1 00:00:00,040 --> 00:00:02,460 The following content is provided under a Creative 2 00:00:02,460 --> 00:00:03,870 Commons license. 3 00:00:03,870 --> 00:00:06,910 Your support will help MIT OpenCourseWare continue to 4 00:00:06,910 --> 00:00:10,560 offer high quality educational resources for free. 5 00:00:10,560 --> 00:00:13,460 To make a donation or view additional materials from 6 00:00:13,460 --> 00:00:19,290 hundreds of MIT courses, visit MIT OpenCourseWare at 7 00:00:19,290 --> 00:00:20,540 ocw.mit.edu. 8 00:00:23,210 --> 00:00:29,640 PROFESSOR: So when we talked about learning, we said that 9 00:00:29,640 --> 00:00:33,280 everything we know comes from learning except that which is 10 00:00:33,280 --> 00:00:35,410 given to us by our genes. 11 00:00:35,410 --> 00:00:38,550 Our knowledge of how to walk around in the world, to read, 12 00:00:38,550 --> 00:00:41,530 to think, to talk, to feel, the values that we have, the 13 00:00:41,530 --> 00:00:44,980 hopes we have, the fears we have, they're all learned 14 00:00:44,980 --> 00:00:46,400 through experience. 15 00:00:46,400 --> 00:00:48,200 And then we talked about another approach to thinking 16 00:00:48,200 --> 00:00:50,690 about how we learn things through memory, and today I'm 17 00:00:50,690 --> 00:00:53,030 going to talk about what we understand to be the brain 18 00:00:53,030 --> 00:00:55,380 organization of human memory. 19 00:00:55,380 --> 00:01:00,050 And Oliver Sacks, in The Lost Mariner, chapter 2, talks 20 00:01:00,050 --> 00:01:04,480 about one of the two major kinds of amnesia, the loss of 21 00:01:04,480 --> 00:01:07,050 memory due to a brain disorder or a brain injury. 22 00:01:07,050 --> 00:01:09,960 But he has a very nice language from Luis Bunuel 23 00:01:09,960 --> 00:01:12,100 talking about memory. "You have begun to lose your 24 00:01:12,100 --> 00:01:14,780 memory, if only in bits and pieces, to realize that memory 25 00:01:14,780 --> 00:01:16,450 is what makes our life. 26 00:01:16,450 --> 00:01:18,570 Life without memory is no life at all. 27 00:01:18,570 --> 00:01:21,110 Our memories, our coherence, our reason, our feeling, even 28 00:01:21,110 --> 00:01:21,740 our action. 29 00:01:21,740 --> 00:01:23,290 Without it, we are nothing. 30 00:01:23,290 --> 00:01:25,870 I can only wait for the final amnesia, the one that erases 31 00:01:25,870 --> 00:01:26,890 an entire life as it did 32 00:01:26,890 --> 00:01:28,120 my mother's." Right? 33 00:01:28,120 --> 00:01:31,360 So our memories of our lives, what we've done, where we've 34 00:01:31,360 --> 00:01:33,760 been, what mattered to us-- 35 00:01:33,760 --> 00:01:36,370 that's a huge piece of who we are. 36 00:01:36,370 --> 00:01:41,290 And he runs into a patient who came into the hospital early 37 00:01:41,290 --> 00:01:45,280 in 1975 with a note saying "Helpless, demented, confused, 38 00:01:45,280 --> 00:01:48,580 and disoriented." He had what we call 39 00:01:48,580 --> 00:01:51,610 clinically Korsakoff's Syndrome. 40 00:01:51,610 --> 00:01:55,500 So these are individuals who have severe alcoholism for 41 00:01:55,500 --> 00:01:59,170 many years, and a subset of those people develop a severe 42 00:01:59,170 --> 00:02:02,260 memory disorder, like this man. 43 00:02:02,260 --> 00:02:05,630 He's 49 years old. 44 00:02:05,630 --> 00:02:08,970 He tells Sacks about his life, details of his life, going 45 00:02:08,970 --> 00:02:10,630 into World War II, that he worked on a 46 00:02:10,630 --> 00:02:12,500 submarine, and so on. 47 00:02:12,500 --> 00:02:14,870 And Sacks says, "a full and interesting life remembered 48 00:02:14,870 --> 00:02:18,650 visually in detail, but for some reason his memories stop 49 00:02:18,650 --> 00:02:19,850 around World War II." 50 00:02:19,850 --> 00:02:21,270 Then he asked him, what year is it? 51 00:02:21,270 --> 00:02:23,250 Remember the year is 1975. 52 00:02:23,250 --> 00:02:24,950 And he says, it's 1945. 53 00:02:24,950 --> 00:02:25,810 What do you mean? 54 00:02:25,810 --> 00:02:27,960 We've won the war, FDR-- 55 00:02:27,960 --> 00:02:30,060 Franklin Delano Roosevelt-- is dead, Truman's at the helm. 56 00:02:30,060 --> 00:02:31,700 These are great times ahead. 57 00:02:31,700 --> 00:02:33,880 And Jimmy, how old would you be? 58 00:02:33,880 --> 00:02:35,820 He stopped and he said, well, I guess I'm 19. 59 00:02:35,820 --> 00:02:39,400 That would have been his age, you know, 20 years ago, right? 60 00:02:39,400 --> 00:02:40,620 30 years ago. 61 00:02:40,620 --> 00:02:42,920 So he's stuck in time. 62 00:02:42,920 --> 00:02:44,860 He thinks it's historically a while ago. 63 00:02:44,860 --> 00:02:46,390 He has the completely wrong age. 64 00:02:46,390 --> 00:02:48,580 And Sacks takes out a mirror and throws it at him and says, 65 00:02:48,580 --> 00:02:49,640 what do you-- 66 00:02:49,640 --> 00:02:50,440 what happened? 67 00:02:50,440 --> 00:02:52,220 And he says, Jesus Christ, what's going on? 68 00:02:52,220 --> 00:02:52,700 What happened? 69 00:02:52,700 --> 00:02:53,200 Is this a nightmare? 70 00:02:53,200 --> 00:02:53,730 Am I crazy? 71 00:02:53,730 --> 00:02:54,680 Is this a joke? 72 00:02:54,680 --> 00:02:58,560 So it's as if he's lost the last 30 years of his life. 73 00:02:58,560 --> 00:03:00,640 And he's living as if it were 30 years ago. 74 00:03:04,230 --> 00:03:06,680 And then when he walks back in, he's hardly recognized. 75 00:03:06,680 --> 00:03:08,770 Sacks is hardly recognized by the person. 76 00:03:08,770 --> 00:03:12,830 On intelligence, he shows excellent ability, but his 77 00:03:12,830 --> 00:03:15,710 memory-- very quickly, he forgets things. 78 00:03:15,710 --> 00:03:17,560 What is this, I asked him, showing him a photo in a 79 00:03:17,560 --> 00:03:18,450 magazine I was holding. 80 00:03:18,450 --> 00:03:19,590 It's the moon. 81 00:03:19,590 --> 00:03:21,240 No it's not, if it's a picture of the Earth 82 00:03:21,240 --> 00:03:22,530 taken from the moon. 83 00:03:22,530 --> 00:03:26,110 I'm mean, don't forget, in 1945, nobody imagined that we 84 00:03:26,110 --> 00:03:28,250 would be sending up people to the moon, right? 85 00:03:28,250 --> 00:03:30,330 And taking pictures from the moon of the Earth. 86 00:03:30,330 --> 00:03:30,970 You're used to it. 87 00:03:30,970 --> 00:03:33,630 It's nothing to you. 88 00:03:33,630 --> 00:03:34,150 No it's not. 89 00:03:34,150 --> 00:03:35,140 It's a picture of the Earth taken from the moon. 90 00:03:35,140 --> 00:03:35,760 Doc, you're kidding. 91 00:03:35,760 --> 00:03:37,510 Somebody would have to get a camera up there. 92 00:03:37,510 --> 00:03:38,000 Naturally. 93 00:03:38,000 --> 00:03:38,730 Hell, you're joking. 94 00:03:38,730 --> 00:03:40,940 How would you know that? 95 00:03:40,940 --> 00:03:46,920 So he has lost the last 30 years of his life, for all 96 00:03:46,920 --> 00:03:48,650 practical purposes, despite normal 97 00:03:48,650 --> 00:03:51,680 intelligence and normal thought. 98 00:03:51,680 --> 00:03:55,000 So we're going to talk more about how this occurs in 99 00:03:55,000 --> 00:03:58,180 another patient, and more generally, how the brain 100 00:03:58,180 --> 00:04:00,820 supports your ability to learn things. 101 00:04:00,820 --> 00:04:02,730 So here's this remarkable brain. 102 00:04:02,730 --> 00:04:06,520 And in one sense, you could say it's almost all there to 103 00:04:06,520 --> 00:04:09,620 absorb things in life. 104 00:04:09,620 --> 00:04:12,910 You have very small insects that can do a lot with the 105 00:04:12,910 --> 00:04:13,830 genes they're given. 106 00:04:13,830 --> 00:04:17,700 We have big brains to learn the life we lead. 107 00:04:17,700 --> 00:04:20,320 And I'm going to come back at the end to this metaphor, but 108 00:04:20,320 --> 00:04:23,740 the idea that in many ways, your brain as you sit there 109 00:04:23,740 --> 00:04:27,150 right now, or any healthy brain, is kind of like a 110 00:04:27,150 --> 00:04:31,700 symphony orchestra that has many specialized instruments 111 00:04:31,700 --> 00:04:33,850 for learning different kinds of things. 112 00:04:33,850 --> 00:04:36,650 And you feel like a unified whole, and you are, and these 113 00:04:36,650 --> 00:04:38,270 instruments interact with each other. 114 00:04:38,270 --> 00:04:40,980 But just like a symphony orchestra, you know, together 115 00:04:40,980 --> 00:04:42,340 they make a sound. 116 00:04:42,340 --> 00:04:45,340 So imagine you're a Martian who lands outside a symphony 117 00:04:45,340 --> 00:04:48,950 hall, and you hear a symphony playing. 118 00:04:48,950 --> 00:04:49,790 It's something beautiful. 119 00:04:49,790 --> 00:04:51,420 It sounds really interesting. 120 00:04:51,420 --> 00:04:54,360 If you're a Martian on the outside of the symphony hall, 121 00:04:54,360 --> 00:04:56,810 how many instruments are you guessing, how many things 122 00:04:56,810 --> 00:04:58,870 might you guess, are making that sound? 123 00:04:58,870 --> 00:05:00,860 Would you have any idea? 124 00:05:00,860 --> 00:05:02,430 One big one? 125 00:05:02,430 --> 00:05:04,220 Two big ones? 126 00:05:04,220 --> 00:05:05,490 50? 127 00:05:05,490 --> 00:05:07,000 It'd be very hard to guess. 128 00:05:07,000 --> 00:05:09,710 And it's only been in the last 20 years or so that we had 129 00:05:09,710 --> 00:05:12,240 some real clarification on the instruments of 130 00:05:12,240 --> 00:05:14,380 learning in our brains. 131 00:05:14,380 --> 00:05:16,260 So I'm going to talk about three things today. 132 00:05:16,260 --> 00:05:19,880 Anterograde amnesia, the loss of the ability to form new 133 00:05:19,880 --> 00:05:23,540 memories; retrograde amnesia, the loss of memories you 134 00:05:23,540 --> 00:05:27,610 already had; and that idea of memory systems, this idea that 135 00:05:27,610 --> 00:05:30,650 each of us has a symphony of learning instruments in our 136 00:05:30,650 --> 00:05:31,990 brain that empowers us to learn 137 00:05:31,990 --> 00:05:34,610 different kinds of things. 138 00:05:34,610 --> 00:05:36,650 So anterograde amnesia is, again, the inability to 139 00:05:36,650 --> 00:05:38,550 remember new information. 140 00:05:38,550 --> 00:05:40,830 And people mostly talk about two kinds, but as you see, 141 00:05:40,830 --> 00:05:42,670 they're most of life, OK? 142 00:05:42,670 --> 00:05:45,220 Not all of that-- we'll talk about that-- but a lot of it, 143 00:05:45,220 --> 00:05:48,190 such as events you experience or facts you encounter. 144 00:05:48,190 --> 00:05:49,400 So think about this. 145 00:05:49,400 --> 00:05:51,380 All the events you've remembered from your entire 146 00:05:51,380 --> 00:05:54,840 life, all the facts you ever learned in school, at home, on 147 00:05:54,840 --> 00:05:55,860 the computer-- 148 00:05:55,860 --> 00:05:58,170 that's a huge amount of what you know. 149 00:05:58,170 --> 00:06:00,350 And a patient like we just described or the patients I'll 150 00:06:00,350 --> 00:06:04,090 describe in a moment lose the ability to remember any event 151 00:06:04,090 --> 00:06:07,180 from the day they become amnesic or remember much in 152 00:06:07,180 --> 00:06:09,990 the way of new information of any kind, in terms of 153 00:06:09,990 --> 00:06:11,570 facts of the world. 154 00:06:11,570 --> 00:06:13,740 So in what sense is memory in the brain 155 00:06:13,740 --> 00:06:14,830 distributed or localized? 156 00:06:14,830 --> 00:06:17,760 In what sense is it in one place or many places? 157 00:06:17,760 --> 00:06:20,430 And this has been a central debate in all of neuroscience, 158 00:06:20,430 --> 00:06:21,430 but in memory, too. 159 00:06:21,430 --> 00:06:24,680 And Karl Lashley, a giant of neuroscience, who worked just 160 00:06:24,680 --> 00:06:28,570 two T stops away at Harvard, said this: "It is not possible 161 00:06:28,570 --> 00:06:31,540 to demonstrate the isolated localization of a memory trace 162 00:06:31,540 --> 00:06:32,810 anywhere in the nervous system. 163 00:06:32,810 --> 00:06:35,730 The engram is represented throughout the brain." The 164 00:06:35,730 --> 00:06:38,700 engram's kind of a magic word in memory and the brain. 165 00:06:38,700 --> 00:06:41,850 The engram is the thing in you that changes in your brain 166 00:06:41,850 --> 00:06:44,110 that is the stuff of a memory. 167 00:06:44,110 --> 00:06:48,250 If you learn today that there's more terrible news in 168 00:06:48,250 --> 00:06:51,770 Japan with the nuclear reactors, and you remember 169 00:06:51,770 --> 00:06:53,740 that because it matters to you, because you care about 170 00:06:53,740 --> 00:06:58,670 the people, there's a physical change in your brain that is 171 00:06:58,670 --> 00:06:59,230 the memory. 172 00:06:59,230 --> 00:07:01,400 If you remember what I'm saying now for more than a few 173 00:07:01,400 --> 00:07:04,070 moments, that is a physical change in your brain. 174 00:07:04,070 --> 00:07:06,430 So all of us in neuroscience are amazed by that. 175 00:07:06,430 --> 00:07:10,240 How can we physically change the brain to be the biological 176 00:07:10,240 --> 00:07:12,230 record of a memory, that we can keep 177 00:07:12,230 --> 00:07:13,730 and use in the future? 178 00:07:13,730 --> 00:07:16,350 And the engram, Karl Lashley said, is represented 179 00:07:16,350 --> 00:07:17,550 throughout the brain. 180 00:07:17,550 --> 00:07:19,150 It's spread throughout the brain. 181 00:07:19,150 --> 00:07:20,830 Here's why he thought that. 182 00:07:20,830 --> 00:07:23,740 So he was working with rats, and they ran a maze. 183 00:07:23,740 --> 00:07:26,340 And you saw how quickly you learned the maze to go from 184 00:07:26,340 --> 00:07:30,240 start to finish to get the food if you're a rat. 185 00:07:30,240 --> 00:07:33,590 And here's what he found, and the results won't amaze you, 186 00:07:33,590 --> 00:07:34,890 to start with. 187 00:07:34,890 --> 00:07:36,150 So what he did is he made-- 188 00:07:36,150 --> 00:07:38,550 this is number of errors during learning, so 189 00:07:38,550 --> 00:07:39,710 it's good to be low. 190 00:07:39,710 --> 00:07:42,480 And this is how much neocortex they took out, ranging from 191 00:07:42,480 --> 00:07:44,860 10% to 80%. 192 00:07:44,860 --> 00:07:47,790 And he discovered that the more neocortex you took out, 193 00:07:47,790 --> 00:07:49,130 the worse learner you were. 194 00:07:49,130 --> 00:07:52,140 Now if it didn't happen in some broad sense, we'd say, 195 00:07:52,140 --> 00:07:54,150 well, what part of us is learning it? 196 00:07:54,150 --> 00:07:56,030 You take out more brain, you're less of a good reader. 197 00:07:56,030 --> 00:07:58,210 10% out, 10% percent bad memory. 198 00:07:58,210 --> 00:08:01,360 50% of brain out, 50% of bad memory. 199 00:08:01,360 --> 00:08:04,030 80% of the brain out, 80% bad memory, right? 200 00:08:04,030 --> 00:08:05,260 OK, that makes sense. 201 00:08:05,260 --> 00:08:08,040 But what he was really impressed by is it didn't seem 202 00:08:08,040 --> 00:08:12,360 to him to matter where he took the brain out of the rat. 203 00:08:12,360 --> 00:08:13,360 It just didn't matter. 204 00:08:13,360 --> 00:08:15,450 It's just the percent that he took out. 205 00:08:15,450 --> 00:08:17,480 Whatever percent he took out is how bad 206 00:08:17,480 --> 00:08:18,730 the learner you were. 207 00:08:18,730 --> 00:08:20,415 And we'll come back to that, but that's why I said, it must 208 00:08:20,415 --> 00:08:22,880 be spread everywhere, because wherever I take out brain, 209 00:08:22,880 --> 00:08:26,430 part of the memory is weakened or disappears. 210 00:08:26,430 --> 00:08:29,210 And sometimes people call that mass action for distributed 211 00:08:29,210 --> 00:08:30,950 memory, that's spread throughout the brain 212 00:08:30,950 --> 00:08:32,000 in this mass way. 213 00:08:32,000 --> 00:08:35,280 It's just spread all over the place. 214 00:08:35,280 --> 00:08:36,760 And a single clinical case-- 215 00:08:36,760 --> 00:08:38,990 I'll spend a few moments on him for two reasons. 216 00:08:38,990 --> 00:08:42,320 It is the historical case that turned this around, and I have 217 00:08:42,320 --> 00:08:44,059 a particular perspective on this because when I was a 218 00:08:44,059 --> 00:08:46,680 graduate student, I did a lot of work with this single 219 00:08:46,680 --> 00:08:49,560 patient whose case turned around our understanding of 220 00:08:49,560 --> 00:08:51,350 the mammalian brain and memory. 221 00:08:51,350 --> 00:08:53,250 So as I start to talk about it-- 222 00:08:53,250 --> 00:08:55,740 I can't tell you what Phineas Gage was really like, beyond 223 00:08:55,740 --> 00:08:56,580 what I read, OK? 224 00:08:56,580 --> 00:08:58,580 Or Broca's patients from the 1900s. 225 00:08:58,580 --> 00:09:00,860 I can tell you what HM, the man we're about to talk about, 226 00:09:00,860 --> 00:09:02,980 was like because I spent many, many hours with him, two 227 00:09:02,980 --> 00:09:05,530 blocks from here, when I was a graduate student in Suzanne 228 00:09:05,530 --> 00:09:06,790 Corkin's lab. 229 00:09:06,790 --> 00:09:09,800 So the structure we'll focus on is something called the 230 00:09:09,800 --> 00:09:10,530 hippocampus. 231 00:09:10,530 --> 00:09:12,060 It looks sort of big in the picture. 232 00:09:12,060 --> 00:09:15,300 It's about the size of about 2/3 of your thumb, one on the 233 00:09:15,300 --> 00:09:19,020 left and one on the right in the insides of the medial part 234 00:09:19,020 --> 00:09:19,880 of the temporal lobes. 235 00:09:19,880 --> 00:09:23,460 A pretty small percentage of the brain. 236 00:09:23,460 --> 00:09:25,910 And you can see it's located here. 237 00:09:25,910 --> 00:09:28,380 Here it is sort of drawn out. 238 00:09:28,380 --> 00:09:30,100 And here's the story of this man. 239 00:09:30,100 --> 00:09:31,760 He died a couple years ago. 240 00:09:31,760 --> 00:09:35,640 There's lots of plays and movies and books in the works. 241 00:09:35,640 --> 00:09:37,870 I can also tell you that when I was a graduate student here, 242 00:09:37,870 --> 00:09:40,390 my fellow graduate students would say, tell us who HM, 243 00:09:40,390 --> 00:09:43,320 what his initials really stand for, as if it really mattered, 244 00:09:43,320 --> 00:09:44,570 particularly. 245 00:09:44,570 --> 00:09:47,270 But I felt privileged to have the secret knowledge of what 246 00:09:47,270 --> 00:09:47,710 his name was. 247 00:09:47,710 --> 00:09:48,980 When he died, they published it. 248 00:09:48,980 --> 00:09:52,190 Everybody knows now, so my secret is out. 249 00:09:52,190 --> 00:09:53,450 Or our secret is out. 250 00:09:53,450 --> 00:09:54,650 He was born in 1926. 251 00:09:54,650 --> 00:09:58,520 At age 16 he had his first major epileptic seizure. 252 00:09:58,520 --> 00:10:03,140 By age 27, he was having many, many seizures a day. 253 00:10:03,140 --> 00:10:05,060 You can have petit mal seizures, where you tune out 254 00:10:05,060 --> 00:10:06,030 from the world. 255 00:10:06,030 --> 00:10:07,990 You can have grand mal seizures that lead to physical 256 00:10:07,990 --> 00:10:09,240 convulsions. 257 00:10:09,240 --> 00:10:12,830 By age 27, the medications were not helping him, in 1953, 258 00:10:12,830 --> 00:10:14,940 very much, that were available. 259 00:10:14,940 --> 00:10:17,280 And he was just sitting in his house just waiting for the 260 00:10:17,280 --> 00:10:18,210 next seizure, basically. 261 00:10:18,210 --> 00:10:19,700 That was his life. 262 00:10:19,700 --> 00:10:22,650 He was a man of normal intelligence and fairly 263 00:10:22,650 --> 00:10:23,980 typical, average background. 264 00:10:23,980 --> 00:10:25,920 Nothing remarkable. 265 00:10:25,920 --> 00:10:28,710 And in order to treat the epilepsy, William Scoville, 266 00:10:28,710 --> 00:10:32,980 the surgeon, resected, or took out surgically, the tissue. 267 00:10:32,980 --> 00:10:36,960 Here's this cartoon of what he took out-- 268 00:10:36,960 --> 00:10:39,160 the hippocampus, also the amygdala just in front of it, 269 00:10:39,160 --> 00:10:41,010 also tissue that surrounds it. 270 00:10:41,010 --> 00:10:43,860 And the reason he took it out is the single most likely 271 00:10:43,860 --> 00:10:48,360 place where epileptic seizures start is the hippocampus. 272 00:10:48,360 --> 00:10:51,660 It's kind of a signal, in many ways, that the hippocampus 273 00:10:51,660 --> 00:10:53,570 does something very dangerous. 274 00:10:53,570 --> 00:10:56,530 It's operating in some sort of fast speed lane of 275 00:10:56,530 --> 00:10:57,550 neurobiology. 276 00:10:57,550 --> 00:11:01,310 It's a very sensitive part of the brain, for lack of oxygen, 277 00:11:01,310 --> 00:11:02,850 for diseases. 278 00:11:02,850 --> 00:11:04,070 We'll talk about Alzheimer's today. 279 00:11:04,070 --> 00:11:06,840 It's a very vulnerable part of the brain, but it does 280 00:11:06,840 --> 00:11:10,490 something magical and essential for memory. 281 00:11:10,490 --> 00:11:12,690 And so they couldn't locate where the seizures were 282 00:11:12,690 --> 00:11:15,110 starting, very well, from him in ways they typically do, so 283 00:11:15,110 --> 00:11:15,720 they said, OK. 284 00:11:15,720 --> 00:11:16,750 He has all these seizures. 285 00:11:16,750 --> 00:11:18,040 We don't know what to do. 286 00:11:18,040 --> 00:11:20,480 Let's take out the left and the right hippocampus and the 287 00:11:20,480 --> 00:11:21,890 surrounding tissue. 288 00:11:21,890 --> 00:11:23,970 And in terms of seizure control, it was pretty 289 00:11:23,970 --> 00:11:25,040 successful. 290 00:11:25,040 --> 00:11:29,040 He had to stay on medications from that day 'til a few years 291 00:11:29,040 --> 00:11:30,960 ago, when he passed away. 292 00:11:30,960 --> 00:11:33,480 But he had very, very few seizures 293 00:11:33,480 --> 00:11:34,350 compared to before that. 294 00:11:34,350 --> 00:11:35,800 So it was medically very successful in 295 00:11:35,800 --> 00:11:37,500 terms of seizure control. 296 00:11:37,500 --> 00:11:39,490 It had a giant side effect. 297 00:11:39,490 --> 00:11:45,150 From that day 'til a couple years ago, HM never formed a 298 00:11:45,150 --> 00:11:48,320 new memory for any event, or for all practical purposes, 299 00:11:48,320 --> 00:11:52,210 for any fact that he was exposed to ever again, despite 300 00:11:52,210 --> 00:11:56,350 his normal intelligence and his 301 00:11:56,350 --> 00:11:58,050 otherwise intact abilities. 302 00:11:58,050 --> 00:11:59,720 So they took an MR of HM. 303 00:11:59,720 --> 00:12:02,530 It took a long time to decide they could even take a MR 304 00:12:02,530 --> 00:12:06,770 picture of HM, because they were very worried that if you 305 00:12:06,770 --> 00:12:10,010 put him in a MR scanner, there's magnetic fields, and 306 00:12:10,010 --> 00:12:12,050 often they put in clips after surgery. 307 00:12:12,050 --> 00:12:14,490 Regularly they put in clips after surgery, to keep the 308 00:12:14,490 --> 00:12:16,940 vessels from bleeding. 309 00:12:16,940 --> 00:12:18,570 And they weren't sure what the clips were 310 00:12:18,570 --> 00:12:19,980 made of for a while. 311 00:12:19,980 --> 00:12:21,630 And so they said, well, we can't put him in, because we 312 00:12:21,630 --> 00:12:26,650 could move the clips and kill him, which would be bad. 313 00:12:26,650 --> 00:12:27,520 So they thought it was dangerous. 314 00:12:27,520 --> 00:12:30,340 And they did a huge detective process of going to factory 315 00:12:30,340 --> 00:12:32,490 that made them and talking to people who built it before 316 00:12:32,490 --> 00:12:34,980 they decided-- it took, like, 10 years of research to decide 317 00:12:34,980 --> 00:12:38,700 that the clips were not metal and they could take an MR. 318 00:12:38,700 --> 00:12:41,010 And even here-- here's the top of the brain, normal person. 319 00:12:41,010 --> 00:12:43,070 Here's the hippocampus, the small structure in you-- 320 00:12:43,070 --> 00:12:44,320 pretty small. 321 00:12:44,320 --> 00:12:46,390 It's removed in him, but you can see he's got a lot of 322 00:12:46,390 --> 00:12:51,240 brain left, except for these removed structures. 323 00:12:51,240 --> 00:12:55,860 But what happened was he had such a fantastic impairment of 324 00:12:55,860 --> 00:12:57,180 learning new information, it got the 325 00:12:57,180 --> 00:12:58,780 label of a global amnesia. 326 00:12:58,780 --> 00:12:59,970 Global amnesia. 327 00:12:59,970 --> 00:13:02,750 It didn't matter whether tests were hard, like remembering 328 00:13:02,750 --> 00:13:04,610 stuff or multiple choice. 329 00:13:04,610 --> 00:13:07,050 He failed practically every standard test of memory you'd 330 00:13:07,050 --> 00:13:08,070 ever give a person. 331 00:13:08,070 --> 00:13:11,120 Or if it's words or nonsense syllables, faces, clicks, 332 00:13:11,120 --> 00:13:14,800 mazes, public events, assassinations of presidents, 333 00:13:14,800 --> 00:13:18,660 wars, going to the moon, whatever 334 00:13:18,660 --> 00:13:20,490 you think of as famous-- 335 00:13:20,490 --> 00:13:22,420 he didn't know they happened at all. 336 00:13:22,420 --> 00:13:23,430 Personal events. 337 00:13:23,430 --> 00:13:25,300 The death of his own parents. 338 00:13:25,300 --> 00:13:27,720 If you asked him how his parents were doing, he would 339 00:13:27,720 --> 00:13:29,830 say something like, I haven't seen them for a while. 340 00:13:29,830 --> 00:13:31,860 He would not know they had passed away. 341 00:13:31,860 --> 00:13:34,710 So no matter how publicly famous something was, no 342 00:13:34,710 --> 00:13:36,860 matter how personally important it was, that 343 00:13:36,860 --> 00:13:37,610 knowledge-- 344 00:13:37,610 --> 00:13:39,860 he could remember it for a few seconds, and we'll talk about 345 00:13:39,860 --> 00:13:41,480 that more, but it would drift away 346 00:13:41,480 --> 00:13:43,030 completely within seconds. 347 00:13:43,030 --> 00:13:45,930 No matter how often he heard it, no matter how personally 348 00:13:45,930 --> 00:13:48,380 important it was. 349 00:13:48,380 --> 00:13:51,360 And you could say, what does he say his experience is like? 350 00:13:51,360 --> 00:13:53,520 So Brenda Milner, the neuropsychologist, who did a 351 00:13:53,520 --> 00:13:55,990 lot of the critical original research with him, describing 352 00:13:55,990 --> 00:13:59,220 his case said that he's said, "Every day is alone in itself, 353 00:13:59,220 --> 00:14:01,460 whatever joy I've had and whatever sorrow I've had." I 354 00:14:01,460 --> 00:14:05,040 mean, it sounds very poetic, and it's true, except that for 355 00:14:05,040 --> 00:14:08,200 HM, his memory lasts seconds. 356 00:14:08,200 --> 00:14:11,730 So he doesn't remember any day since 1950 or something. 357 00:14:11,730 --> 00:14:14,220 So I think his experience is more like this. "Right now I'm 358 00:14:14,220 --> 00:14:17,310 wondering, Have I done or said anything amiss? 359 00:14:17,310 --> 00:14:19,700 You see, at this moment, everything looks clear to me." 360 00:14:19,700 --> 00:14:21,050 His mind is clear. 361 00:14:21,050 --> 00:14:22,070 He's smart. 362 00:14:22,070 --> 00:14:24,720 "But what happened just before?" What happened a 363 00:14:24,720 --> 00:14:27,160 minute ago, or two minutes ago, or five minutes ago? 364 00:14:27,160 --> 00:14:28,270 "That's what worries me. 365 00:14:28,270 --> 00:14:30,740 It's like waking from a dream; I just don't 366 00:14:30,740 --> 00:14:32,280 remember." All right? 367 00:14:32,280 --> 00:14:35,160 So when we worked with him here, a few blocks from here, 368 00:14:35,160 --> 00:14:36,640 he wouldn't know who I was. 369 00:14:36,640 --> 00:14:37,960 He wouldn't know why he was here. 370 00:14:37,960 --> 00:14:40,670 He was an extremely pleasant and wonderful research 371 00:14:40,670 --> 00:14:42,670 participant. 372 00:14:42,670 --> 00:14:44,980 A piece of that was-- he was very nice and very pleasant. 373 00:14:44,980 --> 00:14:47,720 A piece of that was he didn't know time was passing. 374 00:14:47,720 --> 00:14:49,840 So if any of you are involved in experiments as 375 00:14:49,840 --> 00:14:53,690 participants, sometimes people enjoy the experiment for about 376 00:14:53,690 --> 00:14:56,150 five minutes but not for the next 55, because they're 377 00:14:56,150 --> 00:14:58,390 getting a lot of measurements to get a good measurement. 378 00:14:58,390 --> 00:15:01,540 For HM, it was never an hour-long experiment. 379 00:15:01,540 --> 00:15:03,840 It was always a minute and a half experiment. 380 00:15:03,840 --> 00:15:08,470 So you had to be very careful not to abuse that situation as 381 00:15:08,470 --> 00:15:10,160 a researcher. 382 00:15:10,160 --> 00:15:12,030 So here's his name, Henry Molaison. 383 00:15:12,030 --> 00:15:15,660 Here's his pictures from his youth and from this. 384 00:15:15,660 --> 00:15:18,100 But you see how he had a complete reversal? 385 00:15:18,100 --> 00:15:21,600 All of a sudden, the removal just two small regions-- the 386 00:15:21,600 --> 00:15:24,510 left and the right hippocampus in the brain-- 387 00:15:24,510 --> 00:15:27,400 stopped the creation, of formation of new memories 388 00:15:27,400 --> 00:15:30,230 altogether and in any practical way. 389 00:15:30,230 --> 00:15:33,440 So that shows you that memory's not spread throughout 390 00:15:33,440 --> 00:15:36,280 the brain in a sort of undifferentiated mass-action 391 00:15:36,280 --> 00:15:40,120 way, but that particular parts of the brain play very 392 00:15:40,120 --> 00:15:41,800 particular roles in how memories are formed. 393 00:15:41,800 --> 00:15:44,210 And the hippocampus plays a huge role in that. 394 00:15:44,210 --> 00:15:44,700 Can't see it. 395 00:15:44,700 --> 00:15:48,900 So they had a big project where they brought him from 396 00:15:48,900 --> 00:15:50,700 the nursing home in Connecticut where he was. 397 00:15:50,700 --> 00:15:52,630 They drove him by ambulance to 398 00:15:52,630 --> 00:15:54,470 Massachusetts General Hospital. 399 00:15:54,470 --> 00:15:58,670 They overnight did a something like an eight hour MRI scan on 400 00:15:58,670 --> 00:16:00,770 him, to have the world's most detailed MRI scan you 401 00:16:00,770 --> 00:16:02,650 practically have on anybody. 402 00:16:02,650 --> 00:16:04,760 And then they removed his brain and sent it to a 403 00:16:04,760 --> 00:16:09,090 laboratory in San Diego, where they took his brain and they 404 00:16:09,090 --> 00:16:12,895 sliced it into many, many, many incredibly thin slices 405 00:16:12,895 --> 00:16:14,850 that they're going to post on the web. 406 00:16:14,850 --> 00:16:17,790 And on the web for quite a while was the 407 00:16:17,790 --> 00:16:19,470 slicing of his brain. 408 00:16:19,470 --> 00:16:24,530 He consented to this, all this research effort, and finally 409 00:16:24,530 --> 00:16:27,850 his brain is a gift to research and understanding the 410 00:16:27,850 --> 00:16:29,100 brain and memory. 411 00:16:39,220 --> 00:16:41,800 So let me tell you a couple of experimental results from him, 412 00:16:41,800 --> 00:16:44,270 and then you might think of questions you have about what 413 00:16:44,270 --> 00:16:46,290 a man like this is like, OK? 414 00:16:46,290 --> 00:16:49,370 So we talked about last time about that if you give a list 415 00:16:49,370 --> 00:16:51,830 of words to people, and you try to do it yourself, that 416 00:16:51,830 --> 00:16:53,870 people remember the first words best-- 417 00:16:53,870 --> 00:16:56,290 the primacy effect, a long-term memory effect that's 418 00:16:56,290 --> 00:16:59,150 not affected by adding a few seconds of delay-- 419 00:16:59,150 --> 00:17:00,320 and a recency affect-- 420 00:17:00,320 --> 00:17:02,650 superior memory for the last few words of the list that's 421 00:17:02,650 --> 00:17:06,640 strongly affected by adding in just 10 seconds of delay from 422 00:17:06,640 --> 00:17:08,900 the last word until you recall. 423 00:17:08,900 --> 00:17:12,310 And this is done with other amnesic patients, and not HM, 424 00:17:12,310 --> 00:17:13,790 but a similar disorder. 425 00:17:13,790 --> 00:17:15,710 You can see that their memory is worse overall-- 426 00:17:15,710 --> 00:17:16,829 there, the dark line-- 427 00:17:16,829 --> 00:17:19,220 but they have some benefit from the 428 00:17:19,220 --> 00:17:21,680 beginning of the list and-- 429 00:17:21,680 --> 00:17:22,295 but it's small. 430 00:17:22,295 --> 00:17:24,040 It's not the same as the control-- 431 00:17:24,040 --> 00:17:27,040 but they're completely normal, completely normal for the last 432 00:17:27,040 --> 00:17:28,450 two or three words. 433 00:17:28,450 --> 00:17:31,430 So this is what we mean by impaired long-term memory and 434 00:17:31,430 --> 00:17:33,110 spared short-term memory. 435 00:17:33,110 --> 00:17:34,830 But the short-term memory's just moments. 436 00:17:34,830 --> 00:17:37,500 But it's not just an impression you have. 437 00:17:37,500 --> 00:17:41,450 It's a scientific experiment you can do. 438 00:17:41,450 --> 00:17:42,170 Here's another-- 439 00:17:42,170 --> 00:17:43,110 we did this last time. 440 00:17:43,110 --> 00:17:47,030 We said, if you read digits to people and ask them to repeat 441 00:17:47,030 --> 00:17:51,350 them back aloud, that we have a limited short-term memory of 442 00:17:51,350 --> 00:17:52,570 seven plus or minus two. 443 00:17:52,570 --> 00:17:56,860 People get to about seven or eight, typically. 444 00:17:56,860 --> 00:17:59,870 So there's a mean test that's given to look at something. 445 00:17:59,870 --> 00:18:01,420 So here's what they do. 446 00:18:01,420 --> 00:18:03,640 Imagine that you do this test, and you were correct for two 447 00:18:03,640 --> 00:18:06,360 digits, correct for three, repeating them back after you 448 00:18:06,360 --> 00:18:06,960 heard them. 449 00:18:06,960 --> 00:18:10,930 Four, five, six, seven, you did well. 450 00:18:10,930 --> 00:18:13,410 And then you made mistakes at eight, which would be very 451 00:18:13,410 --> 00:18:16,670 typical for a human. 452 00:18:16,670 --> 00:18:19,240 So your span, therefore, is seven. 453 00:18:19,240 --> 00:18:21,170 That's how much you can hold in short-term memory. 454 00:18:21,170 --> 00:18:24,090 It varies a little bit from person to person. 455 00:18:24,090 --> 00:18:26,670 And now they're going to do all the rest of the experiment 456 00:18:26,670 --> 00:18:28,610 at one beyond your span. 457 00:18:28,610 --> 00:18:30,510 One beyond what you can do. 458 00:18:30,510 --> 00:18:32,260 One beyond what your short-term memory-- 459 00:18:32,260 --> 00:18:34,090 here's the limit of your short-term memory. 460 00:18:34,090 --> 00:18:35,770 Let's add one thing. 461 00:18:35,770 --> 00:18:40,490 And one thing that we know helps memory is repetition. 462 00:18:40,490 --> 00:18:43,070 It's not the best way to learn things, but it is a powerful 463 00:18:43,070 --> 00:18:44,400 way to learn things. 464 00:18:44,400 --> 00:18:47,680 So now they give the entire experiment with eight digits 465 00:18:47,680 --> 00:18:51,190 at a time for this person, one beyond what you could report. 466 00:18:51,190 --> 00:18:53,150 So they give you this, and they give you this. 467 00:18:53,150 --> 00:18:56,570 But they give you one boost, which is every third one, it's 468 00:18:56,570 --> 00:18:58,370 the same sequence over and over again. 469 00:18:58,370 --> 00:19:00,970 So some you hear once and once only. 470 00:19:00,970 --> 00:19:03,410 And one, you hear over and over again. 471 00:19:03,410 --> 00:19:04,580 Is that OK? 472 00:19:04,580 --> 00:19:06,380 Now what would happen if you think, if you hear eight 473 00:19:06,380 --> 00:19:08,460 digits over and over again? 474 00:19:08,460 --> 00:19:09,090 What would happen? 475 00:19:09,090 --> 00:19:10,320 You know this in your own life. 476 00:19:10,320 --> 00:19:13,590 Your Social Security number, telephone numbers, things-- 477 00:19:13,590 --> 00:19:14,330 what happens? 478 00:19:14,330 --> 00:19:16,340 Can you learn eight digits if you do it over and--? 479 00:19:16,340 --> 00:19:17,240 Yeah. 480 00:19:17,240 --> 00:19:21,020 It wouldn't be easy, but you get it with repetition. 481 00:19:21,020 --> 00:19:24,360 So here's what happens in typical people. 482 00:19:24,360 --> 00:19:25,380 Here's the repetition. 483 00:19:25,380 --> 00:19:26,980 Here's how well they do for the 484 00:19:26,980 --> 00:19:29,720 non-repeated super-span ones. 485 00:19:29,720 --> 00:19:30,970 They never get that good because they 486 00:19:30,970 --> 00:19:32,470 basically can't do that. 487 00:19:32,470 --> 00:19:34,510 Occasionally they get lucky, but mostly not. 488 00:19:34,510 --> 00:19:37,110 But the ones that repeat, they get better and better. 489 00:19:37,110 --> 00:19:39,790 So repetition is another way to break the bounds of 490 00:19:39,790 --> 00:19:43,480 short-term memory and register something in long-term memory. 491 00:19:43,480 --> 00:19:47,110 But in HM, they did this for hundreds of trials, and he 492 00:19:47,110 --> 00:19:49,890 never got better at the repeated series. 493 00:19:49,890 --> 00:19:52,880 So you could do endless repetition with him, or it 494 00:19:52,880 --> 00:19:53,870 could be personally important. 495 00:19:53,870 --> 00:19:55,330 He wouldn't remember it. 496 00:19:55,330 --> 00:19:58,500 So let me add one more piece to the story. 497 00:19:58,500 --> 00:20:01,460 If I talk to you and say, here are the digits, tell that back 498 00:20:01,460 --> 00:20:03,670 to me, that's an auditory-verbal experiment. 499 00:20:03,670 --> 00:20:05,690 So they're words, and you're hearing them. 500 00:20:05,690 --> 00:20:07,960 You can also test short-term memory and long-term memory 501 00:20:07,960 --> 00:20:10,870 using a visuo-spatial test of blocks. 502 00:20:10,870 --> 00:20:14,260 So you're seeing what the examiner sees, with numbers on 503 00:20:14,260 --> 00:20:16,490 the back of each of these. 504 00:20:16,490 --> 00:20:19,700 The person taking the test just sees these blocks as 505 00:20:19,700 --> 00:20:22,180 black boxes without any number. 506 00:20:22,180 --> 00:20:24,930 You need that because you have a piece of paper with numbers 507 00:20:24,930 --> 00:20:26,830 on it that tell you what to tap. 508 00:20:26,830 --> 00:20:27,490 OK? 509 00:20:27,490 --> 00:20:30,310 So when you give this test, you might see five, seven, 510 00:20:30,310 --> 00:20:33,190 eight, and you would tap with your hand, five, seven, eight, 511 00:20:33,190 --> 00:20:35,970 and the person would tap that back. 512 00:20:35,970 --> 00:20:37,640 And I can tell you what made me pretty nervous when I gave 513 00:20:37,640 --> 00:20:39,850 this test to a person who had a long one? 514 00:20:39,850 --> 00:20:43,170 Because I'd have to read the numbers, practice it, and I'd 515 00:20:43,170 --> 00:20:45,230 be desperately trying to get eight my head, which I could 516 00:20:45,230 --> 00:20:46,530 barely do, maybe. 517 00:20:46,530 --> 00:20:49,400 Because I could tap eight back, so if a person was-- 518 00:20:49,400 --> 00:20:50,300 and then we'd do the same thing. 519 00:20:50,300 --> 00:20:54,380 We'd say, if you can do eight, we'll test you at nine and 520 00:20:54,380 --> 00:20:55,690 repeat them. 521 00:20:55,690 --> 00:20:57,410 And here's two findings, and let's talk 522 00:20:57,410 --> 00:20:58,530 about HM for a moment. 523 00:20:58,530 --> 00:21:02,460 So one finding is now, in patients now-- we're going to 524 00:21:02,460 --> 00:21:03,720 switch one thing a little bit. 525 00:21:03,720 --> 00:21:06,900 HM had the left and the right hippocampus removed. 526 00:21:06,900 --> 00:21:08,960 In these patients, they had either the left 527 00:21:08,960 --> 00:21:10,030 or the right removed. 528 00:21:10,030 --> 00:21:11,510 Either the left or the right. 529 00:21:11,510 --> 00:21:14,870 So here's what happens for normal controls, for the 530 00:21:14,870 --> 00:21:16,360 numbers that are beyond their span. 531 00:21:16,360 --> 00:21:18,780 Not too good, low performance, but they benefit from 532 00:21:18,780 --> 00:21:20,090 repetition. 533 00:21:20,090 --> 00:21:23,050 Here's what happens for the patients with left hippocampal 534 00:21:23,050 --> 00:21:25,290 removals for the auditory-verbal 535 00:21:25,290 --> 00:21:26,540 things for the digits. 536 00:21:31,970 --> 00:21:35,350 So they're good for immediate memory for this stuff, but 537 00:21:35,350 --> 00:21:38,190 they're terrible at developing a long-term memory over here, 538 00:21:38,190 --> 00:21:39,680 if it's verbal. 539 00:21:39,680 --> 00:21:41,790 But the patients with the right temporal 540 00:21:41,790 --> 00:21:44,320 ones are just fine. 541 00:21:44,320 --> 00:21:46,370 For spatial things, it's exactly the opposite. 542 00:21:46,370 --> 00:21:48,870 The group that's really impaired are the patients with 543 00:21:48,870 --> 00:21:52,060 a large right hippocampal removal, and the people with 544 00:21:52,060 --> 00:21:54,360 the left hippocampal do just fine. 545 00:21:54,360 --> 00:21:57,970 So we have two separations in the brain for learning things 546 00:21:57,970 --> 00:21:59,980 in the medial temporal lobes. 547 00:21:59,980 --> 00:22:02,710 Neither the left nor the right are involved in short-term 548 00:22:02,710 --> 00:22:06,180 memory, short-term memory lasting only seconds. 549 00:22:06,180 --> 00:22:09,160 The left is important for verbal long-term memories, and 550 00:22:09,160 --> 00:22:12,840 the right is important for long-term spatial memories, 551 00:22:12,840 --> 00:22:15,390 which is very consistent with what we know about left and 552 00:22:15,390 --> 00:22:19,770 right hemispheres for verbal and spatial knowledge. 553 00:22:19,770 --> 00:22:25,300 So let me say a word more about how we think about the 554 00:22:25,300 --> 00:22:28,040 organization of memory, and we'll come back to this chart. 555 00:22:28,040 --> 00:22:30,040 So we're talking here, so far, about what people call 556 00:22:30,040 --> 00:22:32,160 declarative or explicit memory. 557 00:22:32,160 --> 00:22:34,160 You study some material, you get tested on it. 558 00:22:34,160 --> 00:22:35,710 What did you study? 559 00:22:35,710 --> 00:22:37,430 And people sometimes make a difference between 560 00:22:37,430 --> 00:22:38,930 two kinds of things. 561 00:22:38,930 --> 00:22:43,220 So episodic memory might be if I ask you-- 562 00:22:43,220 --> 00:22:45,360 OK, I need a volunteer in your seat. 563 00:22:45,360 --> 00:22:46,760 It's really easy, this one. 564 00:22:54,580 --> 00:22:55,340 OK, thanks. 565 00:22:55,340 --> 00:22:56,830 I saw some people getting ready to go. 566 00:22:56,830 --> 00:22:59,630 Well, OK. 567 00:22:59,630 --> 00:23:03,110 OK, what did you have for breakfast this morning? 568 00:23:03,110 --> 00:23:05,170 And you don't have to answer honestly if its embarrassing. 569 00:23:05,170 --> 00:23:06,740 You can just give us a standard-- 570 00:23:06,740 --> 00:23:08,460 (LAUGHING) I'm not looking to make-- 571 00:23:08,460 --> 00:23:09,580 yeah. 572 00:23:09,580 --> 00:23:10,020 AUDIENCE: Cereal. 573 00:23:10,020 --> 00:23:10,166 PROFESSOR: Cereal. 574 00:23:10,166 --> 00:23:10,945 How about you? 575 00:23:10,945 --> 00:23:11,280 AUDIENCE: What? 576 00:23:11,280 --> 00:23:11,890 AUDIENCE: Yogurt. 577 00:23:11,890 --> 00:23:12,060 PROFESSOR: Yogurt. 578 00:23:12,060 --> 00:23:12,680 Cereal and yogurt. 579 00:23:12,680 --> 00:23:13,790 Two excellent healthy answers. 580 00:23:13,790 --> 00:23:14,180 OK. 581 00:23:14,180 --> 00:23:17,930 So now I'm going to ask you-- 582 00:23:17,930 --> 00:23:18,990 if I could ask you first. 583 00:23:18,990 --> 00:23:22,080 How many feet in a yard? 584 00:23:22,080 --> 00:23:23,060 AUDIENCE: Three. 585 00:23:23,060 --> 00:23:23,840 PROFESSOR: Excellent. 586 00:23:23,840 --> 00:23:24,710 OK. 587 00:23:24,710 --> 00:23:27,260 And now I'm going to ask you, when and where 588 00:23:27,260 --> 00:23:29,870 did you learn that? 589 00:23:29,870 --> 00:23:30,610 OK? 590 00:23:30,610 --> 00:23:34,520 And you might go, I don't know. 591 00:23:34,520 --> 00:23:35,500 I just learned it. 592 00:23:35,500 --> 00:23:36,360 Right? 593 00:23:36,360 --> 00:23:38,220 Or if I ask you, capital of France. 594 00:23:38,220 --> 00:23:38,670 AUDIENCE: Paris. 595 00:23:38,670 --> 00:23:39,130 PROFESSOR: Paris. 596 00:23:39,130 --> 00:23:40,450 Excellent answer. 597 00:23:40,450 --> 00:23:44,540 When was the shocking moment when this was revealed to you? 598 00:23:44,540 --> 00:23:46,600 When you said, I'll never trust the world again-- 599 00:23:46,600 --> 00:23:47,380 yes. 600 00:23:47,380 --> 00:23:48,250 Who knows, right? 601 00:23:48,250 --> 00:23:51,040 So what you're learning is, episodic memory is memory for 602 00:23:51,040 --> 00:23:53,660 specific events, like what I did last night, what I had for 603 00:23:53,660 --> 00:23:56,880 breakfast, specific time and place. 604 00:23:56,880 --> 00:23:59,410 Semantic memory is what we could call generic memory. 605 00:23:59,410 --> 00:24:02,610 We know lots of things about the world, but we might not 606 00:24:02,610 --> 00:24:04,420 know when or where we learned. 607 00:24:04,420 --> 00:24:06,220 So that's a distinction psychologists find useful to 608 00:24:06,220 --> 00:24:07,280 think about. 609 00:24:07,280 --> 00:24:08,170 So how about in HM? 610 00:24:08,170 --> 00:24:10,850 We said he can't remember digits, or faces, 611 00:24:10,850 --> 00:24:11,810 or things like that. 612 00:24:11,810 --> 00:24:15,100 How about generic memory? 613 00:24:15,100 --> 00:24:19,310 So here's an experiment that I was involved in, where we 614 00:24:19,310 --> 00:24:20,500 said-- because there were some debates 615 00:24:20,500 --> 00:24:21,700 about this at the time. 616 00:24:21,700 --> 00:24:25,270 So we gave HM a multiple choice test where he saw words 617 00:24:25,270 --> 00:24:29,240 or phrases that entered the language after the onset of 618 00:24:29,240 --> 00:24:30,140 his amnesia. 619 00:24:30,140 --> 00:24:32,300 So we thought he wouldn't learn them, but we didn't know 620 00:24:32,300 --> 00:24:34,450 for sure, from just everyday experience. 621 00:24:34,450 --> 00:24:36,530 And by the way, I should tell you, he watched tons of 622 00:24:36,530 --> 00:24:37,670 television. 623 00:24:37,670 --> 00:24:39,710 What his experience was like watching television is an 624 00:24:39,710 --> 00:24:40,760 interesting question. 625 00:24:40,760 --> 00:24:42,230 You should be thinking now about questions you want to 626 00:24:42,230 --> 00:24:44,510 ask about HM. 627 00:24:44,510 --> 00:24:46,180 In a moment, I'll come back to that. 628 00:24:46,180 --> 00:24:48,430 But look at-- so, he has four choices for the word 629 00:24:48,430 --> 00:24:51,290 amniocentesis, including the correct one, but he picks "an 630 00:24:51,290 --> 00:24:53,110 infectious inflammatory disease of the 631 00:24:53,110 --> 00:24:54,630 intestines." apartheid? 632 00:24:54,630 --> 00:24:57,455 In front of him is the correct answer, two other answers, and 633 00:24:57,455 --> 00:25:00,010 he picks, "the separation of young cows that have not yet 634 00:25:00,010 --> 00:25:00,870 given birth to calves." 635 00:25:00,870 --> 00:25:03,000 Boat people? "People who cater bon voyage parties," which is 636 00:25:03,000 --> 00:25:04,600 completely the wrong-- 637 00:25:04,600 --> 00:25:06,360 Brainwash, "a fluid that surrounds and bathes the 638 00:25:06,360 --> 00:25:09,190 brain." Granola, "a portable keyboard wind instrument." 639 00:25:09,190 --> 00:25:11,250 Software, "expensive clothing made of a soft, twilled 640 00:25:11,250 --> 00:25:13,990 fabric." 641 00:25:13,990 --> 00:25:15,290 What's going on with him? 642 00:25:15,290 --> 00:25:18,980 Are these, like, crazy weird answers? 643 00:25:18,980 --> 00:25:21,830 Or how would you-- what do we think is going on with him? 644 00:25:21,830 --> 00:25:22,750 Why is he picking these? 645 00:25:22,750 --> 00:25:24,860 The other one is right in front of him. 646 00:25:24,860 --> 00:25:27,950 What's he doing? 647 00:25:27,950 --> 00:25:29,380 AUDIENCE: Looking at words he knows. 648 00:25:29,380 --> 00:25:30,130 PROFESSOR: Yeah. 649 00:25:30,130 --> 00:25:31,660 He's doing what teachers teach you in school. 650 00:25:31,660 --> 00:25:33,420 Take apart the word into its parts, right? 651 00:25:33,420 --> 00:25:37,680 And so he goes, software, soft clothes that you wear. 652 00:25:37,680 --> 00:25:39,540 But what does that mean? 653 00:25:39,540 --> 00:25:42,850 He's missed, in every sense, the advent of computers and 654 00:25:42,850 --> 00:25:44,140 software in the world. 655 00:25:44,140 --> 00:25:46,450 The idea, the concept, the words-- 656 00:25:46,450 --> 00:25:49,230 it's as if it didn't exist, because in 1953, although 657 00:25:49,230 --> 00:25:52,050 software existed, it wasn't a very popular concept. 658 00:25:52,050 --> 00:25:54,110 Most people didn't know about the concept of that. 659 00:25:54,110 --> 00:25:55,600 In 1953-- 660 00:25:55,600 --> 00:25:57,800 the way we looked at these, these were not words that were 661 00:25:57,800 --> 00:26:02,690 in the dictionary in the 1950s. 662 00:26:02,690 --> 00:26:05,085 So now, what would you like to know about a man like HM? 663 00:26:08,055 --> 00:26:08,550 Yeah. 664 00:26:08,550 --> 00:26:11,025 AUDIENCE: So obviously he couldn't remember something 665 00:26:11,025 --> 00:26:13,747 that happened two hours ago, but if you're having a 666 00:26:13,747 --> 00:26:16,717 conversation with him, would he not remember what you guys 667 00:26:16,717 --> 00:26:17,460 were talking about? 668 00:26:17,460 --> 00:26:20,430 Or could he remember the context of the conversation? 669 00:26:20,430 --> 00:26:20,710 PROFESSOR: Right. 670 00:26:20,710 --> 00:26:22,380 So you're saying, he wouldn't remember something two days 671 00:26:22,380 --> 00:26:23,300 ago, but you're talking with him. 672 00:26:23,300 --> 00:26:23,870 What's that like? 673 00:26:23,870 --> 00:26:25,500 Right? 674 00:26:25,500 --> 00:26:26,650 So let me give you one experimental 675 00:26:26,650 --> 00:26:27,410 thing and then an exper-- 676 00:26:27,410 --> 00:26:29,310 so one experiment they did is they left him with something 677 00:26:29,310 --> 00:26:32,650 like six numbers, well within the span, and said, remember 678 00:26:32,650 --> 00:26:33,850 these numbers. 679 00:26:33,850 --> 00:26:37,210 And it could be, you know, 1, 2, 3, 4, 5, 6-- well, that 680 00:26:37,210 --> 00:26:38,910 wouldn't work so well. 681 00:26:38,910 --> 00:26:40,330 2, 4, 6, 8, 9. 682 00:26:40,330 --> 00:26:40,840 2, 4, 6, 8, 9. 683 00:26:40,840 --> 00:26:42,080 They leave the room for 15 minutes. 684 00:26:42,080 --> 00:26:42,650 They come back in. 685 00:26:42,650 --> 00:26:44,020 He's an excellent subject. 686 00:26:44,020 --> 00:26:44,950 He's going, 2, 4, 6, 8, 9. 687 00:26:44,950 --> 00:26:46,030 2, 4, 6, 8, 9. 688 00:26:46,030 --> 00:26:46,200 What were the numbers? 689 00:26:46,200 --> 00:26:46,840 2, 4, 6, 8, 9. 690 00:26:46,840 --> 00:26:48,480 They go, that's excellent. 691 00:26:48,480 --> 00:26:49,880 Was there any trick you did to do that? 692 00:26:49,880 --> 00:26:50,400 Or did you just-- 693 00:26:50,400 --> 00:26:51,540 And he'd go, oh, oh, oh. 694 00:26:51,540 --> 00:26:53,670 What were the numbers? 695 00:26:53,670 --> 00:26:56,220 As soon as a thought is out of the forefront of 696 00:26:56,220 --> 00:26:58,390 his mind, it's gone. 697 00:26:58,390 --> 00:26:59,590 So, yeah. 698 00:26:59,590 --> 00:27:03,950 He would not recognize us, and we spent many hours with him. 699 00:27:03,950 --> 00:27:06,080 A striking thing, which was amazing at first and then 700 00:27:06,080 --> 00:27:08,040 sometimes irksome if you worked with him-- and he was a 701 00:27:08,040 --> 00:27:09,410 delightful guy-- 702 00:27:09,410 --> 00:27:11,660 was that he would tell you a story from his past. 703 00:27:11,660 --> 00:27:13,455 And he didn't have a huge array of stories, because they 704 00:27:13,455 --> 00:27:16,180 were all from a long time ago. 705 00:27:16,180 --> 00:27:18,250 And he would tell you about a gun collection he had. 706 00:27:18,250 --> 00:27:20,090 And he would tell he had three guns, and they had this 707 00:27:20,090 --> 00:27:21,110 property and that property. 708 00:27:21,110 --> 00:27:24,180 He'd finish the story, and if you just stayed quiet for a 709 00:27:24,180 --> 00:27:28,080 moment, he would forget that he told you the story, but it 710 00:27:28,080 --> 00:27:30,130 would be vaguely on his mind because he 711 00:27:30,130 --> 00:27:31,390 just told it to you. 712 00:27:31,390 --> 00:27:33,200 And he would say to you, hey, did I tell you about my gun 713 00:27:33,200 --> 00:27:33,850 collection? 714 00:27:33,850 --> 00:27:36,730 And he would tell you, almost verbatim, the same story. 715 00:27:36,730 --> 00:27:37,840 You'd just wait a moment. 716 00:27:37,840 --> 00:27:40,790 He forgot that he told you this story, but it's slightly 717 00:27:40,790 --> 00:27:42,080 on his mind because you just told you it. 718 00:27:42,080 --> 00:27:43,300 And he goes, hey, did I tell you my-- 719 00:27:43,300 --> 00:27:47,610 he could tell you this until you could bear it no longer. 720 00:27:47,610 --> 00:27:50,140 So it was kind of amazing how short his 721 00:27:50,140 --> 00:27:51,400 short-term memory was. 722 00:27:51,400 --> 00:27:52,740 Without this part of the brain, 723 00:27:52,740 --> 00:27:54,620 it's just a few seconds. 724 00:27:54,620 --> 00:27:57,200 His conversations were OK, but I would 725 00:27:57,200 --> 00:27:58,240 call them pretty shallow. 726 00:27:58,240 --> 00:28:00,050 I don't know how to put it. 727 00:28:00,050 --> 00:28:02,410 You know, when you talk with somebody and you're on the 728 00:28:02,410 --> 00:28:03,900 phone, and they're doing something 729 00:28:03,900 --> 00:28:04,970 else, and you can tell-- 730 00:28:04,970 --> 00:28:06,900 for him it was a little bit like that. 731 00:28:06,900 --> 00:28:08,195 He was-- so, good social convention. 732 00:28:08,195 --> 00:28:09,080 He would smile. 733 00:28:09,080 --> 00:28:10,170 He would chat with you. 734 00:28:10,170 --> 00:28:12,520 But if what you were talking about depended on remembering 735 00:28:12,520 --> 00:28:15,750 something from three sentences ago in any detail, gone. 736 00:28:15,750 --> 00:28:18,510 Just seconds, unless he's practicing and practicing and 737 00:28:18,510 --> 00:28:19,960 practicing without doing anything else. 738 00:28:19,960 --> 00:28:20,190 Yeah. 739 00:28:20,190 --> 00:28:22,640 AUDIENCE: So he did have the capability to learn 740 00:28:22,640 --> 00:28:23,490 procedurally. 741 00:28:23,490 --> 00:28:23,850 PROFESSOR: Yes. 742 00:28:23,850 --> 00:28:24,550 We're going to come to that. 743 00:28:24,550 --> 00:28:26,510 So the question is, did he ever learn-- he had other 744 00:28:26,510 --> 00:28:28,320 kinds of learning that were amazingly 745 00:28:28,320 --> 00:28:29,600 completely normal in him. 746 00:28:29,600 --> 00:28:30,870 Procedural memory, you're absolutely right. 747 00:28:30,870 --> 00:28:33,590 And we'll come to that just in about 20 minutes, OK? 748 00:28:33,590 --> 00:28:34,480 Exactly right. 749 00:28:34,480 --> 00:28:36,700 And if I don't answer that well, make me do that again. 750 00:28:36,700 --> 00:28:37,250 OK? 751 00:28:37,250 --> 00:28:37,800 But yeah. 752 00:28:37,800 --> 00:28:39,094 Yeah? 753 00:28:39,094 --> 00:28:40,942 AUDIENCE: Was he able to remember that he couldn't 754 00:28:40,942 --> 00:28:41,870 remember things? 755 00:28:41,870 --> 00:28:42,130 PROFESSOR: Yeah. 756 00:28:42,130 --> 00:28:42,740 Really good question. 757 00:28:42,740 --> 00:28:44,990 Was he able to remember that he couldn't remember things? 758 00:28:44,990 --> 00:28:46,480 Yes, he knew he had a bad memory. 759 00:28:46,480 --> 00:28:49,310 So now the question is, in what sense did he know he had 760 00:28:49,310 --> 00:28:50,530 a bad memory? 761 00:28:50,530 --> 00:28:55,060 Like, I know I can't draw very well, amongst many other 762 00:28:55,060 --> 00:28:56,200 things I can't do very well. 763 00:28:56,200 --> 00:28:59,790 But if you talked to him, he'd say, yeah, I 764 00:28:59,790 --> 00:29:00,990 don't have a good memory. 765 00:29:00,990 --> 00:29:02,800 But he's looking at you, and he's going, like, I don't know 766 00:29:02,800 --> 00:29:05,580 where I am, who you are, or what I'm doing. 767 00:29:05,580 --> 00:29:08,660 Everything is vague, for many, many years. 768 00:29:08,660 --> 00:29:09,810 I must have bad memory. 769 00:29:09,810 --> 00:29:11,750 Like, you would too, like a science fiction movie. 770 00:29:11,750 --> 00:29:13,500 You woke up, you didn't know who you were, where you were, 771 00:29:13,500 --> 00:29:15,870 what you were doing, and you can't remember anything except 772 00:29:15,870 --> 00:29:16,850 from the most distant past. 773 00:29:16,850 --> 00:29:18,800 You'd go, something is not good with my memory. 774 00:29:18,800 --> 00:29:20,670 But you're smart, so you would know that. 775 00:29:20,670 --> 00:29:23,030 What I don't know is if you woke him up at 2 AM and you 776 00:29:23,030 --> 00:29:25,510 said, HM, how's your memory? 777 00:29:25,510 --> 00:29:27,940 I don't know if he'd go, well, I'm a famous amnesic, of 778 00:29:27,940 --> 00:29:29,620 course it's terrible. 779 00:29:29,620 --> 00:29:32,240 I don't know if he knew it as a fact, like we might know 780 00:29:32,240 --> 00:29:34,740 about what we're good and not good at, or he just knew it by 781 00:29:34,740 --> 00:29:38,690 constantly being aware that he didn't know anything he ought 782 00:29:38,690 --> 00:29:40,860 to know via memory. 783 00:29:40,860 --> 00:29:42,580 Does that make sense? 784 00:29:42,580 --> 00:29:43,870 Anything else about--? 785 00:29:43,870 --> 00:29:44,210 Yeah. 786 00:29:44,210 --> 00:29:47,870 AUDIENCE: How does one explain scientific consent to--? 787 00:29:47,870 --> 00:29:48,290 PROFESSOR: Oh, this is good. 788 00:29:48,290 --> 00:29:49,310 It's a very interesting question. 789 00:29:49,310 --> 00:29:51,750 Informed consent. 790 00:29:51,750 --> 00:29:55,800 So technically he was conserved by the state once 791 00:29:55,800 --> 00:29:58,790 his family had passed away. 792 00:29:58,790 --> 00:30:00,380 But, you know, his intelligence was fine, so you 793 00:30:00,380 --> 00:30:02,130 had to be a little bit careful to do it right. 794 00:30:02,130 --> 00:30:03,760 But you could tell him, we're going to do an experiment. 795 00:30:03,760 --> 00:30:04,860 We're going to test your memory for words. 796 00:30:04,860 --> 00:30:05,730 Is that OK with you? 797 00:30:05,730 --> 00:30:06,370 And he'd say yes. 798 00:30:06,370 --> 00:30:08,320 Of course, if you had him read a 12-page document, by the 799 00:30:08,320 --> 00:30:10,220 time he got to page 12-- but you could talk him through it. 800 00:30:10,220 --> 00:30:11,895 His intelligence was fine. 801 00:30:11,895 --> 00:30:14,530 You could worry about the edges, if there-- 802 00:30:14,530 --> 00:30:18,920 so I think the investigators felt an extra ethical thing, 803 00:30:18,920 --> 00:30:21,940 also, not to ask him to do anything that a person 804 00:30:21,940 --> 00:30:22,880 might say no to. 805 00:30:22,880 --> 00:30:24,825 He was a wonderful participant, but it was an 806 00:30:24,825 --> 00:30:27,846 extra responsibility for the reason you're saying. 807 00:30:27,846 --> 00:30:31,550 AUDIENCE: Does that mean he was happy all the time? 808 00:30:31,550 --> 00:30:32,630 PROFESSOR: Was he happy all the time? 809 00:30:32,630 --> 00:30:33,620 Excellent question. 810 00:30:33,620 --> 00:30:36,650 He was a very sort of mellow-- 811 00:30:36,650 --> 00:30:36,920 yeah. 812 00:30:36,920 --> 00:30:38,180 Well, you could think for a moment whether having no 813 00:30:38,180 --> 00:30:39,480 memory would make you happy or sad. 814 00:30:39,480 --> 00:30:41,100 So he couldn't hold a job. 815 00:30:41,100 --> 00:30:43,060 He couldn't sustain a human relation because he would 816 00:30:43,060 --> 00:30:44,310 never know he'd met you before. 817 00:30:47,220 --> 00:30:49,680 So, those are things we often think of as pretty big in our 818 00:30:49,680 --> 00:30:51,790 happiness, the kind of the work we do, in some broad 819 00:30:51,790 --> 00:30:54,250 sense, and the people we relate to, right? 820 00:30:54,250 --> 00:30:56,640 And those were all gone for him. 821 00:30:56,640 --> 00:30:58,410 On the other hand, he didn't exactly realize that. 822 00:30:58,410 --> 00:30:59,420 He didn't realize he didn't work. 823 00:30:59,420 --> 00:31:01,460 He didn't realize he didn't have relations he might be 824 00:31:01,460 --> 00:31:04,440 expected to have, because he'd forget that about as fast as 825 00:31:04,440 --> 00:31:06,840 he could think about it. 826 00:31:06,840 --> 00:31:09,180 So I-- 827 00:31:09,180 --> 00:31:12,770 he was kind of a very, I would say, mild, happy person. 828 00:31:12,770 --> 00:31:15,350 So there's three possibilities that crossed my head. 829 00:31:15,350 --> 00:31:17,020 And scientifically, we can never figure them out. 830 00:31:17,020 --> 00:31:21,320 One of them is, maybe just he was that way. 831 00:31:21,320 --> 00:31:23,610 I mean some people are just mellow and happy, right? 832 00:31:23,610 --> 00:31:26,200 They don't have-- without amnesia. 833 00:31:26,200 --> 00:31:29,860 Second possibility is-- he had removed, also, the amygdala. 834 00:31:29,860 --> 00:31:31,930 We'll talk about that later in the course. 835 00:31:31,930 --> 00:31:34,070 That's a structure that's pretty important for some 836 00:31:34,070 --> 00:31:35,990 aspects of emotion and feeling. 837 00:31:35,990 --> 00:31:37,950 So that could have been relevant. 838 00:31:37,950 --> 00:31:39,760 The third one is, but this is kind of getting to your 839 00:31:39,760 --> 00:31:41,700 question, which was just-- 840 00:31:41,700 --> 00:31:42,930 intuitively, I feel like this. 841 00:31:42,930 --> 00:31:45,590 Again, this is not science but is just a feeling. 842 00:31:45,590 --> 00:31:50,030 That what makes us mostly sort of happy or sad? 843 00:31:50,030 --> 00:31:53,840 For me, it's mostly relatively recent things that went well 844 00:31:53,840 --> 00:31:57,400 or didn't go well, or things I'm sad about recently, and 845 00:31:57,400 --> 00:31:59,500 things on my horizon. 846 00:31:59,500 --> 00:32:03,030 Things I'm worried about, or things I'm looking forward to. 847 00:32:03,030 --> 00:32:05,030 And you guys might be different, but I don't get 848 00:32:05,030 --> 00:32:07,490 that worked up these days about second grade. 849 00:32:07,490 --> 00:32:10,170 At the time I'm sure it was pretty emotional about it. 850 00:32:10,170 --> 00:32:13,820 So if you think about him, he doesn't remember anything 851 00:32:13,820 --> 00:32:15,560 recent that was good or bad. 852 00:32:15,560 --> 00:32:20,180 He doesn't remember anything coming up that's interesting, 853 00:32:20,180 --> 00:32:23,020 or threatening, or risky, or unpleasant. 854 00:32:23,020 --> 00:32:24,800 So he lives in this constant now. 855 00:32:24,800 --> 00:32:26,670 You know, people tell you, live in the moment. 856 00:32:26,670 --> 00:32:29,820 Nobody could have lived more in the moment than he did. 857 00:32:29,820 --> 00:32:32,530 It's impossible to live more in the moment when the 858 00:32:32,530 --> 00:32:34,050 previous moment you can consult is from 859 00:32:34,050 --> 00:32:36,140 30, 40 years ago. 860 00:32:36,140 --> 00:32:39,650 So, yeah, he was pretty happy, and a pretty pleasant guy. 861 00:32:39,650 --> 00:32:41,400 Essentially, I don't think most of us want that life, 862 00:32:41,400 --> 00:32:43,180 although he's probably happier than many people who have all 863 00:32:43,180 --> 00:32:45,220 their memories. 864 00:32:45,220 --> 00:32:48,110 One thing he's the opposite of, just to remind you-- 865 00:32:48,110 --> 00:32:49,730 we talked about it now, but just to make it clear-- it's 866 00:32:49,730 --> 00:32:51,460 the opposite of television amnesia. 867 00:32:51,460 --> 00:32:56,010 What happens in soap operas and murder movies or comedy 868 00:32:56,010 --> 00:32:57,460 shows when they get bonked on the head? 869 00:33:00,310 --> 00:33:01,840 Television amnesia. 870 00:33:01,840 --> 00:33:05,850 They forget who they are and where they came from, right? 871 00:33:05,850 --> 00:33:07,820 And then they marry their worst enemy or something like 872 00:33:07,820 --> 00:33:09,800 this, to make the story go forward. 873 00:33:09,800 --> 00:33:10,800 That's television amnesia. 874 00:33:10,800 --> 00:33:12,650 But after that, they're kind of fine, right? 875 00:33:12,650 --> 00:33:14,380 They're kind of operating but they just 876 00:33:14,380 --> 00:33:15,560 forgot where they come-- 877 00:33:15,560 --> 00:33:19,350 that we never see after brain injuries. 878 00:33:19,350 --> 00:33:24,520 We never see a person who forgets who they are but gets 879 00:33:24,520 --> 00:33:25,260 around fine in the world. 880 00:33:25,260 --> 00:33:26,210 HM is the opposite. 881 00:33:26,210 --> 00:33:29,560 He remembers stuff from before, but he 882 00:33:29,560 --> 00:33:30,440 can't learn new things. 883 00:33:30,440 --> 00:33:31,690 Opposite of TV amnesia. 884 00:33:33,950 --> 00:33:35,280 Any other questions about HM? 885 00:33:35,280 --> 00:33:36,698 Yeah. 886 00:33:36,698 --> 00:33:38,634 AUDIENCE: As he got older, could he recognize 887 00:33:38,634 --> 00:33:41,540 people from his past? 888 00:33:41,540 --> 00:33:43,230 AUDIENCE: Yes, and let me talk a little bit about that. 889 00:33:43,230 --> 00:33:45,060 If I don't answer that, let me know. 890 00:33:45,060 --> 00:33:46,080 So let me talk about this. 891 00:33:46,080 --> 00:33:48,160 This sort of touches on this, loss of already-known 892 00:33:48,160 --> 00:33:49,080 information. 893 00:33:49,080 --> 00:33:51,310 And if I don't answer you well, just put your 894 00:33:51,310 --> 00:33:53,550 hand up again, OK? 895 00:33:53,550 --> 00:33:56,780 So it's easy to test learning new things, because you can 896 00:33:56,780 --> 00:33:58,410 give somebody something in the laboratory and you see 897 00:33:58,410 --> 00:33:59,420 if they learn it. 898 00:33:59,420 --> 00:34:00,790 Knowing things they should have known from 899 00:34:00,790 --> 00:34:02,090 before is much harder. 900 00:34:02,090 --> 00:34:05,430 Different people know different things, in the past. 901 00:34:05,430 --> 00:34:06,660 So here's how they'd test it. 902 00:34:06,660 --> 00:34:10,630 And here's a thing that people have discovered, which is 903 00:34:10,630 --> 00:34:14,989 people are pretty unknowledgeable, mostly, about 904 00:34:14,989 --> 00:34:17,550 faces of people who were famous at the 905 00:34:17,550 --> 00:34:18,659 time they were famous. 906 00:34:18,659 --> 00:34:20,929 But if you're, like, 20, you don't know people who were 907 00:34:20,929 --> 00:34:21,929 famous before you were born. 908 00:34:21,929 --> 00:34:22,600 Mostly. 909 00:34:22,600 --> 00:34:24,690 There's some exceptions. 910 00:34:24,690 --> 00:34:28,210 So they'd take faces from different decades, and they'd 911 00:34:28,210 --> 00:34:30,510 show you them and they'd ask you, do you know who this is? 912 00:34:30,510 --> 00:34:32,800 So do you know who this is? 913 00:34:32,800 --> 00:34:34,050 This is Lindbergh. 914 00:34:36,370 --> 00:34:37,620 Frank Sinatra. 915 00:34:39,699 --> 00:34:40,330 Bob Hope. 916 00:34:40,330 --> 00:34:42,679 Does that name even ring a bell? 917 00:34:42,679 --> 00:34:43,639 I know. 918 00:34:43,639 --> 00:34:44,750 This is totally-- 919 00:34:44,750 --> 00:34:49,330 however old you are is totally how you do on this test. 920 00:34:49,330 --> 00:34:51,002 Lyndon Baines Johnson, president of the United States 921 00:34:51,002 --> 00:34:53,780 after Kennedy. 922 00:34:53,780 --> 00:34:56,989 Douglas MacArthur, the general. 923 00:34:56,989 --> 00:34:58,090 This, you might. 924 00:34:58,090 --> 00:34:59,340 Richard Nixon. 925 00:35:02,910 --> 00:35:06,590 McCarthy, as in McCarthyism. 926 00:35:06,590 --> 00:35:08,610 Golda Meir. 927 00:35:08,610 --> 00:35:10,275 Elvis. 928 00:35:10,275 --> 00:35:12,920 OK now. 929 00:35:12,920 --> 00:35:13,790 If you-- 930 00:35:13,790 --> 00:35:15,270 pretend you became amnesic. 931 00:35:15,270 --> 00:35:16,210 You became amnesic. 932 00:35:16,210 --> 00:35:19,320 Pretend you're old enough to become amnesic in 1990. 933 00:35:19,320 --> 00:35:20,520 This is if you're feeling-- 934 00:35:20,520 --> 00:35:24,490 would you know this face, in 1990? 935 00:35:24,490 --> 00:35:25,360 Let's say 1980. 936 00:35:25,360 --> 00:35:26,430 Let's make it simple. 937 00:35:26,430 --> 00:35:27,170 1980? 938 00:35:27,170 --> 00:35:28,280 No. 939 00:35:28,280 --> 00:35:29,956 Would you know this face? 940 00:35:29,956 --> 00:35:30,850 No. 941 00:35:30,850 --> 00:35:31,160 OK. 942 00:35:31,160 --> 00:35:32,630 But you know them now. 943 00:35:32,630 --> 00:35:37,260 So that tells you that you can put faces to decades, roughly. 944 00:35:37,260 --> 00:35:41,000 You know, 1980, only Barack Obama's family knew Barack 945 00:35:41,000 --> 00:35:41,760 Obama's face, right? 946 00:35:41,760 --> 00:35:43,010 And now we all do. 947 00:35:45,410 --> 00:35:47,000 Temporally limited retrograde amnesia. 948 00:35:47,000 --> 00:35:49,400 So this is how well you do-- higher is better-- 949 00:35:49,400 --> 00:35:50,380 in decades. 950 00:35:50,380 --> 00:35:52,110 In 1960, here's HM. 951 00:35:52,110 --> 00:35:55,160 So here's faces that were famous in the '20s, '30s, and 952 00:35:55,160 --> 00:35:57,800 '40s, before he became amnesic, 953 00:35:57,800 --> 00:36:00,120 and he's pretty normal. 954 00:36:00,120 --> 00:36:01,670 These are public faces. 955 00:36:01,670 --> 00:36:03,610 And then he's terrible for the '50s and 956 00:36:03,610 --> 00:36:04,840 '60s, after his amnesia. 957 00:36:04,840 --> 00:36:09,390 So his memory for faces from the past is pretty normal. 958 00:36:09,390 --> 00:36:11,820 His memory for faces from the onset of his amnesia forward 959 00:36:11,820 --> 00:36:12,720 is terrible. 960 00:36:12,720 --> 00:36:13,430 Is that OK? 961 00:36:13,430 --> 00:36:14,725 Does that answer your question reasonably? 962 00:36:17,490 --> 00:36:19,640 But here's another really weird thing that people 963 00:36:19,640 --> 00:36:23,260 observed in many cases, which is kind of hard to understand, 964 00:36:23,260 --> 00:36:24,800 but it's been observed in many cases. 965 00:36:24,800 --> 00:36:26,470 So here's another patient. 966 00:36:26,470 --> 00:36:28,590 He was a bus driver in Washington, DC. 967 00:36:28,590 --> 00:36:30,850 He moved to work in a drugstore in Boston, then a 968 00:36:30,850 --> 00:36:32,480 mattress factory in Boston. 969 00:36:32,480 --> 00:36:36,460 Then he was hospitalized at the Boston VA in November 1965 970 00:36:36,460 --> 00:36:38,685 with a huge hematoma on the right temporal parietal-- a 971 00:36:38,685 --> 00:36:40,010 big bleeding. 972 00:36:40,010 --> 00:36:41,970 And he was pretty aphasic and stuporous. 973 00:36:41,970 --> 00:36:43,750 He couldn't answer questions. 974 00:36:43,750 --> 00:36:47,370 In a month, digit span, his short-term memory returns. 975 00:36:47,370 --> 00:36:52,050 He states the date as approximately something like 976 00:36:52,050 --> 00:36:54,580 September 1965. 977 00:36:54,580 --> 00:36:56,130 He has a severe anterograde amnesia. 978 00:36:56,130 --> 00:36:58,770 For example, he fails to learned the names of the 979 00:36:58,770 --> 00:37:00,550 nurses he sees every day. 980 00:37:00,550 --> 00:37:03,120 But when asked-- this is the striking thing. 981 00:37:03,120 --> 00:37:04,760 When asked, where do you live? 982 00:37:04,760 --> 00:37:08,150 He says, I live in Washington, with certainty, as if he lost 983 00:37:08,150 --> 00:37:10,600 all these memories from before. 984 00:37:10,600 --> 00:37:13,310 By March, he starts to learn the nurses' names. 985 00:37:13,310 --> 00:37:15,640 He's recovering his memory capacity. 986 00:37:15,640 --> 00:37:18,330 He couldn't remember that he'd moved to Boston, but he 987 00:37:18,330 --> 00:37:20,840 doesn't fight the idea that he lives in Boston. 988 00:37:20,840 --> 00:37:22,870 Then he remembers that he worked at a drugstore. 989 00:37:22,870 --> 00:37:24,740 Then he remembers that he worked in a mattress factory. 990 00:37:24,740 --> 00:37:26,840 And by the time that he's discharged, it's only the last 991 00:37:26,840 --> 00:37:29,750 24 hours before he went into the hospital that he's lost. 992 00:37:29,750 --> 00:37:30,730 So two things. 993 00:37:30,730 --> 00:37:33,640 There's a coupling between the anterograde amnesia and the 994 00:37:33,640 --> 00:37:34,600 retrograde amnesia. 995 00:37:34,600 --> 00:37:36,930 He can't learn new things, but he lost old things. 996 00:37:36,930 --> 00:37:40,550 And as the anterograde amnesia resolves, the retrograde 997 00:37:40,550 --> 00:37:43,460 amnesia resolves, in some sense, in temporal order. 998 00:37:43,460 --> 00:37:47,840 It's really odd, but it's been observed many times. 999 00:37:47,840 --> 00:37:51,480 So there is some link between what the hippocampus does and 1000 00:37:51,480 --> 00:37:54,730 memory for the past. 1001 00:37:54,730 --> 00:37:58,010 Now in some ways, it's really hard to study these things in 1002 00:37:58,010 --> 00:37:59,670 detail in a patient like HM. 1003 00:37:59,670 --> 00:38:01,530 But some other patients give us another perspective. 1004 00:38:01,530 --> 00:38:04,330 Although every one of these examples is not quite perfect. 1005 00:38:04,330 --> 00:38:07,180 Here's patients who undergo treatment for depression with 1006 00:38:07,180 --> 00:38:08,470 electroconvulsive therapy. 1007 00:38:08,470 --> 00:38:09,870 And appropriately-- 1008 00:38:09,870 --> 00:38:13,510 in movies like One Flew Over the Cuckoo's Nest, wrongly 1009 00:38:13,510 --> 00:38:16,340 used electroconvulsive therapy is wrong. 1010 00:38:16,340 --> 00:38:19,310 For some patients with severe depression who fail to respond 1011 00:38:19,310 --> 00:38:22,210 to medications and who have suicidal ideation-- 1012 00:38:22,210 --> 00:38:24,060 literally attempt to take their lives or talk a lot 1013 00:38:24,060 --> 00:38:27,320 about it in a believable way to family and physician-- 1014 00:38:27,320 --> 00:38:29,740 electroconvulsive therapy can be very helpful. 1015 00:38:29,740 --> 00:38:32,710 It's a hard choice to make, and a complicated one. 1016 00:38:32,710 --> 00:38:33,330 Here's what happens. 1017 00:38:33,330 --> 00:38:35,650 Patients typically go-- and it varies-- but they go in for 1018 00:38:35,650 --> 00:38:38,040 the electroconvulsive therapy. 1019 00:38:38,040 --> 00:38:39,790 And nowadays, it's done, typically, only in the right 1020 00:38:39,790 --> 00:38:40,270 hemisphere. 1021 00:38:40,270 --> 00:38:42,350 In this study, done some years ago around 1022 00:38:42,350 --> 00:38:44,670 1972, it was bilateral. 1023 00:38:44,670 --> 00:38:46,270 They put electrodes on both sides of the brain. 1024 00:38:46,270 --> 00:38:50,800 They passed current and they induced a seizure. 1025 00:38:50,800 --> 00:38:53,590 And they do that something like every second day for 1026 00:38:53,590 --> 00:38:54,520 about 10 days. 1027 00:38:54,520 --> 00:38:57,460 It's a very aggressive form of treatment, certainly. 1028 00:38:57,460 --> 00:39:00,460 But for some patients, the depression just lifts, and 1029 00:39:00,460 --> 00:39:02,040 they're no longer talking about taking their lives. 1030 00:39:02,040 --> 00:39:06,140 So for some people it seems to work when other things don't. 1031 00:39:06,140 --> 00:39:07,700 During the course of the treatment, these patients 1032 00:39:07,700 --> 00:39:09,700 develop and anterograde amnesia. 1033 00:39:09,700 --> 00:39:11,790 They become HM-like. 1034 00:39:11,790 --> 00:39:13,990 While they're in the hospital, they become HM-like. 1035 00:39:13,990 --> 00:39:15,600 They can't learn new things. 1036 00:39:15,600 --> 00:39:16,560 They forget the nurses. 1037 00:39:16,560 --> 00:39:18,290 You can test them formally. 1038 00:39:18,290 --> 00:39:20,710 And so Larry Squire did the following experiment with 1039 00:39:20,710 --> 00:39:21,910 these kinds of patients. 1040 00:39:21,910 --> 00:39:24,800 So we don't know that it's the hippocampus that's the 1041 00:39:24,800 --> 00:39:26,410 critical thing in these patients, but they 1042 00:39:26,410 --> 00:39:28,740 look a lot like HM. 1043 00:39:28,740 --> 00:39:30,850 And we know that the hippocampus has 1044 00:39:30,850 --> 00:39:32,530 a low seizure threshold. 1045 00:39:32,530 --> 00:39:36,160 That's why it occurs so often as the locus of epilepsy. 1046 00:39:36,160 --> 00:39:38,950 So what they did is they took television shows. 1047 00:39:38,950 --> 00:39:41,020 And this is another world than you can possibly imagine. 1048 00:39:41,020 --> 00:39:43,590 I grew up in a world where there were basically three 1049 00:39:43,590 --> 00:39:44,710 television stations. 1050 00:39:44,710 --> 00:39:46,670 And you're feeling sad for me already, right? 1051 00:39:46,670 --> 00:39:48,690 And so everybody knew what was on those 1052 00:39:48,690 --> 00:39:51,160 three television stations. 1053 00:39:51,160 --> 00:39:52,990 But they took shows that weren't very successful, that 1054 00:39:52,990 --> 00:39:54,900 were on for one season only. 1055 00:39:54,900 --> 00:39:57,320 So they weren't super popular, but a lot of people saw them. 1056 00:39:57,320 --> 00:39:59,250 And there were only three television 1057 00:39:59,250 --> 00:40:01,270 networks and stations. 1058 00:40:01,270 --> 00:40:04,290 So now what they did is they tested them on these events or 1059 00:40:04,290 --> 00:40:07,410 other things like that before they had ECT-- so this is 1060 00:40:07,410 --> 00:40:08,780 their knowledge before they had ECT. 1061 00:40:08,780 --> 00:40:12,930 Of course they remember recent things, 1971, better than 1062 00:40:12,930 --> 00:40:14,840 stuff from years ago. 1063 00:40:14,840 --> 00:40:16,060 We all do. 1064 00:40:16,060 --> 00:40:19,000 But the striking thing is that when these patients got ECT, 1065 00:40:19,000 --> 00:40:22,610 during the course of their amnesia they only lost memory 1066 00:40:22,610 --> 00:40:24,940 for TV shows from the last two years. 1067 00:40:24,940 --> 00:40:26,010 They didn't lose those memories. 1068 00:40:26,010 --> 00:40:27,130 These are the very same patients. 1069 00:40:27,130 --> 00:40:30,780 The very same patients before they got ECT and while they're 1070 00:40:30,780 --> 00:40:35,090 getting ECT, they lose memory only for the last two years of 1071 00:40:35,090 --> 00:40:36,690 TV shows and not all the other ones. 1072 00:40:36,690 --> 00:40:39,850 Or the same thing you can do with famous public events. 1073 00:40:39,850 --> 00:40:41,440 So this is what people call a 1074 00:40:41,440 --> 00:40:43,425 temporally-limited retrograde amnesia. 1075 00:40:43,425 --> 00:40:46,640 It goes back for some years, the knowledge you already had. 1076 00:40:46,640 --> 00:40:48,550 And here's the amazing thing. 1077 00:40:48,550 --> 00:40:50,560 When these patients go home, their memory largely comes 1078 00:40:50,560 --> 00:40:53,410 back and so does their knowledge of the TV shows. 1079 00:40:53,410 --> 00:40:55,030 It's as if it's in their brain. 1080 00:40:55,030 --> 00:40:57,580 They don't have access to it, for the last two years of 1081 00:40:57,580 --> 00:40:58,540 information. 1082 00:40:58,540 --> 00:41:03,290 But it's still sitting there and they regain that access. 1083 00:41:03,290 --> 00:41:05,400 Two more examples on this. 1084 00:41:05,400 --> 00:41:07,110 So here's an example-- 1085 00:41:07,110 --> 00:41:08,620 because with humans it's always tough. 1086 00:41:08,620 --> 00:41:10,120 So they do the same thing with monkeys. 1087 00:41:10,120 --> 00:41:13,180 With monkeys, they could create a surgical lesion like 1088 00:41:13,180 --> 00:41:15,230 HM and train them on material. 1089 00:41:15,230 --> 00:41:17,070 They knew exactly what they learned. 1090 00:41:17,070 --> 00:41:19,940 Here they had the surgery either 2, 4, 8 or 1091 00:41:19,940 --> 00:41:21,940 12, or 8, 16 weeks. 1092 00:41:21,940 --> 00:41:24,630 And you can see the monkeys with the hippocampal damage 1093 00:41:24,630 --> 00:41:28,090 were performing poorly if they learned the material 2 or 4 1094 00:41:28,090 --> 00:41:33,400 weeks ago but not 8 or 16 weeks ago. 1095 00:41:33,400 --> 00:41:36,540 Again, a temporally-limited retrograde amnesia. 1096 00:41:36,540 --> 00:41:39,000 So we're getting the idea that the hippocampus is important, 1097 00:41:39,000 --> 00:41:41,350 not only for forming new memories-- 1098 00:41:41,350 --> 00:41:42,980 and this is kind of wild. 1099 00:41:42,980 --> 00:41:45,590 It's still important for you to remember stuff from a week 1100 00:41:45,590 --> 00:41:48,280 ago, a month ago, and a couple years ago. 1101 00:41:48,280 --> 00:41:52,060 And it takes years for your memory to become independent, 1102 00:41:52,060 --> 00:41:54,510 or what people call consolidated, so that it no 1103 00:41:54,510 --> 00:41:58,280 longer depends upon the hippocampus. 1104 00:41:58,280 --> 00:42:00,960 So the hippocampus both is required to form a new memory, 1105 00:42:00,960 --> 00:42:03,070 and it seems like it's necessary to remember that 1106 00:42:03,070 --> 00:42:06,810 memory from months to years, before that memory becomes 1107 00:42:06,810 --> 00:42:08,380 independent of the hippocampus. 1108 00:42:08,380 --> 00:42:12,770 So right now in you, it's as if you had a neurochemistry 1109 00:42:12,770 --> 00:42:17,960 team finishing your memories from the end of eighth grade. 1110 00:42:17,960 --> 00:42:18,600 We're done. 1111 00:42:18,600 --> 00:42:20,970 We're moving on to ninth grade! 1112 00:42:20,970 --> 00:42:24,340 Because it takes years for your hippocampus to no longer 1113 00:42:24,340 --> 00:42:27,480 be required to get those memories that you 1114 00:42:27,480 --> 00:42:29,010 acquired years ago. 1115 00:42:29,010 --> 00:42:31,070 And the same thing-- they did these famous faces, like the 1116 00:42:31,070 --> 00:42:32,100 ones I showed you before? 1117 00:42:32,100 --> 00:42:33,960 So these had to be somewhat older people. 1118 00:42:33,960 --> 00:42:37,640 Here's activation in the 1990s, if they were looking at 1119 00:42:37,640 --> 00:42:39,880 famous faces and the experiment was done in the 1120 00:42:39,880 --> 00:42:40,670 late 1990s. 1121 00:42:40,670 --> 00:42:44,110 So recent faces, hippocampus turned on, but not for '80s, 1122 00:42:44,110 --> 00:42:46,040 '70s, or '60s, or '50s, or '40s. 1123 00:42:46,040 --> 00:42:48,810 Again, they said the hippocampus is required to 1124 00:42:48,810 --> 00:42:51,260 retrieve memories that's in the rest of your brain for 1125 00:42:51,260 --> 00:42:54,400 some time period, but then after much time passes, it's 1126 00:42:54,400 --> 00:42:55,670 no longer required. 1127 00:42:55,670 --> 00:42:57,630 So this just summarizes those things. 1128 00:42:57,630 --> 00:42:59,560 So now, Tyler, if we could do the film. 1129 00:42:59,560 --> 00:43:01,170 We're going to how you an amnesic patient. 1130 00:43:01,170 --> 00:43:04,460 Most amnesic patients are like this man. 1131 00:43:04,460 --> 00:43:06,570 Very intelligent, very verbal. 1132 00:43:06,570 --> 00:43:10,280 Not dramatic, but with terribly impaired memory. 1133 00:43:21,100 --> 00:43:24,510 So last part of the talk is this idea of memory systems 1134 00:43:24,510 --> 00:43:27,250 and procedural memory, the idea that you're a symphony of 1135 00:43:27,250 --> 00:43:28,880 the neural systems that learn different things. 1136 00:43:28,880 --> 00:43:31,620 So your brain is like the university, right? 1137 00:43:31,620 --> 00:43:33,800 Department of Chemistry, department of Biology, 1138 00:43:33,800 --> 00:43:34,570 department of Brain and 1139 00:43:34,570 --> 00:43:36,130 Cognitive Science, or Economics. 1140 00:43:36,130 --> 00:43:39,770 In you are multiple very specialized learning circuits 1141 00:43:39,770 --> 00:43:41,530 that are good for learning different things. 1142 00:43:41,530 --> 00:43:43,640 So this idea of a memory system, a particular part of 1143 00:43:43,640 --> 00:43:47,690 the brain that has a particular learning process. 1144 00:43:47,690 --> 00:43:50,180 And a key concept in that is, so far we've been talking 1145 00:43:50,180 --> 00:43:52,340 about what people would normally call memory-- 1146 00:43:52,340 --> 00:43:53,710 explicit or direct testing. 1147 00:43:53,710 --> 00:43:55,530 You know, what did you study? 1148 00:43:55,530 --> 00:43:56,200 What year is it? 1149 00:43:56,200 --> 00:43:58,060 You're asked directly to do something. 1150 00:43:58,060 --> 00:44:01,310 But another way to show memory and learning is through 1151 00:44:01,310 --> 00:44:05,220 changes in performance with practice. 1152 00:44:05,220 --> 00:44:07,460 So people will sometimes call the first kind declarative 1153 00:44:07,460 --> 00:44:10,200 memory, where you directly have conscious memory about 1154 00:44:10,200 --> 00:44:11,190 facts and episodes. 1155 00:44:11,190 --> 00:44:13,260 You know that you know something, or 1156 00:44:13,260 --> 00:44:14,890 that something occurred. 1157 00:44:14,890 --> 00:44:16,680 And then the other kind, we'll talk about now, procedural 1158 00:44:16,680 --> 00:44:19,350 memory, accessible only through performance and 1159 00:44:19,350 --> 00:44:21,420 knowing how. 1160 00:44:21,420 --> 00:44:23,480 Now with these kinds of skill learning or procedural memory, 1161 00:44:23,480 --> 00:44:25,900 we see how people get better when they practice. 1162 00:44:25,900 --> 00:44:28,830 Getting better is a change in your behavior that's learned 1163 00:44:28,830 --> 00:44:30,085 and a change in your brain that performs. 1164 00:44:30,085 --> 00:44:32,010 This is for your performance. 1165 00:44:32,010 --> 00:44:34,710 So here's the experiment that was the original one Brenda 1166 00:44:34,710 --> 00:44:36,970 Milner did with HM, where you have to 1167 00:44:36,970 --> 00:44:38,670 trace a star in a mirror. 1168 00:44:38,670 --> 00:44:41,230 You see your hand in a mirror, but you don't have direct view 1169 00:44:41,230 --> 00:44:42,000 of your hand. 1170 00:44:42,000 --> 00:44:44,125 Have any of you done something like this for some odds and 1171 00:44:44,125 --> 00:44:45,060 ends reason? 1172 00:44:45,060 --> 00:44:45,440 Anybody? 1173 00:44:45,440 --> 00:44:47,480 Sometimes-- 1174 00:44:47,480 --> 00:44:49,350 do I see a hand? 1175 00:44:49,350 --> 00:44:49,750 No. 1176 00:44:49,750 --> 00:44:50,750 OK. 1177 00:44:50,750 --> 00:44:51,940 It's surprisingly hard. 1178 00:44:51,940 --> 00:44:53,830 The horizontals and verticals are pretty easy. 1179 00:44:53,830 --> 00:44:55,970 The diagonals, as you move your hand, you 1180 00:44:55,970 --> 00:44:56,920 go, oh, it's no problem. 1181 00:44:56,920 --> 00:44:58,730 I just reverse everything. 1182 00:44:58,730 --> 00:45:01,540 And you see your hand just drift the wrong way. 1183 00:45:01,540 --> 00:45:03,740 And you go, OK, no, no, no, no. 1184 00:45:03,740 --> 00:45:06,350 I just have to go 45 degrees difference. 1185 00:45:06,350 --> 00:45:07,080 I can do it. 1186 00:45:07,080 --> 00:45:09,340 And you're controlling your hand, but then you move again 1187 00:45:09,340 --> 00:45:10,420 and it still goes the wrong way. 1188 00:45:10,420 --> 00:45:12,970 And so at first, you make lots of mistakes. 1189 00:45:12,970 --> 00:45:16,550 We understand this because you have such automaticity between 1190 00:45:16,550 --> 00:45:19,030 what you see and how you move all the time, that the mirror 1191 00:45:19,030 --> 00:45:21,860 reverse, you have to overcome that automatic relationship. 1192 00:45:21,860 --> 00:45:24,410 So at first you make a lot of mistakes and move slowly. 1193 00:45:24,410 --> 00:45:26,000 You practice, and you get better. 1194 00:45:26,000 --> 00:45:28,800 Here's the remarkable thing with-- so here's HM. 1195 00:45:28,800 --> 00:45:32,700 Each of these dots is the next time he does it consecutively. 1196 00:45:32,700 --> 00:45:35,580 He gets better from doing it over and over again. 1197 00:45:35,580 --> 00:45:36,390 That's not a shock. 1198 00:45:36,390 --> 00:45:36,850 Here's the shock. 1199 00:45:36,850 --> 00:45:39,565 He comes the next day, he keeps the learning he had and 1200 00:45:39,565 --> 00:45:40,150 he gets better. 1201 00:45:40,150 --> 00:45:42,510 He comes in day three, he keeps learning. 1202 00:45:42,510 --> 00:45:46,180 Now for him, a day is like infinity, for memory. 1203 00:45:46,180 --> 00:45:48,270 When he comes in the room, he says, what do I do with this? 1204 00:45:48,270 --> 00:45:49,800 You'd go, well, we did it the last two days. 1205 00:45:49,800 --> 00:45:50,230 Don't you know? 1206 00:45:50,230 --> 00:45:52,050 He said, no, I have no idea. 1207 00:45:52,050 --> 00:45:53,050 Have you done this before? 1208 00:45:53,050 --> 00:45:53,540 No. 1209 00:45:53,540 --> 00:45:55,310 You can give him multiple choice of different things he 1210 00:45:55,310 --> 00:45:55,770 might have done. 1211 00:45:55,770 --> 00:45:57,050 He'll pick the wrong thing. 1212 00:45:57,050 --> 00:45:59,600 When you come in on day three and you're this good, you're 1213 00:45:59,600 --> 00:46:00,280 pretty proud. 1214 00:46:00,280 --> 00:46:01,220 In fact, vain. 1215 00:46:01,220 --> 00:46:02,180 You're going, like, I can do this. 1216 00:46:02,180 --> 00:46:02,970 I'm awesome. 1217 00:46:02,970 --> 00:46:04,560 Just let me at it. 1218 00:46:04,560 --> 00:46:06,110 Because you know that you did it. 1219 00:46:06,110 --> 00:46:07,890 You know how good you are through practice. 1220 00:46:07,890 --> 00:46:11,180 He has no idea, but his learning is entirely normal. 1221 00:46:11,180 --> 00:46:13,290 Not just better than you'd think? 1222 00:46:13,290 --> 00:46:15,240 Just as good as you. 1223 00:46:15,240 --> 00:46:18,610 So a memory system in his brain, different than the 1224 00:46:18,610 --> 00:46:22,600 hippocampus, has kept that memory, uses that memory. 1225 00:46:22,600 --> 00:46:24,670 And the amazing thing is that this means that that's also 1226 00:46:24,670 --> 00:46:27,090 true in you, as far as we understand these things. 1227 00:46:27,090 --> 00:46:30,570 When you learn a physical or mental skill, a lot of it is 1228 00:46:30,570 --> 00:46:34,690 learned in a way that has nothing to do with your memory 1229 00:46:34,690 --> 00:46:35,800 that you learned the skill. 1230 00:46:35,800 --> 00:46:37,560 It's all by doing. 1231 00:46:37,560 --> 00:46:39,470 And it doesn't depend on the hippocampus. 1232 00:46:39,470 --> 00:46:42,730 And some years later, I did this again a little bit. 1233 00:46:42,730 --> 00:46:46,390 Here's his performance first, second, third day, a week 1234 00:46:46,390 --> 00:46:48,530 later, two weeks later, and a year later. 1235 00:46:48,530 --> 00:46:52,580 Complete retention for a man who can forget within moments. 1236 00:46:52,580 --> 00:46:54,820 A year later, a skill. 1237 00:46:54,820 --> 00:46:57,770 He forgets that he did it ever within moments. 1238 00:46:57,770 --> 00:47:01,215 So another kind of task that people do-- same idea. 1239 00:47:01,215 --> 00:47:03,710 A motor skill you can lose, it's called rotary pursuit. 1240 00:47:03,710 --> 00:47:06,080 There's a disc like this that revolves around a platter that 1241 00:47:06,080 --> 00:47:07,600 turns pretty fast. 1242 00:47:07,600 --> 00:47:10,360 Your job is to maintain contact between-- 1243 00:47:10,360 --> 00:47:12,100 this was sort of sad before video games, right? 1244 00:47:12,100 --> 00:47:16,490 This is about as interesting as 1940s games got. 1245 00:47:16,490 --> 00:47:19,250 It was whizzed around, and it's fast enough that it's not 1246 00:47:19,250 --> 00:47:19,750 easy to do. 1247 00:47:19,750 --> 00:47:21,550 And at first your hand goes off it, but with practice you 1248 00:47:21,550 --> 00:47:25,060 get really good at revolving with a rotating disc. 1249 00:47:25,060 --> 00:47:29,330 And HM and patients like him learned that very well. 1250 00:47:29,330 --> 00:47:30,460 Another motor skill. 1251 00:47:30,460 --> 00:47:32,210 So who's bad at learning this? 1252 00:47:32,210 --> 00:47:34,620 Which part of the brain is your instrument for learning 1253 00:47:34,620 --> 00:47:36,350 skills through practice? 1254 00:47:36,350 --> 00:47:38,280 So our best evidence comes from patients with a very 1255 00:47:38,280 --> 00:47:40,090 difficult disease called Huntington's disease. 1256 00:47:40,090 --> 00:47:42,030 It's a genetic rare disease. 1257 00:47:42,030 --> 00:47:44,190 Its onset is in the 30s or 40s. 1258 00:47:44,190 --> 00:47:46,760 These patients get severe motor problems and movement 1259 00:47:46,760 --> 00:47:49,380 problems, and then, over time, cognitive ones 1260 00:47:49,380 --> 00:47:52,120 and psychiatric ones. 1261 00:47:52,120 --> 00:47:54,470 There's no treatment for it. 1262 00:47:54,470 --> 00:47:57,240 So this is the caudate withering away in a patient 1263 00:47:57,240 --> 00:47:59,140 with Huntington's disease compared to a healthy 1264 00:47:59,140 --> 00:48:00,670 person's, post mortem. 1265 00:48:00,670 --> 00:48:05,240 Or if you look at an MRI, here's your basal ganglia. 1266 00:48:05,240 --> 00:48:07,850 Here's the withered away basal ganglia in the patients with 1267 00:48:07,850 --> 00:48:09,310 Huntington's disease. 1268 00:48:09,310 --> 00:48:11,290 And there's a brief-- 1269 00:48:11,290 --> 00:48:14,920 can we do, Tyler-- there's a brief video of a patient with 1270 00:48:14,920 --> 00:48:16,280 early-stage Huntington's disease. 1271 00:48:26,740 --> 00:48:30,190 So it's not the most severe problem they have, but when 1272 00:48:30,190 --> 00:48:32,490 they do one of these motor kinds of tasks-- 1273 00:48:32,490 --> 00:48:35,460 here's normal typical people learning a motor task, getting 1274 00:48:35,460 --> 00:48:36,020 better on it. 1275 00:48:36,020 --> 00:48:37,640 It's good to be high on this graph. 1276 00:48:37,640 --> 00:48:39,285 Here's the patients with Huntington's disease showing 1277 00:48:39,285 --> 00:48:40,060 no learning at all. 1278 00:48:40,060 --> 00:48:41,460 And this is a test that an amnesic 1279 00:48:41,460 --> 00:48:43,220 patient would learn normally. 1280 00:48:43,220 --> 00:48:45,160 So very convincing-- and you could say, well, if they have 1281 00:48:45,160 --> 00:48:47,620 a motor problem, they're not going to get a motor skill. 1282 00:48:47,620 --> 00:48:51,700 So one thing they do is they make the platter turn very 1283 00:48:51,700 --> 00:48:54,580 slowly, so at the beginning they're doing just as well. 1284 00:48:54,580 --> 00:48:56,440 And they still show no learning at all. 1285 00:48:56,440 --> 00:48:59,330 So there's a lot of other evidence sparked by this that 1286 00:48:59,330 --> 00:49:02,320 just shows that the basal ganglia is an instrument 1287 00:49:02,320 --> 00:49:06,000 that's essential for us to learn physical or motor 1288 00:49:06,000 --> 00:49:08,220 skills, perceptual skills, and a variety of 1289 00:49:08,220 --> 00:49:09,740 cognitive skills as well. 1290 00:49:09,740 --> 00:49:11,820 Things where we practice, practice, practice to become 1291 00:49:11,820 --> 00:49:12,670 excellent-- 1292 00:49:12,670 --> 00:49:16,080 basal ganglia is doing a lot of that work for you. 1293 00:49:16,080 --> 00:49:18,270 The last kind of learning I'll talk to you about, and the 1294 00:49:18,270 --> 00:49:21,920 last disease, is a sort of odder form of learning called 1295 00:49:21,920 --> 00:49:23,760 repetition priming. 1296 00:49:23,760 --> 00:49:26,520 It's a change in performance because of 1297 00:49:26,520 --> 00:49:28,160 something you did recently. 1298 00:49:28,160 --> 00:49:30,610 And if I give you a concrete example, it'll feel better. 1299 00:49:30,610 --> 00:49:34,230 So here's one of many examples. 1300 00:49:34,230 --> 00:49:37,050 Imagine you study a list of words like stamp, landmark, 1301 00:49:37,050 --> 00:49:37,760 speak, clock. 1302 00:49:37,760 --> 00:49:39,030 You study a list of words like these. 1303 00:49:39,030 --> 00:49:41,390 I can give you an explicit or declarative memory test. 1304 00:49:41,390 --> 00:49:42,630 What words did you see? 1305 00:49:42,630 --> 00:49:43,430 You'd recall them. 1306 00:49:43,430 --> 00:49:45,960 Or which word did you see, that we'd do multiple choice. 1307 00:49:45,960 --> 00:49:48,420 That's regular memory that we know depends on the 1308 00:49:48,420 --> 00:49:49,710 hippocampus. 1309 00:49:49,710 --> 00:49:52,370 I can also give you weird test like this, which says, tell me 1310 00:49:52,370 --> 00:49:55,210 the first word you think of that starts with STA. 1311 00:49:55,210 --> 00:49:57,000 Now if you have good memory, you'll go, do you want me to 1312 00:49:57,000 --> 00:49:58,270 give you stamp? 1313 00:49:58,270 --> 00:49:59,050 Is that the point? 1314 00:49:59,050 --> 00:49:59,940 And you go, no, no, no. 1315 00:49:59,940 --> 00:50:01,380 And they go, oh, it's a Freudian thing. 1316 00:50:01,380 --> 00:50:03,480 You want to know some weird things I'm gonna think of. 1317 00:50:03,480 --> 00:50:04,340 And you go, no, no, no. 1318 00:50:04,340 --> 00:50:06,630 Just tell me the first word you think of, OK? 1319 00:50:06,630 --> 00:50:08,850 And you can give many answers that are all perfectly fine. 1320 00:50:08,850 --> 00:50:11,950 You can give stall, stand, staccato, star, many STA 1321 00:50:11,950 --> 00:50:14,070 words, and all of them are fine. 1322 00:50:14,070 --> 00:50:15,090 That's all you have to do. 1323 00:50:15,090 --> 00:50:18,360 But if you saw stamp, one particular completion of this, 1324 00:50:18,360 --> 00:50:22,240 about 10 minutes ago, you're biased or primed to come up 1325 00:50:22,240 --> 00:50:22,790 with that word. 1326 00:50:22,790 --> 00:50:25,760 Not all the time, but much more than by chance. 1327 00:50:25,760 --> 00:50:29,840 A recent experience biases you to behave in a certain way. 1328 00:50:29,840 --> 00:50:30,990 And here's the remarkable thing. 1329 00:50:30,990 --> 00:50:35,230 When you do this experiment with HM, if you just had the 1330 00:50:35,230 --> 00:50:37,150 list of words and you wait about 20 1331 00:50:37,150 --> 00:50:38,660 seconds, here's your recall. 1332 00:50:38,660 --> 00:50:40,970 Now you're not surprised that recall from a healthy person 1333 00:50:40,970 --> 00:50:42,190 is about seven words, right? 1334 00:50:42,190 --> 00:50:43,280 You tried that yourself. 1335 00:50:43,280 --> 00:50:45,350 HM, sadly, has no score because he always 1336 00:50:45,350 --> 00:50:46,840 goes, like, what list? 1337 00:50:46,840 --> 00:50:48,050 So no recall. 1338 00:50:48,050 --> 00:50:51,670 Multiple choice recognition, where there are three choices, 1339 00:50:51,670 --> 00:50:55,000 here's typical people, HM about chance. 1340 00:50:55,000 --> 00:50:57,270 The probability above chance-- 1341 00:50:57,270 --> 00:51:00,100 that you give stamp as the completion to 1342 00:51:00,100 --> 00:51:02,160 STA if you saw stamp-- 1343 00:51:02,160 --> 00:51:04,550 if I showed you star, probably you'd give star. 1344 00:51:04,550 --> 00:51:07,240 The specific word you saw 10 minutes ago? 1345 00:51:07,240 --> 00:51:10,660 Perfectly the same in HM as normal control subjects. 1346 00:51:10,660 --> 00:51:14,550 He was just as influenced by that word he saw 10 minutes 1347 00:51:14,550 --> 00:51:18,310 ago as you are, to give you that answer. 1348 00:51:18,310 --> 00:51:20,710 So this got people very excited, because they said, 1349 00:51:20,710 --> 00:51:23,370 now we can experimentally and scientifically study something 1350 00:51:23,370 --> 00:51:27,640 that Freud talked about as a very vague idea, the cognitive 1351 00:51:27,640 --> 00:51:28,350 unconscious. 1352 00:51:28,350 --> 00:51:31,760 He's not conscious that he saw a list of words 10 minutes 1353 00:51:31,760 --> 00:51:34,700 ago, but it's making him choose to behave in 1354 00:51:34,700 --> 00:51:36,870 a certain way now. 1355 00:51:36,870 --> 00:51:38,700 Now you have both things in you, as far as 1356 00:51:38,700 --> 00:51:39,670 we understand it. 1357 00:51:39,670 --> 00:51:42,130 You can both remember you saw the word list, but if you 1358 00:51:42,130 --> 00:51:44,340 switch your thinking a little bit, your behavior a little 1359 00:51:44,340 --> 00:51:48,210 bit, the unconscious system gets into the driver's seat. 1360 00:51:48,210 --> 00:51:52,070 Because the people with good memory were giving stamp often 1361 00:51:52,070 --> 00:51:54,770 but no more or less than HM. 1362 00:51:54,770 --> 00:51:55,950 So unconscious. 1363 00:51:55,950 --> 00:51:59,930 So what part of the brain does this kind of memory? 1364 00:51:59,930 --> 00:52:02,860 And our insight to that comes from Alzheimer's disease. 1365 00:52:02,860 --> 00:52:08,390 So HM's kind of amnesia is extremely rare. 1366 00:52:08,390 --> 00:52:09,630 Huntington's is quite rare. 1367 00:52:09,630 --> 00:52:12,200 Alzheimer's is tragically common. 1368 00:52:12,200 --> 00:52:15,510 In fact, they went to East Boston, the area near Logan, 1369 00:52:15,510 --> 00:52:17,780 and knocked on doors of people's homes. 1370 00:52:17,780 --> 00:52:18,850 Not people in nursing homes. 1371 00:52:18,850 --> 00:52:19,670 At home. 1372 00:52:19,670 --> 00:52:20,570 And they estimated-- 1373 00:52:20,570 --> 00:52:22,620 and there's debates about this back and forth. 1374 00:52:22,620 --> 00:52:28,000 But about half the people over 85 who answered the door 1375 00:52:28,000 --> 00:52:32,340 qualify for diagnosis of Alzheimer's disease. 1376 00:52:32,340 --> 00:52:34,480 About half over 85. 1377 00:52:34,480 --> 00:52:35,360 There's debates about this. 1378 00:52:35,360 --> 00:52:37,200 There's debates about whether all of us would get it if we 1379 00:52:37,200 --> 00:52:39,350 lived long enough. 1380 00:52:39,350 --> 00:52:43,790 But as American society gets older, as us baby boomers all 1381 00:52:43,790 --> 00:52:47,920 move into our '60s, '70s, and '80s, there's going to be a 1382 00:52:47,920 --> 00:52:50,800 heck of a lot of people around with Alzheimer's disease. 1383 00:52:50,800 --> 00:52:53,080 And some of you have probably experienced this, with 1384 00:52:53,080 --> 00:52:54,610 grandparents if nothing else. 1385 00:52:54,610 --> 00:52:57,350 It's a very devastating disorder for the patient, for 1386 00:52:57,350 --> 00:52:58,325 the spouse or family. 1387 00:52:58,325 --> 00:53:00,480 It's a very challenging disorder. 1388 00:53:00,480 --> 00:53:01,960 So what is Alzheimer's disease? 1389 00:53:01,960 --> 00:53:03,885 Well behaviorally, it's an insidious 1390 00:53:03,885 --> 00:53:05,180 and progressive dementia. 1391 00:53:05,180 --> 00:53:09,070 Dementia means, unlike HM, it's many losses of abilities. 1392 00:53:09,070 --> 00:53:09,790 Unlike HM. 1393 00:53:09,790 --> 00:53:11,470 HM had his surgery one day, boom. 1394 00:53:11,470 --> 00:53:12,510 That was it. 1395 00:53:12,510 --> 00:53:14,430 Alzheimer's starts very slowly and gets worse 1396 00:53:14,430 --> 00:53:15,740 and worse over time. 1397 00:53:15,740 --> 00:53:18,840 The biggest problem early on is memory, the most common 1398 00:53:18,840 --> 00:53:21,430 problem but over time, language, thinking, 1399 00:53:21,430 --> 00:53:24,060 concentration, spatial thinking, sometimes mood and 1400 00:53:24,060 --> 00:53:28,740 personality, all of these get altered over time. 1401 00:53:28,740 --> 00:53:31,430 In the brain when you look at the changes, you see that the 1402 00:53:31,430 --> 00:53:34,300 changes occur especially in the hippocampal region-- so 1403 00:53:34,300 --> 00:53:36,700 that's why the memory problem is like HM-- 1404 00:53:36,700 --> 00:53:40,270 and also in some other parts of the cortex, but not so 1405 00:53:40,270 --> 00:53:42,960 much, for example, in basal ganglia, that we just spoke 1406 00:53:42,960 --> 00:53:46,000 about as important for procedural memory. 1407 00:53:46,000 --> 00:53:49,640 Here's a control brain and equal-aged Alzheimer's brain. 1408 00:53:49,640 --> 00:53:52,820 The reason why these gyri, this whole side widened is 1409 00:53:52,820 --> 00:53:57,740 because of widespread neuronal shrinkage or death. 1410 00:53:57,740 --> 00:54:00,540 And what's happening inside the brain, when you look at 1411 00:54:00,540 --> 00:54:03,480 post mortem, there's sort of neurofibrillary tangles and 1412 00:54:03,480 --> 00:54:05,740 plaques that are associated with the diseases. 1413 00:54:05,740 --> 00:54:07,800 The tangles are something about the 1414 00:54:07,800 --> 00:54:09,410 cells that have died. 1415 00:54:09,410 --> 00:54:12,130 The plaques are thought to be maybe part of the process that 1416 00:54:12,130 --> 00:54:14,590 leads to the disorder, but there's a debate about 1417 00:54:14,590 --> 00:54:16,840 that to this day. 1418 00:54:16,840 --> 00:54:20,100 And if you look, on post mortem, where the tangles are, 1419 00:54:20,100 --> 00:54:23,050 the tangles up here, you can see they're most dense in the 1420 00:54:23,050 --> 00:54:26,600 hippocampus or near the hippocampus, like HM. 1421 00:54:26,600 --> 00:54:29,030 And so that's why we think so many patients with Alzheimer's 1422 00:54:29,030 --> 00:54:31,830 have an HM-like memory problem and then more 1423 00:54:31,830 --> 00:54:33,710 problems after that. 1424 00:54:33,710 --> 00:54:36,680 So here's a healthy person top of the brain. 1425 00:54:36,680 --> 00:54:40,330 Here's the left and right hippocampus in an 81-year-old. 1426 00:54:40,330 --> 00:54:43,090 And here in an 80-year-old Alzheimer's patient, the 1427 00:54:43,090 --> 00:54:45,905 hippocampus has withered away, both sides of the brain, 1428 00:54:45,905 --> 00:54:48,030 bilaterally. 1429 00:54:48,030 --> 00:54:51,020 So one more brain perspective on this. 1430 00:54:51,020 --> 00:54:53,030 This is a SPECT scan, that just shows you where there's 1431 00:54:53,030 --> 00:54:54,920 blood flow and metabolism. 1432 00:54:54,920 --> 00:54:56,480 Top of the brain, bottom of the brain. 1433 00:54:56,480 --> 00:54:59,500 Here's the insides of the temporal lobes in a healthy 1434 00:54:59,500 --> 00:55:01,290 elderly adult. 1435 00:55:01,290 --> 00:55:02,320 Look how much worse-- 1436 00:55:02,320 --> 00:55:03,100 this is HM. 1437 00:55:03,100 --> 00:55:03,950 He looks pretty good, right? 1438 00:55:03,950 --> 00:55:06,145 You have to look really hard to see that the hippocampus is 1439 00:55:06,145 --> 00:55:08,180 missing because it's such a small structure. 1440 00:55:08,180 --> 00:55:10,830 And here's an early-stage Alzheimer's patient. 1441 00:55:10,830 --> 00:55:13,500 Lots of the tissue is there, but a lot of-- you know, it's 1442 00:55:13,500 --> 00:55:17,550 not functioning because there's so much damage. 1443 00:55:17,550 --> 00:55:20,080 Here's the medial temporal lobes but also cortical areas 1444 00:55:20,080 --> 00:55:21,330 that are compromised. 1445 00:55:23,160 --> 00:55:23,690 OK, again. 1446 00:55:23,690 --> 00:55:26,770 Not their biggest problem, but in terms of thinking about 1447 00:55:26,770 --> 00:55:28,020 different parts of the brain and what parts 1448 00:55:28,020 --> 00:55:30,430 of memory they do-- 1449 00:55:30,430 --> 00:55:32,720 So these are amnesic patients, including HM, Alzheimer's 1450 00:55:32,720 --> 00:55:34,250 patients, and green in controls. 1451 00:55:34,250 --> 00:55:36,340 So recall of the list, what words were on the list, 1452 00:55:36,340 --> 00:55:39,110 explicit memory bad in the two patient groups. 1453 00:55:39,110 --> 00:55:42,190 Recognition pretty poor. 1454 00:55:42,190 --> 00:55:44,240 Word stem completion, the kind of thing that we said is 1455 00:55:44,240 --> 00:55:47,440 completely normal in HM, that's impaired 1456 00:55:47,440 --> 00:55:48,480 in Alzheimer's disease. 1457 00:55:48,480 --> 00:55:50,730 So we think that kind of priming depends on the 1458 00:55:50,730 --> 00:55:54,880 neocortex, the part of the brain that's also injured in 1459 00:55:54,880 --> 00:55:55,490 Alzheimer's. 1460 00:55:55,490 --> 00:55:58,600 Because we know it doesn't depend on the hippocampus, 1461 00:55:58,600 --> 00:55:59,220 because the patients with 1462 00:55:59,220 --> 00:56:01,900 hippocampus-only damage are fine. 1463 00:56:01,900 --> 00:56:05,120 So we end up with a picture like this of something on 1464 00:56:05,120 --> 00:56:05,830 memory systems. 1465 00:56:05,830 --> 00:56:08,680 For explicit or declarative memory, from patients with 1466 00:56:08,680 --> 00:56:11,330 amnesia, we know it depends on the medial temporal lobe. 1467 00:56:11,330 --> 00:56:13,790 Left, verbal; right, spatial. 1468 00:56:13,790 --> 00:56:16,510 For skill learning, anything you practice many times to get 1469 00:56:16,510 --> 00:56:19,880 better at, we know from Huntington's disease, that 1470 00:56:19,880 --> 00:56:21,950 depends on the basal ganglia. 1471 00:56:21,950 --> 00:56:25,080 For kinds of priming, recent experience altering something 1472 00:56:25,080 --> 00:56:27,880 about brain organization, Alzheimer's disease, we know 1473 00:56:27,880 --> 00:56:31,320 from that that it's likely mediated by the neocortex. 1474 00:56:31,320 --> 00:56:32,740 These are from patient studies, but the imaging 1475 00:56:32,740 --> 00:56:34,730 studies are very well aligned with these things. 1476 00:56:34,730 --> 00:56:38,050 So we think it's true not only of patients, but of you, in 1477 00:56:38,050 --> 00:56:40,550 terms of the instruments of your brain. 1478 00:56:40,550 --> 00:56:42,935 So now we have not only episodic memory 1479 00:56:42,935 --> 00:56:43,820 and semantic memory. 1480 00:56:43,820 --> 00:56:44,910 We talked about procedural memory. 1481 00:56:44,910 --> 00:56:46,040 We talked about priming. 1482 00:56:46,040 --> 00:56:47,520 I didn't talk about conditioning today, but we've 1483 00:56:47,520 --> 00:56:50,240 talked about that before. 1484 00:56:50,240 --> 00:56:53,290 So I have two more slides to add on conceptually. 1485 00:56:53,290 --> 00:56:56,160 So in what sense was Karl Ashley right or wrong when he 1486 00:56:56,160 --> 00:56:57,450 said memory's all over the brain? 1487 00:56:57,450 --> 00:56:59,240 Here's how we think about it now. 1488 00:56:59,240 --> 00:57:02,230 We think he was right that all of your brain is learning. 1489 00:57:02,230 --> 00:57:04,670 Practically all of your brain is plastic. 1490 00:57:04,670 --> 00:57:06,090 It changes with experience. 1491 00:57:06,090 --> 00:57:07,960 But different parts of your brain are 1492 00:57:07,960 --> 00:57:08,880 learning different things. 1493 00:57:08,880 --> 00:57:10,130 The basal ganglia is learning how to 1494 00:57:10,130 --> 00:57:11,680 be skilled at something. 1495 00:57:11,680 --> 00:57:14,410 The neocortex, how to gain knowledge and shift your 1496 00:57:14,410 --> 00:57:17,100 representation of knowledge, like in priming. 1497 00:57:17,100 --> 00:57:19,510 The medial temporal lobe on the left is learning verbal 1498 00:57:19,510 --> 00:57:21,590 facts, and the right is nonverbal 1499 00:57:21,590 --> 00:57:22,980 facts or spatial facts. 1500 00:57:22,980 --> 00:57:25,400 So all of your brain is learning, but it's learning 1501 00:57:25,400 --> 00:57:26,430 different things. 1502 00:57:26,430 --> 00:57:28,895 And in that sense we end up with this metaphor that-- you 1503 00:57:28,895 --> 00:57:31,430 know, just like there's a string section and a 1504 00:57:31,430 --> 00:57:34,320 percussion section or something like that, in you, 1505 00:57:34,320 --> 00:57:36,290 there's all these different instruments that are highly 1506 00:57:36,290 --> 00:57:39,470 tuned in the way they're organized to learn all the 1507 00:57:39,470 --> 00:57:40,610 different things you learned. 1508 00:57:40,610 --> 00:57:43,650 They're all pretty useful instruments to have. 1509 00:57:43,650 --> 00:57:45,870 And without these patients and the imaging studies, we 1510 00:57:45,870 --> 00:57:46,760 wouldn't have known that. 1511 00:57:46,760 --> 00:57:47,950 You would be like the Martian. 1512 00:57:47,950 --> 00:57:49,440 One instrument? 1513 00:57:49,440 --> 00:57:50,300 A thousand instruments? 1514 00:57:50,300 --> 00:57:52,990 Well, we know there's multiple ones, and we know pretty much 1515 00:57:52,990 --> 00:57:54,560 which structures are essential for them. 1516 00:57:54,560 --> 00:57:55,810 Thanks.