32:20,600 Speaker 1: be in tight communication with each other. This is called integration. 499 00:32:21,520 --> 00:32:27,280 Speaker 1: So in this framework, the balance of differentiation and integration 500 00:32:28,160 --> 00:32:31,880 Speaker 1: can be quantified, and he proposes that only systems in 501 00:32:31,920 --> 00:32:36,800 Speaker 1: the right range experience consciousness. Now, if this theory turns 502 00:32:36,840 --> 00:32:39,480 Speaker 1: out to be correct, they can give a non invasive 503 00:32:39,520 --> 00:32:44,600 Speaker 1: assessment of the level of consciousness in coma patients. Now 504 00:32:44,640 --> 00:32:47,560 Speaker 1: it would also give us the means to tell whether 505 00:32:47,720 --> 00:32:51,680 Speaker 1: inanimate systems have consciousness. So, coming back to this question 506 00:32:51,760 --> 00:32:55,840 Speaker 1: of whether a city is conscious, this could in theory 507 00:32:55,880 --> 00:32:59,440 Speaker 1: be answered. It would depend on whether the information flow 508 00:32:59,680 --> 00:33:02,360 Speaker 1: is a ranged in just the right way with the 509 00:33:02,480 --> 00:33:07,760 Speaker 1: perfect amount of differentiation and integration. So if we can 510 00:33:07,800 --> 00:33:10,400 Speaker 1: come up with the right sort of network structure that's 511 00:33:10,520 --> 00:33:14,280 Speaker 1: needed to give rise to consciousness, we're on our way 512 00:33:14,600 --> 00:33:20,800 Speaker 1: to understanding whether consciousness could escape its biological origins. In 513 00:33:20,840 --> 00:33:24,640 Speaker 1: other words, although consciousness evolved along a particular path that 514 00:33:24,720 --> 00:33:28,000 Speaker 1: resulted in a brain, maybe it doesn't have to be 515 00:33:28,040 --> 00:33:31,320 Speaker 1: built on top of organic matter. Maybe you could build 516 00:33:31,320 --> 00:33:35,280 Speaker 1: it just as easily out of silicon, assuming the interactions 517 00:33:35,320 --> 00:33:38,880 Speaker 1: are organized in the right way. So as our understanding 518 00:33:38,880 --> 00:33:42,600 Speaker 1: of the brain continues to evolve, we may be eventually 519 00:33:42,640 --> 00:33:46,040 Speaker 1: able to answer the question of whether a city is 520 00:33:46,160 --> 00:33:50,280 Speaker 1: conscious or a set of tinker toys, or eventually AI 521 00:33:51,520 --> 00:33:55,760 Speaker 1: and this all comes down to the philosophical idea of materialism. 522 00:33:56,040 --> 00:33:58,560 Speaker 1: This is the notion that you can build consciousness out 523 00:33:58,560 --> 00:34:02,400 Speaker 1: of material stuff, whether that's beer cans and tennis balls, 524 00:34:02,480 --> 00:34:06,880 Speaker 1: or tinker toys or computers. The magic of conscious experience 525 00:34:07,000 --> 00:34:11,480 Speaker 1: emerges from the physical pieces and parts arranged in exactly 526 00:34:11,520 --> 00:34:14,440 Speaker 1: the right way. And if we can figure out that 527 00:34:14,520 --> 00:34:17,239 Speaker 1: right way, then we should be able to build it. 528 00:34:17,640 --> 00:34:20,879 Speaker 1: But I want to mention some important caveats. The main 529 00:34:20,920 --> 00:34:24,160 Speaker 1: one is that it's just a hypothesis that we can 530 00:34:24,200 --> 00:34:27,120 Speaker 1: build consciousness out of physical stuff. It always needs to 531 00:34:27,120 --> 00:34:29,640 Speaker 1: be kept in mind. Then our science is still quite young, 532 00:34:29,719 --> 00:34:32,480 Speaker 1: and there may be other things that were simply not 533 00:34:32,719 --> 00:34:36,239 Speaker 1: aware of. There's a hypothetical that I shared in my 534 00:34:36,280 --> 00:34:46,840 Speaker 1: book Incognito to demonstrate this idea. Imagine that somebody living 535 00:34:46,960 --> 00:34:50,400 Speaker 1: in a primitive tribe out in the desert somewhere finds 536 00:34:50,400 --> 00:34:53,800 Speaker 1: a radio in the sand, and he's never seen anything 537 00:34:53,920 --> 00:34:56,799 Speaker 1: like this, and so he picks it up and examines it, 538 00:34:56,840 --> 00:34:59,200 Speaker 1: and he notices there's a knob on it, and so 539 00:34:59,280 --> 00:35:01,200 Speaker 1: he sort of touched and playing with that, and he 540 00:35:01,320 --> 00:35:05,360 Speaker 1: realizes that if he turns the knob that suddenly voices 541 00:35:05,480 --> 00:35:09,319 Speaker 1: emerged from the box, and so he says, Okay, I'm 542 00:35:09,320 --> 00:35:12,360 Speaker 1: going to figure out how this box is producing the noise. 543 00:35:12,800 --> 00:35:14,760 Speaker 1: And he goes through a lot of trial and error, 544 00:35:14,960 --> 00:35:16,719 Speaker 1: and he figures out that he can take off the 545 00:35:16,800 --> 00:35:19,439 Speaker 1: back of the radio and there's these wires in there, 546 00:35:19,960 --> 00:35:23,719 Speaker 1: and with this nest of wires, he does experiments and 547 00:35:23,760 --> 00:35:25,680 Speaker 1: he figures out that if you pull out this wire 548 00:35:25,719 --> 00:35:29,640 Speaker 1: temporarily the voices get garbled, and if you pull out 549 00:35:29,640 --> 00:35:32,839 Speaker 1: this wire over here, the voices stop entirely, and so on. 550 00:35:33,560 --> 00:35:38,040 Speaker 1: So this person becomes a radio materialist. What he would 551 00:35:38,080 --> 00:35:40,759 Speaker 1: do is he'd conclude that if you put together this 552 00:35:40,880 --> 00:35:42,759 Speaker 1: nest of wires in just the right way, with the 553 00:35:42,840 --> 00:35:46,920 Speaker 1: right structure, the whole thing becomes alive and talks to you. 554 00:35:47,440 --> 00:35:50,120 Speaker 2: But he has no idea that. 555 00:35:50,000 --> 00:35:55,080 Speaker 1: There are radio towers that are beaming electromagnetic radiation from 556 00:35:55,160 --> 00:35:58,160 Speaker 1: distant cities. It would never strike him that any of 557 00:35:58,200 --> 00:36:00,480 Speaker 1: that is going on, because that's not part of it world. 558 00:36:01,000 --> 00:36:03,799 Speaker 1: So he would come to the erroneous conclusion that if 559 00:36:03,800 --> 00:36:06,600 Speaker 1: you put together the wires in the right way, they 560 00:36:06,760 --> 00:36:10,279 Speaker 1: generate voices. And so my point in bringing up this 561 00:36:10,320 --> 00:36:12,680 Speaker 1: analogy is not to say that our consciousness is getting 562 00:36:12,719 --> 00:36:15,400 Speaker 1: beamed in from somewhere else. But it is to say 563 00:36:15,880 --> 00:36:19,240 Speaker 1: it is certainly possible that we're missing big, giant pieces 564 00:36:19,280 --> 00:36:21,879 Speaker 1: of the puzzle, and that there's something that for us 565 00:36:21,920 --> 00:36:24,600 Speaker 1: would be the equivalent of not realizing that there's a 566 00:36:25,000 --> 00:36:28,560 Speaker 1: giant tower beaming signals to the radio. So I began 567 00:36:28,640 --> 00:36:30,600 Speaker 1: by pointing out that all the data we have in 568 00:36:30,640 --> 00:36:34,720 Speaker 1: neuroscience says that the physical integrity of the brain needs 569 00:36:34,760 --> 00:36:36,960 Speaker 1: to be there to have conscious experience, and if you 570 00:36:37,080 --> 00:36:40,520 Speaker 1: damage your brain, you change consciousness. But the radio example 571 00:36:40,560 --> 00:36:43,239 Speaker 1: is just meant to demonstrate that there still may be 572 00:36:43,600 --> 00:36:46,800 Speaker 1: lots of unknowns, And a specific example of an unknown 573 00:36:46,920 --> 00:36:50,560 Speaker 1: is this, does consciousness arise from hooking things up in 574 00:36:50,600 --> 00:36:53,520 Speaker 1: the right way or does it instead depend on some 575 00:36:53,800 --> 00:36:58,040 Speaker 1: special property of biological cells? In other words, is there 576 00:36:58,239 --> 00:37:01,680 Speaker 1: something special about our biology and the material that makes 577 00:37:01,719 --> 00:37:06,120 Speaker 1: up our brain that allows us to be conscious? For example, 578 00:37:06,200 --> 00:37:08,640 Speaker 1: one question that people have been asking is whether there 579 00:37:08,719 --> 00:37:14,040 Speaker 1: are quantum mechanical effects that happen in biological cells. Quantum 580 00:37:14,080 --> 00:37:17,280 Speaker 1: mechanics is a branch of physics. It's considered the best 581 00:37:17,320 --> 00:37:20,799 Speaker 1: scientific theory that we have because it predicts experiments out 582 00:37:20,840 --> 00:37:24,760 Speaker 1: to fourteen decimal places. But it's very counterintuitive. It's difficult 583 00:37:24,800 --> 00:37:28,080 Speaker 1: to understand because there are all kinds of very weird 584 00:37:28,120 --> 00:37:31,640 Speaker 1: effects that happen at the level of atoms. I'll go 585 00:37:31,680 --> 00:37:34,960 Speaker 1: into detail on that another episode, but for now, I'll 586 00:37:35,000 --> 00:37:37,440 Speaker 1: just say that some people suggest that some of the 587 00:37:37,480 --> 00:37:41,040 Speaker 1: spooky properties of quantum mechanics are just the kind of 588 00:37:41,080 --> 00:37:45,040 Speaker 1: thing we need to explain the mysteries of consciousness. Now, 589 00:37:45,120 --> 00:37:48,840 Speaker 1: other people have suggested that you can't have quantum mechanical 590 00:37:48,920 --> 00:37:52,640 Speaker 1: interactions happening in the brain because of the hot temperature, 591 00:37:52,920 --> 00:37:56,399 Speaker 1: and that may be true, but quantum effects are more 592 00:37:56,440 --> 00:38:00,000 Speaker 1: and more commonly being discovered in biology, so it's prematu 593 00:38:00,080 --> 00:38:02,840 Speaker 1: sure to rule it out entirely. For example, it was 594 00:38:02,840 --> 00:38:06,759 Speaker 1: discovered in recent years that photosynthesis in plants is a 595 00:38:06,840 --> 00:38:10,680 Speaker 1: quantum mechanical effect, So there are quantum mechanical effects that 596 00:38:10,760 --> 00:38:14,279 Speaker 1: happen at this temperature and this level. So I'm not 597 00:38:14,280 --> 00:38:17,160 Speaker 1: asserting there definitely are quantum effects in the human brain, 598 00:38:17,560 --> 00:38:21,239 Speaker 1: but that's one type of possibility that people consider for 599 00:38:21,360 --> 00:38:24,279 Speaker 1: how we might get consciousness in a human brain, but 600 00:38:24,400 --> 00:38:28,280 Speaker 1: perhaps we wouldn't in a classical computer. Just for completeness, 601 00:38:28,320 --> 00:38:31,000 Speaker 1: I'll mention one other theory that consciousness is like a 602 00:38:31,400 --> 00:38:35,359 Speaker 1: fifth force in physics. This theory is called pan psychism, 603 00:38:35,800 --> 00:38:39,040 Speaker 1: and the idea is that consciousness is a property that's 604 00:38:39,120 --> 00:38:40,799 Speaker 1: present in all physical matter. 605 00:38:40,840 --> 00:38:42,600 Speaker 2: It's a property of atoms, and. 606 00:38:42,560 --> 00:38:45,200 Speaker 1: When you get a bunch of atoms and cells together 607 00:38:45,280 --> 00:38:48,960 Speaker 1: and you collect enough of the material of consciousness, that's 608 00:38:49,000 --> 00:38:53,200 Speaker 1: when consciousness emerges. The theory suggests that the details of 609 00:38:53,239 --> 00:38:56,160 Speaker 1: the system don't really matter. It's all about getting enough 610 00:38:56,280 --> 00:38:59,760 Speaker 1: of the material of consciousness together. Now I'm not suggesting 611 00:38:59,760 --> 00:39:03,400 Speaker 1: pan psychism is true, but I'm mentioning this for completeness 612 00:39:03,680 --> 00:39:06,560 Speaker 1: to illustrate that our science is quite young and we 613 00:39:06,640 --> 00:39:09,320 Speaker 1: have no idea what the answer is, so we certainly 614 00:39:09,360 --> 00:39:12,600 Speaker 1: can't rule things out prematurely. Okay, So we've talked about 615 00:39:12,600 --> 00:39:16,680 Speaker 1: the mystery of consciousness and fundamentally how little we still 616 00:39:16,680 --> 00:39:19,560 Speaker 1: know about it. And there's more, which is that to 617 00:39:19,640 --> 00:39:23,080 Speaker 1: make progress towards the solution, we first need to get 618 00:39:23,120 --> 00:39:27,960 Speaker 1: straight what phenomenon we're trying to explain. Consciousness is probably 619 00:39:27,960 --> 00:39:30,960 Speaker 1: not like a light bulb, where it's either on or off. 620 00:39:31,000 --> 00:39:34,680 Speaker 1: It may be that consciousness varies a lot between one 621 00:39:34,719 --> 00:39:38,600 Speaker 1: person and another, between one species and another, and. 622 00:39:38,680 --> 00:39:41,080 Speaker 2: Also within you over time. 623 00:39:42,160 --> 00:39:46,120 Speaker 1: So consciousness is a diverse phenomenon and we still haven't 624 00:39:46,200 --> 00:39:50,560 Speaker 1: yet figured out how the physical equals the mental. The 625 00:39:50,600 --> 00:39:53,480 Speaker 1: ideas that we've looked at today start to help us 626 00:39:53,560 --> 00:39:56,160 Speaker 1: understand some of the structure that might have to be 627 00:39:56,200 --> 00:39:59,319 Speaker 1: in place for consciousness to emerge, but there are many 628 00:39:59,400 --> 00:40:02,839 Speaker 1: questions to be answered. So for the next episode, I'm 629 00:40:02,880 --> 00:40:05,560 Speaker 1: going to dive a little deeper into one aspect of this. 630 00:40:06,080 --> 00:40:08,880 Speaker 1: I want to ask if it would be possible to 631 00:40:09,160 --> 00:40:13,719 Speaker 1: upload our consciousness from our heads onto another substrate like silicon. 632 00:40:14,239 --> 00:40:19,239 Speaker 1: Is it possible to transfer our consciousness to someone else 633 00:40:19,400 --> 00:40:22,080 Speaker 1: or something else? And if so, could that be a 634 00:40:22,120 --> 00:40:29,480 Speaker 1: solution to the problem of mortality. To find out more 635 00:40:29,520 --> 00:40:32,239 Speaker 1: and to find further readings on this topic, head to 636 00:40:32,480 --> 00:40:36,000 Speaker 1: eagleman dot com slash podcast, and if you have any 637 00:40:36,080 --> 00:40:39,680 Speaker 1: questions or discussions, please send an email to podcast at 638 00:40:39,760 --> 00:40:43,120 Speaker 1: eagleman dot com. You can also watch full episodes of 639 00:40:43,160 --> 00:40:47,560 Speaker 1: Inner Cosmos on YouTube. Subscribe to inner cosmospods so you 640 00:40:47,600 --> 00:40:51,120 Speaker 1: can follow along each week with new updates until next time. 641 00:40:51,480 --> 00:41:04,040 Speaker 1: I'm David Eagleman, and this is Inner Cosmos.