WEBVTT 00:00:00.040 --> 00:00:02.460 The following content is provided under a Creative 00:00:02.460 --> 00:00:03.870 Commons license. 00:00:03.870 --> 00:00:06.910 Your support will help MIT OpenCourseWare continue to 00:00:06.910 --> 00:00:10.560 offer high quality educational resources for free. 00:00:10.560 --> 00:00:13.460 To make a donation, or view additional materials from 00:00:13.460 --> 00:00:19.290 hundreds of MIT courses, visit MIT OpenCourseWare, at 00:00:19.290 --> 00:00:20.540 ocw.mit.edu. 00:00:29.330 --> 00:00:30.580 PROFESSOR: Good afternoon. 00:00:32.560 --> 00:00:36.930 In the last lecture we talked about the remarkable human 00:00:36.930 --> 00:00:39.937 brain, and how it empowers our thoughts, or feelings, or 00:00:39.937 --> 00:00:42.920 desires, or actions in the world, and how we began to 00:00:42.920 --> 00:00:46.376 understand this remarkable complexity, or at least grasp 00:00:46.376 --> 00:00:47.798 something of the complexity. 00:00:47.798 --> 00:00:51.890 How we understand the potential for things like 00:00:51.890 --> 00:00:53.570 moral character, and judgments. 00:00:53.570 --> 00:00:57.250 The case of Phineas Gage, to produce language, to speak our 00:00:57.250 --> 00:01:00.250 feelings and thoughts that's blocked in a patient like 00:01:00.250 --> 00:01:03.350 Broca's patient, with Broca's aphasia. 00:01:03.350 --> 00:01:05.650 We talked about the fact that split brain patients show us 00:01:05.650 --> 00:01:08.550 not only to the left and right hemispheres of the human brain 00:01:08.550 --> 00:01:13.130 mediate separate mental abilities, but that they also 00:01:13.130 --> 00:01:15.220 seem to have almost independent forms of 00:01:15.220 --> 00:01:17.070 consciousness, or they don't have to be 00:01:17.070 --> 00:01:18.580 aware of one another. 00:01:18.580 --> 00:01:22.670 And so my focus today is to say we would learn from very 00:01:22.670 --> 00:01:24.480 unusual clinical cases. 00:01:24.480 --> 00:01:27.250 And I'm going to focus today on tools we have to study the 00:01:27.250 --> 00:01:29.580 typical human brain. 00:01:29.580 --> 00:01:34.860 And what is it that we can do to understand how your brain-- 00:01:34.860 --> 00:01:36.060 without having a 00:01:36.060 --> 00:01:37.830 hemispherectomy or a big stroke-- 00:01:37.830 --> 00:01:40.380 how does it operate, and what are the principles of human 00:01:40.380 --> 00:01:44.280 brain function they gave rise to the human mind? 00:01:44.280 --> 00:01:46.260 So what are the ways we can learn about the human brain? 00:01:46.260 --> 00:01:49.370 And one thing we can't do is when animal researchers can 00:01:49.370 --> 00:01:52.510 do, we can't literally go inside the brain except in 00:01:52.510 --> 00:01:54.280 very rare clinical situations. 00:01:54.280 --> 00:01:58.460 I'll talk about them, but it's a rare source of evidence. 00:01:58.460 --> 00:02:00.390 So there's a million ways in which are trying to understand 00:02:00.390 --> 00:02:02.190 which part of the brain is which part of the mind, and we 00:02:02.190 --> 00:02:07.280 talked about the fact that phronology was a big misstep 00:02:07.280 --> 00:02:10.990 in assigning the functions of mental life to different parts 00:02:10.990 --> 00:02:11.750 of the brain. 00:02:11.750 --> 00:02:13.990 And so we hope we can do a bit better than that. 00:02:13.990 --> 00:02:17.030 And I'm going to review with you today some of the core 00:02:17.030 --> 00:02:19.620 methods, and there's a number of them 00:02:19.620 --> 00:02:20.250 studying the human brain. 00:02:20.250 --> 00:02:23.130 The reason there's a number is none of them 00:02:23.130 --> 00:02:24.560 are the magic answer. 00:02:24.560 --> 00:02:26.470 All of them are limited in their own ways, and we sort of 00:02:26.470 --> 00:02:29.630 need all of them to begin to grasp how your 00:02:29.630 --> 00:02:32.830 brain makes your mind. 00:02:32.830 --> 00:02:35.210 There's three huge ways in which we now have the human 00:02:35.210 --> 00:02:36.990 brain organized. 00:02:36.990 --> 00:02:40.690 Lesions, injuries to the brain, stimulation when you're 00:02:40.690 --> 00:02:42.390 allowed to stimulate the brain-- 00:02:42.390 --> 00:02:44.140 rarer, but we'll talk about that. 00:02:44.140 --> 00:02:46.330 And the most common, the one you see all the time in books 00:02:46.330 --> 00:02:50.360 and magazines, recording, functional MRI, EEG, methods 00:02:50.360 --> 00:02:52.750 where we record brain activity, and try to 00:02:52.750 --> 00:02:56.800 understand how that relates to the life of the human mind. 00:02:56.800 --> 00:02:58.400 And so we're going to go through these things a little 00:02:58.400 --> 00:03:00.800 bit and show you how they're applied in some ways that I 00:03:00.800 --> 00:03:02.600 hope that you'll find interesting. 00:03:02.600 --> 00:03:05.100 We'll come back to many of these things as we go through 00:03:05.100 --> 00:03:08.080 the semester, and as we talk about aging, or child 00:03:08.080 --> 00:03:11.040 development, or personality, or other 00:03:11.040 --> 00:03:13.300 topics, social cognition. 00:03:13.300 --> 00:03:15.980 We'll use these tools to understand the brain bases of 00:03:15.980 --> 00:03:18.690 those kinds of aspects of our mental lives. 00:03:18.690 --> 00:03:20.010 So what's a big injury you can have? 00:03:20.010 --> 00:03:23.470 You can have a stroke, where tissue in the brain no longer 00:03:23.470 --> 00:03:27.030 receives its vascular supply that it depends on so greatly. 00:03:27.030 --> 00:03:29.980 And a lot of different things like hypoxia, lack of oxygen, 00:03:29.980 --> 00:03:32.310 the brain is very sensitive to oxygen. 00:03:32.310 --> 00:03:35.030 Tumors can grow, you could have degenerative disorders 00:03:35.030 --> 00:03:37.120 like Alzheimer's, Huntington's, Parkinson's, and 00:03:37.120 --> 00:03:39.190 others, epilepsy. 00:03:39.190 --> 00:03:41.010 So there's lots of different ways in which you can end up 00:03:41.010 --> 00:03:43.740 with brain injury, and ultimately neuronal death. 00:03:46.460 --> 00:03:48.050 What's the strength of this form of evidence? 00:03:48.050 --> 00:03:49.940 Well first of all, it's causal. 00:03:49.940 --> 00:03:51.880 We've talked about the difference between causal and 00:03:51.880 --> 00:03:54.260 correlational sources of evidence, causal ones be more 00:03:54.260 --> 00:03:56.980 powerful for scientific explanation. 00:03:56.980 --> 00:03:59.100 A certain part of the brain is injured in you no longer can 00:03:59.100 --> 00:04:02.180 speak, you change your character, you no longer can 00:04:02.180 --> 00:04:03.370 make memories. 00:04:03.370 --> 00:04:05.600 We're pretty sure that part of the brain in some way is 00:04:05.600 --> 00:04:08.340 required, or causal, for that part of your 00:04:08.340 --> 00:04:11.300 mental life to operate. 00:04:11.300 --> 00:04:14.090 The deficits you see following brain injuries can be amazing, 00:04:14.090 --> 00:04:16.480 we talked about Phineas Gage changing his character, unable 00:04:16.480 --> 00:04:18.820 to produce language, unable to make new memories. 00:04:18.820 --> 00:04:21.579 We'll talk a little bit about patients with Prosopagnosia, 00:04:21.579 --> 00:04:24.110 it's a good big word to go home on spring break and if 00:04:24.110 --> 00:04:25.570 your parents ask what have you learned about, you say 00:04:25.570 --> 00:04:27.270 Prosopagnosia. 00:04:27.270 --> 00:04:29.730 That just means a deficit in recognizing faces. 00:04:29.730 --> 00:04:32.310 Patients with Prosopagnosia will be unable to recognize 00:04:32.310 --> 00:04:34.540 their own spouse by their face. 00:04:34.540 --> 00:04:36.720 They'll recognize it by the voice, by the physical 00:04:36.720 --> 00:04:39.780 movements, but not by their face. 00:04:39.780 --> 00:04:42.940 We learn amazing things about the brain that until it 00:04:42.940 --> 00:04:45.300 happens we didn't know that could happen, what people like 00:04:45.300 --> 00:04:46.370 to call counterintuitive. 00:04:46.370 --> 00:04:49.020 So we'll talk later in the course in a couple times about 00:04:49.020 --> 00:04:52.420 blindsight, patients who say, I see nothing, but their 00:04:52.420 --> 00:04:55.850 behavior shows some part of their brain sees something. 00:04:55.850 --> 00:04:57.920 We'll talk about category specific deficits where 00:04:57.920 --> 00:05:01.900 patients all of the sudden can no longer name living things, 00:05:01.900 --> 00:05:04.100 but they can name nonliving things. 00:05:04.100 --> 00:05:05.220 So you wouldn't have thought of that if 00:05:05.220 --> 00:05:06.730 you didn't see that. 00:05:06.730 --> 00:05:08.310 And we get separations in the brain 00:05:08.310 --> 00:05:09.090 between different things. 00:05:09.090 --> 00:05:11.040 We talked about the difference between the left hemisphere 00:05:11.040 --> 00:05:12.840 being important for local features, 00:05:12.840 --> 00:05:14.250 the right for global. 00:05:14.250 --> 00:05:16.320 The left thinking in terms of functional things in the 00:05:16.320 --> 00:05:19.320 world, the right in terms of appearances. 00:05:19.320 --> 00:05:20.780 We talked about that already. 00:05:20.780 --> 00:05:23.150 We'll talk about other things, the hippocampus is important 00:05:23.150 --> 00:05:26.690 for knowing that, knowing a piece of information but the 00:05:26.690 --> 00:05:29.170 Basal Ganglia is important for learning how to do things, 00:05:29.170 --> 00:05:30.930 mental skills and physical skills. 00:05:30.930 --> 00:05:33.070 We'll come back to all of those, it gives us way to 00:05:33.070 --> 00:05:34.800 organize things. 00:05:34.800 --> 00:05:37.170 Much of our most solid understanding of the human 00:05:37.170 --> 00:05:39.320 brain still comes from the history of 00:05:39.320 --> 00:05:41.170 neurology and lesions. 00:05:41.170 --> 00:05:42.390 But what are its limitations? 00:05:42.390 --> 00:05:46.500 First, brain injuries don't follow anatomical boundaries, 00:05:46.500 --> 00:05:48.630 they sort of crossover things depending on the injury. 00:05:48.630 --> 00:05:51.770 So they're not going to selectively damage one part of 00:05:51.770 --> 00:05:53.850 the brain and not touch an adjacent one they could be 00:05:53.850 --> 00:05:55.520 doing something different. 00:05:55.520 --> 00:05:58.430 People can be variable in their response. 00:05:58.430 --> 00:06:01.150 Nearby systems, if you have two things in the brain that 00:06:01.150 --> 00:06:04.050 are next door to one another, do quite different things. 00:06:04.050 --> 00:06:09.170 Injuries are likely to injure them both, and you will have a 00:06:09.170 --> 00:06:10.930 wrong conclusion about the architecture 00:06:10.930 --> 00:06:13.280 of the human brain. 00:06:13.280 --> 00:06:15.940 When we test a patient and ask them to do things after a 00:06:15.940 --> 00:06:18.910 brain injury, we don't really test the part of the brain 00:06:18.910 --> 00:06:20.390 that's not there. 00:06:20.390 --> 00:06:22.340 We really test a part of the brain that is there, people do 00:06:22.340 --> 00:06:23.820 the best they can. 00:06:23.820 --> 00:06:26.530 So there's secondary degeneration to an injury, 00:06:26.530 --> 00:06:27.930 there's recovery from injury, there's 00:06:27.930 --> 00:06:29.010 compensation from an injury. 00:06:29.010 --> 00:06:31.650 When you test a patient with a brain injury, you're testing 00:06:31.650 --> 00:06:34.970 what the rest of the brain can do in the absence of one of 00:06:34.970 --> 00:06:37.820 its companions. 00:06:37.820 --> 00:06:39.510 And finally can offer limited views of 00:06:39.510 --> 00:06:40.990 normal brain function. 00:06:40.990 --> 00:06:43.200 Let me pick one and we'll come back in the course. 00:06:43.200 --> 00:06:46.320 We're very interested in variation in people-- 00:06:46.320 --> 00:06:47.160 individuality-- 00:06:47.160 --> 00:06:49.340 what's the neurology of individuality? 00:06:49.340 --> 00:06:52.580 That's very hard to study in lesion cases, because we don't 00:06:52.580 --> 00:06:53.490 see enough of a lesion. 00:06:53.490 --> 00:06:56.760 we don't have enough Phineas Gages to ask would that injury 00:06:56.760 --> 00:07:00.762 look different if you grew up in one culture or another, if 00:07:00.762 --> 00:07:03.610 you were outgoing versus shy. 00:07:03.610 --> 00:07:05.120 Those kinds of things are very hard to 00:07:05.120 --> 00:07:08.260 answer patient by patient. 00:07:08.260 --> 00:07:11.080 But we can test large groups of people with imaging and ask 00:07:11.080 --> 00:07:12.940 what's the influence of culture on your brain 00:07:12.940 --> 00:07:13.860 organization? 00:07:13.860 --> 00:07:15.985 What's the influence of personality on how your 00:07:15.985 --> 00:07:16.690 brain's organized? 00:07:16.690 --> 00:07:19.220 And you'll see later on in the semester evidence about those 00:07:19.220 --> 00:07:20.750 sorts of things. 00:07:20.750 --> 00:07:25.650 So let's go back to Paul Broca, the neurologist who 00:07:25.650 --> 00:07:28.030 they gave a name to Broca's area, because he sought a 00:07:28.030 --> 00:07:30.220 patient like this, like [INAUDIBLE]. 00:07:30.220 --> 00:07:32.630 That this patient had a big injury in this area could no 00:07:32.630 --> 00:07:33.510 longer speak. 00:07:33.510 --> 00:07:36.100 And every course you ever take about the brain almost will 00:07:36.100 --> 00:07:38.370 include a discussion about Broca's area. 00:07:38.370 --> 00:07:41.570 So I'm going to warp your world in a very narrow way, 00:07:41.570 --> 00:07:44.330 but maybe a shocking way, and tell you we don't even know 00:07:44.330 --> 00:07:46.170 how to think about Broca's area once we get more 00:07:46.170 --> 00:07:47.860 scientific than that. 00:07:47.860 --> 00:07:50.930 So because this is MIT so we're willing to 00:07:50.930 --> 00:07:52.100 tell the truth, OK. 00:07:52.100 --> 00:07:54.780 So some years later Nina Dronkers said the following 00:07:54.780 --> 00:07:58.150 thing, she studied a large group of patients who had 00:07:58.150 --> 00:08:00.170 Broca's aphasia by behavior. 00:08:00.170 --> 00:08:03.100 That is they had trouble speaking, but the 00:08:03.100 --> 00:08:05.160 comprehension was pretty good. 00:08:05.160 --> 00:08:07.660 And then she made maps of their injuries and she 00:08:07.660 --> 00:08:10.050 overlaid those maps. 00:08:10.050 --> 00:08:14.120 And she said who has Broca's aphasia, and if you have 00:08:14.120 --> 00:08:17.520 Broca's aphasia, what's the one part of the brain that 00:08:17.520 --> 00:08:20.690 every patient with Broca's aphasia has damage to. 00:08:20.690 --> 00:08:21.650 Because these patients-- 00:08:21.650 --> 00:08:24.090 what you see on these maps is, some patients have damage 00:08:24.090 --> 00:08:25.620 here, or here, or here. 00:08:25.620 --> 00:08:29.220 But you line them all up and you say, what's the one spot 00:08:29.220 --> 00:08:32.179 that you have to have injured to have Broca's aphasia? 00:08:32.179 --> 00:08:35.549 And it's not this area that you saw in the picture, it's 00:08:35.549 --> 00:08:38.364 this area, in yellow, an area called the Precentral Gyrus of 00:08:38.364 --> 00:08:39.975 the Insula. 00:08:39.975 --> 00:08:42.860 The Insula is a fascinating, mysterious little structure-- 00:08:42.860 --> 00:08:44.490 you have one on the left, and one on the right-- 00:08:44.490 --> 00:08:46.590 that runs along from the temporal lobe, up to the 00:08:46.590 --> 00:08:48.230 frontal cortex. 00:08:48.230 --> 00:08:51.310 Just a couple years ago there was a paper reporting that 00:08:51.310 --> 00:08:54.860 patients who had stroke in posterior insula instantly 00:08:54.860 --> 00:08:57.670 gave up smoking, and never wanted to smoke again. 00:08:57.670 --> 00:09:00.120 There's huge research efforts to help people quit smoking, 00:09:00.120 --> 00:09:04.250 just because it's such a difficult health problem. 00:09:04.250 --> 00:09:06.520 Nobody is doing insula lesions to help people 00:09:06.520 --> 00:09:07.710 stop smoking, OK. 00:09:07.710 --> 00:09:11.090 But it just stopped the smoking, and their desire to 00:09:11.090 --> 00:09:13.290 smoke, just like that. 00:09:13.290 --> 00:09:15.770 This is now more towards the front of the brain, this is 00:09:15.770 --> 00:09:18.730 not what anybody in a book or a course will tell you is 00:09:18.730 --> 00:09:20.850 Broca's area, that's out here. 00:09:20.850 --> 00:09:23.110 But it turns out this is the hot spot, and you could say, 00:09:23.110 --> 00:09:25.230 well what about the original patient? 00:09:25.230 --> 00:09:27.530 So kind of creatively Nina Dronkers went back and they 00:09:27.530 --> 00:09:31.285 did an MRI of the brain of the deceased original Broca's 00:09:31.285 --> 00:09:32.910 aphasic patient. 00:09:32.910 --> 00:09:36.150 They still had his brain, they put it in a scanner and they 00:09:36.150 --> 00:09:37.870 ran a structural MRI. 00:09:37.870 --> 00:09:41.010 And what they found was sure enough he had damage way 00:09:41.010 --> 00:09:46.040 inside the exterior limit of this damage, in as well as in 00:09:46.040 --> 00:09:48.010 white matter that connects to it. 00:09:48.010 --> 00:09:51.740 So even now imaging evidence lets us rediscover what is the 00:09:51.740 --> 00:09:54.370 true basis of your ability to speak, or its 00:09:54.370 --> 00:09:55.840 vulnerability to injury. 00:09:55.840 --> 00:09:57.520 And it turns out not to be exactly what 00:09:57.520 --> 00:09:59.300 Broca thought it was. 00:09:59.300 --> 00:10:02.750 He saw big lesion and he said, this is the part of matters. 00:10:02.750 --> 00:10:04.870 It turns out, as far as we understand, it's a slightly 00:10:04.870 --> 00:10:06.700 different part that he thought was just at the 00:10:06.700 --> 00:10:08.440 edge and not important. 00:10:08.440 --> 00:10:12.050 So we can get better even going back to 150 years of 00:10:12.050 --> 00:10:15.590 imaging a brain, we don't have many of those brains around. 00:10:15.590 --> 00:10:17.950 Stimulation, so you like to go in the brain is stimulate. 00:10:17.950 --> 00:10:20.260 People who do animal work will go in and stimulate a neuron 00:10:20.260 --> 00:10:21.860 and see what happens. 00:10:21.860 --> 00:10:25.030 It's rare, you only get into the patient's brain when they 00:10:25.030 --> 00:10:28.440 have a neurosurgical procedure and they're considering a 00:10:28.440 --> 00:10:29.880 resection, or removal of tissue. 00:10:29.880 --> 00:10:31.820 You can also do recordings by putting grids on 00:10:31.820 --> 00:10:34.260 top of those brains. 00:10:34.260 --> 00:10:36.610 And Penfield did famous studies for patients with 00:10:36.610 --> 00:10:40.230 epilepsy, where he would stimulate and map things that 00:10:40.230 --> 00:10:41.920 contributed a lot to our thinking about the brain. 00:10:41.920 --> 00:10:45.720 But that's a rare source of evidence, as you can imagine. 00:10:45.720 --> 00:10:47.630 Another one that's much more common-- there's one of these 00:10:47.630 --> 00:10:50.340 devices down the street in building 46-- 00:10:50.340 --> 00:10:53.660 is Transcranial Magnetic Stimulation, or TMS. 00:10:53.660 --> 00:10:56.062 So this is one in which people are allowed ethically, and 00:10:56.062 --> 00:10:58.980 responsibly to give you a virtual lesion for a few 00:10:58.980 --> 00:11:02.180 moments, if you volunteer to do so. 00:11:02.180 --> 00:11:04.990 So they put some sort of wire, there's different 00:11:04.990 --> 00:11:08.460 configurations, over your head in a targeted location. 00:11:08.460 --> 00:11:10.642 It generates a magnetic field that passes through the skull 00:11:10.642 --> 00:11:12.540 and induces a current. 00:11:12.540 --> 00:11:15.050 And what happens is the current drives lots 00:11:15.050 --> 00:11:16.660 of neurons to fire. 00:11:16.660 --> 00:11:19.440 Turns out, this is kind of interesting, if all your 00:11:19.440 --> 00:11:22.580 neurons are firing at the same moment, in one sense it's as 00:11:22.580 --> 00:11:25.420 if none of them were, because there's no information. 00:11:25.420 --> 00:11:26.810 There's a lot of different ways you could think about 00:11:26.810 --> 00:11:30.670 that, but for example if on your 300 channel television 00:11:30.670 --> 00:11:33.030 you had all the channels on simultaneously on the same 00:11:33.030 --> 00:11:35.410 screen, it wouldn't be very easy to watch, 00:11:35.410 --> 00:11:36.180 something like that. 00:11:36.180 --> 00:11:38.910 All the neurons firing pretty much wipes out the 00:11:38.910 --> 00:11:40.460 function of that area. 00:11:40.460 --> 00:11:44.580 People do feel a little bit of a physical sensation, if 00:11:44.580 --> 00:11:47.360 you're prone to epilepsy it's not a good idea to try this, 00:11:47.360 --> 00:11:49.240 so it does require some careful supervision 00:11:49.240 --> 00:11:49.930 experimentally. 00:11:49.930 --> 00:11:52.270 But you can do this with healthy people, and if for 00:11:52.270 --> 00:11:55.480 example you do it on this side of the motor cortex, people 00:11:55.480 --> 00:11:57.630 twitch or say they felt somebody touch them. 00:11:57.630 --> 00:12:00.220 Nobody touched them, but the part of the brain that codes 00:12:00.220 --> 00:12:02.510 for touch just got turned on. 00:12:02.510 --> 00:12:05.900 If you put it on the occipital cortex, visual cortex, and you 00:12:05.900 --> 00:12:08.220 turn on at a certain moment, you could put a word up and 00:12:08.220 --> 00:12:10.690 word down, and the person will say they saw nothing. 00:12:10.690 --> 00:12:12.570 You'll make them functionally, cortically 00:12:12.570 --> 00:12:14.960 blind for a few moments. 00:12:14.960 --> 00:12:17.430 People have done experiments like this to suppress 00:12:17.430 --> 00:12:20.140 activity, to enhance activity, sometimes it makes people even 00:12:20.140 --> 00:12:22.160 faster, like naming pictures. 00:12:22.160 --> 00:12:24.550 And it's also been used there's still experimental 00:12:24.550 --> 00:12:26.310 studies of whether it can be helpful for treatments of 00:12:26.310 --> 00:12:28.870 neuropsychiatric disorders. 00:12:28.870 --> 00:12:31.770 It's not invasive, in a sense of you're not going literally 00:12:31.770 --> 00:12:35.620 inside, you have a causal thing because turning the 00:12:35.620 --> 00:12:38.290 brain on or off. 00:12:38.290 --> 00:12:41.530 It's not very well targeted, it can't go into subcortical 00:12:41.530 --> 00:12:45.270 areas, but it's a very interesting tool. 00:12:45.270 --> 00:12:48.670 Let's talk about recording brain structure for a moment. 00:12:48.670 --> 00:12:50.730 It's really important to separate this concept between 00:12:50.730 --> 00:12:53.400 recording structure, which is a picture of anatomy, or 00:12:53.400 --> 00:12:56.340 function, which is a picture of physiology. 00:12:56.340 --> 00:12:58.880 So there's old ones angiography, and things like 00:12:58.880 --> 00:12:59.940 that, I'll show you two. 00:12:59.940 --> 00:13:02.410 Computed Tomography, and MR and a really cool measure 00:13:02.410 --> 00:13:03.650 called Diffusion Tensor Imaging. 00:13:03.650 --> 00:13:05.910 And then, dysfunctional measures, and we'll talk about 00:13:05.910 --> 00:13:09.710 those, EEG, PET, fMRI, MEG. 00:13:09.710 --> 00:13:11.670 So here's some different images you can 00:13:11.670 --> 00:13:12.920 get from the brain. 00:13:15.650 --> 00:13:18.120 This is a post-mortem brain, this is a cut brain, here's 00:13:18.120 --> 00:13:19.960 the front, here's the back. 00:13:19.960 --> 00:13:22.000 If a brain was open in front of you, this is 00:13:22.000 --> 00:13:23.620 what you would see. 00:13:23.620 --> 00:13:25.890 So here's an MRI, Magnetic Resonance Imaging, and it's 00:13:25.890 --> 00:13:29.120 pretty good, and I'll show you some more pictures, in showing 00:13:29.120 --> 00:13:30.070 you lots of information. 00:13:30.070 --> 00:13:32.700 Not as good as if you were in there, but pretty good. 00:13:32.700 --> 00:13:35.120 Here's a CT scan, Computed Tomography. 00:13:35.120 --> 00:13:36.840 It's not as good, it's more blurry. 00:13:36.840 --> 00:13:40.430 And this thing that looks really sad, it looks like get 00:13:40.430 --> 00:13:43.810 your camera to focus, that's actually the quality of the 00:13:43.810 --> 00:13:46.040 picture that we see that underlies maybe the most 00:13:46.040 --> 00:13:48.290 widely used tool these days for understanding the human 00:13:48.290 --> 00:13:50.720 mind and brain, Functional Magnetic Resonance Imaging. 00:13:50.720 --> 00:13:52.830 It's a very smudgy picture, but it has some really 00:13:52.830 --> 00:13:54.660 interesting properties. 00:13:54.660 --> 00:13:56.970 So here's the kind of thing you go into for an MRI, both 00:13:56.970 --> 00:13:59.550 structural or functional. 00:13:59.550 --> 00:14:03.040 Some of you have almost certainly been participants in 00:14:03.040 --> 00:14:04.690 research or experiments, or studies, stick up 00:14:04.690 --> 00:14:05.870 your hand if you have. 00:14:05.870 --> 00:14:09.930 Oh, a lot of you, OK, so you'll speak up on this, is it 00:14:09.930 --> 00:14:12.110 quiet or noisy? 00:14:12.110 --> 00:14:17.570 It's super noisy, so you have to have ear plugs in. 00:14:17.570 --> 00:14:19.980 And this is why people doing experiments with this 00:14:19.980 --> 00:14:22.320 Functional MRI want to do visual studies, because 00:14:22.320 --> 00:14:23.300 auditory ones are tricky. 00:14:23.300 --> 00:14:26.030 So Tyler, your head TA, likes auditory stuff, it's 10 times 00:14:26.030 --> 00:14:27.420 harder to pull off those experiments. 00:14:27.420 --> 00:14:29.700 Everybody tries to do visual stuff, so you don't have the 00:14:29.700 --> 00:14:30.940 noise problem. 00:14:30.940 --> 00:14:33.485 But you get some beautiful pictures, here's Computed 00:14:33.485 --> 00:14:35.250 Tomography. 00:14:35.250 --> 00:14:38.160 And here's an MRI structural scan from the brain, the 00:14:38.160 --> 00:14:39.500 ventricles, here's Basal Ganglia. 00:14:42.000 --> 00:14:45.570 With an MRI, beautifully you can see the difference between 00:14:45.570 --> 00:14:47.460 white and gray matter. 00:14:47.460 --> 00:14:49.080 I'm always impressed that the gray matter is 00:14:49.080 --> 00:14:50.520 just this thin ribbon. 00:14:50.520 --> 00:14:52.580 Cortex really means bark, it's just like 00:14:52.580 --> 00:14:54.860 the bark on our tree. 00:14:54.860 --> 00:14:56.600 And when you look at the brain this way, look at how much 00:14:56.600 --> 00:14:57.350 white matter there is. 00:14:57.350 --> 00:14:59.500 Here's your frontal cortex, look at all that white matter 00:14:59.500 --> 00:15:02.490 and then this thin, cortical mantle, or ribbon, or bark. 00:15:02.490 --> 00:15:06.070 That's what we think of as the smarts of language, and social 00:15:06.070 --> 00:15:07.380 planning, and things like that. 00:15:07.380 --> 00:15:10.970 So that's a structural picture. 00:15:10.970 --> 00:15:14.370 And then these two pictures are sort of fun. 00:15:14.370 --> 00:15:18.750 This is just recorded down the street, we're going to fly 00:15:18.750 --> 00:15:32.550 through your brain from one ear to the other. 00:15:36.650 --> 00:15:38.940 And you get amazing resolution, it's not the same 00:15:38.940 --> 00:15:40.230 thing like being inside the brain. 00:15:40.230 --> 00:15:42.890 There's things that you don't see, we know that, 00:15:42.890 --> 00:15:43.960 but you see a lot. 00:15:43.960 --> 00:15:45.210 Isn't that cool? 00:15:49.770 --> 00:15:52.640 Let's examine what you can see now. 00:15:52.640 --> 00:15:55.120 Only about 40 years ago, you would have to have a person 00:15:55.120 --> 00:15:55.970 die to see this. 00:15:55.970 --> 00:15:57.540 This is a patient with Huntington's disease, we'll 00:15:57.540 --> 00:15:59.630 come back and talk about that disorder. 00:15:59.630 --> 00:16:01.770 Here's a healthy person, top of the brain. 00:16:01.770 --> 00:16:04.290 This is the caudate here, part of the Basal Ganglia. 00:16:04.290 --> 00:16:06.870 And you could see in a patient who has passed away that part 00:16:06.870 --> 00:16:08.850 of the brain is completely withered away in 00:16:08.850 --> 00:16:11.720 Huntington's disease. 00:16:11.720 --> 00:16:13.530 You would have to wait until person passed away to see 00:16:13.530 --> 00:16:15.960 something like that. 00:16:15.960 --> 00:16:17.640 Here's a healthy person top of the brain, 00:16:17.640 --> 00:16:19.140 again lining the ventricle. 00:16:19.140 --> 00:16:20.310 This is the caudate. 00:16:20.310 --> 00:16:22.160 And here in a living Huntington's patients you can 00:16:22.160 --> 00:16:23.490 see the great withering away. 00:16:23.490 --> 00:16:26.110 Some of cortex 2 in later stage of disease, but 00:16:26.110 --> 00:16:27.360 especially in the Basal Ganglia. 00:16:29.950 --> 00:16:33.470 Here's a healthy older person, about 70 years of age, top of 00:16:33.470 --> 00:16:35.940 the brain, bottom of the brain, the ventricle. 00:16:35.940 --> 00:16:38.700 Here's on the left and right of the hippocampus, the 00:16:38.700 --> 00:16:41.900 structure we'll talk about, without which you can cannot 00:16:41.900 --> 00:16:44.870 learn any new fact, or remember any 00:16:44.870 --> 00:16:47.220 event in your life. 00:16:47.220 --> 00:16:51.090 So powerful for almost every sense of learning. 00:16:51.090 --> 00:16:53.990 And look what happens the structure in the same aged 00:16:53.990 --> 00:16:56.510 patient with Alzheimer's disease. 00:16:56.510 --> 00:16:59.120 It's virtually gone, it's greatly weathered. 00:16:59.120 --> 00:17:02.190 You see it's much wider here, because the tissue's greatly 00:17:02.190 --> 00:17:05.290 shrunk in the Alzheimer's patient. 00:17:05.290 --> 00:17:08.599 So we can see these kinds of changes in living people, for 00:17:08.599 --> 00:17:12.089 both research purposes and clinical purposes. 00:17:12.089 --> 00:17:14.530 Here's one that's more cheerful, and more reflecting 00:17:14.530 --> 00:17:15.740 your experience. 00:17:15.740 --> 00:17:20.400 Here are studies of brain changes from age four to 21. 00:17:20.400 --> 00:17:22.700 So they follow a large number of people at NIH 00:17:22.700 --> 00:17:24.890 from age four to 21. 00:17:24.890 --> 00:17:27.940 And what this shows is this color coding is the thickness 00:17:27.940 --> 00:17:29.360 of the cortex. 00:17:29.360 --> 00:17:32.810 And you might imagine that as you get older, and smarter and 00:17:32.810 --> 00:17:34.890 go through grade school, and middle school, and high 00:17:34.890 --> 00:17:37.340 school, and MIT college, and as you head towards grad 00:17:37.340 --> 00:17:38.960 school, your brain will get thicker, and 00:17:38.960 --> 00:17:40.290 thicker with cortex. 00:17:40.290 --> 00:17:42.050 It's exactly the opposite. 00:17:42.050 --> 00:17:43.950 Ever since you were about five years old, you've been 00:17:43.950 --> 00:17:48.280 shedding neurons by the millions, and connections 00:17:48.280 --> 00:17:50.980 among them by the trillions. 00:17:50.980 --> 00:17:52.530 And you're still going to do that until your 00:17:52.530 --> 00:17:54.630 probably about 22 or 23. 00:17:54.630 --> 00:17:57.930 Then you peak, and you decline and become faculty members. 00:18:01.490 --> 00:18:04.450 But that's really interesting, we'll come back to this, that 00:18:04.450 --> 00:18:07.750 what happens as your brain get smart, experienced, 00:18:07.750 --> 00:18:10.820 knowledgeable, all the differences between you now, 00:18:10.820 --> 00:18:14.390 if you're 17, 18, 19, 20, and when you were four, it all 00:18:14.390 --> 00:18:17.970 goes with your cortex getting thinner. 00:18:17.970 --> 00:18:19.690 And we'll come back to that and how people think about 00:18:19.690 --> 00:18:23.240 that, but let's see if I can get this next movie to run. 00:18:23.240 --> 00:18:24.930 There's also an ordering-- and we'll come back this but I 00:18:24.930 --> 00:18:26.640 want to show you this movie. 00:18:26.640 --> 00:18:29.090 So the more blue you are, the thinner you are, the more 00:18:29.090 --> 00:18:31.670 advanced you are in terms of ultimate young adult 00:18:31.670 --> 00:18:32.900 development. 00:18:32.900 --> 00:18:35.740 Here's visual cortex, vision coming in. 00:18:35.740 --> 00:18:39.150 This is Somatomotor Cortex, how you feel, your body, and 00:18:39.150 --> 00:18:40.580 how you move yourself. 00:18:40.580 --> 00:18:44.200 And what you see is, as you go from age four to 21, the blue 00:18:44.200 --> 00:18:49.960 spreads, that spreading is your brain maturing in higher 00:18:49.960 --> 00:18:51.510 thought areas. 00:18:51.510 --> 00:18:55.755 So we're going to review your life on average right now, 00:18:55.755 --> 00:18:57.005 here you go. 00:19:03.150 --> 00:19:06.020 And now you're ready to graduate. 00:19:06.020 --> 00:19:09.540 It's kind of an amazing story of fantastic brain changes 00:19:09.540 --> 00:19:12.240 that move you from what you could do and not do at four, 00:19:12.240 --> 00:19:15.910 to what you can do and not do at age 21. 00:19:15.910 --> 00:19:18.600 And we couldn't see these things, we couldn't begin to 00:19:18.600 --> 00:19:21.230 see these things, until just a few years ago in any 00:19:21.230 --> 00:19:22.360 scientific sense. 00:19:22.360 --> 00:19:24.990 All these things are like miraculous sources of 00:19:24.990 --> 00:19:27.540 information. 00:19:27.540 --> 00:19:29.080 So let's pick another thing, and we'll tie 00:19:29.080 --> 00:19:30.620 it to school work. 00:19:30.620 --> 00:19:32.300 Here's the structure we said, the hippocampus. 00:19:32.300 --> 00:19:36.790 So important for the formation of new memories on an everyday 00:19:36.790 --> 00:19:40.210 basis, everything that's important and that you learn. 00:19:40.210 --> 00:19:43.060 So here's a fun study they took, and as you hear it, 00:19:43.060 --> 00:19:46.130 think about its scientific limitation, but it's fun as 00:19:46.130 --> 00:19:47.740 students to think about. 00:19:47.740 --> 00:19:51.900 They looked at students in medical school in Germany. 00:19:51.900 --> 00:19:55.080 They looked at the measure of an anatomic thickness of the 00:19:55.080 --> 00:19:59.790 hippocampus before and after they studied like crazy for a 00:19:59.790 --> 00:20:02.600 huge exam over some number of periods. 00:20:06.330 --> 00:20:08.260 This is the difference between the two, and what they're 00:20:08.260 --> 00:20:11.650 showing you is that as you study, your hippocampus got 00:20:11.650 --> 00:20:13.980 thicker as you crammed for your test. 00:20:13.980 --> 00:20:16.350 So will there be a day where instead of having to give you 00:20:16.350 --> 00:20:17.910 tests we could just measure the thickness of your 00:20:17.910 --> 00:20:19.910 hippocampus to know how much you studied, and you could 00:20:19.910 --> 00:20:22.520 just zoom in and out of a scanner, I don't know. 00:20:22.520 --> 00:20:24.660 But one cool thing about it is it's showing you that we can 00:20:24.660 --> 00:20:27.950 see structural changes not just on a giant scale from 00:20:27.950 --> 00:20:30.990 when you're four to 21, but from some number of months of 00:20:30.990 --> 00:20:34.770 experience, we can see a physical change in your brain. 00:20:34.770 --> 00:20:37.100 Now that's trivial for animal researchers, they can show 00:20:37.100 --> 00:20:40.410 amazing things in seconds, but you see the human brain 00:20:40.410 --> 00:20:41.740 physically changing. 00:20:41.740 --> 00:20:43.870 So let's take a look at another one, slightly more 00:20:43.870 --> 00:20:47.590 controlled, we'll look at two more examples. 00:20:47.590 --> 00:20:50.850 London taxi cab drivers. 00:20:50.850 --> 00:20:52.650 If you've travelled in various cities, and have gone in 00:20:52.650 --> 00:20:55.370 various taxis, you may have had better or worse 00:20:55.370 --> 00:20:57.630 experiences whether the taxi driver knows where he or she 00:20:57.630 --> 00:20:58.720 is going exactly. 00:20:58.720 --> 00:21:02.120 London is famous for having a very high code, taxi drivers 00:21:02.120 --> 00:21:07.650 have to take big exams to get their official taxi license, 00:21:07.650 --> 00:21:09.980 they create a very demanding thing. 00:21:09.980 --> 00:21:13.020 And when they ask this in the hippocampus if you learn lots 00:21:13.020 --> 00:21:16.315 of routes, if you know tons of routes in London, what happens 00:21:16.315 --> 00:21:18.100 to the hippocampus as it's memorizing all 00:21:18.100 --> 00:21:19.170 these special routes? 00:21:19.170 --> 00:21:23.180 And what they saw, that taxi drivers had bigger hippocampi, 00:21:23.180 --> 00:21:27.660 and the longer they drove, the bigger it was. 00:21:27.660 --> 00:21:28.830 So is this a causal or 00:21:28.830 --> 00:21:30.085 correlational source of evidence? 00:21:33.050 --> 00:21:35.490 It's correlational right? 00:21:35.490 --> 00:21:37.560 So let's start with this, they have bigger hippocampi, and 00:21:37.560 --> 00:21:40.870 now maybe that's simply because, what? 00:21:40.870 --> 00:21:43.300 Maybe somebody who has an awesome hippocampus is ready 00:21:43.300 --> 00:21:44.940 to go to be a taxi driver. 00:21:44.940 --> 00:21:48.630 Maybe they pass the test, and the one who got lost all the 00:21:48.630 --> 00:21:50.940 time, and was driving to the wrong airport and stuff, small 00:21:50.940 --> 00:21:53.080 hippocampus, never became a taxi driver. 00:21:53.080 --> 00:21:56.290 So the size of the hippocampus is the cause of your success, 00:21:56.290 --> 00:21:57.660 not the consequence. 00:21:57.660 --> 00:22:00.560 Because the longer you drove, the bigger it got, that kind 00:22:00.560 --> 00:22:01.960 of goes with that. 00:22:01.960 --> 00:22:05.620 But you could do a causal experiment this way. 00:22:05.620 --> 00:22:08.280 They taught people to juggle three balls, they practiced 00:22:08.280 --> 00:22:10.470 every day for three months. 00:22:10.470 --> 00:22:12.760 Three months juggling every day. 00:22:12.760 --> 00:22:15.413 What you see in yellow are parts of the brain-- that's a 00:22:15.413 --> 00:22:17.400 statistical map-- 00:22:17.400 --> 00:22:21.260 parts of the brain that significantly got thicker in 00:22:21.260 --> 00:22:22.295 three months of practice. 00:22:22.295 --> 00:22:24.730 So they could compare directly before and after, it's a 00:22:24.730 --> 00:22:27.050 causal experiment. 00:22:27.050 --> 00:22:30.730 And these are areas that are involved in the visual motion, 00:22:30.730 --> 00:22:34.190 and it makes sense that areas involved in visual motion 00:22:34.190 --> 00:22:35.140 would somehow change. 00:22:35.140 --> 00:22:37.490 But the fact that we can see three months of experience 00:22:37.490 --> 00:22:40.340 change the structure of your brain, it's kind of remarkable 00:22:40.340 --> 00:22:42.580 in they way that we can measure and scientifically 00:22:42.580 --> 00:22:43.760 scrutinize. 00:22:43.760 --> 00:22:46.550 You might be curious if you did three months of this and 00:22:46.550 --> 00:22:48.150 you were a pretty good juggler, you're impressing 00:22:48.150 --> 00:22:51.700 your friends at parties, your brain scan is different. 00:22:51.700 --> 00:22:52.790 What do you think happened-- 00:22:52.790 --> 00:22:55.070 they followed these people up-- after the juggling 00:22:55.070 --> 00:22:57.150 requirements stopped? 00:22:57.150 --> 00:22:59.490 They kind of stop, most of the people, they were too busy. 00:22:59.490 --> 00:23:01.300 They would show off here and there, but that was it. 00:23:01.300 --> 00:23:04.060 They measured their brain's again about six months later, 00:23:04.060 --> 00:23:05.890 and this change was gone. 00:23:05.890 --> 00:23:09.210 It came in, and it went out with the activity, it's 00:23:09.210 --> 00:23:10.210 activity dependent. 00:23:10.210 --> 00:23:13.710 So depending on what you do, you could think about every 00:23:13.710 --> 00:23:16.090 activity you do-- mental and physical that you do-- is 00:23:16.090 --> 00:23:18.710 constantly slightly changing your brain. 00:23:18.710 --> 00:23:21.440 And if you do a lot of it, you're fundamentally changing 00:23:21.440 --> 00:23:22.510 it like in these individuals. 00:23:22.510 --> 00:23:25.320 But if you stop doing it you go right back to where you 00:23:25.320 --> 00:23:28.460 were, because you're going to be doing something else. 00:23:28.460 --> 00:23:31.210 And another fun measure that's kind of beautiful and 00:23:31.210 --> 00:23:33.110 intriguing is Diffusion Tensor Imaging. 00:23:33.110 --> 00:23:35.020 Now every [INAUDIBLE] we talked about so far has been 00:23:35.020 --> 00:23:37.470 gray matter of the brain, the neurons and then the 00:23:37.470 --> 00:23:38.820 circuits they form. 00:23:38.820 --> 00:23:40.310 We're going to turn to white matter, which is the 00:23:40.310 --> 00:23:44.720 myelinated axons that are the super conducting 00:23:44.720 --> 00:23:46.750 highways of the brain. 00:23:46.750 --> 00:23:49.270 And what Diffusion Tensor Imaging does, it shows you 00:23:49.270 --> 00:23:51.100 something about the organization of that white 00:23:51.100 --> 00:23:55.360 matter, measuring directly the movement of water at very, 00:23:55.360 --> 00:23:58.850 very tiny distances. 00:23:58.850 --> 00:24:01.740 This is a cross-section of a myelinated nerve fiber. 00:24:01.740 --> 00:24:04.170 Those are the fibers that are covered with white matter that 00:24:04.170 --> 00:24:05.550 have to go some distance. 00:24:05.550 --> 00:24:08.470 And the myelin protects the quality and speed of that 00:24:08.470 --> 00:24:10.310 signal through your brain. 00:24:10.310 --> 00:24:13.000 And you could see at the level of, if you're a tiny, tiny 00:24:13.000 --> 00:24:16.570 drop of water, or smaller than that, this is a pretty big 00:24:16.570 --> 00:24:18.670 bump in the road. 00:24:18.670 --> 00:24:21.770 So imagine you're a little drop of water moving a little 00:24:21.770 --> 00:24:24.530 bit, and you bump up against the myelin, you go oh, can't 00:24:24.530 --> 00:24:26.200 go that way, and you go back this way, and 00:24:26.200 --> 00:24:27.005 you go with the flow. 00:24:27.005 --> 00:24:30.180 You go parallel with a myelin, it's hard to cross it at that 00:24:30.180 --> 00:24:32.000 microscopic scale. 00:24:32.000 --> 00:24:35.360 But we can measure that movement in areas where it's 00:24:35.360 --> 00:24:39.290 highly constrained, and that's a property of the water. 00:24:39.290 --> 00:24:41.980 Here cerebral spinal fluid, things can go anywhere. 00:24:41.980 --> 00:24:43.970 Here's where there's a lot of white matter, and the water 00:24:43.970 --> 00:24:46.930 tends to flow along parallel with the white matter, just 00:24:46.930 --> 00:24:49.960 for physical reasons it can't cross it over. 00:24:49.960 --> 00:24:54.530 And here for example, is a statistical map comparing this 00:24:54.530 --> 00:24:57.760 measure of white matter organization between adults, 00:24:57.760 --> 00:25:01.780 who either in their childhood had a diagnosis of dyslexia, 00:25:01.780 --> 00:25:04.060 reading was difficult for these individuals. 00:25:04.060 --> 00:25:07.370 Or people who typical reading development, where you learned 00:25:07.370 --> 00:25:09.440 to read and wasn't particularly difficult. 00:25:09.440 --> 00:25:11.610 And you can see that in this area around the Temporal 00:25:11.610 --> 00:25:14.670 Parietal Cortex, there's a significant difference. 00:25:14.670 --> 00:25:17.400 But we can do one more thing. 00:25:17.400 --> 00:25:20.540 These are reading scores this way, this is the measure of 00:25:20.540 --> 00:25:22.110 the white matter organization from the 00:25:22.110 --> 00:25:23.970 Diffusion Tensor Imaging. 00:25:23.970 --> 00:25:26.630 Each of these as an individual person now. 00:25:26.630 --> 00:25:29.380 So the open dots are the people who had typical reading 00:25:29.380 --> 00:25:30.940 development. 00:25:30.940 --> 00:25:34.550 The filled dots are the people who had poor development, and 00:25:34.550 --> 00:25:36.600 you can see it's pretty continuous. 00:25:36.600 --> 00:25:38.950 Even in the people with the open circles who never had a 00:25:38.950 --> 00:25:42.280 problem, the better they read, the more the 00:25:42.280 --> 00:25:44.930 organization is here. 00:25:44.930 --> 00:25:46.570 So this is not just the difference between good and 00:25:46.570 --> 00:25:50.040 bad readers, it's a difference between really good readers, 00:25:50.040 --> 00:25:52.710 and medium readers, and poor readers, right, continuous. 00:25:52.710 --> 00:25:54.000 So now, cause or effect? 00:25:57.630 --> 00:26:00.180 Were those of you who at three, who had awesome myelin, 00:26:00.180 --> 00:26:01.480 were you going, reading's a snap. 00:26:01.480 --> 00:26:04.880 I love this stuff, where's War and Peace, mom? 00:26:04.880 --> 00:26:09.960 Or, were you like the jugglers, and you were reading 00:26:09.960 --> 00:26:12.210 a lot, and you were exercising this part of the brain, and 00:26:12.210 --> 00:26:15.240 altered its physical structure. 00:26:15.240 --> 00:26:17.200 And the answer is we don't know. 00:26:17.200 --> 00:26:20.080 How could we know? 00:26:20.080 --> 00:26:21.330 How could we know? 00:26:23.350 --> 00:26:26.400 If you were scientists and were given a pot of money to 00:26:26.400 --> 00:26:30.010 do this, how could you know? 00:26:30.010 --> 00:26:30.670 Well-- 00:26:30.670 --> 00:26:31.679 yeah? 00:26:31.679 --> 00:26:36.170 AUDIENCE: Track the entire lives of multiple people. 00:26:36.170 --> 00:26:37.590 PROFESSOR: Yeah, do a longitudinal study and start 00:26:37.590 --> 00:26:40.190 like, before people read. 00:26:40.190 --> 00:26:42.950 And you could see is it different then? 00:26:42.950 --> 00:26:47.130 Are we born to be big readers, or by being big readers do we 00:26:47.130 --> 00:26:50.740 alter the architecture our brain. 00:26:50.740 --> 00:26:52.510 What's the effort, and what's the talent, or what's the 00:26:52.510 --> 00:26:56.350 predisposition at birth, and what's the time you put in 00:26:56.350 --> 00:26:57.010 creating this part. 00:26:57.010 --> 00:27:00.500 We don't know that yet, but we have a place to look at that. 00:27:00.500 --> 00:27:02.940 And then you can create these kinds of beautiful pictures, 00:27:02.940 --> 00:27:04.240 and I'll say a word about this. 00:27:04.240 --> 00:27:06.350 So this is an individual person's white matter 00:27:06.350 --> 00:27:07.910 organization. 00:27:07.910 --> 00:27:10.150 So we could take this picture of you, or anybody you know 00:27:10.150 --> 00:27:12.870 who wants to go in a scanner. 00:27:12.870 --> 00:27:16.450 And what's color coded here in blue are fibers that are 00:27:16.450 --> 00:27:19.690 running up or down, we can't tell with the fibers which 00:27:19.690 --> 00:27:22.110 direction they're going, but we can tell other 00:27:22.110 --> 00:27:22.850 orientations. 00:27:22.850 --> 00:27:26.150 Up and down, left and right in red, up and down in blue, and 00:27:26.150 --> 00:27:27.400 green is front to back. 00:27:31.470 --> 00:27:32.320 Pretty cool, huh? 00:27:32.320 --> 00:27:35.146 I can tell you that I'll say a word about this. 00:27:40.750 --> 00:27:42.000 Should we do that again? 00:27:44.480 --> 00:27:47.180 I like it, but I work in this area. 00:27:49.700 --> 00:27:52.210 This is fantastic, this is an individual person's white 00:27:52.210 --> 00:27:54.050 matter organization. 00:27:54.050 --> 00:27:56.750 As information is flowing around in your mind, here's 00:27:56.750 --> 00:27:59.520 the paths that it's flowing around in as you just do 00:27:59.520 --> 00:28:01.790 anything that's interesting in your feelings 00:28:01.790 --> 00:28:02.440 or thoughts or anything. 00:28:02.440 --> 00:28:03.250 It's fantastic. 00:28:03.250 --> 00:28:08.840 I can tell you that the algorithms that are used to 00:28:08.840 --> 00:28:10.450 create these maps, there's some debate 00:28:10.450 --> 00:28:11.880 about the better ones. 00:28:11.880 --> 00:28:14.990 So the last steps of this are a bit debated, and a bit 00:28:14.990 --> 00:28:19.570 depending on how cool you are as a visual engineer. 00:28:19.570 --> 00:28:21.310 But there's a lot of things that's right about Diffusion 00:28:21.310 --> 00:28:24.340 Tensor Imaging, there's a lot of things that 00:28:24.340 --> 00:28:25.590 are right about it. 00:28:28.280 --> 00:28:32.870 Function, so most of all we're interested in structure, not 00:28:32.870 --> 00:28:36.510 just for itself, but how is it makes your mind do the things 00:28:36.510 --> 00:28:37.490 you could do. 00:28:37.490 --> 00:28:39.290 And when we think about different functional measures 00:28:39.290 --> 00:28:40.930 that are available to neuroscientists or 00:28:40.930 --> 00:28:44.047 psychologists, we often think in two dimensions, Spatial 00:28:44.047 --> 00:28:47.100 Resolution, and Temporal Resolution. 00:28:47.100 --> 00:28:51.370 How precise are we where we are, and what's the time scale 00:28:51.370 --> 00:28:54.150 that we're measuring in, milliseconds, are we averaging 00:28:54.150 --> 00:28:56.460 over many seconds, many hours. 00:28:56.460 --> 00:29:00.020 We know mental operations, roughly speaking, occur at the 00:29:00.020 --> 00:29:02.640 millisecond level, or maybe 10 milliseconds. 00:29:02.640 --> 00:29:05.260 There's no answer to that, but we know lots of things happen 00:29:05.260 --> 00:29:07.020 that fast in the mind. 00:29:07.020 --> 00:29:10.410 So if you look at this here you can see that, for example, 00:29:10.410 --> 00:29:12.880 if you're in animal work, looking at size, you can get 00:29:12.880 --> 00:29:14.730 down to the Synapse or the Dendrite. 00:29:14.730 --> 00:29:17.980 We can't touch that in humans, we can't touch 00:29:17.980 --> 00:29:19.660 that cellular stuff. 00:29:19.660 --> 00:29:23.010 And it's not until we get up to here, which is like big 00:29:23.010 --> 00:29:26.720 patches of the brain, that we can state things about people. 00:29:26.720 --> 00:29:28.530 That's why it's always going to be fundamental in 00:29:28.530 --> 00:29:31.590 neuroscience to link the human work to the animal work, 00:29:31.590 --> 00:29:34.620 because we can't get to the neurons or anything like that 00:29:34.620 --> 00:29:37.210 in a person almost ever. 00:29:37.210 --> 00:29:38.900 That has to come from animal work, where you can do 00:29:38.900 --> 00:29:40.030 invasive work. 00:29:40.030 --> 00:29:41.630 So we have to look at a pretty big patches 00:29:41.630 --> 00:29:42.830 of the human brain. 00:29:42.830 --> 00:29:44.040 How about time? 00:29:44.040 --> 00:29:46.950 Well, we can get down to milliseconds in time in the 00:29:46.950 --> 00:29:47.910 human brain. 00:29:47.910 --> 00:29:51.190 Functional things like PET and MRI are here and in the order 00:29:51.190 --> 00:29:53.850 of multiple seconds, I'll come back to this. 00:29:53.850 --> 00:29:55.360 But you can see all these things have strengths. 00:29:55.360 --> 00:29:59.690 Now you don't always want to be down to a single synapse, 00:29:59.690 --> 00:30:01.870 it's not clear that we would understand much of the 00:30:01.870 --> 00:30:04.500 organization of the brain at the level of the synapse. 00:30:04.500 --> 00:30:06.510 There's things happening in the synapse, but a thing like 00:30:06.510 --> 00:30:08.650 knowledge, or love, or something like that probably 00:30:08.650 --> 00:30:11.240 we can't study at the level of the synapse. 00:30:11.240 --> 00:30:12.590 Effectively, yet. 00:30:12.590 --> 00:30:15.290 Bigger units are probably more interpretable. 00:30:15.290 --> 00:30:18.180 So here's a fun one, EEG's, Electroencephalography. 00:30:18.180 --> 00:30:22.370 So they put on your head some sort of a cap with electrodes, 00:30:22.370 --> 00:30:25.760 and they measure changes in electrical activity that are 00:30:25.760 --> 00:30:28.070 being picked up through the skull. 00:30:28.070 --> 00:30:30.860 And you're picking up huge changes in hundreds of 00:30:30.860 --> 00:30:33.510 thousands of neurons, but you're able to do it 00:30:33.510 --> 00:30:35.950 millisecond by millisecond at the speed of thought. 00:30:39.410 --> 00:30:42.270 The same electrical signal for EEG and ERP, that evoke 00:30:42.270 --> 00:30:46.280 response potentials, with EEG you just watch it over time. 00:30:46.280 --> 00:30:49.210 So you can see these different rhythms that go with a person 00:30:49.210 --> 00:30:53.870 in coma, or in deep sleep, asleep, drowsy, relaxed. 00:30:53.870 --> 00:30:56.480 You can see these characteristic rhythms that 00:30:56.480 --> 00:30:58.190 people can measure. 00:30:58.190 --> 00:31:02.480 If you do an experiment, you can time lock these moment by 00:31:02.480 --> 00:31:06.140 moment to some stimulus or task you give the person. 00:31:06.140 --> 00:31:08.800 So here we're going to time lock these, and then you get a 00:31:08.800 --> 00:31:11.470 thing like this that says, here's a response, maybe the 00:31:11.470 --> 00:31:14.220 first moment after I see a word, a second moment after I 00:31:14.220 --> 00:31:16.050 see a word or something like that. 00:31:16.050 --> 00:31:18.430 So you can time lock large electrical 00:31:18.430 --> 00:31:20.890 responses in the brain. 00:31:20.890 --> 00:31:22.550 And you get some studies like this, and we'll come back to 00:31:22.550 --> 00:31:26.030 this, but here's a fun one in language for example. 00:31:26.030 --> 00:31:30.270 You read a sentence like, It was his first day at work, OK 00:31:30.270 --> 00:31:32.850 that's the baseline condition in purple, not a particularly 00:31:32.850 --> 00:31:34.195 exciting sentence. 00:31:34.195 --> 00:31:35.730 Although, your first day at work is actually pretty 00:31:35.730 --> 00:31:38.140 interesting-- but to read the sentence. 00:31:38.140 --> 00:31:41.090 How about this one: He spread the warm bread with socks. 00:31:41.090 --> 00:31:42.130 You go, Socks? 00:31:42.130 --> 00:31:44.280 I'm shocked, that makes no sense at all. 00:31:44.280 --> 00:31:47.350 What happens as you read it, here's in broken blue line, 00:31:47.350 --> 00:31:50.670 you go wow, and that's called the N400. 00:31:50.670 --> 00:31:53.730 But that's kind of cool, that's 400 milliseconds after 00:31:53.730 --> 00:31:56.100 you saw that word you said, I get it's socks but it doesn't 00:31:56.100 --> 00:31:56.960 make sense. 00:31:56.960 --> 00:32:01.180 So you're violating semantics. 00:32:01.180 --> 00:32:02.920 And then they have to do a control experiment. 00:32:02.920 --> 00:32:06.050 And a lot of psychology, in a course like this, we can't 00:32:06.050 --> 00:32:06.950 devote enough time to this. 00:32:06.950 --> 00:32:09.720 But I can tell you high quality research in psychology 00:32:09.720 --> 00:32:12.170 is high quality thoughtfulness like in any other field. 00:32:12.170 --> 00:32:15.580 You could say, well maybe it's not the word "socks" that's 00:32:15.580 --> 00:32:19.220 bothering you, maybe just because it's odd, just like a 00:32:19.220 --> 00:32:22.260 weirded out signal, it's a weirded out signal. 00:32:22.260 --> 00:32:25.070 So they do this, She put on her high-heeled shoes, but 00:32:25.070 --> 00:32:27.970 they put shoes in big print that you didn't expect. 00:32:27.970 --> 00:32:30.650 So now you're weirded out, but it makes sense. 00:32:30.650 --> 00:32:32.540 So what happens in your mind, you a very 00:32:32.540 --> 00:32:34.320 different response here. 00:32:34.320 --> 00:32:37.700 So here the meaning is wrong, here the size is wrong. 00:32:37.700 --> 00:32:39.950 And see you can read a person's mind in this sense, 00:32:39.950 --> 00:32:42.650 millisecond by millisecond as they understand something like 00:32:42.650 --> 00:32:44.420 a sentence. 00:32:44.420 --> 00:32:47.500 You can do it with babies, which is pretty cute, and 00:32:47.500 --> 00:32:49.410 incredibly exciting too. 00:32:49.410 --> 00:32:51.230 So we can measure to the milliseconds. 00:32:51.230 --> 00:32:53.420 Lots of people can take doing it, it's relatively 00:32:53.420 --> 00:32:54.720 inexpensive. 00:32:54.720 --> 00:32:56.550 Why don't we just run around and do that? 00:32:56.550 --> 00:32:59.060 And we do that at MIT, and lots of places do this too. 00:32:59.060 --> 00:33:02.000 Well, Spatial Resolution is really problematic, we don't 00:33:02.000 --> 00:33:04.230 know where in the brain the signals are 00:33:04.230 --> 00:33:05.070 really coming from. 00:33:05.070 --> 00:33:08.060 We know where the electrode is on the head, but that's 00:33:08.060 --> 00:33:10.330 picking up a lot of stuff below it, we don't know where 00:33:10.330 --> 00:33:12.010 the brain is coming from. 00:33:12.010 --> 00:33:14.050 The way I think about it a little bit, imagine you went 00:33:14.050 --> 00:33:16.000 to a football game, and you were on the outside of the 00:33:16.000 --> 00:33:18.410 stadium, and you heard big cheering on the side that you 00:33:18.410 --> 00:33:20.150 knew was MIT. 00:33:20.150 --> 00:33:22.270 You might think something good happened to MIT, then you hear 00:33:22.270 --> 00:33:25.340 big cheering on the side where CalTech team is sitting, and 00:33:25.340 --> 00:33:28.310 there's fans, it'd be the usual Rose Bowl. 00:33:32.010 --> 00:33:33.755 You might figure something good happened at CalTech, but 00:33:33.755 --> 00:33:35.510 you don't really know exactly what happened, and exactly 00:33:35.510 --> 00:33:37.380 where it happened. 00:33:37.380 --> 00:33:40.230 So we don't know where the signals are coming from in a 00:33:40.230 --> 00:33:42.560 very precise way. 00:33:42.560 --> 00:33:44.770 There's another method that's sort of very intriguing too, 00:33:44.770 --> 00:33:47.260 and we're just installing it at MIT, and you could be 00:33:47.260 --> 00:33:49.240 amongst the first generation of participants, if you so 00:33:49.240 --> 00:33:50.380 choose to be. 00:33:50.380 --> 00:33:53.330 This is called Magnetoencephalography, active 00:33:53.330 --> 00:33:55.230 neurons produce small magnetic fields. 00:33:55.230 --> 00:33:58.630 You can use a superconducting quantum device to measure this 00:33:58.630 --> 00:34:01.210 tiny, tiny change to the magnetic field, they're 00:34:01.210 --> 00:34:03.400 secondary to the neurons firing. 00:34:03.400 --> 00:34:06.390 These signals are problematic to measure because they're 00:34:06.390 --> 00:34:08.900 estimated to be 100 million times smaller than the earth's 00:34:08.900 --> 00:34:10.710 magnetic field. 00:34:10.710 --> 00:34:13.389 And all these measures we have in human brain function, all 00:34:13.389 --> 00:34:16.650 of them, the signal is terrible compared to the 00:34:16.650 --> 00:34:19.270 noise, it's terrible compared to the noise. 00:34:19.270 --> 00:34:21.710 And MEG might be the worst, there's a number of places 00:34:21.710 --> 00:34:25.750 that installed MEG, and had to take it out because the local 00:34:25.750 --> 00:34:29.270 traffic on the road was too big relative to the difference 00:34:29.270 --> 00:34:31.620 between the earth's magnetic field in the signal they get. 00:34:31.620 --> 00:34:34.920 Signal to noise is terrible in every noninvasive human brain 00:34:34.920 --> 00:34:36.250 measure we have. 00:34:36.250 --> 00:34:37.889 But you get something beautiful. 00:34:37.889 --> 00:34:42.230 Now, any mental thought we have of any interest of any 00:34:42.230 --> 00:34:45.370 kind, we pretty much understand to be the property 00:34:45.370 --> 00:34:48.150 not of a single part of the brain doing its thing, but a 00:34:48.150 --> 00:34:52.210 remarkable concert, different parts of your brain playing or 00:34:52.210 --> 00:34:53.750 interacting with one another. 00:34:53.750 --> 00:34:56.920 It's a symphony orchestra doing anything interesting in 00:34:56.920 --> 00:34:59.180 the human mind, and MEG can show that beautifully. 00:34:59.180 --> 00:35:01.770 So here's an individual's structural MRI that's been 00:35:01.770 --> 00:35:05.070 inflated, they've sort of blown it out like a balloon so 00:35:05.070 --> 00:35:06.400 it's sort of easy to look at. 00:35:06.400 --> 00:35:09.360 And what you're going to see now from Dale & Halgren in an 00:35:09.360 --> 00:35:13.520 MEG measurement millisecond by millisecond of what your brain 00:35:13.520 --> 00:35:17.550 does, roughly speaking, when you read a single word, OK 00:35:17.550 --> 00:35:18.800 here we go. 00:35:22.110 --> 00:35:24.490 See, back and forth, back and forth, and there's all this 00:35:24.490 --> 00:35:27.050 interaction feeding forward from when you see it, feeding 00:35:27.050 --> 00:35:29.040 being backward from parts of your brain that say, I think I 00:35:29.040 --> 00:35:31.970 know what it is, let's double check. 00:35:31.970 --> 00:35:33.040 Back and forth, back and forth. 00:35:33.040 --> 00:35:34.080 Let me do it one more time, because I think 00:35:34.080 --> 00:35:35.920 it's just so cool. 00:35:35.920 --> 00:35:39.580 Anything interesting that your brain does is an incredibly 00:35:39.580 --> 00:35:43.070 complicated millisecond by millisecond interaction 00:35:43.070 --> 00:35:45.810 between large scale brain networks. 00:35:45.810 --> 00:35:48.620 So here we go again, reading a single word, arrives in the 00:35:48.620 --> 00:35:50.340 back of the brain, front's thinking about back, front, 00:35:50.340 --> 00:35:52.210 back, front, back front. 00:35:52.210 --> 00:35:53.460 We read the word. 00:35:55.350 --> 00:35:59.280 It's just amazing, and MEG is one of the better measures for 00:35:59.280 --> 00:36:02.470 us to see this time based way in which your mind 00:36:02.470 --> 00:36:03.720 accomplishes things. 00:36:07.030 --> 00:36:09.070 The strengths are it has great temporal resolution, 00:36:09.070 --> 00:36:12.600 noninvasive, Spatial Resolution is it maybe better 00:36:12.600 --> 00:36:15.510 than EEG, or perhaps better, not as good as a fMRI, we'll 00:36:15.510 --> 00:36:17.470 come to that. 00:36:17.470 --> 00:36:20.200 And it only can measure neurons in the cortex that are 00:36:20.200 --> 00:36:22.900 parallel to the skull, so we can't see lots of things like 00:36:22.900 --> 00:36:24.385 support local structures like the hippocampus. 00:36:27.160 --> 00:36:29.410 So now we're moving to the measures that you most often 00:36:29.410 --> 00:36:32.080 see, but these other ones all help us a lot. 00:36:32.080 --> 00:36:34.280 And they are all derived from the following things. 00:36:34.280 --> 00:36:38.400 Sadly, for PET or fMRI, the most widely used studies to 00:36:38.400 --> 00:36:42.170 understand how your mind works, we can't interrogate 00:36:42.170 --> 00:36:44.650 the neurons to compute your mind, we can't, they're off 00:36:44.650 --> 00:36:46.050 bounds to us. 00:36:46.050 --> 00:36:48.810 The other measures you just saw are based on neurons. 00:36:48.810 --> 00:36:51.690 What we have to do is we have to look for gossipy neighbors, 00:36:51.690 --> 00:36:54.440 that is the vasculature that surrounds and supports the 00:36:54.440 --> 00:36:56.500 neurons that compute the mind. 00:36:56.500 --> 00:36:59.470 And we know the neurons require oxygen and glucose, 00:36:59.470 --> 00:37:02.860 metabolically to do their work, the cellular life. 00:37:02.860 --> 00:37:05.190 And the brain area's active, there's increased blood flow, 00:37:05.190 --> 00:37:06.900 and increased energy supplies that come to that. 00:37:06.900 --> 00:37:09.790 So it's all the sort of inference by the secondary 00:37:09.790 --> 00:37:13.270 consequence of neurons doing their business. 00:37:13.270 --> 00:37:16.310 So the brain is about 3 and 1/2 pounds, it's about 2% of 00:37:16.310 --> 00:37:18.310 your total body mass. 00:37:18.310 --> 00:37:22.980 So it has a tenfold, 20% extra demand of body oxygen, your 00:37:22.980 --> 00:37:25.880 brain cries out for oxygen at every moment. 00:37:25.880 --> 00:37:29.390 So 2% of your body, but 20% of the oxygen demand. 00:37:29.390 --> 00:37:32.060 And it's so sensitive that only 10 minutes of loss of 00:37:32.060 --> 00:37:35.260 oxygen can often cause irreversible brain damage, 00:37:35.260 --> 00:37:36.950 especially in structures like the hippocampus. 00:37:40.370 --> 00:37:46.030 The first discovery that blood changes that are going with 00:37:46.030 --> 00:37:48.150 brain changes, blood changes that are the sort of the 00:37:48.150 --> 00:37:52.240 echoes, if you will, a secondary consequence, is low 00:37:52.240 --> 00:37:54.360 tech character current machines. 00:37:54.360 --> 00:37:57.140 This is work from Angelo Mosso in the late 1880's, and he saw 00:37:57.140 --> 00:38:00.105 a patient who had a unusual sort of malformation, so he 00:38:00.105 --> 00:38:02.950 had almost no skull here. 00:38:02.950 --> 00:38:04.970 And he put on it something that measured the pressure 00:38:04.970 --> 00:38:09.760 there, and he also measured-- and what's shown here in red 00:38:09.760 --> 00:38:15.690 is this pressure as a control thing, that's pretty clever-- 00:38:15.690 --> 00:38:19.890 pulses of blood in the forearm, so those are in blue. 00:38:19.890 --> 00:38:22.850 That's the control, that's not just blood everywhere. 00:38:22.850 --> 00:38:24.770 And what he did is, the guy's still sitting there, nothing 00:38:24.770 --> 00:38:28.070 happening, and he noticed that when the church bells rang 00:38:28.070 --> 00:38:33.660 nearby, boom, this device picked up increased pressure 00:38:33.660 --> 00:38:34.960 over this part of the head. 00:38:34.960 --> 00:38:37.530 That's pretty cool, it has to be blood, it's not neurons, 00:38:37.530 --> 00:38:39.260 OK, it's blood. 00:38:39.260 --> 00:38:43.560 But now he has the signature of mental life in your brain, 00:38:43.560 --> 00:38:45.520 the blood consequence of a thought, which 00:38:45.520 --> 00:38:46.970 is I hear the Church. 00:38:46.970 --> 00:38:48.850 They asked the guy, does it have to be something that you 00:38:48.850 --> 00:38:50.740 hear, he says, did you make your prayers 00:38:50.740 --> 00:38:52.060 today, your Ave Maria? 00:38:52.060 --> 00:38:54.620 Again nothing happening peripherally, but boom, as he 00:38:54.620 --> 00:38:57.730 gives his answer, a change in blood pressure there. 00:38:57.730 --> 00:39:01.800 Or do math problem, boom, a change there. 00:39:01.800 --> 00:39:04.380 So all of the sudden, blood changes of a part of the brain 00:39:04.380 --> 00:39:08.120 become the witness to that part of the brain supporting 00:39:08.120 --> 00:39:11.110 the mental operations to do that task. 00:39:11.110 --> 00:39:13.513 And here's a PET study, the first weighted Positron 00:39:13.513 --> 00:39:16.400 Emission Tomography, which is basically used to measure 00:39:16.400 --> 00:39:20.280 local brain activity by looking at the consequences of 00:39:20.280 --> 00:39:23.590 photons disintegrating as they're measured in this sort 00:39:23.590 --> 00:39:25.090 of a device. 00:39:25.090 --> 00:39:27.860 And here's the way they use this task to discover which 00:39:27.860 --> 00:39:30.370 parts to map the neural organization 00:39:30.370 --> 00:39:32.040 of the human mind. 00:39:32.040 --> 00:39:35.140 So I need somebody who's willing to do a task at their 00:39:35.140 --> 00:39:38.460 seat, and it's just going to be reading words, or coming up 00:39:38.460 --> 00:39:39.560 with words. 00:39:39.560 --> 00:39:41.240 OK, thanks. 00:39:41.240 --> 00:39:42.330 Here you go, ready? 00:39:42.330 --> 00:39:45.560 Look at that, in our field we call that fixation, you're 00:39:45.560 --> 00:39:47.330 just looking, OK, just looking. 00:39:47.330 --> 00:39:48.720 Alright, good job. 00:39:48.720 --> 00:39:49.750 Ready for something else? 00:39:49.750 --> 00:39:52.830 Alright, now just look at these things, 00:39:52.830 --> 00:39:54.260 OK, you see the words? 00:39:54.260 --> 00:39:56.670 The technical word is reading. 00:39:56.670 --> 00:39:59.030 Alright, now imagine we did one more thing with you-- and 00:39:59.030 --> 00:40:00.130 actually if you were in a PET scanner 00:40:00.130 --> 00:40:00.940 here's what would happen. 00:40:00.940 --> 00:40:03.510 If in a PET scanner, you'd be sitting down there like that, 00:40:03.510 --> 00:40:06.070 there'd be a physician in their lab coat like this. 00:40:06.070 --> 00:40:09.460 There'd be physicist in the basement making up some sort 00:40:09.460 --> 00:40:13.110 of a tracer they're going to inject into you 00:40:13.110 --> 00:40:16.330 every round of this. 00:40:16.330 --> 00:40:18.470 Because that's what they need to sort of track this, and it 00:40:18.470 --> 00:40:20.690 comes up an elevator, and people take turns running down 00:40:20.690 --> 00:40:23.180 the hall with it, because it has a pretty short half-life. 00:40:23.180 --> 00:40:25.915 The shortness of its half-life is what makes you able to do 00:40:25.915 --> 00:40:27.300 these multiple measures. 00:40:27.300 --> 00:40:30.200 This is a pretty big deal process, and in fact the one 00:40:30.200 --> 00:40:32.935 or two PET sessions I ever attended, you would rotate who 00:40:32.935 --> 00:40:35.360 would run down the field with the radioactive substance, so 00:40:35.360 --> 00:40:38.490 you would share the radioactive substance. 00:40:41.840 --> 00:40:43.540 So now you've done that, and you feel like, I'm doing 00:40:43.540 --> 00:40:44.050 pretty good. 00:40:44.050 --> 00:40:44.940 So now they come and they say, are you 00:40:44.940 --> 00:40:45.960 ready for another injection? 00:40:45.960 --> 00:40:48.010 They have a catheter running into your arm, and they inject 00:40:48.010 --> 00:40:50.870 you again, here comes the radioactive stuff, the oxygen. 00:40:50.870 --> 00:40:54.440 And now they ask you to read the words aloud presented one 00:40:54.440 --> 00:40:56.330 at a time, why don't you just read aloud one 00:40:56.330 --> 00:40:57.411 at a time, go ahead. 00:40:57.411 --> 00:40:59.616 AUDIENCE: Rose, cat, apple, pen, plane. 00:40:59.616 --> 00:41:01.553 PROFESSOR: OK, and they say thank you very much, and we're 00:41:01.553 --> 00:41:03.510 going to do one more injection if that's OK with you, of 00:41:03.510 --> 00:41:05.430 radioactive substance. 00:41:05.430 --> 00:41:07.070 And now we're going to ask you to do one thing, and this is 00:41:07.070 --> 00:41:11.490 harder, as you see each word tell us a verb that describes 00:41:11.490 --> 00:41:13.710 what you might do with that object, or what a person might 00:41:13.710 --> 00:41:16.110 do, so go ahead, for rose tell us. 00:41:16.110 --> 00:41:19.519 AUDIENCE: Smell, pet, eat, write, fly. 00:41:19.519 --> 00:41:20.670 PROFESSOR: Perfect. 00:41:20.670 --> 00:41:22.490 Yeah, I can tell you that in the experiment they present a 00:41:22.490 --> 00:41:24.190 lot of these, and a lot of subjects after while just go 00:41:24.190 --> 00:41:29.800 use, use, use, use, hold, hold, hold, hold. 00:41:29.800 --> 00:41:31.050 But you did a good job, OK. 00:41:33.240 --> 00:41:35.040 This is just looking at something, this is looking at 00:41:35.040 --> 00:41:35.900 a word, which is reading. 00:41:35.900 --> 00:41:39.890 Now don't forget, we're the only species that ever read, 00:41:39.890 --> 00:41:43.050 reading has been around in our culture only for about 700 00:41:43.050 --> 00:41:46.840 years on any scale, and reading is an incredible thing 00:41:46.840 --> 00:41:47.710 to work correctly. 00:41:47.710 --> 00:41:50.990 And you saw the whole brain flicker to get it right. 00:41:50.990 --> 00:41:52.560 But now you're going to say the word in the next 00:41:52.560 --> 00:41:54.580 condition, so you're not just looking at the word, but 00:41:54.580 --> 00:41:56.030 you're also saying it. 00:41:56.030 --> 00:41:58.430 And now finally you're not only saying a word and looking 00:41:58.430 --> 00:42:00.270 at it, but you are thinking about it to come up with 00:42:00.270 --> 00:42:02.500 smell, or pet. 00:42:02.500 --> 00:42:04.150 So they say, what we're going to do is we're going to do a 00:42:04.150 --> 00:42:08.160 hierarchy of your mind, just looking, reading, reading and 00:42:08.160 --> 00:42:10.490 talking, reading and talking and thinking. 00:42:10.490 --> 00:42:12.500 And by comparing those different conditions, we'll 00:42:12.500 --> 00:42:15.050 subtract them against each other, and pull out the part 00:42:15.050 --> 00:42:19.090 of your mind that sees a word, that speaks a word, and that 00:42:19.090 --> 00:42:20.790 thinks about a word, and we'll separate 00:42:20.790 --> 00:42:23.700 those out in the brain. 00:42:23.700 --> 00:42:26.340 So basically the subtraction method. 00:42:26.340 --> 00:42:28.920 So when we compare looking at fixation versus looking at 00:42:28.920 --> 00:42:30.950 words, we'll see what part of your brain discovers that it's 00:42:30.950 --> 00:42:33.490 a word, knows how to read words, looking at words versus 00:42:33.490 --> 00:42:34.440 repeating them. 00:42:34.440 --> 00:42:38.490 We'll discover the basis of speech, speaking a word versus 00:42:38.490 --> 00:42:41.150 coming up with the verb, thinking about stuff, their 00:42:41.150 --> 00:42:42.970 meaning, and coming up with an answer. 00:42:46.640 --> 00:42:50.930 So again the idea is if you're saying something like pet for 00:42:50.930 --> 00:42:52.910 the cat, you're doing all these things. 00:42:52.910 --> 00:42:54.770 Or you might just be reading it aloud, and 00:42:54.770 --> 00:42:57.080 we'll subtract them. 00:42:57.080 --> 00:43:01.540 In both these conditions, here you saw a word and read it, 00:43:01.540 --> 00:43:06.010 here you saw a word and came up and produced a verb, you 00:43:06.010 --> 00:43:07.980 subtract these two and you end up with a 00:43:07.980 --> 00:43:09.320 statistical image like this. 00:43:09.320 --> 00:43:13.350 This is not a raw image of blood, all these you ever see 00:43:13.350 --> 00:43:16.200 those are statistics of the areas that differed by some 00:43:16.200 --> 00:43:18.540 statistical criterion between one condition and another. 00:43:18.540 --> 00:43:20.890 They're all statistics, they're not blood, or raw 00:43:20.890 --> 00:43:24.780 blood, that underlies it, but what you see is a statistic, 00:43:24.780 --> 00:43:26.110 and here's the statistic. 00:43:26.110 --> 00:43:28.740 Now in both of these cases, you saw the word. 00:43:28.740 --> 00:43:31.520 In this case you simply read it, in this case you read it 00:43:31.520 --> 00:43:34.110 in your head and you came up with a verb. 00:43:34.110 --> 00:43:36.710 But why don't we see anything back here? 00:43:36.710 --> 00:43:39.550 Why don't we see the seeing of the word, even though the 00:43:39.550 --> 00:43:40.960 seeing occurred in those conditions? 00:43:40.960 --> 00:43:45.370 Why isn't it visible in this brain picture? 00:43:45.370 --> 00:43:47.750 Because it's been subtracted out. 00:43:47.750 --> 00:43:50.130 So always in these brain imaging experiments, for 00:43:50.130 --> 00:43:52.570 reasons I'm about to tell you, we almost always have to do 00:43:52.570 --> 00:43:53.600 some kind of subtraction. 00:43:53.600 --> 00:43:57.590 And I'll tell you why, but that subtraction is very big. 00:43:57.590 --> 00:44:00.040 Because what you subtract out, that's the heart of the 00:44:00.040 --> 00:44:03.060 experiment, and your decision about what's a legitimate 00:44:03.060 --> 00:44:03.850 subtraction. 00:44:03.850 --> 00:44:06.610 And the reason we have to do it is this, look 00:44:06.610 --> 00:44:07.330 at these two things. 00:44:07.330 --> 00:44:09.190 Here's one condition, and here's the other condition. 00:44:09.190 --> 00:44:11.950 Do you see that they look pretty similar? 00:44:11.950 --> 00:44:14.450 Again, signal to noise. 00:44:14.450 --> 00:44:18.700 Your brain is busy all the time, now we ask you to do 00:44:18.700 --> 00:44:20.300 something and see the difference. 00:44:20.300 --> 00:44:22.820 And the difference is very tiny by the way we measure it. 00:44:22.820 --> 00:44:26.860 It's not tiny mentally, it's not tiny in terms of the 00:44:26.860 --> 00:44:29.700 consequences for civilization in the world. 00:44:29.700 --> 00:44:33.770 It's tiny because of the weird way we have to measure it. 00:44:33.770 --> 00:44:36.760 I can tell you that if I've put on an optimal 00:44:36.760 --> 00:44:38.600 checkerboard, the psychophysicists have said, 00:44:38.600 --> 00:44:40.690 this turns on your visual cortex. 00:44:40.690 --> 00:44:44.010 I'll get about a 3% to 5% change in your brain signal. 00:44:44.010 --> 00:44:48.530 If you wave your arm, I can get 3% to 5% signal change in 00:44:48.530 --> 00:44:49.870 your cortex here. 00:44:49.870 --> 00:44:52.400 If I ask you to do everything in between seeing something 00:44:52.400 --> 00:44:56.250 and moving your lips or hand, everything about thought, 00:44:56.250 --> 00:45:00.690 emotion, memory, desire, motivation, everything that's 00:45:00.690 --> 00:45:03.650 big in our life will get something like that one tenth 00:45:03.650 --> 00:45:05.290 of 1% of the signal change. 00:45:05.290 --> 00:45:08.395 One tenth of 1% of the signal change. 00:45:08.395 --> 00:45:11.420 Yeah, Tyler's like yeah, that means you have to test a lot 00:45:11.420 --> 00:45:14.660 of subjects, and work 40 years on your Ph.D. 00:45:14.660 --> 00:45:17.280 So we have to do that subtraction, because if we 00:45:17.280 --> 00:45:19.880 just take a picture of what's going on in your head, it's so 00:45:19.880 --> 00:45:22.200 much that we can't tell what's going on at all. 00:45:22.200 --> 00:45:23.980 And if we have you do something that's pretty big, 00:45:23.980 --> 00:45:26.310 like seeing like a really provocative picture, we'll 00:45:26.310 --> 00:45:29.220 just get one tenth of 1% of the signal change. 00:45:29.220 --> 00:45:31.380 So we have to do the subtraction to have a hint. 00:45:31.380 --> 00:45:33.540 And then we do one other weird thing, we don't have to but we 00:45:33.540 --> 00:45:34.420 often do it. 00:45:34.420 --> 00:45:36.630 We want to average people to make some general statement 00:45:36.630 --> 00:45:40.060 about humanity, as far as we can do it, based on the 10 MIT 00:45:40.060 --> 00:45:42.510 students we test. 00:45:42.510 --> 00:45:45.030 So we scrunch everybody's brain into common space, 00:45:45.030 --> 00:45:46.540 everybody's brain's a little bit different, like their 00:45:46.540 --> 00:45:47.750 bodies are a little bit different. 00:45:47.750 --> 00:45:50.320 We scrunch everybody to line them all up so we have a 00:45:50.320 --> 00:45:51.820 common physical space. 00:45:51.820 --> 00:45:54.250 So by the time you see this picture, it's a statistic on 00:45:54.250 --> 00:45:57.000 an average of people in most cases, but you 00:45:57.000 --> 00:45:58.020 get an amazing story. 00:45:58.020 --> 00:46:00.810 Which up until these pictures-- 00:46:00.810 --> 00:46:05.060 about the late 1980s, it was unimaginable that you could go 00:46:05.060 --> 00:46:08.390 inside a living person's brain, and see what it is that 00:46:08.390 --> 00:46:13.020 allows you to hear a word in auditory cortex, to see a word 00:46:13.020 --> 00:46:18.910 in visual cortex, to move your mouth to speak, or to think, 00:46:18.910 --> 00:46:21.820 what's the verb that goes with that word? 00:46:21.820 --> 00:46:24.800 Unimaginable at your-- 00:46:24.800 --> 00:46:26.900 OK, now I have to do the quick math, but you'll help me out-- 00:46:26.900 --> 00:46:30.710 what year were you born in? 00:46:30.710 --> 00:46:32.410 '82? 00:46:32.410 --> 00:46:32.920 '92? 00:46:32.920 --> 00:46:36.320 I know, at my age it all blends. '92? 00:46:36.320 --> 00:46:38.580 OK, so just a year or two before you were born-- this 00:46:38.580 --> 00:46:41.550 was 5 years before you were-- unimaginable that you could 00:46:41.550 --> 00:46:42.750 see such a picture. 00:46:42.750 --> 00:46:44.830 When I was a graduate student at Harvard, and the people at 00:46:44.830 --> 00:46:46.370 Washington St. Louis University-- 00:46:46.370 --> 00:46:47.600 who did the first of these-- 00:46:47.600 --> 00:46:49.930 did an incredible service to the field. 00:46:49.930 --> 00:46:51.880 Here we saw, oh my gosh, it was like landing on the moon. 00:46:51.880 --> 00:46:54.320 Going inside the human brain, and knowing which part of the 00:46:54.320 --> 00:46:57.500 brain endows us with human capacities. 00:46:57.500 --> 00:47:00.600 Now, we can be appreciative or we can be skeptical 00:47:00.600 --> 00:47:03.600 scientists, and we can say this, let's pick this one. 00:47:03.600 --> 00:47:06.820 Let's compare seeing a word like "board," 00:47:06.820 --> 00:47:07.970 versus seeing a fixation. 00:47:07.970 --> 00:47:11.610 We do that subtraction, and that's seeing a word. 00:47:11.610 --> 00:47:15.200 Just by common sense, what's wrong with this comparison? 00:47:15.200 --> 00:47:18.460 It's OK it's not terrible. 00:47:18.460 --> 00:47:20.419 How can you control it better? 00:47:20.419 --> 00:47:25.180 To understand what this part of the brain is really doing? 00:47:25.180 --> 00:47:28.426 I heard something? 00:47:28.426 --> 00:47:31.000 Well partly it's a meaningful word, versus something that 00:47:31.000 --> 00:47:33.390 doesn't mean anything to a plus. 00:47:33.390 --> 00:47:35.460 But what else could you say is different between them? 00:47:35.460 --> 00:47:36.362 Yeah? 00:47:36.362 --> 00:47:37.346 [INAUDIBLE] 00:47:37.346 --> 00:47:39.810 GUEST SPEAKER: [INAUDIBLE] 00:47:39.810 --> 00:47:43.100 PROFESSOR: In this case, oh my gosh, yes, and I'll come back 00:47:43.100 --> 00:47:44.960 to that, but let me not do that one for the moment, 00:47:44.960 --> 00:47:47.690 because that's a giant story which I can't fit in today. 00:47:47.690 --> 00:47:50.070 Yes your mind can be all over the place. 00:47:50.070 --> 00:47:52.210 So that's definitely the case, so that's a good one. 00:47:52.210 --> 00:47:52.700 Yeah? 00:47:52.700 --> 00:47:54.972 GUEST SPEAKER: You could replace the plus, which is 00:47:54.972 --> 00:47:57.090 like really small, with [INAUDIBLE] 00:47:57.090 --> 00:47:58.882 PROFESSOR: Yeah, that's perfect, OK that's the way I 00:47:58.882 --> 00:48:01.480 was going-- the other one's great too, two great comments. 00:48:01.480 --> 00:48:03.140 Yeah you could say like, maybe this is a part of your brain 00:48:03.140 --> 00:48:04.850 it goes with five things, or something this 00:48:04.850 --> 00:48:05.920 big versus this big. 00:48:05.920 --> 00:48:08.340 No you go, that's not so interesting, the part of your 00:48:08.340 --> 00:48:10.360 brain that looks at something this big, versus this big. 00:48:10.360 --> 00:48:13.150 But that's just as legitimate a conclusion here. 00:48:13.150 --> 00:48:16.590 How about this, five different things, versus only this. 00:48:16.590 --> 00:48:18.400 There's a lot of different ways in which you could say, 00:48:18.400 --> 00:48:20.620 what is the mental operation that I've discovered in the 00:48:20.620 --> 00:48:23.730 human brain and mind, it all comes down to the comparison. 00:48:23.730 --> 00:48:26.880 So here's what they did to try to do a better job. 00:48:26.880 --> 00:48:30.080 They showed you a more complicated thing that doesn't 00:48:30.080 --> 00:48:32.000 mean anything. 00:48:32.000 --> 00:48:36.490 A bunch of letters that you can't pronounce, a bunch of 00:48:36.490 --> 00:48:38.330 letters that you can pronounce, but it's not a real 00:48:38.330 --> 00:48:41.190 word, and here's the real world itself. 00:48:41.190 --> 00:48:43.130 So if you want to say, what do you think this part of the 00:48:43.130 --> 00:48:45.760 mind is doing? 00:48:45.760 --> 00:48:48.160 What part the mind does this part of the brain allow to 00:48:48.160 --> 00:48:50.870 happen in humans, and only humans on this planet? 00:48:50.870 --> 00:48:54.150 And every word you ever read only happens because this part 00:48:54.150 --> 00:48:55.880 of the brain does what it does. 00:48:55.880 --> 00:48:57.360 What is that part of the brain doing? 00:48:57.360 --> 00:48:59.090 Is it just simply responding too complicated 00:48:59.090 --> 00:49:01.372 things, five of them? 00:49:01.372 --> 00:49:04.260 No, not much, a little bit, but not much. 00:49:04.260 --> 00:49:06.470 How about letters, letters are pretty interesting, but there 00:49:06.470 --> 00:49:09.760 can't be a word by English, you can't pronounce this. 00:49:09.760 --> 00:49:12.270 Not too interested? 00:49:12.270 --> 00:49:14.930 A word, a set of letters you've never seen together 00:49:14.930 --> 00:49:17.290 before, but you can pronounce by the rules of English. 00:49:17.290 --> 00:49:18.710 Boom. 00:49:18.710 --> 00:49:20.870 That's what I do, says this part of the brain, 00:49:20.870 --> 00:49:22.360 that's what I do. 00:49:22.360 --> 00:49:25.080 I say, I see something, and it's possibly a word and I can 00:49:25.080 --> 00:49:26.780 say it by the rules of English. 00:49:26.780 --> 00:49:27.900 And by the way, if it's a word I've done 00:49:27.900 --> 00:49:29.430 before, I do that too. 00:49:29.430 --> 00:49:31.600 I'm pretty flexible, I can do new words, I can do words I've 00:49:31.600 --> 00:49:33.030 known before. 00:49:33.030 --> 00:49:39.180 It matches what you see with language, that's reading. 00:49:39.180 --> 00:49:41.870 Only our species can take our visual system, and the 00:49:41.870 --> 00:49:44.730 language you learn as a child, and put them together, and 00:49:44.730 --> 00:49:47.180 allow our civilization to read. 00:49:47.180 --> 00:49:52.400 And this is a part of the brain where those roads meet. 00:49:52.400 --> 00:49:54.570 And by the way, we talked about local and global, the 00:49:54.570 --> 00:49:56.470 forest and the trees. 00:49:56.470 --> 00:49:58.416 And consistent with what we talked about the split brain 00:49:58.416 --> 00:50:00.932 patients, looking at global stuff right hemisphere, if 00:50:00.932 --> 00:50:02.640 you're looking at local stuff, left hemisphere. 00:50:02.640 --> 00:50:05.270 So we like it when the information we have from 00:50:05.270 --> 00:50:07.170 split-brain patients, or stroke patients aligns with 00:50:07.170 --> 00:50:10.210 healthy people doing a task as they typically do. 00:50:10.210 --> 00:50:11.600 Because then we sort of believe there's something 00:50:11.600 --> 00:50:13.590 right about that. 00:50:13.590 --> 00:50:18.610 So PET, pretty good spatial resolution, I mean, depends 00:50:18.610 --> 00:50:19.750 what you mean by good. 00:50:19.750 --> 00:50:22.860 My neuroscience colleagues dismiss everything we ever do 00:50:22.860 --> 00:50:25.310 as sort of pathetically imprecise. 00:50:25.310 --> 00:50:27.380 But 5 to 10 millimeters, not as good as fMRI. 00:50:29.950 --> 00:50:32.160 The temporal resolution is very poor we can only take one 00:50:32.160 --> 00:50:35.560 picture that lasts about a minute, and averages 00:50:35.560 --> 00:50:36.770 everything across that. 00:50:36.770 --> 00:50:40.280 You have to inject people with radioactive stuff, and it's 00:50:40.280 --> 00:50:42.120 correlational. 00:50:42.120 --> 00:50:43.880 But it has one other thing that's really, really 00:50:43.880 --> 00:50:46.020 interesting, Positron Emission Tomography. 00:50:46.020 --> 00:50:49.240 Because you're injecting a radioactive label, you can 00:50:49.240 --> 00:50:51.510 create different kinds of labels that go to different 00:50:51.510 --> 00:50:52.620 parts of the brain. 00:50:52.620 --> 00:50:55.830 So here's Parkinson's disease, which involves damage the 00:50:55.830 --> 00:50:57.840 Substantia nigra, and the Basal Ganglia. 00:50:57.840 --> 00:51:00.770 Here's a healthy persons Substantia nigra, and here's a 00:51:00.770 --> 00:51:02.640 person with Parkinson's disease, where these cells 00:51:02.640 --> 00:51:04.210 have died away. 00:51:04.210 --> 00:51:06.760 Typically, at least 80% of these have to die before a 00:51:06.760 --> 00:51:11.410 person shows Parkinson's disease symptoms clinically. 00:51:11.410 --> 00:51:14.200 Here's an injection of radioactive stuff using PET 00:51:14.200 --> 00:51:17.840 that binds to Dopamine receiving neurons. 00:51:17.840 --> 00:51:20.210 And you can see that in the living Parkinson's patient, 00:51:20.210 --> 00:51:22.710 this tremendous reduction in these 00:51:22.710 --> 00:51:24.960 receptors waiting for Dopamine. 00:51:24.960 --> 00:51:26.040 In a living patient 00:51:26.040 --> 00:51:28.410 specifically Dopamine receptors. 00:51:28.410 --> 00:51:30.860 So that's a disease. 00:51:30.860 --> 00:51:33.550 Here's why video games are taking over the world. 00:51:33.550 --> 00:51:34.160 Oh no, not yet. 00:51:34.160 --> 00:51:35.530 We can do one more thing. 00:51:35.530 --> 00:51:38.550 We can track the disease from a typical person, to a person 00:51:38.550 --> 00:51:41.680 with moderate Parkinson's disease or severe. 00:51:41.680 --> 00:51:43.850 Within the disease, we can see differences. 00:51:43.850 --> 00:51:46.860 But here's why video games are taking over the world, because 00:51:46.860 --> 00:51:49.670 if we take a healthy person, young adults, give them this 00:51:49.670 --> 00:51:53.640 kind of Dopamine binding tracer, and have them play a 00:51:53.640 --> 00:51:55.680 video game, two things happen. 00:51:55.680 --> 00:51:59.150 A, the parts of your brain that are involved in reward, 00:51:59.150 --> 00:52:01.020 Dopamine, is the strongest to reward 00:52:01.020 --> 00:52:02.100 neurotransmitter that we know. 00:52:02.100 --> 00:52:07.430 Things go crazy, and what this graph is showing you is the 00:52:07.430 --> 00:52:10.260 better you do, the more rewarded you are. 00:52:10.260 --> 00:52:12.900 This is why you will go for the next level, because to get 00:52:12.900 --> 00:52:14.720 that dopamine fix, you got to keep going. 00:52:18.130 --> 00:52:20.210 And we think these reward mechanisms underlie 00:52:20.210 --> 00:52:23.330 everything, in many ways they relate to everything. 00:52:23.330 --> 00:52:26.890 Why do you do whatever you do, because at some level, in some 00:52:26.890 --> 00:52:28.910 way, you find it rewarding. 00:52:28.910 --> 00:52:33.070 And the data is very compelling that way. 00:52:33.070 --> 00:52:36.570 The last method I'll talk about is functional MRI, and 00:52:36.570 --> 00:52:39.310 it's the one that's most widely visible. 00:52:39.310 --> 00:52:42.256 So you sit in a scanner, stimula are presented to you 00:52:42.256 --> 00:52:43.360 to perform a task. 00:52:43.360 --> 00:52:45.700 We do a lot of stuff in our lab with children, we show 00:52:45.700 --> 00:52:48.640 them how the frog would do it. 00:52:48.640 --> 00:52:50.680 For those of you who've done a functional MRI experiment, 00:52:50.680 --> 00:52:52.280 because there were so many hands that were put up. 00:52:52.280 --> 00:52:55.570 Do any of you want to say a word about your experience 00:52:55.570 --> 00:52:56.850 doing that? 00:52:56.850 --> 00:52:59.280 What was it like, easy, huge fun, recommend, 00:52:59.280 --> 00:53:00.200 no, not so much fun. 00:53:00.200 --> 00:53:03.720 It will vary a little bit. 00:53:03.720 --> 00:53:04.970 We said noisy. 00:53:09.630 --> 00:53:12.174 Some people find it claustrophobic. 00:53:12.174 --> 00:53:13.108 GUEST SPEAKER: I dont know, I didn't really do anything. 00:53:13.108 --> 00:53:16.380 I just had to sit there for a really long time and not move. 00:53:16.380 --> 00:53:18.030 PROFESSOR: Oh, so they didn't ask you to do a task, maybe. 00:53:18.030 --> 00:53:20.716 GUEST SPEAKER: Well, for a big part of it, I 00:53:20.716 --> 00:53:21.890 was watching a movie. 00:53:21.890 --> 00:53:25.840 PROFESSOR: So for the student they were watching a movie not 00:53:25.840 --> 00:53:27.242 doing anything, 00:53:27.242 --> 00:53:29.990 GUEST SPEAKER: [INAUDIBLE] 00:53:29.990 --> 00:53:31.640 PROFESSOR: You were doing yes or no clicks. 00:53:31.640 --> 00:53:33.380 So that would be typical functional MRI kind of 00:53:33.380 --> 00:53:36.110 experiment, some of them are more obnoxious, some are less, 00:53:36.110 --> 00:53:40.000 some are funny, some are not as funny. 00:53:40.000 --> 00:53:42.340 Any other experiences? 00:53:42.340 --> 00:53:46.830 Was it comfortable, not so comfortable, medium. 00:53:46.830 --> 00:53:49.755 Anybody else want to share? 00:53:49.755 --> 00:53:50.530 No, OK. 00:53:50.530 --> 00:53:51.780 OK. 00:53:54.320 --> 00:53:56.940 So how does this work? 00:53:56.940 --> 00:54:00.370 Functional MRI takes advantage of MRI but it focuses on 00:54:00.370 --> 00:54:03.260 hemoglobin, the stuff that carries oxygen in your blood. 00:54:03.260 --> 00:54:06.920 And it rests on the fact that after oxygen has been 00:54:06.920 --> 00:54:10.060 extracted it's more sensitive to the magnetic field than 00:54:10.060 --> 00:54:11.470 oxygenated hemoglobin. 00:54:11.470 --> 00:54:12.960 So it's like this. 00:54:12.960 --> 00:54:19.160 Here's basically capillaries and veins, arteries and veins. 00:54:19.160 --> 00:54:22.050 And as you go through the capillary bed, the smallest 00:54:22.050 --> 00:54:25.400 vessels, neurons are extracting oxygen to support 00:54:25.400 --> 00:54:27.700 their physical life. 00:54:27.700 --> 00:54:31.260 What happens when this part of the brain gets active, is that 00:54:31.260 --> 00:54:35.070 more oxygen is extracted to support the active neurons. 00:54:35.070 --> 00:54:40.140 So we call this BOLD effect, blood oxygen level dependent. 00:54:40.140 --> 00:54:43.560 So we're measuring the change in blood, changes the ratio of 00:54:43.560 --> 00:54:46.420 oxygenated to deoxygenated hemoglobins, that changes the 00:54:46.420 --> 00:54:48.430 magnetic field as we measure it. 00:54:48.430 --> 00:54:51.100 And that's what we directly measure, not the neurons. 00:54:51.100 --> 00:54:53.770 So if the neurons are using up oxygen, why does the BOLD 00:54:53.770 --> 00:54:57.570 signal increase, why does this ratio go up? 00:54:57.570 --> 00:55:00.480 Because intuitively you'd think it would go down, 00:55:00.480 --> 00:55:02.940 because oxygen is being extracted at a higher rate. 00:55:06.260 --> 00:55:09.140 If you look at oxygen being extracted, right after 00:55:09.140 --> 00:55:13.440 something happens, 10 seconds, there's an 00:55:13.440 --> 00:55:14.730 initial dip of oxygen. 00:55:14.730 --> 00:55:17.830 That's the neurons extracting oxygen to replenish themselves 00:55:17.830 --> 00:55:20.750 from their activity, their activity has been to give your 00:55:20.750 --> 00:55:23.490 mind its life. 00:55:23.490 --> 00:55:27.950 Then what happens is there's this vast oversupply for much 00:55:27.950 --> 00:55:30.180 longer time. 00:55:30.180 --> 00:55:33.420 Intuitively, it's as if we said it's so important to 00:55:33.420 --> 00:55:35.730 metabolically support the neurons that make up our 00:55:35.730 --> 00:55:39.580 minds, that if some areas demanding a lot of blood, we 00:55:39.580 --> 00:55:43.990 send over way too much extra as soon as we can, from a 00:55:43.990 --> 00:55:47.480 distance to make sure everything's OK. 00:55:47.480 --> 00:55:51.720 And because our measurement is so sad, we almost can never 00:55:51.720 --> 00:55:54.720 measure this initial dip. 00:55:54.720 --> 00:55:58.470 We almost always measure the sustained oversupply of oxygen 00:55:58.470 --> 00:56:00.470 to that part of the brain. 00:56:00.470 --> 00:56:04.040 So you could say it's such a house of cards. 00:56:04.040 --> 00:56:07.690 The oversupply of the blood going to a part of the brain 00:56:07.690 --> 00:56:10.840 changes the balance of oxygenated to deoxygenated 00:56:10.840 --> 00:56:13.950 hemoglobin that changes the magnetic property. 00:56:13.950 --> 00:56:16.440 And that's how we try to figure out what that part of 00:56:16.440 --> 00:56:18.950 the brain is doing for your mind. 00:56:18.950 --> 00:56:22.000 But it works pretty well in some cases. 00:56:22.000 --> 00:56:26.820 Decent Spatial Resolution, no injection, you can zoom in a 00:56:26.820 --> 00:56:28.710 scanner and do a lot of different things. 00:56:28.710 --> 00:56:31.500 Modest Temporal Resolution, because it's not milliseconds, 00:56:31.500 --> 00:56:34.960 it's always on the order of seconds, that's correlational, 00:56:34.960 --> 00:56:36.560 not causal. 00:56:36.560 --> 00:56:38.150 But you get some amazing results, I'm just going to 00:56:38.150 --> 00:56:40.300 present to you two or three. 00:56:40.300 --> 00:56:42.800 So here's one, a thing we're very interested about humans 00:56:42.800 --> 00:56:44.420 is empathy. 00:56:44.420 --> 00:56:48.500 How much we understand and feel other people's happiness, 00:56:48.500 --> 00:56:50.200 or sadness, or pain. 00:56:50.200 --> 00:56:52.430 So the "observation or imagination of another person 00:56:52.430 --> 00:56:55.420 in a particular emotional state automatically activates 00:56:55.420 --> 00:56:58.660 a representation of that state in the observer," empathy. 00:56:58.660 --> 00:57:02.780 And how do we understand how another person feels, and we 00:57:02.780 --> 00:57:04.570 think that's a big thing in how we relate to 00:57:04.570 --> 00:57:06.680 one another as humans. 00:57:06.680 --> 00:57:11.250 So Tania Singer did the following experiment, we 00:57:11.250 --> 00:57:12.280 talked about this before a little 00:57:12.280 --> 00:57:13.960 bit, embodied cognition. 00:57:13.960 --> 00:57:17.420 That we understand others out there by the feelings 00:57:17.420 --> 00:57:18.590 we know within us. 00:57:18.590 --> 00:57:20.620 We don't know their feelings, but we know our 00:57:20.620 --> 00:57:22.470 feelings inside us. 00:57:22.470 --> 00:57:25.390 So here's what she did, she brought in pairs of people who 00:57:25.390 --> 00:57:28.920 were friends, or romantic partners. 00:57:28.920 --> 00:57:33.650 And she either had them get some pain, it was a shock, 00:57:33.650 --> 00:57:38.090 within ethical boundaries, but not pleasant, that's the pain. 00:57:38.090 --> 00:57:41.780 Or, you got to watch through a video camera, while you're 00:57:41.780 --> 00:57:44.730 being imaged, your partner getting the shock. 00:57:44.730 --> 00:57:47.370 So think about somebody you care about and think about 00:57:47.370 --> 00:57:49.960 them getting something painful, and how you would 00:57:49.960 --> 00:57:51.490 feel at that moment. 00:57:51.490 --> 00:57:54.330 And they asked in the brain, what's similar and dissimilar, 00:57:54.330 --> 00:57:56.940 and we'll focus on what's similar right now, between 00:57:56.940 --> 00:58:01.250 feeling pain yourself, and observing pain in somebody you 00:58:01.250 --> 00:58:05.140 care about, emphasizing with the pain you see them having. 00:58:05.140 --> 00:58:07.900 And what they found is two areas, something of an 00:58:07.900 --> 00:58:10.270 Anterior Cingulate, and something in the Insula, which 00:58:10.270 --> 00:58:13.500 we talked about before, where there was a lot of overlap. 00:58:13.500 --> 00:58:17.110 So this phrase, I'm feeling your pain, in your brain when 00:58:17.110 --> 00:58:20.800 you feel for somebody else's pain in this physical sense, 00:58:20.800 --> 00:58:23.910 you turn on some of the same brain areas as when you feel 00:58:23.910 --> 00:58:25.660 physical pain directly. 00:58:25.660 --> 00:58:27.690 It's as if the basis to imagine another person's 00:58:27.690 --> 00:58:31.290 feelings is the feelings you know so well yourself. 00:58:31.290 --> 00:58:33.600 And this is literally shown now by the brain imaging. 00:58:33.600 --> 00:58:36.430 It could've been a story, a metaphor, an argument, this is 00:58:36.430 --> 00:58:40.350 scientific evidence that supports that likelihood. 00:58:40.350 --> 00:58:43.970 So we're going to expend it in a slightly fun way. 00:58:43.970 --> 00:58:46.970 There's been a lot of study in neuroeconomics thinking about 00:58:46.970 --> 00:58:50.120 how we think about, for example, things like trust. 00:58:50.120 --> 00:58:52.210 So one game, and there's a number of them, is called the 00:58:52.210 --> 00:58:53.000 ultimatum game. 00:58:53.000 --> 00:58:54.260 And many people probably know this, but let me 00:58:54.260 --> 00:58:55.520 remind you of this. 00:58:55.520 --> 00:58:57.900 This version of it has two players, a 00:58:57.900 --> 00:59:00.520 proposer, and a responder. 00:59:00.520 --> 00:59:03.210 And what they do is they give to proposer a certain amount 00:59:03.210 --> 00:59:11.450 of money, and the proposer is allowed to make an offer to 00:59:11.450 --> 00:59:13.500 the responder. 00:59:13.500 --> 00:59:17.990 If the responder says, No, nobody gets any money. 00:59:17.990 --> 00:59:20.620 Usually people offered about 50%, so let's make this 00:59:20.620 --> 00:59:22.050 concrete just for a moment. 00:59:22.050 --> 00:59:24.620 Can I pick you for a second? 00:59:24.620 --> 00:59:25.870 You can decline. 00:59:28.320 --> 00:59:34.080 Imagine if Tyler came over to me and give me $10, and I 00:59:34.080 --> 00:59:37.710 said, how would you feel if I gave you five and I kept five. 00:59:37.710 --> 00:59:39.400 What do you think? 00:59:39.400 --> 00:59:40.240 Might you go for It? 00:59:40.240 --> 00:59:42.010 GUEST SPEAKER: Yeah, sure. 00:59:42.010 --> 00:59:43.620 PROFESSOR: I mean, you go, I'm $5 dollars ahead, you're $5 00:59:43.620 --> 00:59:47.440 ahead, Tyler won't eat this month because graduate student 00:59:47.440 --> 00:59:50.480 stipends are modest, but it's a zero sum game in the end. 00:59:53.440 --> 00:59:57.270 So now Tyler comes over hands me 10 more dollars, and I 00:59:57.270 --> 00:59:59.300 offer you one. 00:59:59.300 --> 01:00:01.950 What's your first feeling assuming that I wasn't your 01:00:01.950 --> 01:00:03.200 teacher grading you? 01:00:06.230 --> 01:00:08.660 He saw me get ten, I say here's one. 01:00:08.660 --> 01:00:09.972 What's your feeling? 01:00:09.972 --> 01:00:11.780 Think about it just for-- 01:00:11.780 --> 01:00:13.136 GUEST SPEAKER: You'd feel kind of cheated. 01:00:13.136 --> 01:00:14.040 PROFESSOR: --yeah. 01:00:14.040 --> 01:00:18.490 You don't have to, by purely economic perspective, would 01:00:18.490 --> 01:00:20.690 you be ahead by taking that dollar? 01:00:20.690 --> 01:00:21.530 Yeah. 01:00:21.530 --> 01:00:24.140 A dollar's a dollar, $2 is $2, but people 01:00:24.140 --> 01:00:26.430 have a sense of fairness. 01:00:26.430 --> 01:00:32.410 Even to their own detriment, if you offer $2 and lower. 01:00:32.410 --> 01:00:35.990 Even knowing that you're just ruining $1 or two you would've 01:00:35.990 --> 01:00:38.630 gotten for nothing, except saying yes, people half the 01:00:38.630 --> 01:00:40.500 time will say no. 01:00:40.500 --> 01:00:42.540 It's like, you are so unfair-- 01:00:42.540 --> 01:00:45.210 you were saying to me, I would never say this to you-- you 01:00:45.210 --> 01:00:47.960 are so unfair, that we're going to take us both down, 01:00:47.960 --> 01:00:49.750 rather than you have the pleasure of the $8. 01:00:49.750 --> 01:00:51.620 OK It's so unfair, that my sense 01:00:51.620 --> 01:00:54.860 of fairness is disturbed. 01:00:54.860 --> 01:00:57.010 It's an interesting way to think about it, imagine a 01:00:57.010 --> 01:01:00.215 friend of yours is handed $10, and they offer you half, and 01:01:00.215 --> 01:01:02.810 if you say no, nobody gets anything, so 01:01:02.810 --> 01:01:05.210 it's a trust game. 01:01:05.210 --> 01:01:07.310 They had the people in the scanner playing this game with 01:01:07.310 --> 01:01:09.490 two people they saw on a video monitor. 01:01:09.490 --> 01:01:11.930 The two people they're playing with are set up. 01:01:11.930 --> 01:01:13.690 The person in the scanner is the real participant, the 01:01:13.690 --> 01:01:16.490 people out there they see, are confederates, 01:01:16.490 --> 01:01:17.700 they're play actors. 01:01:17.700 --> 01:01:20.890 And one is a fair person, here's $5, thank you, here's 01:01:20.890 --> 01:01:22.430 $5, thank you. 01:01:22.430 --> 01:01:26.160 Here's $6, oh, you're awesome, we can get along, And then 01:01:26.160 --> 01:01:28.450 there's an unfair player, here's $1. 01:01:28.450 --> 01:01:31.300 And you go, why is this guy a jerk? 01:01:31.300 --> 01:01:33.210 How about $2? 01:01:33.210 --> 01:01:36.670 And after a while, you go the fair player was very decent, 01:01:36.670 --> 01:01:38.070 this unfair player-- 01:01:38.070 --> 01:01:40.450 who you believe is part of the experiment, but is a set up-- 01:01:40.450 --> 01:01:42.310 and you're just thinking, why is this person such a jerk? 01:01:42.310 --> 01:01:45.300 They're constantly getting $10, and constantly giving me 01:01:45.300 --> 01:01:46.380 one or two. 01:01:46.380 --> 01:01:47.630 No, no, no thank you. 01:01:51.840 --> 01:01:55.870 Now, you get a shock, and you see these two strangers, one 01:01:55.870 --> 01:01:58.210 of whom was a wonderful, fair player, and one of whom was an 01:01:58.210 --> 01:01:59.780 absurdly unfair player. 01:01:59.780 --> 01:02:02.350 You see them get a shock. 01:02:02.350 --> 01:02:04.300 And they had both men and women in the scanner watching 01:02:04.300 --> 01:02:05.220 these things happen. 01:02:05.220 --> 01:02:07.450 And here's what happened, and it's kind of 01:02:07.450 --> 01:02:09.280 funny, but you know. 01:02:09.280 --> 01:02:12.830 For the women they had overlap again between the parts of the 01:02:12.830 --> 01:02:15.710 brain to turn on in here in the insula, when they got a 01:02:15.710 --> 01:02:19.240 shock, and when either the fair player got a shock, or 01:02:19.240 --> 01:02:20.350 the unfair player. 01:02:20.350 --> 01:02:23.150 They felt bad for both by this measure. 01:02:23.150 --> 01:02:25.840 Look at the men in the study. 01:02:25.840 --> 01:02:29.730 I feel bad if the fair guy gets it, but this part of the 01:02:29.730 --> 01:02:31.950 brain's like, yeah, give it to 'em, can 01:02:31.950 --> 01:02:35.370 you push up the voltage? 01:02:35.370 --> 01:02:37.590 It just came out this way, whether it would work that way 01:02:37.590 --> 01:02:40.930 under all circumstances, all ages, all societies, other 01:02:40.930 --> 01:02:42.250 groups of men and women, don't know. 01:02:42.250 --> 01:02:45.610 But in this sample in the United Kingdom, 01:02:45.610 --> 01:02:49.050 the men had no empathy. 01:02:49.050 --> 01:02:51.480 It's worse than that, it's worse than they had no 01:02:51.480 --> 01:02:54.520 empathy, let me show you this. 01:02:54.520 --> 01:02:56.940 If they asked to indicate their 01:02:56.940 --> 01:02:59.020 desire for revenge against-- 01:02:59.020 --> 01:03:00.390 this is a behavioral response-- their desire for 01:03:00.390 --> 01:03:03.370 revenge against the bad player. 01:03:03.370 --> 01:03:06.390 I don't think they pursued the unfair player down the street, 01:03:06.390 --> 01:03:07.760 but just that feeling. 01:03:07.760 --> 01:03:11.550 And the women said, a little bit, the men said yes, if only 01:03:11.550 --> 01:03:13.550 I could take down this person, that would be great. 01:03:13.550 --> 01:03:15.160 And here's the amazing thing, we'll come back to the 01:03:15.160 --> 01:03:16.520 structure called a nucleus accumbens. 01:03:16.520 --> 01:03:19.450 It sits in the bottom of the Basal Ganglia. 01:03:19.450 --> 01:03:22.590 It's the structure that in the human brain is most identified 01:03:22.590 --> 01:03:25.675 with reward and pleasure, most identified with reward and 01:03:25.675 --> 01:03:27.540 pleasure by fMRI imaging. 01:03:27.540 --> 01:03:29.280 Look at the nucleus accumbens when the 01:03:29.280 --> 01:03:33.930 unfair player gets zapped. 01:03:33.930 --> 01:03:37.770 The women, nothing much, the men boom, big reward. 01:03:37.770 --> 01:03:40.380 Revenge is rewarding in their brain. 01:03:40.380 --> 01:03:44.260 No sympathy, and lots of revenge satisfaction for the 01:03:44.260 --> 01:03:45.260 unfair player. 01:03:45.260 --> 01:03:47.870 Now you can decide on your own life who this applies to or 01:03:47.870 --> 01:03:50.880 not, but it's sort of fun to explore 01:03:50.880 --> 01:03:51.680 these different things. 01:03:51.680 --> 01:03:55.140 How we form ideas about empathy, trust, whether they 01:03:55.140 --> 01:03:57.490 are in a society we grow up in. 01:03:57.490 --> 01:04:00.120 Somewhat different on average men and women, huge ranges 01:04:00.120 --> 01:04:01.840 within men huge ranges within women. 01:04:01.840 --> 01:04:03.530 So it's a sort of fun thing to explore. 01:04:03.530 --> 01:04:07.540 Let me end with something that's much more difficult and 01:04:07.540 --> 01:04:10.050 disturbing, but another place where imaging is giving us 01:04:10.050 --> 01:04:14.260 insights that you could not imagined having some time ago. 01:04:14.260 --> 01:04:16.760 So this is a very difficult case, I don't know if any of 01:04:16.760 --> 01:04:19.370 you gone through it, I don't wish it for you. 01:04:19.370 --> 01:04:21.220 Some of you probably have, and many of you will at sometime 01:04:21.220 --> 01:04:23.930 in your life, when you have to make an end of life decision. 01:04:23.930 --> 01:04:30.380 And amongst the most famous of these cases was Terry Schiavo. 01:04:30.380 --> 01:04:32.990 Now I don't know that name even rings a bell for you, but 01:04:32.990 --> 01:04:36.670 it got very, very famous amongst these kinds of cases. 01:04:36.670 --> 01:04:39.260 So she had a cardiac arrest, she had took a lot of diet 01:04:39.260 --> 01:04:40.700 pills, and that may have contributed. 01:04:40.700 --> 01:04:43.820 In February 25, 1990, she went into a coma, and then a 01:04:43.820 --> 01:04:44.750 vegetative state. 01:04:44.750 --> 01:04:47.860 So a vegetative state is when a person seems to be kind of 01:04:47.860 --> 01:04:50.430 awake, but when you talk with them, they're not very aware, 01:04:50.430 --> 01:04:51.990 they're not responsive, they're not noticing, they're 01:04:51.990 --> 01:04:52.270 not talking. 01:04:52.270 --> 01:04:54.230 But their eyes are open, and they're awake, their eyes are 01:04:54.230 --> 01:04:57.040 not closed, so that's what she is. 01:04:57.040 --> 01:04:59.650 And they put in her a feeding tube, because without that she 01:04:59.650 --> 01:05:04.580 wouldn't live, she couldn't eat and feed herself. 01:05:04.580 --> 01:05:07.270 It was a heartbreaking difference of opinion between 01:05:07.270 --> 01:05:09.510 her husband and her parents. 01:05:09.510 --> 01:05:13.460 Her husband petitioned some years later, actually eight 01:05:13.460 --> 01:05:15.680 years later, to remove the feeding tube and 01:05:15.680 --> 01:05:17.330 let her pass away. 01:05:17.330 --> 01:05:19.750 The parents opposed that, they said that's not her wishes, 01:05:19.750 --> 01:05:21.730 she would want to keep on going with the feeding tube. 01:05:21.730 --> 01:05:23.620 The husband said no, I don't believe that's her wishes. 01:05:23.620 --> 01:05:26.950 So you have this very tragic confrontation between the 01:05:26.950 --> 01:05:29.350 parents who loved her, and the husband who presumably loved 01:05:29.350 --> 01:05:33.270 her having different ideas about what to do with her, 01:05:33.270 --> 01:05:35.440 whether to end her life or not. 01:05:35.440 --> 01:05:38.470 So finally her tube was removed, but then the parents 01:05:38.470 --> 01:05:40.770 went to court, and a judge reversed it, and they 01:05:40.770 --> 01:05:41.820 put the tube back. 01:05:41.820 --> 01:05:45.850 She became, sadly, kind of back and forth, living 01:05:45.850 --> 01:05:48.220 nonliving, on judicial decisions. 01:05:48.220 --> 01:05:51.630 Her case became particularly famous, for a bunch of 01:05:51.630 --> 01:05:55.290 reasons, and it went back and forth from court, to court. 01:05:55.290 --> 01:05:58.440 Moving up in the state courts, and there were several US 01:05:58.440 --> 01:06:02.590 Supreme Court decisions about whether to remove the tube, or 01:06:02.590 --> 01:06:03.980 keep the tube in. 01:06:03.980 --> 01:06:06.520 And it's a tragic thing, it's a tragic choice between the 01:06:06.520 --> 01:06:07.860 parents and the husband. 01:06:07.860 --> 01:06:10.170 It got to the US Congress, in the US Senate. 01:06:10.170 --> 01:06:14.840 President Bush signed a bill to keep her alive. 01:06:14.840 --> 01:06:18.380 Everybody got involved, with various opinions, finally the 01:06:18.380 --> 01:06:21.520 Supreme Court made a series of decisions. 01:06:21.520 --> 01:06:23.680 It was disconnected in 2005, and she died in 01:06:23.680 --> 01:06:25.200 March 31 of that year. 01:06:25.200 --> 01:06:28.450 So tragic difficult decision, and a tragic family situation 01:06:28.450 --> 01:06:30.180 that became kind of a political, 01:06:30.180 --> 01:06:32.260 and judicial football. 01:06:32.260 --> 01:06:34.610 So what's going on in the mind of somebody like this, and how 01:06:34.610 --> 01:06:37.215 could we even begin to interpret it for a person who 01:06:37.215 --> 01:06:40.620 can't speak for themselves and can't respond. 01:06:40.620 --> 01:06:41.760 So let me tell you about a different case, we 01:06:41.760 --> 01:06:43.790 don't know her case. 01:06:43.790 --> 01:06:48.640 So, again a vegetative state is one where you appear to be 01:06:48.640 --> 01:06:50.100 awake, but there's no sign of awareness. 01:06:50.100 --> 01:06:51.790 Eyes are open, but the person's not talking or 01:06:51.790 --> 01:06:53.300 responding to anything in their environment. 01:06:53.300 --> 01:06:56.700 So here's a different woman, 23 years old, in 2005 she had 01:06:56.700 --> 01:06:59.460 a road traffic accident, severe traumatic brain injury. 01:06:59.460 --> 01:07:02.120 Five months later she's un-responsive, but she has 01:07:02.120 --> 01:07:03.970 preserved sleep-wake, like she's waking up going to 01:07:03.970 --> 01:07:04.930 sleep, waking up going to sleep. 01:07:04.930 --> 01:07:09.650 Eyes open, but un-responsive in every other way. 01:07:09.650 --> 01:07:12.810 They put her into an fMRI scanner, as well as healthy 01:07:12.810 --> 01:07:15.550 comparison people, and they have them do to 01:07:15.550 --> 01:07:19.060 mental imagery tasks. 01:07:19.060 --> 01:07:21.130 they read instructions to her. 01:07:21.130 --> 01:07:24.940 But you go into scanner, and you're told to imagine two 01:07:24.940 --> 01:07:26.300 different things. 01:07:26.300 --> 01:07:30.120 Playing tennis, so imagine in your mind's eye you playing 01:07:30.120 --> 01:07:32.040 tennis for a moment, imagine that. 01:07:32.040 --> 01:07:34.880 Or imagine visiting all the rooms of your house starting 01:07:34.880 --> 01:07:37.790 with your front door, in the house that you are living in 01:07:37.790 --> 01:07:38.930 now, or where you grew up. 01:07:38.930 --> 01:07:40.870 Imagine those two things in your mind. 01:07:40.870 --> 01:07:42.820 First of all, just a pure cognitive neuroscience level, 01:07:42.820 --> 01:07:45.250 and we'll come back to that, imagination is a really 01:07:45.250 --> 01:07:46.480 interesting thing. 01:07:46.480 --> 01:07:50.290 And it turns out when we imagine things, again we use 01:07:50.290 --> 01:07:52.340 the parts of our brain that does them, imagination is 01:07:52.340 --> 01:07:53.820 perception run backwards. 01:07:53.820 --> 01:07:56.700 We can see imagination in the human brain. 01:07:56.700 --> 01:07:58.680 And depending on what you're imagining, you use the same 01:07:58.680 --> 01:08:00.570 systems that you see with. 01:08:00.570 --> 01:08:02.610 If you imagine something you're looking at, it will 01:08:02.610 --> 01:08:04.120 turn on your visual system, it's even more 01:08:04.120 --> 01:08:05.590 specific than that. 01:08:05.590 --> 01:08:08.500 So let's first look at what happens with the controls. 01:08:08.500 --> 01:08:10.810 When they imagine they're playing tennis, they turn on 01:08:10.810 --> 01:08:14.010 the supplementary motor area, that's a part of your brain 01:08:14.010 --> 01:08:16.960 that plans your physical movements. 01:08:16.960 --> 01:08:19.830 You're not moving, but you're thinking about it, this is 01:08:19.830 --> 01:08:21.640 imagination of movement. 01:08:21.640 --> 01:08:24.120 When you plan a movement., you turn that on. 01:08:24.120 --> 01:08:26.819 When you go around your house, you turn on spatial areas that 01:08:26.819 --> 01:08:30.529 are in the parahippocampal cortex, and similar areas, 01:08:30.529 --> 01:08:32.710 parietal cortex, and parahippocampal cortex. 01:08:32.710 --> 01:08:35.080 They're turned on if we show you a movie where you're 01:08:35.080 --> 01:08:36.189 moving around in spaces. 01:08:36.189 --> 01:08:39.479 If you see spaces, you turn those on, if you imagine 01:08:39.479 --> 01:08:40.439 spaces, you turn them on. 01:08:40.439 --> 01:08:44.229 So imagination in the brain is perception run backwards, or 01:08:44.229 --> 01:08:47.640 physical action run backwards, you're not actually doing it. 01:08:47.640 --> 01:08:50.050 But look at this patient who got in the scanner, who was 01:08:50.050 --> 01:08:53.910 non responsive, you read her the instructions, and see what 01:08:53.910 --> 01:08:56.500 she does, and look at her brain. 01:08:56.500 --> 01:08:59.859 Asked to imagine tennis, asked to imagine the 01:08:59.859 --> 01:09:01.270 rooms in her house. 01:09:01.270 --> 01:09:02.920 It looks just like that. 01:09:02.920 --> 01:09:04.569 What does that mean, just in a common sense, 01:09:04.569 --> 01:09:07.260 what does that mean? 01:09:07.260 --> 01:09:10.319 Did she understand the instruction, at some level 01:09:10.319 --> 01:09:14.279 yes, she wouldn't turn on those parts of the brain if 01:09:14.279 --> 01:09:18.335 she didn't understand the instruction, she imagines the 01:09:18.335 --> 01:09:20.950 thing you ask her to instruct. 01:09:20.950 --> 01:09:22.340 So this guy on the front page of the New York Times said 01:09:22.340 --> 01:09:25.310 fMRI could tell you the internal mental life of a 01:09:25.310 --> 01:09:27.609 person could no longer speak, or communicate 01:09:27.609 --> 01:09:29.470 with any other way. 01:09:29.470 --> 01:09:33.270 Now it's turned out since then, that when they put in 01:09:33.270 --> 01:09:35.490 other patients into the scanner, most of them don't 01:09:35.490 --> 01:09:37.170 show this pattern. 01:09:37.170 --> 01:09:40.830 So it's not that every patient in a vegetative state this is 01:09:40.830 --> 01:09:43.149 full of mental life like this person. 01:09:43.149 --> 01:09:45.359 And a deeper way, we don't really understand what this 01:09:45.359 --> 01:09:46.740 mental life is like. 01:09:46.740 --> 01:09:49.422 We don't know whether she simply understands some 01:09:49.422 --> 01:09:51.899 things, but doesn't have feelings, or plans, or 01:09:51.899 --> 01:09:53.830 desires, or whether she has those too. 01:09:53.830 --> 01:09:56.860 We don't understand really the full range of mental life, but 01:09:56.860 --> 01:09:59.950 we know that she can understand an instruction, and 01:09:59.950 --> 01:10:01.760 her brain follows through with it. 01:10:01.760 --> 01:10:04.480 Most patients, it turns out, don't look like that in 01:10:04.480 --> 01:10:05.850 vegetative states. 01:10:05.850 --> 01:10:08.840 So again, brain imaging has taken us inside the mind of 01:10:08.840 --> 01:10:11.120 somebody who cannot communicate for themselves and 01:10:11.120 --> 01:10:13.060 let us say something about what it is that's 01:10:13.060 --> 01:10:15.340 going on in that mind. 01:10:15.340 --> 01:10:17.800 In conclusion, we've talked about different ways of 01:10:17.800 --> 01:10:20.680 learning about the brain, different methods to record 01:10:20.680 --> 01:10:22.920 structure and function that vary in their temporal and 01:10:22.920 --> 01:10:24.280 spatial acuity. 01:10:24.280 --> 01:10:28.480 And incredibly different ways in which we can understand the 01:10:28.480 --> 01:10:31.190 organization in time and space of how the brain supports the 01:10:31.190 --> 01:10:32.440 human mind.