1 00:00:00,250 --> 00:00:01,800 The following content is provided 2 00:00:01,800 --> 00:00:04,040 under a Creative Commons license. 3 00:00:04,040 --> 00:00:06,890 Your support will help MIT OpenCourseWare continue 4 00:00:06,890 --> 00:00:10,750 to offer high-quality educational resources for free. 5 00:00:10,750 --> 00:00:13,370 To make a donation or view additional materials 6 00:00:13,370 --> 00:00:17,239 from hundreds of MIT courses, visit MIT OpenCourseWare 7 00:00:17,239 --> 00:00:17,864 at ocw.mit.edu. 8 00:00:23,260 --> 00:00:25,010 PROFESSOR: Two things I want to do today-- 9 00:00:25,010 --> 00:00:28,090 just briefly go through chapter six, which 10 00:00:28,090 --> 00:00:30,100 is about brain specializations. 11 00:00:30,100 --> 00:00:32,299 It was meant to be sort of an interlude. 12 00:00:32,299 --> 00:00:36,830 There's a little bit of a break before we 13 00:00:36,830 --> 00:00:42,370 get into some of the forebrain connections. 14 00:00:42,370 --> 00:00:51,750 But these all involve specializations because 15 00:00:51,750 --> 00:00:53,930 of the evolution of head receptors 16 00:00:53,930 --> 00:00:58,170 and the resulting expansions of the brain that have occurred. 17 00:00:58,170 --> 00:01:00,870 And we start with electroreception 18 00:01:00,870 --> 00:01:06,395 in some fish that's led to this enormous expansion 19 00:01:06,395 --> 00:01:10,670 of the cerebellum in the mormyrids. 20 00:01:10,670 --> 00:01:15,080 And my first question here was, what cranial nerves carrying 21 00:01:15,080 --> 00:01:17,720 information from electroreceptors 22 00:01:17,720 --> 00:01:20,980 in the fish that have electroreception? 23 00:01:20,980 --> 00:01:24,300 And also, why is it needed? 24 00:01:24,300 --> 00:01:26,637 Why don't they use vision? 25 00:01:26,637 --> 00:01:27,553 AUDIENCE: [INAUDIBLE]. 26 00:01:30,530 --> 00:01:34,300 PROFESSOR: They're cranial nerves, that's right. 27 00:01:34,300 --> 00:01:37,196 But what cranial nerves are they? 28 00:01:37,196 --> 00:01:38,112 AUDIENCE: [INAUDIBLE]. 29 00:01:42,370 --> 00:01:44,390 PROFESSOR: There's actually up to six of them. 30 00:01:44,390 --> 00:01:47,970 And what are they called? 31 00:01:47,970 --> 00:01:50,870 The lateral line nerves. 32 00:01:50,870 --> 00:01:52,920 Because fish have these receptors 33 00:01:52,920 --> 00:01:58,320 along a line along the side of their body. 34 00:01:58,320 --> 00:02:02,270 They also have mechanical receptors there. 35 00:02:02,270 --> 00:02:06,210 There's a mechanical lateral line row of receptors also, 36 00:02:06,210 --> 00:02:09,229 but we're concerned here with the electroreceptors. 37 00:02:09,229 --> 00:02:10,990 So what are they doing? 38 00:02:10,990 --> 00:02:12,144 Why is it so important? 39 00:02:12,144 --> 00:02:13,560 Why aren't they just using vision? 40 00:02:16,680 --> 00:02:17,965 Yeah, go ahead. 41 00:02:17,965 --> 00:02:18,881 AUDIENCE: [INAUDIBLE]. 42 00:02:21,574 --> 00:02:23,240 PROFESSOR: Yeah, because they can't see. 43 00:02:23,240 --> 00:02:26,460 They're living in muddy waters. 44 00:02:26,460 --> 00:02:28,230 They thrive in those waters, but they've 45 00:02:28,230 --> 00:02:29,892 got to be able to find things. 46 00:02:29,892 --> 00:02:31,350 They've got to be able to find prey 47 00:02:31,350 --> 00:02:33,930 if they're feeding on them. 48 00:02:33,930 --> 00:02:37,190 So what are they detecting? 49 00:02:37,190 --> 00:02:39,010 There's two kinds of electoreception. 50 00:02:39,010 --> 00:02:40,840 Let's just deal with one of them-- 51 00:02:40,840 --> 00:02:43,120 the fish that generate an electric field 52 00:02:43,120 --> 00:02:45,200 around their body. 53 00:02:45,200 --> 00:02:46,880 It's not a big electric field. 54 00:02:46,880 --> 00:02:49,540 There are a few of them that can generate 55 00:02:49,540 --> 00:02:54,520 such a big jolt of electricity that they can stun prey, 56 00:02:54,520 --> 00:02:55,960 but we're not talking about those. 57 00:02:55,960 --> 00:03:00,470 We're just talking about them that use it as a sense. 58 00:03:00,470 --> 00:03:03,690 They generate an electric field, but they also 59 00:03:03,690 --> 00:03:07,130 detect the electric field all around the side of their body. 60 00:03:07,130 --> 00:03:11,100 So any disturbance in that field they can detect. 61 00:03:11,100 --> 00:03:17,410 So all that computation involved in this specialized brain here, 62 00:03:17,410 --> 00:03:23,940 the cerebellum-- this is the area in one of the mormyrids-- 63 00:03:23,940 --> 00:03:31,900 are involved in computing where the animal is in order 64 00:03:31,900 --> 00:03:35,500 to get a particular disturbance in the electric field. 65 00:03:35,500 --> 00:03:38,170 It's not an easy task. 66 00:03:38,170 --> 00:03:40,010 And it's a huge computational problem, 67 00:03:40,010 --> 00:03:43,120 and there are computational neuroscientists still trying 68 00:03:43,120 --> 00:03:44,570 to figure that out. 69 00:03:44,570 --> 00:03:46,610 All right. 70 00:03:46,610 --> 00:03:50,500 No placental mammals have electoreceptor abilities. 71 00:03:50,500 --> 00:03:55,720 But one non-placental mammal does have such an ability. 72 00:03:55,720 --> 00:03:57,780 Do you know which one? 73 00:03:57,780 --> 00:04:00,490 It is in the chapter. 74 00:04:00,490 --> 00:04:01,480 Sorry? 75 00:04:01,480 --> 00:04:03,120 The duck-billed platypus, yes. 76 00:04:06,270 --> 00:04:09,220 How are this animal's electroreceptor 77 00:04:09,220 --> 00:04:13,500 inputs different for electrosensory fish? 78 00:04:13,500 --> 00:04:15,510 They use a different cranial nerve. 79 00:04:15,510 --> 00:04:16,740 And somebody said it. 80 00:04:19,290 --> 00:04:21,360 Anybody else know? 81 00:04:21,360 --> 00:04:24,430 I think you said it before. 82 00:04:24,430 --> 00:04:27,040 It's a trigeminal nerve, that's right. 83 00:04:27,040 --> 00:04:31,010 But not in those fish-- just in the duck-billed platypus. 84 00:04:31,010 --> 00:04:33,020 It's in their bill. 85 00:04:33,020 --> 00:04:33,980 So how do they feed? 86 00:04:33,980 --> 00:04:37,900 They stick that bill down in the muck and in the water. 87 00:04:37,900 --> 00:04:39,760 And they're detecting electric fields. 88 00:04:43,170 --> 00:04:46,260 Many animals do emit some kind of electric fields. 89 00:04:46,260 --> 00:04:48,670 I don't know the details for the duck-billed platypus. 90 00:04:48,670 --> 00:04:50,300 I know a little more about the fish. 91 00:04:54,310 --> 00:04:58,000 Another sense that is not highly developed in mammals 92 00:04:58,000 --> 00:05:01,190 is infrared detection. 93 00:05:01,190 --> 00:05:04,265 In what animals is this particularly important, 94 00:05:04,265 --> 00:05:06,780 and what cranial nerve is involved? 95 00:05:06,780 --> 00:05:07,680 Anybody else? 96 00:05:07,680 --> 00:05:09,732 Somebody that's not talked today yet. 97 00:05:13,590 --> 00:05:15,400 The pit vipers, yes. 98 00:05:15,400 --> 00:05:16,560 Snakes. 99 00:05:16,560 --> 00:05:18,530 But only particular snakes. 100 00:05:18,530 --> 00:05:20,740 Snakes, like the rattlesnake. 101 00:05:20,740 --> 00:05:22,940 So here, in this little picture-- 102 00:05:22,940 --> 00:05:26,580 I think this is the same one I used in the book-- 103 00:05:26,580 --> 00:05:30,840 I added to the picture I found in a drawing 104 00:05:30,840 --> 00:05:33,120 in the [INAUDIBLE] book. 105 00:05:33,120 --> 00:05:35,002 But this is the pit. 106 00:05:35,002 --> 00:05:36,600 It literally is a pit. 107 00:05:36,600 --> 00:05:37,570 It's recessed. 108 00:05:37,570 --> 00:05:40,590 What would be the value of that? 109 00:05:40,590 --> 00:05:43,360 Why put the infrared detectors at the bottom 110 00:05:43,360 --> 00:05:46,544 of a little pit in their face? 111 00:05:46,544 --> 00:05:47,460 AUDIENCE: [INAUDIBLE]. 112 00:05:50,800 --> 00:05:53,700 PROFESSOR: Yeah, because you just imagine, 113 00:05:53,700 --> 00:05:57,890 I have a cup here, and the receptors are back here. 114 00:05:57,890 --> 00:06:00,130 Now it's got directionality. 115 00:06:00,130 --> 00:06:02,760 Now it's not responding to things over there. 116 00:06:02,760 --> 00:06:05,210 It's only responding to things in this direction. 117 00:06:05,210 --> 00:06:08,440 So they have to move their head, of course. 118 00:06:08,440 --> 00:06:10,740 It doesn't give them directional selectivity 119 00:06:10,740 --> 00:06:12,920 if they keep their head still, except they 120 00:06:12,920 --> 00:06:16,910 know it's right in front of them. 121 00:06:16,910 --> 00:06:19,820 And you can see, it comes in through a branch 122 00:06:19,820 --> 00:06:23,440 of the trigeminal nerve to a particular group 123 00:06:23,440 --> 00:06:27,730 of secondary sensory cells and then 124 00:06:27,730 --> 00:06:31,570 through a circuit involving the trigeminal neurons. 125 00:06:34,120 --> 00:06:38,680 It goes from there to the optic tectum. 126 00:06:38,680 --> 00:06:40,320 Remember, we call it optic tectum, 127 00:06:40,320 --> 00:06:43,450 but it actually gets many different sensory modalities-- 128 00:06:43,450 --> 00:06:46,160 distance receptors, it gets auditory somatosensory, 129 00:06:46,160 --> 00:06:47,120 and visual. 130 00:06:47,120 --> 00:06:52,080 And now, as we see, it gets information in these snakes 131 00:06:52,080 --> 00:06:55,110 from their infared detection. 132 00:06:55,110 --> 00:07:00,924 So they can use it to orient towards their prey. 133 00:07:00,924 --> 00:07:01,840 AUDIENCE: [INAUDIBLE]. 134 00:07:04,470 --> 00:07:05,350 PROFESSOR: No. 135 00:07:05,350 --> 00:07:06,995 Only the pit vipers have that. 136 00:07:09,840 --> 00:07:11,720 And it would be interesting to look 137 00:07:11,720 --> 00:07:13,870 to see what other kinds of infrared 138 00:07:13,870 --> 00:07:16,130 detection you have in animals. 139 00:07:16,130 --> 00:07:18,870 I'm sure other animals have evolved that. 140 00:07:18,870 --> 00:07:22,750 It's too useful to evolve only in one small group like that. 141 00:07:25,940 --> 00:07:30,570 Bats are not the only mammal with echolocation ability, 142 00:07:30,570 --> 00:07:33,190 another special sense. 143 00:07:33,190 --> 00:07:39,330 So you'd expect specializations in the brain of the bat. 144 00:07:39,330 --> 00:07:45,360 But what other mammals have echo reception ability? 145 00:07:45,360 --> 00:07:46,430 AUDIENCE: The dolphin. 146 00:07:46,430 --> 00:07:48,100 PROFESSOR: The dolphin, OK. 147 00:07:48,100 --> 00:07:50,890 And what cranial nerve do you think is expanded? 148 00:07:50,890 --> 00:07:53,440 I've actually studied that with Eric Montie, 149 00:07:53,440 --> 00:07:55,490 who's a marine mammalogist. 150 00:08:00,570 --> 00:08:04,550 Using MRIs, we were able to reconstruct 151 00:08:04,550 --> 00:08:08,110 the brain of the Atlantic white-sided dolphin. 152 00:08:08,110 --> 00:08:12,390 And it was confusing at the beginning, 153 00:08:12,390 --> 00:08:14,640 because I had never seen-- I mean, 154 00:08:14,640 --> 00:08:18,120 I was helping him identify everything. 155 00:08:18,120 --> 00:08:21,060 And I thought it must be the trigeminal nerve. 156 00:08:21,060 --> 00:08:23,345 Any mammal I've ever seen, the trigeminal nerve 157 00:08:23,345 --> 00:08:26,095 is the biggest, but not in that animal. 158 00:08:26,095 --> 00:08:30,670 It was the eighth nerve, the auditory nerve. 159 00:08:30,670 --> 00:08:35,360 And similarly, if you look at the surface of the midbrain, 160 00:08:35,360 --> 00:08:39,600 look at this enormous inferior colliculus. 161 00:08:39,600 --> 00:08:44,400 The superior colliculus is relatively smaller, 162 00:08:44,400 --> 00:08:48,690 and it's the same in the bat-- at least very similar. 163 00:08:48,690 --> 00:08:52,510 The dolphin, of course, has an enormous endbrain too, 164 00:08:52,510 --> 00:08:56,360 and so I've taken a picture there with an endbrain that's 165 00:08:56,360 --> 00:08:59,999 been removed in the dolphin, but not the bat. 166 00:08:59,999 --> 00:09:00,915 AUDIENCE: [INAUDIBLE]. 167 00:09:11,760 --> 00:09:15,000 PROFESSOR: Humans that use some echolocation, 168 00:09:15,000 --> 00:09:16,700 it does become specialized. 169 00:09:16,700 --> 00:09:21,130 And there are indications that blind people, that 170 00:09:21,130 --> 00:09:25,010 are more likely to be able to use such an ability, 171 00:09:25,010 --> 00:09:26,911 do have changes in their cortex. 172 00:09:26,911 --> 00:09:28,410 And we're going to talk a little bit 173 00:09:28,410 --> 00:09:30,780 about that towards the end of the class. 174 00:09:30,780 --> 00:09:33,030 It's a very good question. 175 00:09:33,030 --> 00:09:36,010 Just notice here, the other two animals in this picture, 176 00:09:36,010 --> 00:09:40,010 it shows animals where the superior colliculus, the more 177 00:09:40,010 --> 00:09:43,730 anterior surface of the midbrain, is enlarged. 178 00:09:43,730 --> 00:09:46,170 Are they're very visual animals. 179 00:09:46,170 --> 00:09:49,850 Here's a goat, a wild goat, an ibex. 180 00:09:49,850 --> 00:09:53,850 And tarsier, a prosimian primate. 181 00:09:53,850 --> 00:09:58,090 It can literally locate using that structure. 182 00:09:58,090 --> 00:10:03,140 It's got this innate ability to orient and reach out 183 00:10:03,140 --> 00:10:07,980 with his hand and grab insects literally right out of the air. 184 00:10:07,980 --> 00:10:13,880 All right, what is a brain manifestation 185 00:10:13,880 --> 00:10:17,170 of the specialization of primates for vision? 186 00:10:17,170 --> 00:10:20,640 That includes us. 187 00:10:20,640 --> 00:10:23,280 Most of the primates have very special-- 188 00:10:23,280 --> 00:10:26,230 they're very specialized for vision. 189 00:10:26,230 --> 00:10:30,490 That's why monkeys are used so much in studies of vision, 190 00:10:30,490 --> 00:10:33,820 because of their similarity to humans. 191 00:10:33,820 --> 00:10:36,020 You know, rats used to-- and cats 192 00:10:36,020 --> 00:10:38,550 used to be the most popular animal, but no longer. 193 00:10:38,550 --> 00:10:41,040 It's because of the specialization. 194 00:10:41,040 --> 00:10:44,324 So you see, what has expanded so much? 195 00:10:47,290 --> 00:10:50,710 It isn't that tectum. 196 00:10:50,710 --> 00:10:54,770 It's not like in the ibex and the tariser here. 197 00:10:54,770 --> 00:10:57,130 But it's a part of the brain more involved 198 00:10:57,130 --> 00:10:58,810 in visual learning. 199 00:11:01,530 --> 00:11:05,680 And this shows an owl monkey. 200 00:11:05,680 --> 00:11:12,980 There's the striate cortex, what we call primary visual cortex. 201 00:11:12,980 --> 00:11:17,960 But every area that you see outlined with the black line, 202 00:11:17,960 --> 00:11:20,980 and many of them are also in different colors, 203 00:11:20,980 --> 00:11:24,420 are separate representations of the visual field 204 00:11:24,420 --> 00:11:30,050 or separate in some way in the electrophysiological 205 00:11:30,050 --> 00:11:30,820 recording studies. 206 00:11:33,700 --> 00:11:36,380 They all have at least a partial representation, 207 00:11:36,380 --> 00:11:40,480 separate from the others, of the visual field. 208 00:11:40,480 --> 00:11:43,230 So you can see how the visual areas have expanded 209 00:11:43,230 --> 00:11:45,970 into the posterior parietal region 210 00:11:45,970 --> 00:11:50,540 and the temporal region-- from the middle temporal area 211 00:11:50,540 --> 00:11:54,950 here, all the way down into the inferior temporal lobe. 212 00:12:00,970 --> 00:12:04,295 What's the specialization of small rodents 213 00:12:04,295 --> 00:12:07,160 for using their whiskers? 214 00:12:07,160 --> 00:12:10,080 What's happened in the brain of these animals? 215 00:12:10,080 --> 00:12:13,090 They have a specialized sense too, 216 00:12:13,090 --> 00:12:16,560 but it's not like any of the others we just looked at it, 217 00:12:16,560 --> 00:12:20,460 and we don't have it. 218 00:12:20,460 --> 00:12:26,540 The barrel fields, each barrel-- named because of the way 219 00:12:26,540 --> 00:12:31,160 it looks in histology-- represents one whisker. 220 00:12:31,160 --> 00:12:36,380 And these are sections of the cortex that 221 00:12:36,380 --> 00:12:42,390 have been-- they try to flatten the cortex and cut it, 222 00:12:42,390 --> 00:12:45,410 or at least they cut it tangential to the surface. 223 00:12:45,410 --> 00:12:47,660 And here they've taken different levels, 224 00:12:47,660 --> 00:12:52,590 and they go down through this area of the parietal lobe, 225 00:12:52,590 --> 00:12:56,380 and they see these barrels. 226 00:12:56,380 --> 00:12:58,910 We'd have to blow that up to see how these really 227 00:12:58,910 --> 00:13:00,090 look like barrels. 228 00:13:00,090 --> 00:13:03,550 They're a crowd of neurons, packed neurons around 229 00:13:03,550 --> 00:13:05,410 the edges, very few in the middle. 230 00:13:05,410 --> 00:13:08,120 And if you look in the middle of the barrels, 231 00:13:08,120 --> 00:13:11,630 all the cells would be in the dark areas here. 232 00:13:11,630 --> 00:13:14,250 This is stained for axons. 233 00:13:14,250 --> 00:13:18,700 You see, the axons from the thalamus 234 00:13:18,700 --> 00:13:22,830 come up representing each whisker coming up 235 00:13:22,830 --> 00:13:24,940 in the middle of those barrels and terminating. 236 00:13:24,940 --> 00:13:26,880 So it's a very specialized organization. 237 00:13:26,880 --> 00:13:31,750 It's been very useful for electrophysiological studies. 238 00:13:31,750 --> 00:13:33,890 Other somatosensory specializations 239 00:13:33,890 --> 00:13:38,050 exist too, like the hand with apes and raccoons 240 00:13:38,050 --> 00:13:43,200 and certainly humans, because we have such high acuity and motor 241 00:13:43,200 --> 00:13:49,630 control and also expanded cerebellum, [? for ?] 242 00:13:49,630 --> 00:13:51,810 coordinating those movements. 243 00:13:51,810 --> 00:13:53,920 And I mention here the prehensile tail 244 00:13:53,920 --> 00:13:55,550 in the spider monkey. 245 00:13:55,550 --> 00:13:57,700 And you get expanded representation 246 00:13:57,700 --> 00:14:01,610 of that tail in sensory and motor neocortex. 247 00:14:01,610 --> 00:14:03,980 And this just shows the raccoon. 248 00:14:03,980 --> 00:14:06,080 This is a picture from the book. 249 00:14:06,080 --> 00:14:09,820 And it's comparing the coatimundi and the raccoon. 250 00:14:09,820 --> 00:14:15,200 They differ tremendously in their use of their forepaw. 251 00:14:15,200 --> 00:14:17,570 The raccoon literally has a sensitive hand, 252 00:14:17,570 --> 00:14:19,420 just like we do. 253 00:14:19,420 --> 00:14:24,980 And if you look in the cortex, this whole area outlined in red 254 00:14:24,980 --> 00:14:28,920 there-- here's an enlargement of part of it-- 255 00:14:28,920 --> 00:14:32,040 there's a separate little gyrus for each digit. 256 00:14:34,770 --> 00:14:39,820 They have very fine sensory ability and corresponding motor 257 00:14:39,820 --> 00:14:43,510 control of that hand. 258 00:14:43,510 --> 00:14:46,320 Whereas if you look at the coatimundi, who also uses 259 00:14:46,320 --> 00:14:49,510 her forepaws as many animals do in feeding, 260 00:14:49,510 --> 00:14:52,520 the corresponding area is much smaller. 261 00:14:52,520 --> 00:14:57,580 And he doesn't have a separate gyrus for each digit. 262 00:14:57,580 --> 00:14:58,496 AUDIENCE: [INAUDIBLE]. 263 00:15:03,190 --> 00:15:07,232 PROFESSOR: He does have enhanced sensory abilities, yeah. 264 00:15:09,940 --> 00:15:13,870 And what may be a brain specialization 265 00:15:13,870 --> 00:15:16,790 of the human ability for complex social interactions? 266 00:15:16,790 --> 00:15:19,490 And this would apply to any other primates that 267 00:15:19,490 --> 00:15:24,390 live in groups with complex social behavior. 268 00:15:24,390 --> 00:15:25,390 What do we think? 269 00:15:25,390 --> 00:15:28,030 There's an increasing amount of work on this now, 270 00:15:28,030 --> 00:15:30,920 especially the people studying the social brain here 271 00:15:30,920 --> 00:15:31,830 in building. 272 00:15:31,830 --> 00:15:33,308 Yes? 273 00:15:33,308 --> 00:15:35,680 AUDIENCE: [INAUDIBLE]. 274 00:15:35,680 --> 00:15:39,210 PROFESSOR: In the neocortex, especially prefrontal area, 275 00:15:39,210 --> 00:15:42,120 which is frontal lobe association areas. 276 00:15:42,120 --> 00:15:46,560 We'll be defining all that later. 277 00:15:46,560 --> 00:15:51,895 These are the areas that keep localizing higher functions to. 278 00:15:51,895 --> 00:15:53,460 And we'll talk about their evolution. 279 00:15:56,240 --> 00:15:58,710 And I just want to point out, I want 280 00:15:58,710 --> 00:16:02,592 to ask you if you remember, what the specialization 281 00:16:02,592 --> 00:16:06,600 that I illustrate in the book, in the echidna, which 282 00:16:06,600 --> 00:16:09,390 is the spiny anteater of Australia. 283 00:16:09,390 --> 00:16:14,240 He's got an enormous prefrontal cortex. 284 00:16:14,240 --> 00:16:15,475 Why would he have that? 285 00:16:18,700 --> 00:16:21,036 AUDIENCE: [INAUDIBLE]. 286 00:16:21,036 --> 00:16:22,785 PROFESSOR: You think it has to do with it? 287 00:16:22,785 --> 00:16:24,820 This is the pink area here. 288 00:16:24,820 --> 00:16:27,490 It's relatively larger even than in humans, 289 00:16:27,490 --> 00:16:29,560 just in relative terms. 290 00:16:29,560 --> 00:16:33,680 And the colors here are the motor area, somatosensory area, 291 00:16:33,680 --> 00:16:37,855 visual area in green, and the darker green 292 00:16:37,855 --> 00:16:39,442 is the auditory area. 293 00:16:39,442 --> 00:16:44,520 And we would call them association areas. 294 00:16:44,520 --> 00:16:48,300 But look at that prefrontal area. 295 00:16:48,300 --> 00:16:53,010 So I assume it must have to do with the specialized feeding. 296 00:16:53,010 --> 00:16:54,590 He's an anteater. 297 00:16:54,590 --> 00:16:56,370 And ants are very small. 298 00:16:56,370 --> 00:16:59,170 Obviously maximize his intake. 299 00:16:59,170 --> 00:17:02,080 I think there's tremendous demand on his working memory. 300 00:17:02,080 --> 00:17:05,109 In a single glance, he has to remember where dozens of ants 301 00:17:05,109 --> 00:17:07,220 are, where they're disappearing, and he's 302 00:17:07,220 --> 00:17:08,660 got to be able to go after them. 303 00:17:11,609 --> 00:17:13,740 But that has never been analyzed. 304 00:17:17,869 --> 00:17:20,910 One way to get it to be analyzed is to put it in a book 305 00:17:20,910 --> 00:17:26,050 and raise the issue so people will look at it. 306 00:17:26,050 --> 00:17:27,660 This is a question for you. 307 00:17:27,660 --> 00:17:31,240 What other specializations might have noticeable brain 308 00:17:31,240 --> 00:17:32,015 manifestations? 309 00:17:32,015 --> 00:17:33,780 I want you to think of something that I 310 00:17:33,780 --> 00:17:36,930 didn't mention in the chapter. 311 00:17:36,930 --> 00:17:40,950 What other specializations in animals 312 00:17:40,950 --> 00:17:44,390 that you know about must have some special brain 313 00:17:44,390 --> 00:17:46,136 representation? 314 00:17:46,136 --> 00:17:46,635 Sorry? 315 00:17:46,635 --> 00:17:47,551 AUDIENCE: [INAUDIBLE]. 316 00:17:51,969 --> 00:17:52,760 PROFESSOR: Anybody? 317 00:17:52,760 --> 00:17:53,736 Anybody else? 318 00:17:53,736 --> 00:17:54,652 AUDIENCE: [INAUDIBLE]. 319 00:17:57,550 --> 00:18:00,730 PROFESSOR: OK, that's never been investigated. 320 00:18:00,730 --> 00:18:04,367 Do they have a specialized vestibular system? 321 00:18:04,367 --> 00:18:05,825 What would you expect in that case? 322 00:18:11,970 --> 00:18:12,619 Anybody else? 323 00:18:12,619 --> 00:18:13,285 Specializations? 324 00:18:18,095 --> 00:18:18,595 Yeah. 325 00:18:18,595 --> 00:18:19,545 Go ahead, Rachel. 326 00:18:19,545 --> 00:18:20,461 AUDIENCE: [INAUDIBLE]. 327 00:18:26,210 --> 00:18:31,320 PROFESSOR: Parietal neocortex, parietal association-- the area 328 00:18:31,320 --> 00:18:34,260 where we retain long-term memories, 329 00:18:34,260 --> 00:18:36,750 the map of the environment. 330 00:18:36,750 --> 00:18:39,210 That's right, there is some evidence for that. 331 00:18:39,210 --> 00:18:42,370 It's a correlation, and it's difficult to prove cause 332 00:18:42,370 --> 00:18:45,130 and effect, but it's a very interesting correlation. 333 00:18:45,130 --> 00:18:47,840 These are London taxi drivers. 334 00:18:47,840 --> 00:18:50,340 We know that the cortex is affected 335 00:18:50,340 --> 00:18:54,670 by learning in pretty interesting ways, some of which 336 00:18:54,670 --> 00:18:56,450 are still being discovered. 337 00:18:56,450 --> 00:18:58,760 I asked my wife this question this morning, 338 00:18:58,760 --> 00:19:01,930 and she came up with specializations 339 00:19:01,930 --> 00:19:04,560 in the nose of some animals. 340 00:19:04,560 --> 00:19:06,310 What was the one you thought of? 341 00:19:06,310 --> 00:19:07,660 AUDIENCE: [INAUDIBLE]. 342 00:19:07,660 --> 00:19:10,440 PROFESSOR: The star-nosed mole. 343 00:19:10,440 --> 00:19:14,210 John Kaas actually turns out to be 344 00:19:14,210 --> 00:19:17,350 one of the guys who's wrote an endorsement of my book, 345 00:19:17,350 --> 00:19:19,440 so I like John Kaas. 346 00:19:19,440 --> 00:19:23,790 And he has studied the star-nosed mole 347 00:19:23,790 --> 00:19:27,090 and published a representation of that. 348 00:19:27,090 --> 00:19:30,710 It looks almost like a hand, multiple fingers. 349 00:19:30,710 --> 00:19:32,812 It's on their nose, and they use it 350 00:19:32,812 --> 00:19:36,064 when they go through the ground. 351 00:19:36,064 --> 00:19:37,230 And they use it for feeding. 352 00:19:37,230 --> 00:19:38,176 Yes? 353 00:19:38,176 --> 00:19:39,092 AUDIENCE: [INAUDIBLE]. 354 00:19:48,100 --> 00:19:50,340 PROFESSOR: That's another thing that we'll 355 00:19:50,340 --> 00:19:53,250 be dealing with a little bit, but you're right. 356 00:19:53,250 --> 00:19:56,690 There are changes that occur in blind people. 357 00:19:56,690 --> 00:19:58,900 And that's been studied in animals 358 00:19:58,900 --> 00:20:01,400 in very interesting ways. 359 00:20:01,400 --> 00:20:04,550 And I would just add the one other animal 360 00:20:04,550 --> 00:20:08,580 with a specialized nose, the elephant. 361 00:20:08,580 --> 00:20:13,195 He's got incredible motor and sensory ability in that nose, 362 00:20:13,195 --> 00:20:15,090 in that trunk. 363 00:20:15,090 --> 00:20:15,630 All right. 364 00:20:22,860 --> 00:20:24,260 This is the bigger class. 365 00:20:24,260 --> 00:20:28,260 We won't quite get through it today, but we'll do our best. 366 00:20:28,260 --> 00:20:31,720 I want to give you an overview of forebrain structures 367 00:20:31,720 --> 00:20:34,140 and introduce the neocortex. 368 00:20:34,140 --> 00:20:35,740 I want to start with this question. 369 00:20:35,740 --> 00:20:38,870 What can an animal do without a forebrain? 370 00:20:38,870 --> 00:20:40,300 And this has actually been done. 371 00:20:40,300 --> 00:20:42,700 It's a pretty gross lesion. 372 00:20:42,700 --> 00:20:47,100 They either disconnect the forebrain 373 00:20:47,100 --> 00:20:49,890 from the midbrain with a cut. 374 00:20:49,890 --> 00:20:54,470 In some cases, they leave some of the connections. 375 00:20:54,470 --> 00:21:00,630 So the initial studies were done in the cat, 376 00:21:00,630 --> 00:21:03,350 but then they were done on rats and pigeons. 377 00:21:03,350 --> 00:21:04,740 It's all in early literature. 378 00:21:07,600 --> 00:21:09,710 And let me just go through some of that. 379 00:21:09,710 --> 00:21:12,370 You call that a decerebration. 380 00:21:12,370 --> 00:21:14,950 Basically we move the cerebral hemispheres 381 00:21:14,950 --> 00:21:19,200 or completely disconnect them from other parts of the brain. 382 00:21:19,200 --> 00:21:21,200 So this is our earlier diagram. 383 00:21:21,200 --> 00:21:26,760 And what I'm showing here is the division-- spinal cord, 384 00:21:26,760 --> 00:21:28,310 hindbrain, midbrain. 385 00:21:28,310 --> 00:21:33,590 And everything from here on is the forebrain. 386 00:21:33,590 --> 00:21:36,970 But the cerebral hemispheres are everything 387 00:21:36,970 --> 00:21:40,234 in front of this line here. 388 00:21:40,234 --> 00:21:41,650 This is thalamus and hypothalamus. 389 00:21:41,650 --> 00:21:43,570 They're tweenbrain. 390 00:21:43,570 --> 00:21:46,655 So they're disconnected-- all of these structures. 391 00:21:49,440 --> 00:21:52,730 And of course, in the mammals if they're doing it, 392 00:21:52,730 --> 00:21:55,670 this area has expanded tremendously. 393 00:21:55,670 --> 00:21:57,745 The neocortex has grown. 394 00:21:57,745 --> 00:21:59,160 So they get rid of all of that. 395 00:22:02,160 --> 00:22:05,130 Why do you think they've got huge differences 396 00:22:05,130 --> 00:22:11,480 between the results in the cat and in the rat? 397 00:22:11,480 --> 00:22:14,930 They both are mammals, they both have a neocortex, 398 00:22:14,930 --> 00:22:18,680 they both have a corpus striatum. 399 00:22:18,680 --> 00:22:23,350 And in both animals, they disconnected those areas 400 00:22:23,350 --> 00:22:27,090 from the lower brain stem, or from the brain stem period, 401 00:22:27,090 --> 00:22:30,350 from the entire brains. 402 00:22:30,350 --> 00:22:32,150 They got big differences. 403 00:22:32,150 --> 00:22:39,120 What is the main thing I claim in the book is the difference? 404 00:22:39,120 --> 00:22:46,710 Because the early interpretations were not this. 405 00:22:46,710 --> 00:22:49,560 And there's been all kinds of arguments about it. 406 00:22:49,560 --> 00:22:50,476 Yes? 407 00:22:50,476 --> 00:22:51,392 AUDIENCE: [INAUDIBLE]. 408 00:22:53,690 --> 00:22:57,125 PROFESSOR: Yeah, the quantity-- the number of connections 409 00:22:57,125 --> 00:22:57,830 severed. 410 00:22:57,830 --> 00:23:00,930 Very good. 411 00:23:00,930 --> 00:23:06,070 Why would you be disconnecting so many more connections 412 00:23:06,070 --> 00:23:10,180 if you're dealing with a cat than in a rat? 413 00:23:10,180 --> 00:23:12,380 They have the same kinds of connections 414 00:23:12,380 --> 00:23:13,610 in qualitative terms. 415 00:23:16,220 --> 00:23:20,850 But think of the size of the cat hemispheres. 416 00:23:20,850 --> 00:23:24,180 He's got the highly folded cortex. 417 00:23:24,180 --> 00:23:26,170 He's got a relatively large neocortex, 418 00:23:26,170 --> 00:23:31,430 whereas the rat's a smooth-brained mammal-- 419 00:23:31,430 --> 00:23:33,770 in relative terms, a much smaller cortex. 420 00:23:37,332 --> 00:23:38,915 AUDIENCE: Does this mean that it would 421 00:23:38,915 --> 00:23:40,482 cause more damage in the rat? 422 00:23:40,482 --> 00:23:42,690 PROFESSOR: Well, that's what we're going to consider. 423 00:23:42,690 --> 00:23:44,338 Why? 424 00:23:44,338 --> 00:23:45,360 Why is that? 425 00:23:45,360 --> 00:23:47,520 I claim it's quantitative. 426 00:23:47,520 --> 00:23:49,240 Let's go through this. 427 00:23:49,240 --> 00:23:51,110 But there's another question here. 428 00:23:53,740 --> 00:23:56,950 Actually, both rats and cats, the only way 429 00:23:56,950 --> 00:23:59,870 you can keep them alive after this kind of lesion 430 00:23:59,870 --> 00:24:02,340 is to force feed them. 431 00:24:02,340 --> 00:24:03,925 Why was that the case? 432 00:24:07,250 --> 00:24:10,660 They couldn't keep themselves alive. 433 00:24:10,660 --> 00:24:13,710 Does that mean they weren't hungry? 434 00:24:13,710 --> 00:24:16,930 Well, in a sense, that's true. 435 00:24:16,930 --> 00:24:19,980 They never showed signs of hunger. 436 00:24:19,980 --> 00:24:26,250 But if you put food in their mouth, they ate. 437 00:24:26,250 --> 00:24:28,880 So it's not true that they wouldn't eat. 438 00:24:28,880 --> 00:24:32,585 They just didn't show the signs of hunger motivation. 439 00:24:35,920 --> 00:24:41,110 Now, the extensive study of decerebration in the cat 440 00:24:41,110 --> 00:24:44,000 was done by these guys, Bard and Macht, published in '58. 441 00:24:47,030 --> 00:24:50,530 They called it the animal a purely reflex animal. 442 00:24:50,530 --> 00:24:52,460 All he had was the reflexes, they say. 443 00:24:52,460 --> 00:24:56,060 He couldn't do any act that requires a series of reflexes, 444 00:24:56,060 --> 00:24:57,950 that's the way they put it. 445 00:24:57,950 --> 00:25:02,770 They were still very affected by the SR model of behavior. 446 00:25:02,770 --> 00:25:06,480 And they thought, they just couldn't put the reflexes 447 00:25:06,480 --> 00:25:07,900 together. 448 00:25:07,900 --> 00:25:12,340 We would say it more broadly now in terms of sensory motor 449 00:25:12,340 --> 00:25:13,890 responses. 450 00:25:13,890 --> 00:25:16,845 So let's look at what the animal can actually do, 451 00:25:16,845 --> 00:25:19,880 and can it learn anything? 452 00:25:19,880 --> 00:25:23,160 First of all, the cats were anosmic and blind, 453 00:25:23,160 --> 00:25:28,870 because those are two forebrain senses. 454 00:25:28,870 --> 00:25:31,760 The cranial nerves for olfaction and vision 455 00:25:31,760 --> 00:25:33,399 come into the forebrain. 456 00:25:33,399 --> 00:25:34,940 They are disconnecting the forebrain, 457 00:25:34,940 --> 00:25:37,557 so of course, vision and olfaction 458 00:25:37,557 --> 00:25:38,640 can affect their behavior. 459 00:25:41,710 --> 00:25:45,360 They didn't eat spontaneously, as we said. 460 00:25:45,360 --> 00:25:47,770 But they also didn't groom themselves. 461 00:25:47,770 --> 00:25:50,280 They showed no spontaneous sexual or other 462 00:25:50,280 --> 00:25:51,330 social behavior. 463 00:25:51,330 --> 00:25:54,650 They could, though, illicit sexual reflexes 464 00:25:54,650 --> 00:25:57,560 by stimulating the genitals. 465 00:25:57,560 --> 00:26:00,520 They could get lordosis response from females. 466 00:26:00,520 --> 00:26:02,340 They could get penile erection. 467 00:26:02,340 --> 00:26:06,380 But it required stimulation. 468 00:26:06,380 --> 00:26:11,530 They didn't show it in normal behavior. 469 00:26:11,530 --> 00:26:14,360 OK, let's look at what they could do. 470 00:26:14,360 --> 00:26:15,370 They could stand. 471 00:26:15,370 --> 00:26:16,510 They could sit. 472 00:26:16,510 --> 00:26:19,490 They could right themselves if they tipped over. 473 00:26:19,490 --> 00:26:20,850 They could walk. 474 00:26:20,850 --> 00:26:22,410 They did show some abnormalities. 475 00:26:25,630 --> 00:26:32,610 They even showed rage, but only if you pinched them, especially 476 00:26:32,610 --> 00:26:34,610 their tail. 477 00:26:34,610 --> 00:26:37,730 They didn't bite or strike out normally. 478 00:26:37,730 --> 00:26:40,360 They showed some autonomic regulation. 479 00:26:40,360 --> 00:26:42,290 They showed piloerection. 480 00:26:42,290 --> 00:26:46,750 They would fluff up their hair in response to cold. 481 00:26:46,750 --> 00:26:48,660 They had some thermal regulation. 482 00:26:48,660 --> 00:26:51,180 It wasn't as good as normal. 483 00:26:51,180 --> 00:26:53,415 Their temperature would fluctuate more 484 00:26:53,415 --> 00:26:55,960 with changing temperatures of the environment, 485 00:26:55,960 --> 00:26:58,580 but they still had some thermal regulation. 486 00:26:58,580 --> 00:27:02,480 So commonly, if they wanted to have an easier time maintaining 487 00:27:02,480 --> 00:27:05,390 these animals and not have to give them injections 488 00:27:05,390 --> 00:27:10,140 of electrolytes and things, they left 489 00:27:10,140 --> 00:27:13,490 the hypothalamus attached to the pituitary, 490 00:27:13,490 --> 00:27:16,190 even though it was disconnected from the midbrain. 491 00:27:16,190 --> 00:27:19,505 They left that hypothalamic island attached 492 00:27:19,505 --> 00:27:23,846 to the pituitary, and then they had much better regulation 493 00:27:23,846 --> 00:27:25,095 of their internal environment. 494 00:27:28,480 --> 00:27:29,590 They couldn't learn much. 495 00:27:29,590 --> 00:27:33,750 They had conditioned eye blink, condition respiratory changes. 496 00:27:33,750 --> 00:27:35,720 But they didn't maintain it very long. 497 00:27:42,260 --> 00:27:43,090 So what was it? 498 00:27:43,090 --> 00:27:45,720 I just said this-- describe the behavior that 499 00:27:45,720 --> 00:27:48,945 shows how a cat without a forebrain shows no hunger 500 00:27:48,945 --> 00:27:52,591 and yet will eat when you put food in its mouth. 501 00:27:52,591 --> 00:27:53,450 So what's he doing? 502 00:28:00,522 --> 00:28:04,010 He's responding to the simulation. 503 00:28:04,010 --> 00:28:08,250 He will open his mouth, touch his lip. 504 00:28:08,250 --> 00:28:11,100 He will close his mouth on the food. 505 00:28:11,100 --> 00:28:13,740 What does that if he's not hungry? 506 00:28:17,140 --> 00:28:17,820 Sorry? 507 00:28:17,820 --> 00:28:19,712 AUDIENCE: [INAUDIBLE]. 508 00:28:19,712 --> 00:28:21,920 PROFESSOR: No, I wouldn't say it's procedural memory. 509 00:28:21,920 --> 00:28:24,090 I would say it's innate reflexes. 510 00:28:27,530 --> 00:28:31,280 Exactly, like the baby suckling. 511 00:28:31,280 --> 00:28:38,970 Except babies, the suckling will vary with how hungry they are. 512 00:28:38,970 --> 00:28:42,470 Here, it didn't seem to. 513 00:28:42,470 --> 00:28:44,850 But that's the question. 514 00:28:44,850 --> 00:28:47,580 Maybe it did vary a little bit with how hungry they were. 515 00:28:47,580 --> 00:28:50,350 But the point is, they didn't show any motivation. 516 00:28:53,779 --> 00:28:54,695 AUDIENCE: [INAUDIBLE]. 517 00:29:12,050 --> 00:29:19,290 PROFESSOR: That's a big issue in how the dopamine pathways, 518 00:29:19,290 --> 00:29:20,855 the role they play in feeding. 519 00:29:28,300 --> 00:29:34,400 The representation of the motivational state, the drive 520 00:29:34,400 --> 00:29:36,500 state, there's no longer-- it doesn't 521 00:29:36,500 --> 00:29:39,960 mean they don't have it if they left the forebrain there 522 00:29:39,960 --> 00:29:42,160 but just disconnected it, but it means 523 00:29:42,160 --> 00:29:45,050 it can't influence the midbrain, hindbrain, and spinal cord 524 00:29:45,050 --> 00:29:47,530 anymore. 525 00:29:47,530 --> 00:29:49,140 All right. 526 00:29:49,140 --> 00:29:54,950 So then this just summarises if you do the same thing to a rat, 527 00:29:54,950 --> 00:29:56,190 he can do more. 528 00:29:56,190 --> 00:30:00,040 He's faster to recover his righting reflexes 529 00:30:00,040 --> 00:30:01,000 and locomotion. 530 00:30:01,000 --> 00:30:04,190 I said the cat had righting reflexes and locomotion, 531 00:30:04,190 --> 00:30:06,210 but in fact he lost it for a while. 532 00:30:06,210 --> 00:30:08,095 It took him a long time to recover it. 533 00:30:08,095 --> 00:30:09,095 The rats recover faster. 534 00:30:11,720 --> 00:30:14,360 They did show some eating and drinking responses. 535 00:30:14,360 --> 00:30:17,335 But again-- and more than the cat did. 536 00:30:17,335 --> 00:30:21,490 It was a little more than the normal, just simple reflexes. 537 00:30:21,490 --> 00:30:25,555 But they didn't seek food, so it was still fatal 538 00:30:25,555 --> 00:30:27,770 if they didn't force feed them. 539 00:30:27,770 --> 00:30:29,920 And now the rats would groom themselves. 540 00:30:29,920 --> 00:30:32,540 The cats never did. 541 00:30:32,540 --> 00:30:36,580 So against that Bard and Macht conclusion, 542 00:30:36,580 --> 00:30:38,610 they did show a series of-- you could 543 00:30:38,610 --> 00:30:40,440 call it a series of reflexes if that's 544 00:30:40,440 --> 00:30:44,100 the language you want to use. 545 00:30:44,100 --> 00:30:45,880 We would describe it as a fixed action 546 00:30:45,880 --> 00:30:49,880 pattern, inherited pattern of behavior. 547 00:30:49,880 --> 00:30:52,130 They also showed some defensive behavior 548 00:30:52,130 --> 00:30:54,240 that went beyond what the cat did. 549 00:30:54,240 --> 00:30:57,265 They would localize, they would try to escape. 550 00:30:57,265 --> 00:31:00,520 They would claw and bite. 551 00:31:00,520 --> 00:31:03,580 They even showed some auditory localization in space. 552 00:31:03,580 --> 00:31:06,130 Remember, the audition is the eighth cranial nerve, 553 00:31:06,130 --> 00:31:08,620 and it comes into the hindbrain. 554 00:31:08,620 --> 00:31:12,590 And it can reach the midbrain and cause orienting movements. 555 00:31:12,590 --> 00:31:14,520 Why did the rat do that and not the cat? 556 00:31:17,130 --> 00:31:19,450 So some people said, the cat's forebrain 557 00:31:19,450 --> 00:31:22,870 has taken over more of the function than the rat 558 00:31:22,870 --> 00:31:25,660 forebrain. 559 00:31:25,660 --> 00:31:28,940 But as the upper parts of the brain involved, 560 00:31:28,940 --> 00:31:32,950 especially the cortex, it takes over lower functions. 561 00:31:32,950 --> 00:31:36,750 That was the way people thought about it. 562 00:31:36,750 --> 00:31:39,715 And I'm asking, is that the best way to describe the results? 563 00:31:43,560 --> 00:31:44,830 And I say, no. 564 00:31:47,550 --> 00:31:52,254 So some people said, well, you take the cerebral hemispheres 565 00:31:52,254 --> 00:31:54,045 away, they lose all their learned behavior. 566 00:31:57,620 --> 00:32:01,340 Let's look at that by looking now at another animal 567 00:32:01,340 --> 00:32:03,490 where decerebration has occurred, 568 00:32:03,490 --> 00:32:05,860 and that was in the pigeon. 569 00:32:05,860 --> 00:32:08,090 These were earlier than the other studies, 570 00:32:08,090 --> 00:32:11,260 earlier than the cat and rat studies. 571 00:32:11,260 --> 00:32:15,710 They were done by Dutch people, and it was all 572 00:32:15,710 --> 00:32:17,460 written in German-- Visser and Radamaker. 573 00:32:17,460 --> 00:32:22,680 And in 1935 and '37, they published this. 574 00:32:27,390 --> 00:32:31,320 They showed after decerebration, they 575 00:32:31,320 --> 00:32:35,690 showed their basic repertoire of unlearned reactions. 576 00:32:35,690 --> 00:32:40,050 They would fly if you threw them into the air. 577 00:32:40,050 --> 00:32:44,050 But they wouldn't start flying spontaneously. 578 00:32:44,050 --> 00:32:46,610 You had to throw them into the air. 579 00:32:46,610 --> 00:32:51,320 And while they were flying, they would avoid vertical sticks. 580 00:32:51,320 --> 00:32:54,180 Of course, this was all done indoors. 581 00:32:54,180 --> 00:32:57,047 They would land on horizontal sticks. 582 00:32:57,047 --> 00:32:58,880 But then they found out they would land even 583 00:32:58,880 --> 00:33:01,190 on the back of a dog or a cat. 584 00:33:01,190 --> 00:33:04,080 So what's happened? 585 00:33:04,080 --> 00:33:07,890 They forgot dogs and cats can be dangerous to pigeons. 586 00:33:11,180 --> 00:33:14,410 There was a lot of indication that more complicated behavior 587 00:33:14,410 --> 00:33:17,320 patterns that depended some degree on learning 588 00:33:17,320 --> 00:33:21,630 during development were lost in these animals. 589 00:33:21,630 --> 00:33:26,630 So my hypothesis is that the forebrain 590 00:33:26,630 --> 00:33:29,450 is very important in linking together 591 00:33:29,450 --> 00:33:34,390 by learning the species' typical action patterns, fixed action 592 00:33:34,390 --> 00:33:39,520 patterns that are built in, and therefore 593 00:33:39,520 --> 00:33:40,790 genetically determined. 594 00:33:40,790 --> 00:33:44,910 But we still learn to link those things together. 595 00:33:44,910 --> 00:33:49,340 We inherit the ability to do this and to do this, 596 00:33:49,340 --> 00:33:54,150 but that doesn't mean we learn how to grasp a corner. 597 00:33:54,150 --> 00:33:56,730 That doesn't mean we learn how to play the piano. 598 00:33:56,730 --> 00:33:57,750 It's not innate. 599 00:33:57,750 --> 00:34:00,960 Just the movements are, but we link them in different ways 600 00:34:00,960 --> 00:34:02,300 by learning. 601 00:34:02,300 --> 00:34:08,255 And that's mostly a function of the corpus striatum. 602 00:34:08,255 --> 00:34:11,039 But first I want you to understand Nauta's terms. 603 00:34:11,039 --> 00:34:16,250 He uses these terms-- stability of the internal environment, 604 00:34:16,250 --> 00:34:21,300 stability in space, and stability in time. 605 00:34:21,300 --> 00:34:23,429 And they involve different parts of the brain. 606 00:34:29,370 --> 00:34:32,760 So without a forebrain, Nauta said, 607 00:34:32,760 --> 00:34:35,510 they still had pretty good stability in space, 608 00:34:35,510 --> 00:34:39,630 meaning they could balance, they could right themselves, 609 00:34:39,630 --> 00:34:41,739 they could move around. 610 00:34:41,739 --> 00:34:43,224 They had quite a bit of stability 611 00:34:43,224 --> 00:34:45,909 in the internal environment, but that 612 00:34:45,909 --> 00:34:49,110 was much better if the hypothalamus was left intact. 613 00:34:49,110 --> 00:34:53,320 But their stability in time was really 614 00:34:53,320 --> 00:34:55,500 messed up, because their behavior 615 00:34:55,500 --> 00:34:58,630 is just-- their actions seemed to depend 616 00:34:58,630 --> 00:35:01,630 on the current inputs. 617 00:35:01,630 --> 00:35:03,350 And they had little or no motivation 618 00:35:03,350 --> 00:35:08,380 initiated behavior, little or no long-term memory. 619 00:35:08,380 --> 00:35:10,625 And of course, when you're dealing with mammals, 620 00:35:10,625 --> 00:35:14,120 they lose a lot of sensory and motor acuity. 621 00:35:14,120 --> 00:35:17,540 They don't have fine movements. 622 00:35:17,540 --> 00:35:22,534 They can't respond to detail the way they can with the cortex. 623 00:35:22,534 --> 00:35:24,400 If you spare the corpus striatum, 624 00:35:24,400 --> 00:35:25,590 they could do a lot more. 625 00:35:28,420 --> 00:35:30,300 I'm not going to spend a lot of time on that. 626 00:35:30,300 --> 00:35:31,530 You can read this. 627 00:35:31,530 --> 00:35:33,400 It's all in the chapter. 628 00:35:33,400 --> 00:35:37,370 They've also varied-- instead of taking out the whole forebrain, 629 00:35:37,370 --> 00:35:41,400 they just do decortications in various animals. 630 00:35:41,400 --> 00:35:43,410 And the basic conclusion of those studies 631 00:35:43,410 --> 00:35:46,160 is that the more of the cortex you take out, 632 00:35:46,160 --> 00:35:51,500 the more deficient the animal is in its sensory motor control. 633 00:35:51,500 --> 00:35:55,720 Again, a lot depends on quantity. 634 00:35:55,720 --> 00:35:59,165 As much as people tried to explain the behavior, 635 00:35:59,165 --> 00:36:01,170 the effects of these lesions in terms 636 00:36:01,170 --> 00:36:04,720 of specific cortical areas removed-- 637 00:36:04,720 --> 00:36:09,190 and there was some correlation, but it seemed that the biggest 638 00:36:09,190 --> 00:36:11,592 factor was just the amount of cortex they took out. 639 00:36:15,290 --> 00:36:23,750 So that leads us to explaining this term invented 640 00:36:23,750 --> 00:36:27,632 by Von Monikow a long time ago when 641 00:36:27,632 --> 00:36:31,200 he discussed corticospinal diaschisis. 642 00:36:31,200 --> 00:36:34,830 It's a very interesting analysis. 643 00:36:34,830 --> 00:36:37,330 What is meant by that term? 644 00:36:37,330 --> 00:36:40,725 What does it mean, diaschisis? 645 00:36:40,725 --> 00:36:46,700 You know what a schism is-- cut something into two parts. 646 00:36:46,700 --> 00:36:52,910 Diaschisis, separation of two things. 647 00:36:52,910 --> 00:36:55,400 So I want to know why is understanding 648 00:36:55,400 --> 00:36:59,800 of this phenomenon so important in interpreting these species' 649 00:36:59,800 --> 00:37:03,340 differences in brain lesion effects, and in fact 650 00:37:03,340 --> 00:37:06,610 in interpreting recovery of function 651 00:37:06,610 --> 00:37:10,830 in the human beings with brain damage. 652 00:37:10,830 --> 00:37:13,510 And that's why I think it's so important to understand it. 653 00:37:17,810 --> 00:37:23,570 In simple terms, it means deafferentation depression. 654 00:37:23,570 --> 00:37:26,560 If you deafferent a structure, it 655 00:37:26,560 --> 00:37:31,330 means you remove the inputs, or at least a lot of them. 656 00:37:31,330 --> 00:37:34,660 It's always a partial deafferentation. 657 00:37:34,660 --> 00:37:37,410 But with greater deafferentation, the greater 658 00:37:37,410 --> 00:37:40,720 the effect on those neurons. 659 00:37:40,720 --> 00:37:45,295 So for example, take the phenomenon of spinal shock. 660 00:37:45,295 --> 00:37:47,659 Do you know that term? 661 00:37:47,659 --> 00:37:48,700 Have you ever heard that? 662 00:37:48,700 --> 00:37:53,420 Has anybody ever heard of spinal shock before? 663 00:37:53,420 --> 00:37:55,192 What is it? 664 00:37:55,192 --> 00:37:56,108 AUDIENCE: [INAUDIBLE]. 665 00:38:10,400 --> 00:38:13,330 PROFESSOR: But here, you're thinking of deafferentation 666 00:38:13,330 --> 00:38:16,830 as removal of sensory input. 667 00:38:16,830 --> 00:38:20,550 And you're right, that will cause deafferentation 668 00:38:20,550 --> 00:38:25,280 of the dorsal horn neurons that are getting those inputs. 669 00:38:25,280 --> 00:38:28,350 Now let's talk about spinal shock. 670 00:38:28,350 --> 00:38:30,930 It's a lesion of the spinal cord. 671 00:38:30,930 --> 00:38:34,100 If I get a spinal cord transection-- say, 672 00:38:34,100 --> 00:38:40,380 at the bottom of the cervical region-- 673 00:38:40,380 --> 00:38:43,060 I don't just lose control of my legs 674 00:38:43,060 --> 00:38:45,975 and much of the control of my arms. 675 00:38:45,975 --> 00:38:47,740 No, I lose much more. 676 00:38:47,740 --> 00:38:50,510 I lose even spinal reflexes. 677 00:38:50,510 --> 00:38:54,310 I don't even show withdrawal reflexes or stretch reflexes. 678 00:38:54,310 --> 00:38:56,020 The reflexes go. 679 00:38:56,020 --> 00:39:00,700 But wait a minute, they're spinal reflexes. 680 00:39:00,700 --> 00:39:03,350 That's called spinal shock. 681 00:39:03,350 --> 00:39:07,110 It takes a long time for spinal functions, 682 00:39:07,110 --> 00:39:11,420 simple spinal reflexes that don't involve pathways 683 00:39:11,420 --> 00:39:15,270 outside the spinal cord, to recover. 684 00:39:15,270 --> 00:39:16,690 So here's my diagram of it. 685 00:39:16,690 --> 00:39:18,340 And here I've taken two species. 686 00:39:18,340 --> 00:39:20,430 I'm showing something like a cortex here 687 00:39:20,430 --> 00:39:24,070 and an animal with a lot of it and an animal with less of it. 688 00:39:24,070 --> 00:39:26,690 And here's a little diagram of the spinal cord, 689 00:39:26,690 --> 00:39:28,440 and I'm showing a reflex pathway. 690 00:39:28,440 --> 00:39:34,700 I just show neurons coming in and other neurons going out, 691 00:39:34,700 --> 00:39:37,880 and they're connected in some way [INAUDIBLE]. 692 00:39:37,880 --> 00:39:40,390 OK, and then you do this. 693 00:39:40,390 --> 00:39:45,180 You eliminate all those corticospinal connections. 694 00:39:45,180 --> 00:39:48,700 This is really a simple way to depict 695 00:39:48,700 --> 00:39:52,220 what Von Monikow described when he first described diaschisis 696 00:39:52,220 --> 00:39:54,190 and he talked about corticospinal diaschisis. 697 00:39:54,190 --> 00:39:57,450 I just put into diagrams what he was saying. 698 00:39:57,450 --> 00:39:59,560 I'm showing excitatory connections. 699 00:39:59,560 --> 00:40:03,410 We'll ignore the inhibitory ones for now. 700 00:40:03,410 --> 00:40:06,350 A lot more excitatory connections 701 00:40:06,350 --> 00:40:08,580 removed from the spinal cord in the animal 702 00:40:08,580 --> 00:40:11,390 with the larger cortex. 703 00:40:11,390 --> 00:40:13,476 So what happens? 704 00:40:13,476 --> 00:40:14,850 All these fibers are degenerated. 705 00:40:17,710 --> 00:40:20,550 These neurons are less deafferented 706 00:40:20,550 --> 00:40:23,070 in the smaller-brained animals, tan these. 707 00:40:25,830 --> 00:40:29,640 That means the diaschisis effect, the degree 708 00:40:29,640 --> 00:40:35,980 of deafferentation, is greater in the larger brained animal. 709 00:40:35,980 --> 00:40:41,410 So the spinal cord reflexes, the spinal reflexes, 710 00:40:41,410 --> 00:40:44,990 will take much longer to recover. 711 00:40:44,990 --> 00:40:50,150 If I transect the spinal cord of a frog, in not many days, 712 00:40:50,150 --> 00:40:53,790 his spinal reflexes will recover. 713 00:40:53,790 --> 00:40:57,775 If I do it in a dog, it might take weeks. 714 00:40:57,775 --> 00:41:02,660 And if I do it in humans, it might take months, 715 00:41:02,660 --> 00:41:07,440 just to get the spinal reflexes back. 716 00:41:07,440 --> 00:41:08,210 Why? 717 00:41:08,210 --> 00:41:11,330 Because the neuron can fire action 718 00:41:11,330 --> 00:41:20,820 potentials only if there is a depolarization 719 00:41:20,820 --> 00:41:22,820 of the membrane at the axon hillock 720 00:41:22,820 --> 00:41:24,380 that reaches a critical level. 721 00:41:24,380 --> 00:41:28,490 You know that from basic physiology. 722 00:41:28,490 --> 00:41:34,520 If you remove a lot of excitatory inputs, 723 00:41:34,520 --> 00:41:37,180 then there will be more inhibitory inputs 724 00:41:37,180 --> 00:41:40,570 from spinal interneurons that are left, 725 00:41:40,570 --> 00:41:45,390 and you just can't bring the cell to threshold anymore. 726 00:41:45,390 --> 00:41:50,270 OK, so then what happens after such lesions? 727 00:41:50,270 --> 00:41:52,860 These two things happen. 728 00:41:52,860 --> 00:41:56,540 There's collateral sprouting in the cord, collateral 729 00:41:56,540 --> 00:42:00,060 sprouting by remaining inputs. 730 00:42:00,060 --> 00:42:04,530 There's also what we call denervation supersensitivity. 731 00:42:04,530 --> 00:42:12,210 That means the neuron adjusts by increasing 732 00:42:12,210 --> 00:42:15,540 the number of receptors that respond 733 00:42:15,540 --> 00:42:21,940 to the neurotransmitters of the axons that are now missing. 734 00:42:21,940 --> 00:42:26,590 So it will respond more strongly to other inputs that 735 00:42:26,590 --> 00:42:30,410 use the excitatory neurotransmitter. 736 00:42:30,410 --> 00:42:39,010 OK, so this animal will show some sprouting here. 737 00:42:39,010 --> 00:42:43,000 This animal, because he has more deafferentation, 738 00:42:43,000 --> 00:42:46,580 will show more sprouting, and there 739 00:42:46,580 --> 00:42:50,800 will be more receptors on these neurons, 740 00:42:50,800 --> 00:42:53,300 and it will be more on the animal with the larger cortex. 741 00:42:53,300 --> 00:42:56,130 You'll get more supersensitivity. 742 00:42:56,130 --> 00:42:58,340 Those are the two factors. 743 00:42:58,340 --> 00:43:01,760 And just over the time course of collateral sprouting, 744 00:43:01,760 --> 00:43:04,200 what we know about and that has been studied, 745 00:43:04,200 --> 00:43:11,890 you get quite a bit of recovery from this deafferentation. 746 00:43:19,600 --> 00:43:23,180 So basically these quantitative effects have to be considered. 747 00:43:23,180 --> 00:43:27,620 Whenever I get a brain lesion-- hopefully 748 00:43:27,620 --> 00:43:31,490 I won't, but if I did-- if I get a brain lesion, 749 00:43:31,490 --> 00:43:34,070 I can't just consider, well, what were the functions 750 00:43:34,070 --> 00:43:35,350 now removed? 751 00:43:35,350 --> 00:43:39,450 I've got to consider the areas that that area was connected to 752 00:43:39,450 --> 00:43:41,990 and how much deafferentation that it's caused. 753 00:43:41,990 --> 00:43:43,860 I will lose midbrain function too, 754 00:43:43,860 --> 00:43:46,840 if it projects heavily to the midbrain. 755 00:43:46,840 --> 00:43:49,110 That's been studied-- corticotectal diaschisis. 756 00:43:54,180 --> 00:43:57,940 All right, what part of the forebrain 757 00:43:57,940 --> 00:43:59,780 is most involved in the changes that 758 00:43:59,780 --> 00:44:01,660 occur during habit formation? 759 00:44:01,660 --> 00:44:06,040 We call it procedural learning or implicit learning. 760 00:44:06,040 --> 00:44:08,800 Anybody? 761 00:44:08,800 --> 00:44:10,300 It's the corpus striatum. 762 00:44:10,300 --> 00:44:12,140 And we'll be talking about that. 763 00:44:12,140 --> 00:44:13,730 We already mentioned it. 764 00:44:13,730 --> 00:44:17,800 Remember, I said early inputs, very early, 765 00:44:17,800 --> 00:44:22,430 when olfaction was the main sense, 766 00:44:22,430 --> 00:44:26,100 before there were anything except olfaction coming 767 00:44:26,100 --> 00:44:31,610 into the forebrain or the endbrain, it was all olfactory. 768 00:44:31,610 --> 00:44:33,450 If they went to the striatum, that 769 00:44:33,450 --> 00:44:37,690 was the link to the lower structures 770 00:44:37,690 --> 00:44:40,910 that control movement. 771 00:44:40,910 --> 00:44:43,360 And those connections were plastic. 772 00:44:43,360 --> 00:44:47,420 They could be changed depending on the results, the movement. 773 00:44:50,270 --> 00:44:56,070 All right, so what about the tweenbrain? 774 00:44:56,070 --> 00:44:58,240 Just think of the main inputs to the tweenbrain. 775 00:45:01,830 --> 00:45:04,817 And it's relevant to this question. 776 00:45:04,817 --> 00:45:06,650 According to the suggestions in the chapter, 777 00:45:06,650 --> 00:45:10,300 what is the reason why sensory pathways ascending 778 00:45:10,300 --> 00:45:13,070 to the forebrain almost always have a connection 779 00:45:13,070 --> 00:45:15,690 to the thalamus? 780 00:45:15,690 --> 00:45:19,940 Even the olfactory, actually, to get to the neocortex, 781 00:45:19,940 --> 00:45:23,000 have to go through the tweenbrain. 782 00:45:23,000 --> 00:45:24,105 But why would that be? 783 00:45:24,105 --> 00:45:27,570 Why don't they just go directly? 784 00:45:27,570 --> 00:45:30,620 So let's look at the early inputs. 785 00:45:30,620 --> 00:45:33,295 Optic inputs were very early. 786 00:45:33,295 --> 00:45:35,540 And this is the picture of it. 787 00:45:35,540 --> 00:45:40,990 Here I'm showing them coming into the pineal area, 788 00:45:40,990 --> 00:45:42,670 the pineal eye. 789 00:45:42,670 --> 00:45:45,910 And here's a lateral eye. 790 00:45:45,910 --> 00:45:47,580 The most primitive connection there 791 00:45:47,580 --> 00:45:49,820 goes directly to hypothalamus. 792 00:45:49,820 --> 00:45:51,630 What is it doing? 793 00:45:51,630 --> 00:45:57,910 It's controlling the activity rhythm, the changes 794 00:45:57,910 --> 00:46:01,662 with the day-night cycle, the cycle of the sun, 795 00:46:01,662 --> 00:46:03,330 in just about all animals. 796 00:46:05,870 --> 00:46:08,370 That is a system that's modulating 797 00:46:08,370 --> 00:46:11,940 the entire central nervous system. 798 00:46:11,940 --> 00:46:14,402 That's what sleep and waking is-- 799 00:46:14,402 --> 00:46:17,419 it's a cycle of change that affects 800 00:46:17,419 --> 00:46:18,460 the whole nervous system. 801 00:46:21,530 --> 00:46:25,740 There's many other system-wide modulations too. 802 00:46:25,740 --> 00:46:28,590 The pituitary here, another area where secretions 803 00:46:28,590 --> 00:46:32,380 affect the whole animal, the whole nervous system. 804 00:46:35,350 --> 00:46:38,650 And there's more than that. 805 00:46:38,650 --> 00:46:43,650 Hypothalamus is affecting what goes through the thalamus. 806 00:46:43,650 --> 00:46:45,010 It's a modulator. 807 00:46:45,010 --> 00:46:49,140 There are connections from hypothalamus to the thalamus. 808 00:46:49,140 --> 00:46:53,330 We'll go over that in more detail later. 809 00:46:53,330 --> 00:46:57,085 And I think it was that modulation of the whole system 810 00:46:57,085 --> 00:47:00,520 that made-- it was important enough 811 00:47:00,520 --> 00:47:06,550 that I think it prevented the evolution of more 812 00:47:06,550 --> 00:47:07,450 direct connections. 813 00:47:07,450 --> 00:47:09,610 There are a few more direct connections 814 00:47:09,610 --> 00:47:12,070 that have evolved, but very few. 815 00:47:12,070 --> 00:47:15,580 Almost all the sensory pathways that go 816 00:47:15,580 --> 00:47:20,000 to the neocortex stop in the thalamus. 817 00:47:20,000 --> 00:47:23,665 OK, another part in those decerebrated animals 818 00:47:23,665 --> 00:47:27,370 that you're removing is what we call the limbic endbrain-- 819 00:47:27,370 --> 00:47:35,035 basically all the parts that are connected to one structure. 820 00:47:35,035 --> 00:47:37,386 You know what I'm talking about? 821 00:47:37,386 --> 00:47:39,210 The limbic system is characterized 822 00:47:39,210 --> 00:47:42,640 by close interconnections with one portion of the upper brain 823 00:47:42,640 --> 00:47:43,140 stem. 824 00:47:43,140 --> 00:47:46,640 What is it? 825 00:47:46,640 --> 00:47:51,590 You can define the limbic system, 826 00:47:51,590 --> 00:47:55,630 those structures at the fringe of our hemispheres-- limbic 827 00:47:55,630 --> 00:48:00,950 means fringe-- they're the more primitive parts that 828 00:48:00,950 --> 00:48:07,650 were there before any neocortex evolved and expanded. 829 00:48:07,650 --> 00:48:08,970 What was the structure? 830 00:48:12,920 --> 00:48:13,810 You didn't get that? 831 00:48:17,615 --> 00:48:18,115 Sorry? 832 00:48:18,115 --> 00:48:20,340 AUDIENCE: [INAUDIBLE]. 833 00:48:20,340 --> 00:48:21,470 What was it? 834 00:48:21,470 --> 00:48:25,470 Not the neocortex, because the limbic system 835 00:48:25,470 --> 00:48:29,066 is more primitive-- it was there before there was a neocortex. 836 00:48:32,830 --> 00:48:34,375 It's this structure here. 837 00:48:38,000 --> 00:48:40,910 And I'm showing here hypothalamus 838 00:48:40,910 --> 00:48:43,140 and how it is interconnected, not 839 00:48:43,140 --> 00:48:49,300 only with the olfactory system but with all these structures 840 00:48:49,300 --> 00:48:54,010 of the older parts of the brain, the whole ancient pallium. 841 00:48:54,010 --> 00:48:59,105 We call them the dorsal pallium, the medial pallium 842 00:48:59,105 --> 00:49:03,117 and dorsal pallium up here, the medial pallium 843 00:49:03,117 --> 00:49:06,110 is the hippocampus, and then the lateral pallium, 844 00:49:06,110 --> 00:49:08,620 which is olfactory cortex, and the ventral pallium, 845 00:49:08,620 --> 00:49:13,400 which also gets olfactory input, includes the amygdala area. 846 00:49:13,400 --> 00:49:15,910 Those areas are all interconnected 847 00:49:15,910 --> 00:49:17,520 with the hypothalamus. 848 00:49:17,520 --> 00:49:22,870 And that pretty much defines the limbic system. 849 00:49:22,870 --> 00:49:24,890 And there are structures also in the midbrain 850 00:49:24,890 --> 00:49:27,160 that Nauta pointed out should be part of that 851 00:49:27,160 --> 00:49:29,580 because they are also closely interconnected 852 00:49:29,580 --> 00:49:35,200 with the hypothalamus and with the limbic system [INAUDIBLE]. 853 00:49:39,110 --> 00:49:42,190 All right, I want you to read the rest of these. 854 00:49:42,190 --> 00:49:44,210 I'll redo a little bit of it at the beginning 855 00:49:44,210 --> 00:49:45,840 of the next class. 856 00:49:45,840 --> 00:49:50,280 But I will mark this, this is where we stopped. 857 00:49:50,280 --> 00:49:54,280 And then I will post these online. 858 00:49:54,280 --> 00:49:58,460 And we'll be able to finish this quickly next time 859 00:49:58,460 --> 00:50:05,950 and go on to class seven.