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 --> 00:00:10,740 to offer high quality educational resources for free. 5 00:00:10,740 --> 00:00:13,360 To make a donation or view additional materials 6 00:00:13,360 --> 00:00:17,241 from hundreds of MIT courses, visit MIT OpenCourseWare 7 00:00:17,241 --> 00:00:17,866 at ocw.mit.edu. 8 00:00:23,020 --> 00:00:24,990 PROFESSOR: OK, I had told some of you 9 00:00:24,990 --> 00:00:26,515 that there would be a quiz today. 10 00:00:30,130 --> 00:00:34,780 I won't give the quiz because I didn't announce it online, 11 00:00:34,780 --> 00:00:37,750 but I would like you to take it anyway. 12 00:00:37,750 --> 00:00:41,830 Take for your own benefit. 13 00:00:45,130 --> 00:00:46,140 So it won't count. 14 00:00:49,180 --> 00:00:55,170 I just want you to see if you can write down 15 00:00:55,170 --> 00:00:59,470 the names of the 12 traditionally-named cranial 16 00:00:59,470 --> 00:01:02,760 nerves for humans. 17 00:01:02,760 --> 00:01:08,240 I want you to see if what you remember-- just number them 1 18 00:01:08,240 --> 00:01:10,680 through 12 and see if you remember their names, 19 00:01:10,680 --> 00:01:16,670 and see if you know which ones are mixed nerve, which ones are 20 00:01:16,670 --> 00:01:20,200 purely motor, which ones are purely sensory. 21 00:01:20,200 --> 00:01:23,215 Just try it. 22 00:01:23,215 --> 00:01:25,680 Just take a few minutes and try to do that. 23 00:01:54,700 --> 00:01:56,720 And if you're not in class, you're at home 24 00:01:56,720 --> 00:01:59,310 listening to this, I would still like you to do it. 25 00:02:07,154 --> 00:02:08,570 And if you're home, you can let me 26 00:02:08,570 --> 00:02:11,430 know by email how many you have got. 27 00:02:30,120 --> 00:02:31,530 Do you need the mnemonic? 28 00:02:37,680 --> 00:02:42,210 On old Olympus' towering top, a Finn and German 29 00:02:42,210 --> 00:02:43,350 viewed some hops. 30 00:02:47,230 --> 00:02:49,870 I don't know why, but I can remember that mnemonic 31 00:02:49,870 --> 00:02:53,250 better than I can rem-- at least when I was learning them, 32 00:02:53,250 --> 00:02:54,090 I used it. 33 00:02:57,576 --> 00:03:06,620 On old Olympus' towering top, a Finn and German 34 00:03:06,620 --> 00:03:08,133 viewed some hops. 35 00:03:12,067 --> 00:03:13,275 So use all the first letters. 36 00:03:50,100 --> 00:03:51,220 Write it? 37 00:03:51,220 --> 00:03:52,210 AUDIENCE: Yes. 38 00:03:52,210 --> 00:03:53,960 PROFESSOR: Just write these first letters, 39 00:03:53,960 --> 00:04:06,800 on old Olympus', O-O-O, then towering top, so O-O-O-T-P, 40 00:04:06,800 --> 00:04:18,895 a Finn, so A and F. A Finn and German viewed some hops. 41 00:05:16,630 --> 00:05:20,150 OK, so there is a table in the book which 42 00:05:20,150 --> 00:05:28,000 you can find, obviously that occurs in those earlier 43 00:05:28,000 --> 00:05:34,102 chapters, but I keep referring to cranial nerves 44 00:05:34,102 --> 00:05:34,935 throughout the book. 45 00:05:38,350 --> 00:05:43,491 How many of you think you could name all of them? 46 00:05:43,491 --> 00:05:43,990 Yeah? 47 00:05:48,330 --> 00:05:58,020 Olfactory, optic, oculomotor, trochlear, trigeminal, 48 00:05:58,020 --> 00:06:03,290 abducens, it's an oculomotor nerve. 49 00:06:03,290 --> 00:06:05,210 AUDIENCE: Facial, [INAUDIBLE]. 50 00:06:12,430 --> 00:06:15,625 PROFESSOR: So you give 10, 11 and 12 again. 51 00:06:15,625 --> 00:06:16,500 AUDIENCE: [INAUDIBLE] 52 00:06:19,075 --> 00:06:19,825 PROFESSOR: First-- 53 00:06:19,825 --> 00:06:21,260 AUDIENCE: Oh, oh, vagus. 54 00:06:21,260 --> 00:06:24,250 PROFESSOR: Vagus nerve. 55 00:06:24,250 --> 00:06:29,040 Spinal accessory, OK, excellent. 56 00:06:29,040 --> 00:06:32,670 Now you need to know just whether there 57 00:06:32,670 --> 00:06:38,310 are a few purely motor ones, somatic motor, the oculomotor 58 00:06:38,310 --> 00:06:46,920 nerves, and the one controlling the tongue, 59 00:06:46,920 --> 00:06:51,530 glossopharyngeal nerve and the-- sorry, 60 00:06:51,530 --> 00:06:53,750 not the glossopharyngeal but the hypoglossal. 61 00:07:03,750 --> 00:07:08,240 And of course there's several purely sensory nerves. 62 00:07:08,240 --> 00:07:11,080 The others are mixed. 63 00:07:11,080 --> 00:07:14,330 And the mixed nerves always have-- 64 00:07:14,330 --> 00:07:15,820 they're [? attached ?] where they 65 00:07:15,820 --> 00:07:18,580 come in and join the brain. 66 00:07:18,580 --> 00:07:24,090 Sort of in that middle region, whereas the purely sensory ones 67 00:07:24,090 --> 00:07:26,465 in the hind brain are like dorsal roots. 68 00:07:26,465 --> 00:07:28,460 They come in dorsally. 69 00:07:28,460 --> 00:07:30,430 Purely motor ones are like ventral roots. 70 00:07:38,990 --> 00:07:43,520 Except the trochlear actually, doesn't actually 71 00:07:43,520 --> 00:07:47,220 leave the cranium ventrally. 72 00:07:47,220 --> 00:07:52,450 It comes around, comes up between the cerebellum 73 00:07:52,450 --> 00:07:55,190 and the inferior colliculus, and exits that way. 74 00:08:01,600 --> 00:08:05,275 But it's very useful to know these in neuroanatomy. 75 00:08:09,270 --> 00:08:09,840 All right. 76 00:08:19,460 --> 00:08:26,260 Throughout the book I've emphasized these two 77 00:08:26,260 --> 00:08:32,312 structures, the medial pallium and the corpus striatum. 78 00:08:32,312 --> 00:08:36,520 The early striatums, mainly an olfactory structure, 79 00:08:36,520 --> 00:08:39,940 but the striatum provided the link to motor systems. 80 00:08:42,568 --> 00:08:46,600 And that's still true of the whole striatum, 81 00:08:46,600 --> 00:08:49,825 except it's not just olfactory anymore. 82 00:08:49,825 --> 00:08:52,370 And the other system is the medial pallium, 83 00:08:52,370 --> 00:08:55,870 which as you probably remember is the hippocampal formation. 84 00:08:59,377 --> 00:09:03,260 But what did I suggest was, even very early, 85 00:09:03,260 --> 00:09:07,190 was the role, the major role, of these. 86 00:09:07,190 --> 00:09:13,130 They both concern learning, but different types of learning. 87 00:09:13,130 --> 00:09:16,380 And you could see the entire neocortex organized 88 00:09:16,380 --> 00:09:20,386 around these two systems, two types of learning. 89 00:09:20,386 --> 00:09:26,530 Because cortical areas, many cortical areas, 90 00:09:26,530 --> 00:09:29,470 have projections that go towards one 91 00:09:29,470 --> 00:09:30,845 or the other of these structures. 92 00:09:34,100 --> 00:09:36,080 So what is the striatum involved in? 93 00:09:40,054 --> 00:09:40,970 What kind of learning? 94 00:09:44,050 --> 00:09:49,930 It's always sensory motor habits of various sorts. 95 00:09:49,930 --> 00:09:53,250 But now we think it's much more than sensory motor in higher 96 00:09:53,250 --> 00:09:54,530 primates. 97 00:09:54,530 --> 00:09:56,420 We think it's probably habits of thought, 98 00:09:56,420 --> 00:09:58,170 habits of even feeling. 99 00:10:01,300 --> 00:10:05,860 A habit of feeling is something like a prejudice, 100 00:10:05,860 --> 00:10:09,790 so your prejudices probably depend 101 00:10:09,790 --> 00:10:13,368 on connections that have been learned 102 00:10:13,368 --> 00:10:20,440 and the change that's occurred in that parts of the striatum. 103 00:10:20,440 --> 00:10:24,730 And what about the medial pallium or hippocampus? 104 00:10:24,730 --> 00:10:29,630 Originally a type of memory, though, 105 00:10:29,630 --> 00:10:32,240 because what we just talked about is all memory too. 106 00:10:32,240 --> 00:10:33,820 Habit memory is memory. 107 00:10:38,650 --> 00:10:49,050 Spatial memories, where we are in the environment, 108 00:10:49,050 --> 00:10:52,850 episodic memory, came out of this. 109 00:10:52,850 --> 00:10:56,530 And yes, it's become important for navigating 110 00:10:56,530 --> 00:11:07,370 our cognitive space, our social space, our imaginary spaces. 111 00:11:07,370 --> 00:11:10,390 But that's not how it originated. 112 00:11:10,390 --> 00:11:14,940 It all evolved out of the system for navigating the world 113 00:11:14,940 --> 00:11:18,490 and remembering, being able to remember, 114 00:11:18,490 --> 00:11:20,960 good places and bad places. 115 00:11:20,960 --> 00:11:23,690 That required a somewhat different kind of learning, 116 00:11:23,690 --> 00:11:26,280 different kinds of algorithms had 117 00:11:26,280 --> 00:11:33,160 to evolve to underlie those two kinds of memory. 118 00:11:33,160 --> 00:11:36,455 And then why did dorsal and ventral parts of the striatum 119 00:11:36,455 --> 00:11:36,955 segregate? 120 00:11:39,600 --> 00:11:40,720 What was the big event? 121 00:11:45,360 --> 00:11:49,920 I said it was olfactory originally, 122 00:11:49,920 --> 00:11:51,825 and that became ventral striatum. 123 00:11:55,150 --> 00:11:59,410 So that should tell you what happened. 124 00:11:59,410 --> 00:12:06,500 Other senses projected mostly through the thalamus 125 00:12:06,500 --> 00:12:08,090 into the striatum also. 126 00:12:08,090 --> 00:12:11,450 And they took advantage of that ability 127 00:12:11,450 --> 00:12:19,850 to form-- to change connections that became habits. 128 00:12:19,850 --> 00:12:22,290 Obviously we don't just form olfactory habits, 129 00:12:22,290 --> 00:12:29,540 we form visual motor habits. 130 00:12:29,540 --> 00:12:32,920 Think of the sports you learn, think of simpler things 131 00:12:32,920 --> 00:12:41,160 like riding a bicycle or various things 132 00:12:41,160 --> 00:12:43,980 you learn when you're growing up. 133 00:12:43,980 --> 00:12:46,410 Learning how to throw a baseball properly, 134 00:12:46,410 --> 00:12:50,040 learning how to hit a baseball, all these things in sports. 135 00:12:50,040 --> 00:12:51,880 But many things that we don't even think 136 00:12:51,880 --> 00:12:55,350 about, they're not sports, they're things that we learn, 137 00:12:55,350 --> 00:12:56,220 part of our lives. 138 00:12:59,540 --> 00:13:03,500 Those habits depend on the striatum. 139 00:13:03,500 --> 00:13:08,990 And we call that kind of memory, implicit memory, 140 00:13:08,990 --> 00:13:12,930 they are not-- we don't remember individual events. 141 00:13:12,930 --> 00:13:17,180 If you're talking about your memory for an event, 142 00:13:17,180 --> 00:13:21,260 where you learned how to ride a bike, that's different, 143 00:13:21,260 --> 00:13:24,890 that's not a striatum, but actually learning. 144 00:13:28,330 --> 00:13:34,900 We say, well, I know how to type, I remember in my fingers. 145 00:13:34,900 --> 00:13:38,380 Well, that's striatal. 146 00:13:38,380 --> 00:13:38,880 All right. 147 00:13:44,330 --> 00:13:52,420 So I go through this, call it a likely scenario, 148 00:13:52,420 --> 00:13:55,170 for the origins of corpus striatum. 149 00:13:55,170 --> 00:14:02,430 And I'm just going to go to this picture here, 150 00:14:02,430 --> 00:14:05,390 this just summarises that whole scenario. 151 00:14:05,390 --> 00:14:10,770 If you go through this, I describe it in the book, 152 00:14:10,770 --> 00:14:13,970 that the beginnings is a link between olfactory input 153 00:14:13,970 --> 00:14:15,116 and motor control. 154 00:14:18,080 --> 00:14:21,560 This is slide 37. 155 00:14:21,560 --> 00:14:24,410 And that became a ventral striatum, that early link, 156 00:14:24,410 --> 00:14:28,530 and then I said, well, the outputs 157 00:14:28,530 --> 00:14:36,510 went to the hypothalamus as you see them drawn here 158 00:14:36,510 --> 00:14:38,430 in a primitive brain. 159 00:14:38,430 --> 00:14:40,510 And then the major point that I added 160 00:14:40,510 --> 00:14:46,230 was that these were modifiable links. 161 00:14:46,230 --> 00:14:50,040 And that was a big innovation, different from spinal cord. 162 00:14:50,040 --> 00:14:52,430 You have a little bit of learning in the spinal cord, 163 00:14:52,430 --> 00:14:53,800 but nothing like this. 164 00:14:56,830 --> 00:14:58,560 Types of learning you get in spinal cord 165 00:14:58,560 --> 00:14:59,740 are rather short term. 166 00:14:59,740 --> 00:15:03,125 This is long term. 167 00:15:03,125 --> 00:15:05,470 These are the formation of habits. 168 00:15:05,470 --> 00:15:08,760 And then I talk about the non-olfact-- well, 169 00:15:08,760 --> 00:15:11,820 I talk about the feedback you need for learning. 170 00:15:11,820 --> 00:15:16,080 We know that it involves the dopamine pathways 171 00:15:16,080 --> 00:15:18,046 pretty heavily. 172 00:15:18,046 --> 00:15:22,425 We know that very early taste as well as olfaction 173 00:15:22,425 --> 00:15:25,880 were important sources of feedback 174 00:15:25,880 --> 00:15:29,870 that affected that system. 175 00:15:29,870 --> 00:15:32,955 And then I talk about the non-olfactory inputs 176 00:15:32,955 --> 00:15:36,733 that resulted in a dorsal striatum as well 177 00:15:36,733 --> 00:15:37,810 as ventral striatum. 178 00:15:41,009 --> 00:15:45,510 And then I talk about the early expansions of the endbrain. 179 00:15:45,510 --> 00:15:50,470 It wasn't just the striatum, but it was the pallium as well. 180 00:15:50,470 --> 00:15:54,516 Originally, the pallium was olfactory, 181 00:15:54,516 --> 00:15:55,735 the olfactory cortex. 182 00:15:58,360 --> 00:16:03,810 But very, very early the medial pallium began to evolve. 183 00:16:11,220 --> 00:16:13,710 We will look more at that, I'll show you 184 00:16:13,710 --> 00:16:18,780 pictures of the way that looks in non-mammals. 185 00:16:18,780 --> 00:16:20,620 You'll see, for example, in the frog, 186 00:16:20,620 --> 00:16:24,450 the major pallial structure is the medial pallium. 187 00:16:24,450 --> 00:16:29,370 They have a little bit of structures adjacent to it, 188 00:16:29,370 --> 00:16:32,670 but they're just-- they provide input to that medial pallium. 189 00:16:32,670 --> 00:16:36,110 It's called the dorsal cortex, and yes, the neocortex 190 00:16:36,110 --> 00:16:37,330 did evolve out of that. 191 00:16:40,390 --> 00:16:44,570 OK, and then you had the expansions 192 00:16:44,570 --> 00:16:46,550 of both the cortex and the striatum. 193 00:16:50,850 --> 00:16:53,440 But the major change that occurred in mammals 194 00:16:53,440 --> 00:17:00,570 was that a major output of the striatum went to the cortex, 195 00:17:00,570 --> 00:17:03,130 because it projected to the thalamus. 196 00:17:03,130 --> 00:17:04,301 So we'll see that. 197 00:17:04,301 --> 00:17:04,800 All right. 198 00:17:09,810 --> 00:17:16,230 We get a good idea about origins and the relationship 199 00:17:16,230 --> 00:17:20,700 of different major segments of the endbrain and other brain 200 00:17:20,700 --> 00:17:23,990 regions by looking at gene expression. 201 00:17:23,990 --> 00:17:28,832 And this was one of the earliest studies that did that. 202 00:17:28,832 --> 00:17:34,680 It showed that genes expressed in neocortex as well 203 00:17:34,680 --> 00:17:41,120 as adjacent areas like hippocampal area 204 00:17:41,120 --> 00:17:44,220 and the olfactory cortex. 205 00:17:44,220 --> 00:17:48,060 You can find closely related genes 206 00:17:48,060 --> 00:17:55,390 in the hyperpallium of birds, in the dorsal cortex of reptiles, 207 00:17:55,390 --> 00:17:59,650 including turtles, and in this dorsal cortex of the frog. 208 00:17:59,650 --> 00:18:03,525 And that thick part there is the medial pallium 209 00:18:03,525 --> 00:18:08,720 of the frog, that is the hippocampal formation. 210 00:18:08,720 --> 00:18:11,160 And then you can see the other genes are expressed 211 00:18:11,160 --> 00:18:15,570 in the striatal regions and the adjoining septum. 212 00:18:15,570 --> 00:18:18,310 Notice that it goes all way down to the base of the brain 213 00:18:18,310 --> 00:18:22,730 where the olfactory inputs come in, even in mammals. 214 00:18:22,730 --> 00:18:28,200 And there is a corresponding striatal area in the birds, 215 00:18:28,200 --> 00:18:32,810 in the reptiles, and in the amphibians. 216 00:18:32,810 --> 00:18:34,620 And then there are additional regions 217 00:18:34,620 --> 00:18:41,190 that aren't expressing the genes of those two major regions. 218 00:18:41,190 --> 00:18:49,090 And that includes this in the reptilian dorsal ventricular 219 00:18:49,090 --> 00:18:51,528 ridge area. 220 00:18:51,528 --> 00:18:56,370 In birds, there is also a dorsal ventricular ridge area. 221 00:18:56,370 --> 00:19:00,820 It isn't called that anymore in the adult bird, 222 00:19:00,820 --> 00:19:05,540 but its connections are pallial-like, 223 00:19:05,540 --> 00:19:08,160 and that's true in the reptiles too. 224 00:19:08,160 --> 00:19:10,480 But if you look at mammals, you don't 225 00:19:10,480 --> 00:19:15,190 find that gene expressed in the neocortex. 226 00:19:15,190 --> 00:19:19,230 You find it mainly here in the amygdala. 227 00:19:19,230 --> 00:19:21,870 But we know now that the amygdala 228 00:19:21,870 --> 00:19:31,850 does get projections of various senses, somewhat like cortex. 229 00:19:31,850 --> 00:19:37,150 And we also know that from these subcortical regions 230 00:19:37,150 --> 00:19:41,195 there are cells migrating to the neocortex. 231 00:19:41,195 --> 00:19:44,270 And this just shows, from more recent studies, 232 00:19:44,270 --> 00:19:46,180 the same picture holds. 233 00:19:46,180 --> 00:19:48,490 But it shows how come-- this is just 234 00:19:48,490 --> 00:19:51,255 to give you an idea of the complexity of these gene 235 00:19:51,255 --> 00:19:53,470 expression studies. 236 00:19:53,470 --> 00:20:01,100 And because the gene expression studies don't always-- they 237 00:20:01,100 --> 00:20:04,470 are sometimes hard to interpret because of the number of genes 238 00:20:04,470 --> 00:20:07,980 involved and the relative degree of expression. 239 00:20:07,980 --> 00:20:11,850 I still like the studies that depend more on connections, 240 00:20:11,850 --> 00:20:15,470 and the reason for that is that the connections are what 241 00:20:15,470 --> 00:20:19,090 underlies behavior, and the behavior 242 00:20:19,090 --> 00:20:24,840 is really critical in evolution. 243 00:20:24,840 --> 00:20:31,740 Brains change in order to change function, 244 00:20:31,740 --> 00:20:34,510 which of course includes behavior. 245 00:20:34,510 --> 00:20:39,390 This just gives you another view, one based on connections. 246 00:20:39,390 --> 00:20:45,650 This is Karten and one of his students publishing back 247 00:20:45,650 --> 00:20:47,720 in 1989. 248 00:20:47,720 --> 00:20:50,570 Karten was the guy who was at MIT with [? Nauda ?] 249 00:20:50,570 --> 00:20:54,400 and was the first to discover these pathways in birds 250 00:20:54,400 --> 00:20:58,250 from thalamus carrying visual and auditory 251 00:20:58,250 --> 00:21:01,520 information to that big subcortical region 252 00:21:01,520 --> 00:21:02,155 in the birds. 253 00:21:12,540 --> 00:21:16,230 This was more like neocortex up here, the hyperpallium, 254 00:21:16,230 --> 00:21:21,600 but this region here also had connections just 255 00:21:21,600 --> 00:21:24,825 like neocortex. 256 00:21:24,825 --> 00:21:25,325 All right. 257 00:21:28,010 --> 00:21:32,770 So he related the specific kinds of connections in mammals 258 00:21:32,770 --> 00:21:37,900 to similar connections in birds and where they were located. 259 00:21:44,400 --> 00:21:47,280 So then I discuss the medial pallium a little bit. 260 00:21:47,280 --> 00:21:51,000 We've already done that. 261 00:21:51,000 --> 00:21:54,140 But I wanted to point out this one rather interesting study, 262 00:21:54,140 --> 00:21:57,810 it's a highly cited study. 263 00:21:57,810 --> 00:22:00,280 This was a group of investigators 264 00:22:00,280 --> 00:22:08,580 who realized that in one genus of birds, 265 00:22:08,580 --> 00:22:13,702 there were some birds that formed food caches, 266 00:22:13,702 --> 00:22:18,260 they stored food when food was plentiful, 267 00:22:18,260 --> 00:22:20,556 and then they had to remember where they put it. 268 00:22:20,556 --> 00:22:24,880 They had to remember well above chance levels for it 269 00:22:24,880 --> 00:22:25,820 to be really adaptive. 270 00:22:29,610 --> 00:22:33,170 Whereas other members of the very same genus didn't do that. 271 00:22:36,000 --> 00:22:41,500 So these people studied the brains of these two groups 272 00:22:41,500 --> 00:22:48,470 of birds and other songbirds as well that formed these food 273 00:22:48,470 --> 00:22:53,180 storage locations, the food caches, and those that didn't. 274 00:22:53,180 --> 00:22:59,670 And this is a plot of the size of the hippocampus 275 00:22:59,670 --> 00:23:04,056 versus the volume of the whole telencephalon, 276 00:23:04,056 --> 00:23:07,100 the whole endbrain. 277 00:23:07,100 --> 00:23:10,470 And you can see here this is the dimension 278 00:23:10,470 --> 00:23:12,720 you want to pay attention to. 279 00:23:12,720 --> 00:23:15,510 OK? 280 00:23:15,510 --> 00:23:18,580 How far they are from that diagonal line, and you can see 281 00:23:18,580 --> 00:23:19,785 there's no overlap. 282 00:23:19,785 --> 00:23:22,420 The birds that formed the food caches had bigger hippocampus. 283 00:23:26,370 --> 00:23:31,330 So the correlations aren't just statistically 284 00:23:31,330 --> 00:23:32,540 reliable, they're dramatic. 285 00:23:35,540 --> 00:23:39,636 Animals need that structure for spatial memory. 286 00:23:39,636 --> 00:23:40,950 AUDIENCE: [INAUDIBLE] 287 00:23:40,950 --> 00:23:41,805 PROFESSOR: Sorry? 288 00:23:41,805 --> 00:23:45,579 AUDIENCE: What's the difference in [INAUDIBLE]? 289 00:23:45,579 --> 00:23:46,620 PROFESSOR: Difference in? 290 00:23:46,620 --> 00:23:51,560 Oh, the members of the one group, these 291 00:23:51,560 --> 00:23:53,810 are all the same genes. 292 00:23:53,810 --> 00:23:55,530 The triangles. 293 00:23:55,530 --> 00:23:59,660 The others are not members of that genus. 294 00:23:59,660 --> 00:24:03,054 I did reproduce this, I believe, in the book, 295 00:24:03,054 --> 00:24:04,980 so you can find the source. 296 00:24:04,980 --> 00:24:10,840 And I probably spelled some of that out in the legend. 297 00:24:10,840 --> 00:24:12,180 All right. 298 00:24:12,180 --> 00:24:13,805 And then there was a parallel evolution 299 00:24:13,805 --> 00:24:18,900 of the pallial and subpallial structures, expansion of both, 300 00:24:18,900 --> 00:24:22,916 although we know that it was the pallial structures that 301 00:24:22,916 --> 00:24:25,506 expanded the most, especially in mammals 302 00:24:25,506 --> 00:24:27,150 with the evolution of neocortex. 303 00:24:32,140 --> 00:24:36,200 So I pretty much answered question eight, 304 00:24:36,200 --> 00:24:39,470 part of the primitive endbrain that the neocortex evolved from 305 00:24:39,470 --> 00:24:41,910 was that dorsal cortex. 306 00:24:41,910 --> 00:24:47,110 There's a parahippocampal region, 307 00:24:47,110 --> 00:24:51,315 and it's supported by gene expression data. 308 00:24:55,710 --> 00:24:58,080 And you should know that some mammals 309 00:24:58,080 --> 00:25:00,000 have a very small neocortex. 310 00:25:00,000 --> 00:25:05,390 Although having a neocortex is fundamental to being a mammal, 311 00:25:05,390 --> 00:25:11,510 not just having mammary glands and some other characteristics, 312 00:25:11,510 --> 00:25:15,920 hair on the skin and so forth. 313 00:25:15,920 --> 00:25:21,960 I redrew the gross views here of a couple of hedgehogs. 314 00:25:21,960 --> 00:25:26,760 European hedgehogs just have a really small neocortex, 315 00:25:26,760 --> 00:25:28,465 smaller than the hamster. 316 00:25:28,465 --> 00:25:34,370 A West African hedgehog, a possum, a prairie vole, 317 00:25:34,370 --> 00:25:38,470 they're all fairly similar to a hamster. 318 00:25:38,470 --> 00:25:40,955 And the relatively slightly larger 319 00:25:40,955 --> 00:25:44,510 are animals like the vole and mouse, other voles 320 00:25:44,510 --> 00:25:48,210 and mouse, rat. 321 00:25:48,210 --> 00:25:51,580 And these are what cross sections look like. 322 00:25:51,580 --> 00:25:53,825 Here we have a tenrec. 323 00:25:53,825 --> 00:25:59,820 It's another animal that like the European hedgehog has, 324 00:25:59,820 --> 00:26:03,075 I think relatively speaking, the smallest neocortex 325 00:26:03,075 --> 00:26:04,896 of all the mammals. 326 00:26:04,896 --> 00:26:09,850 And that's shown in this section through the middle 327 00:26:09,850 --> 00:26:10,665 of the brain. 328 00:26:10,665 --> 00:26:13,400 This is the mid-frontal section through the middle 329 00:26:13,400 --> 00:26:14,790 of the hemisphere. 330 00:26:14,790 --> 00:26:19,220 You see the neocortex is even smaller, or at least no bigger, 331 00:26:19,220 --> 00:26:21,540 than the whole hippocampus there. 332 00:26:21,540 --> 00:26:23,330 And this is all olfactory cortex. 333 00:26:30,300 --> 00:26:33,275 And then the opossums and the hedgehogs 334 00:26:33,275 --> 00:26:36,810 also have relatively small neocortexes. 335 00:26:36,810 --> 00:26:41,920 OK, and then we went through these pictures, 336 00:26:41,920 --> 00:26:43,580 and now we want to do this. 337 00:26:43,580 --> 00:26:45,170 We want to get started with talking 338 00:26:45,170 --> 00:26:46,566 about the limbic system, and this 339 00:26:46,566 --> 00:26:49,040 will be the first session on that. 340 00:26:49,040 --> 00:26:51,390 Stressing the hypothalamus at the beginning, 341 00:26:51,390 --> 00:26:53,436 and then we'll talk about striatum 342 00:26:53,436 --> 00:26:54,885 and then the neocortex. 343 00:27:05,030 --> 00:27:06,656 All right. 344 00:27:06,656 --> 00:27:11,550 So this is actually called class 28. 345 00:27:11,550 --> 00:27:16,530 When I put the slides up after the class I call them sessions, 346 00:27:16,530 --> 00:27:19,060 so they will start with the slides we just 347 00:27:19,060 --> 00:27:23,520 covered on the forebrain introduction. 348 00:27:26,268 --> 00:27:27,860 OK, so what is that term? 349 00:27:27,860 --> 00:27:29,596 Where does it come from? 350 00:27:29,596 --> 00:27:31,380 Why do we call it limbic system? 351 00:27:34,740 --> 00:27:36,180 AUDIENCE: [INAUDIBLE] 352 00:27:36,180 --> 00:27:37,140 PROFESSOR: Sorry? 353 00:27:37,140 --> 00:27:40,020 AUDIENCE: Doesn't "limbic" mean the edge of something? 354 00:27:40,020 --> 00:27:41,410 PROFESSOR: Yeah, the fringe. 355 00:27:41,410 --> 00:27:43,275 The fringe or border or edge. 356 00:27:50,350 --> 00:28:01,310 It came-- I must have brought that up a little bit later. 357 00:28:01,310 --> 00:28:04,890 Let's come back to that in a minute, 358 00:28:04,890 --> 00:28:07,810 and talk about the structure that 359 00:28:07,810 --> 00:28:10,513 is central to any discussion of the limbic system, 360 00:28:10,513 --> 00:28:14,650 the hypothalamus, and why it became 361 00:28:14,650 --> 00:28:19,510 important to separate out an endbrain system that 362 00:28:19,510 --> 00:28:23,160 was closely connected with it. 363 00:28:23,160 --> 00:28:24,760 All the endbrain structures that we 364 00:28:24,760 --> 00:28:28,450 call limbic system, or limbic endbrain system, 365 00:28:28,450 --> 00:28:32,110 are all closely connected to the hypothalamus. 366 00:28:32,110 --> 00:28:34,470 Sherrington, remember, called it the head ganglion 367 00:28:34,470 --> 00:28:37,490 of the autonomic nervous system. 368 00:28:37,490 --> 00:28:41,800 It's much more than that, because it controls 369 00:28:41,800 --> 00:28:48,200 motivated behavior including eating, defending, attacking. 370 00:28:48,200 --> 00:28:53,506 The structures there underlie motivational states, 371 00:28:53,506 --> 00:28:54,285 the drives. 372 00:28:56,810 --> 00:29:00,055 And of course they're associated with strong feelings, 373 00:29:00,055 --> 00:29:02,590 so we also associate it with emotion. 374 00:29:05,170 --> 00:29:08,205 And we call them, when we talked about motor system, 375 00:29:08,205 --> 00:29:12,170 we called them central pattern generators. 376 00:29:12,170 --> 00:29:18,692 This is the picture of-- what it shows 377 00:29:18,692 --> 00:29:22,318 is the locomotor hierarchy with the pattern 378 00:29:22,318 --> 00:29:24,270 generators in the spinal cord. 379 00:29:24,270 --> 00:29:28,260 Here's the motor neurons. 380 00:29:28,260 --> 00:29:33,350 And then, in the midbrain and 'tweenbrain, 381 00:29:33,350 --> 00:29:38,440 Swanson called the structures that 382 00:29:38,440 --> 00:29:43,270 initiated locomotion the locomotor pattern 383 00:29:43,270 --> 00:29:45,210 initiator, the midbrain locomotor 384 00:29:45,210 --> 00:29:48,190 region, and the locomotor pattern 385 00:29:48,190 --> 00:29:53,600 controller, the hypothalamic locomotor region. 386 00:29:53,600 --> 00:29:55,182 And when we're in the hypothalamus, 387 00:29:55,182 --> 00:29:58,170 we're concerned with structures that 388 00:29:58,170 --> 00:30:01,820 underlie what we call the biological drives. 389 00:30:01,820 --> 00:30:04,235 So why is there a locomotor pattern generator 390 00:30:04,235 --> 00:30:05,320 in the hypothalamus? 391 00:30:07,950 --> 00:30:10,865 It doesn't directly control locomotion. 392 00:30:10,865 --> 00:30:15,340 It controls the structures in the midbrain and hindbrain 393 00:30:15,340 --> 00:30:19,035 and spinal cord that underlie locomotor movements. 394 00:30:23,810 --> 00:30:27,990 But with every drive, think of hunger drive. 395 00:30:27,990 --> 00:30:30,175 Locomotion is always involved. 396 00:30:30,175 --> 00:30:37,440 If an animal has a high level of hunger, he will move more. 397 00:30:37,440 --> 00:30:40,470 Unless he's so hungry, he's getting weak. 398 00:30:40,470 --> 00:30:43,410 But that comes rather late, we're talking about just 399 00:30:43,410 --> 00:30:45,116 in the normal state. 400 00:30:45,116 --> 00:30:46,490 When you're hungrier, you're more 401 00:30:46,490 --> 00:30:50,335 likely to locomote to the refrigerator or to the store. 402 00:30:53,827 --> 00:30:58,080 But think of animals who are motivated to forage. 403 00:30:58,080 --> 00:31:02,560 Or if they're food storing animals, like a hungry hamster, 404 00:31:02,560 --> 00:31:04,880 will only forage at certain times of day 405 00:31:04,880 --> 00:31:13,370 when he's safest, when the sun is very low in the sky. 406 00:31:13,370 --> 00:31:16,936 But other times when he's hungry, 407 00:31:16,936 --> 00:31:21,060 he will generate locomotion to get to the places 408 00:31:21,060 --> 00:31:22,865 where he's stored food. 409 00:31:22,865 --> 00:31:27,540 And he has an elaborate tunnel, and will go to various places 410 00:31:27,540 --> 00:31:29,500 in his tunnel to do that. 411 00:31:29,500 --> 00:31:33,820 So locomotion is associated with all the drives. 412 00:31:33,820 --> 00:31:37,462 So it is connected to the other neurons in the hypothalamus 413 00:31:37,462 --> 00:31:41,060 that underlie the various motivational states. 414 00:31:43,820 --> 00:31:51,100 So now the cortical layers that we call limbic endbrain 415 00:31:51,100 --> 00:31:55,220 structures, they are closely connected to the hypothalamus. 416 00:31:55,220 --> 00:31:56,392 Where are they found? 417 00:31:58,990 --> 00:32:04,080 And that tells you the origin of the term limbic system. 418 00:32:04,080 --> 00:32:06,560 We already discussed the meaning. 419 00:32:06,560 --> 00:32:13,840 The term came from Paul Broca, Pierre Paul Broca, 420 00:32:13,840 --> 00:32:20,470 who used this phrase, "the great limbic lobe," in French 421 00:32:20,470 --> 00:32:24,220 in 1878, for the human brain. 422 00:32:24,220 --> 00:32:26,950 But I have to point out that that doesn't mean that Broca 423 00:32:26,950 --> 00:32:31,230 understood the functions, OK, or the connections, 424 00:32:31,230 --> 00:32:33,883 because the methods simply weren't good enough 425 00:32:33,883 --> 00:32:35,060 for him to know that. 426 00:32:38,010 --> 00:32:43,740 It wasn't until the 20th century that we began to realize that. 427 00:32:43,740 --> 00:32:48,560 But what Broca called the great limbic lobe, 428 00:32:48,560 --> 00:32:50,150 you have to look at a human hemisphere 429 00:32:50,150 --> 00:32:53,140 from the medial side. 430 00:32:53,140 --> 00:32:57,140 And this particular picture of the human brain 431 00:32:57,140 --> 00:33:01,910 on top and rodent brains down below, 432 00:33:01,910 --> 00:33:04,810 I've divided it according to major functions. 433 00:33:04,810 --> 00:33:10,550 And I say that these are all structures closely tied 434 00:33:10,550 --> 00:33:13,870 to motivational states because they're closely 435 00:33:13,870 --> 00:33:16,075 linked to the hypothalamus. 436 00:33:16,075 --> 00:33:21,340 And notice that they're always around this edge 437 00:33:21,340 --> 00:33:24,124 of the hemisphere. 438 00:33:24,124 --> 00:33:26,480 So if you start just at the corpus callosum 439 00:33:26,480 --> 00:33:29,480 and go just above it, you're in limbic areas 440 00:33:29,480 --> 00:33:31,656 of singular cortex. 441 00:33:31,656 --> 00:33:34,380 These are the parolfactory regions. 442 00:33:34,380 --> 00:33:40,810 The orbital frontal region is closely connected to these. 443 00:33:40,810 --> 00:33:43,660 Broca's area would not be included. 444 00:33:43,660 --> 00:33:47,560 This would be Broca's area here, and this 445 00:33:47,560 --> 00:33:52,350 would be the area controlling the movements of speaking, 446 00:33:52,350 --> 00:34:00,160 just behind Broca's area but in the motor areas of the cortex. 447 00:34:00,160 --> 00:34:03,000 But that doesn't mean that Broca's area is not 448 00:34:03,000 --> 00:34:04,820 connected to these areas. 449 00:34:04,820 --> 00:34:05,710 It is. 450 00:34:05,710 --> 00:34:11,260 The various, multi-sensory association areas of cortex 451 00:34:11,260 --> 00:34:15,760 are the areas most closely tied to these limbic structures. 452 00:34:15,760 --> 00:34:19,810 We often call them paralimbic, and reserve 453 00:34:19,810 --> 00:34:22,929 the term limbic structures to the subcortical structures that 454 00:34:22,929 --> 00:34:26,036 are closely tied to the brain stem. 455 00:34:26,036 --> 00:34:29,019 But the paralimbic structures are these structures 456 00:34:29,019 --> 00:34:30,150 that are near that. 457 00:34:32,750 --> 00:34:39,370 But that's the great limbic lobe that forms this whole ring. 458 00:34:39,370 --> 00:34:41,350 The medial edge of the brain, and here you 459 00:34:41,350 --> 00:34:43,239 see them in a rodent brain. 460 00:34:43,239 --> 00:34:47,125 Some of this would be connected to the [? MD, ?] which means 461 00:34:47,125 --> 00:34:52,020 it's prefrontal neocortex, but in the rodent those areas get 462 00:34:52,020 --> 00:34:56,137 connections from the anterior nuclei too, 463 00:34:56,137 --> 00:34:58,220 which cannot be the [? singular. ?] We'll be going 464 00:34:58,220 --> 00:34:59,690 over that. 465 00:34:59,690 --> 00:35:02,660 So I've shown that ring of cortical areas, 466 00:35:02,660 --> 00:35:06,900 there, indicated by the arrow here, just on the medial view. 467 00:35:06,900 --> 00:35:09,100 But we include with it the olfactory areas. 468 00:35:09,100 --> 00:35:10,990 So here you see it in the rodent. 469 00:35:10,990 --> 00:35:17,490 I've used that same designation because the olfactory areas 470 00:35:17,490 --> 00:35:19,820 are paralimbic too in that sense. 471 00:35:19,820 --> 00:35:24,490 They are closely linked to the hypothalamus. 472 00:35:24,490 --> 00:35:27,255 And then I continue that designation here on the brain 473 00:35:27,255 --> 00:35:30,900 stem, and I show the hypothalamus and epithalamus 474 00:35:30,900 --> 00:35:39,185 marked that way, and I show it continuing into the midbrain, 475 00:35:39,185 --> 00:35:44,880 as [? Nauda ?] described in his work on the cats and monkeys 476 00:35:44,880 --> 00:35:45,380 primarily. 477 00:35:48,410 --> 00:35:52,280 OK, now there are various types of studies 478 00:35:52,280 --> 00:35:58,940 that separate limbic system areas from what we've 479 00:35:58,940 --> 00:36:02,340 been calling somatic areas, the non-limbic areas. 480 00:36:05,050 --> 00:36:07,640 And when it was done a number of years 481 00:36:07,640 --> 00:36:13,600 ago in describing systems in the brain that cause arousal, 482 00:36:13,600 --> 00:36:19,020 in electrical stimulation studies 483 00:36:19,020 --> 00:36:22,310 and in behavioral studies, aroused animals 484 00:36:22,310 --> 00:36:26,080 are very different from unaroused animals. 485 00:36:26,080 --> 00:36:28,650 So let's just go through that a little bit 486 00:36:28,650 --> 00:36:33,830 and talk about the two arousal systems in the midbrain. 487 00:36:33,830 --> 00:36:36,076 One of them we associate with the midbrain reticular 488 00:36:36,076 --> 00:36:36,575 formation. 489 00:36:36,575 --> 00:36:38,490 It's somatic. 490 00:36:38,490 --> 00:36:40,670 The other is associated with the limbic areas. 491 00:36:43,530 --> 00:36:50,590 So we've already seen this picture 492 00:36:50,590 --> 00:36:54,910 when we talked about midbrain and diencephalon 493 00:36:54,910 --> 00:36:57,490 and those chapters where I was introducing 494 00:36:57,490 --> 00:36:59,790 all the various levels of brain. 495 00:36:59,790 --> 00:37:03,390 So there are the limbic midbrain areas [INAUDIBLE] 496 00:37:03,390 --> 00:37:07,590 central gray area and the ventral tegmental area. 497 00:37:07,590 --> 00:37:08,970 And the rest are all somatic. 498 00:37:08,970 --> 00:37:12,780 And the part with the horizontal black lines, 499 00:37:12,780 --> 00:37:17,100 here in the midbrain picture, is called the midbrain reticular 500 00:37:17,100 --> 00:37:18,690 formation. 501 00:37:18,690 --> 00:37:20,010 OK. 502 00:37:20,010 --> 00:37:22,720 And that's the area, you can get arousal 503 00:37:22,720 --> 00:37:26,070 from stimulating anywhere in the midbrain, 504 00:37:26,070 --> 00:37:32,592 but it's that region where you primarily get arousal. 505 00:37:32,592 --> 00:37:36,666 And you get it from stimulating those limbic areas too. 506 00:37:36,666 --> 00:37:38,420 But then I'm asking this question. 507 00:37:38,420 --> 00:37:41,646 I want you to compare the two arousal systems. 508 00:37:41,646 --> 00:37:43,220 What structures are involved? 509 00:37:43,220 --> 00:37:44,695 Well, we just mentioned that. 510 00:37:44,695 --> 00:37:47,260 What are the major types of connections 511 00:37:47,260 --> 00:37:48,835 of these structures? 512 00:37:48,835 --> 00:37:50,793 What are the effects of electrical stimulation? 513 00:37:53,390 --> 00:37:57,466 Is there habituation when you use electrical stimulation? 514 00:37:57,466 --> 00:37:59,760 If you just keep the stimulation on one point 515 00:37:59,760 --> 00:38:03,220 and stimulate again and again, do you 516 00:38:03,220 --> 00:38:04,510 keep getting the same effect? 517 00:38:04,510 --> 00:38:06,340 Or do you get habituation? 518 00:38:06,340 --> 00:38:10,425 It's very different for the two systems. 519 00:38:10,425 --> 00:38:12,280 Just like they give different inputs, 520 00:38:12,280 --> 00:38:15,240 the effects of electrical stimulation are different. 521 00:38:15,240 --> 00:38:18,020 What are the differences? 522 00:38:18,020 --> 00:38:21,680 It's a complex question. 523 00:38:21,680 --> 00:38:22,180 OK. 524 00:38:22,180 --> 00:38:23,800 Does anybody want to say anything? 525 00:38:26,734 --> 00:38:34,069 AUDIENCE: So the non-limbic system is more physical 526 00:38:34,069 --> 00:38:39,448 responses to, with physical manifestations of, arousal 527 00:38:39,448 --> 00:38:40,440 whereas-- 528 00:38:40,440 --> 00:38:43,400 PROFESSOR: What do you mean? 529 00:38:43,400 --> 00:38:45,975 Physical manifestations of arousal? 530 00:38:45,975 --> 00:38:48,015 In non-limbic? 531 00:38:48,015 --> 00:38:50,098 AUDIENCE: And then limbic would be more associated 532 00:38:50,098 --> 00:38:52,090 with pleasure. 533 00:38:52,090 --> 00:38:54,220 PROFESSOR: OK, so you're saying limbic 534 00:38:54,220 --> 00:38:56,970 is associated with [? affect ?] feelings, 535 00:38:56,970 --> 00:39:02,600 positive or negative feelings, pleasurable or not pleasurable. 536 00:39:02,600 --> 00:39:05,540 The opposite-- unpleasant or very pleasant. 537 00:39:05,540 --> 00:39:06,570 And that's all correct. 538 00:39:09,270 --> 00:39:13,090 What kind of inputs did they get? 539 00:39:13,090 --> 00:39:15,710 They get different kinds of inputs. 540 00:39:15,710 --> 00:39:19,010 Those limbic areas-- what kind of inputs 541 00:39:19,010 --> 00:39:20,420 are they getting from below? 542 00:39:24,310 --> 00:39:27,975 They're the inputs that come in mainly through the vagus nerve. 543 00:39:30,630 --> 00:39:33,020 From the viscera. 544 00:39:33,020 --> 00:39:39,300 They're visceral inputs, OK, visceral sensory inputs. 545 00:39:43,280 --> 00:39:46,749 From above, they come from hypothalamus 546 00:39:46,749 --> 00:39:48,040 and limbic endbrain structures. 547 00:39:50,840 --> 00:39:52,670 OK. 548 00:39:52,670 --> 00:39:57,670 Now the non-limbic areas get all the various inputs 549 00:39:57,670 --> 00:40:02,226 from the various sensory systems and also from the cerebellum, 550 00:40:02,226 --> 00:40:05,170 that is the motor system and sensory systems. 551 00:40:09,122 --> 00:40:12,420 So there are these big differences. 552 00:40:12,420 --> 00:40:16,380 We've shown how they're located in different places, the types 553 00:40:16,380 --> 00:40:21,150 of inputs, and the types of outputs are different too. 554 00:40:21,150 --> 00:40:21,650 OK. 555 00:40:25,390 --> 00:40:31,280 Now, electrical simulation, both systems 556 00:40:31,280 --> 00:40:36,450 cause the arousal patterns in the electroencephalogram. 557 00:40:36,450 --> 00:40:38,680 That is, you're recording with large electrodes, 558 00:40:38,680 --> 00:40:41,570 recording from the scalp of a human. 559 00:40:41,570 --> 00:40:46,055 You get this fast, high frequency pattern. 560 00:40:50,050 --> 00:40:52,570 Very different from the pattern of a drowsy person 561 00:40:52,570 --> 00:40:54,550 or a sleeping person. 562 00:40:54,550 --> 00:40:55,050 OK. 563 00:41:00,640 --> 00:41:04,050 And if you stimulate repeatedly in the same place 564 00:41:04,050 --> 00:41:09,720 in the midbrain, the effects decrease, you get habituation. 565 00:41:09,720 --> 00:41:11,940 If you move the site where you're 566 00:41:11,940 --> 00:41:15,550 stimulating a little bit, the arousal comes back. 567 00:41:15,550 --> 00:41:21,140 So just like behavioral effects of novel stimulation 568 00:41:21,140 --> 00:41:24,856 that habituate as the stimulus becomes more familiar. 569 00:41:29,140 --> 00:41:34,790 Now if you do the same thing in the limbic structures, 570 00:41:34,790 --> 00:41:36,880 you get the EEG arousal, all right, 571 00:41:36,880 --> 00:41:38,930 but it doesn't go away with repeated stimulation. 572 00:41:42,330 --> 00:41:46,910 It's a little bit more like someone 573 00:41:46,910 --> 00:41:49,220 calling your name repeatedly, thus 574 00:41:49,220 --> 00:41:52,350 stimulating the limbic system a lot more. 575 00:41:52,350 --> 00:41:56,790 We tend to be pretty attached to our name, 576 00:41:56,790 --> 00:41:58,960 and we don't habituate readily at all. 577 00:42:04,760 --> 00:42:08,326 Just like we don't habituate readily to good taste in food 578 00:42:08,326 --> 00:42:10,331 if we're hungry. 579 00:42:10,331 --> 00:42:15,420 If we're not hungry, sure, but that's something else. 580 00:42:15,420 --> 00:42:17,340 We just keep everything else constant. 581 00:42:17,340 --> 00:42:18,830 Hunger is constant. 582 00:42:18,830 --> 00:42:21,620 You keep responding, you don't habituate, 583 00:42:21,620 --> 00:42:24,511 at least not very much. 584 00:42:24,511 --> 00:42:25,010 OK. 585 00:42:28,580 --> 00:42:31,690 Now you said pleasant and unpleasant. 586 00:42:31,690 --> 00:42:37,480 If you're in the non-limbic areas, 587 00:42:37,480 --> 00:42:42,074 there is a very mild rewarding effect of being stimulated. 588 00:42:42,074 --> 00:42:44,490 But if someone's very sleepy, it's probably non-rewarding. 589 00:42:48,350 --> 00:42:50,530 But if you're in those limbic areas, 590 00:42:50,530 --> 00:42:52,280 and you're up and around the central gray, 591 00:42:52,280 --> 00:42:56,710 it's generally negatively rewarding. 592 00:42:56,710 --> 00:42:58,410 If you stimulate an animal there, 593 00:42:58,410 --> 00:43:00,930 they generally will work in order 594 00:43:00,930 --> 00:43:05,350 to be able to-- they'll do something, take some action, 595 00:43:05,350 --> 00:43:06,940 if they've learned how to turn it off. 596 00:43:06,940 --> 00:43:09,690 And they will work to be able to turn it off. 597 00:43:09,690 --> 00:43:11,649 They don't like to be stimulated there. 598 00:43:11,649 --> 00:43:13,440 Whereas if you're in those ventral regions, 599 00:43:13,440 --> 00:43:16,320 the ventral tegmental area, we say 600 00:43:16,320 --> 00:43:19,856 you get high levels of self stimulation. 601 00:43:19,856 --> 00:43:23,785 That is, they will turn the stimulus on by themselves. 602 00:43:26,740 --> 00:43:28,060 They very quickly learn. 603 00:43:28,060 --> 00:43:34,020 It's a very effective way to train animals to do things 604 00:43:34,020 --> 00:43:37,640 if you have the electrodes placed in those areas 605 00:43:37,640 --> 00:43:39,131 and they can stimulate. 606 00:43:42,120 --> 00:43:43,560 And then I just talk a little bit 607 00:43:43,560 --> 00:43:46,600 about ascending and descending connections. 608 00:43:46,600 --> 00:43:53,543 I do the same thing here for the second type of arousal, 609 00:43:53,543 --> 00:43:55,650 you can call it limbic arousal. 610 00:43:59,880 --> 00:44:03,610 And notice here I mention, besides the hypothalamus, 611 00:44:03,610 --> 00:44:08,140 connections to the limbic midbrain area. 612 00:44:08,140 --> 00:44:10,300 These are the other major forebrain 613 00:44:10,300 --> 00:44:13,490 systems besides hypothalamus. 614 00:44:13,490 --> 00:44:17,210 I didn't mention epithalamus, but it should be included. 615 00:44:17,210 --> 00:44:21,200 But in the endbrain septal area in front 616 00:44:21,200 --> 00:44:23,724 of the thalamus right between the hemispheres 617 00:44:23,724 --> 00:44:26,130 there's a structure right on the midline. 618 00:44:26,130 --> 00:44:27,890 It's called the septal area. 619 00:44:27,890 --> 00:44:30,225 And then below it, the basal forebrain 620 00:44:30,225 --> 00:44:33,440 in front of the hypothalamus, between the hypothalamus 621 00:44:33,440 --> 00:44:36,460 and the olfactory bulbs. 622 00:44:36,460 --> 00:44:41,300 We'll see that picture a number of times in the next five 623 00:44:41,300 --> 00:44:42,750 classes. 624 00:44:42,750 --> 00:44:46,536 Then the hippocampal formation. 625 00:44:46,536 --> 00:44:48,214 We talked about the medial pallium 626 00:44:48,214 --> 00:44:49,630 being important to spatial memory, 627 00:44:49,630 --> 00:44:53,268 that it is part of the limbic system. 628 00:44:53,268 --> 00:44:57,000 And there's a good reason why it evolved that way. 629 00:44:57,000 --> 00:45:01,830 And then the amygdala which you probably know very well by now. 630 00:45:01,830 --> 00:45:10,893 It's associated with pleasant and unpleasant feelings 631 00:45:10,893 --> 00:45:13,080 towards things that we perceive. 632 00:45:13,080 --> 00:45:13,600 All right. 633 00:45:19,670 --> 00:45:23,682 So let's talk about the hypothalamus here, 634 00:45:23,682 --> 00:45:29,290 and what it does besides controlling 635 00:45:29,290 --> 00:45:32,151 the autonomic nervous system. 636 00:45:32,151 --> 00:45:36,270 It controls the endocrine system by way of the pituitary. 637 00:45:36,270 --> 00:45:39,640 The pituitary is attached to the hypothalamus. 638 00:45:39,640 --> 00:45:43,590 So how does the hypothalamus-- how do hypothalamic neurons 639 00:45:43,590 --> 00:45:49,870 control secretions from the two major parts of the pituitary? 640 00:45:49,870 --> 00:45:52,690 One that's directly [? between ?] part 641 00:45:52,690 --> 00:45:56,020 of the CNS, and one that's a gland that's 642 00:45:56,020 --> 00:45:58,358 right next to the CNS. 643 00:45:58,358 --> 00:46:00,180 Those two parts of the pituitary, 644 00:46:00,180 --> 00:46:03,140 they're called anterior and posterior, 645 00:46:03,140 --> 00:46:05,430 because of how they're placed in humans. 646 00:46:05,430 --> 00:46:08,220 In the rodent, the posterior pituitary 647 00:46:08,220 --> 00:46:12,780 is above the glandular pituitary. 648 00:46:12,780 --> 00:46:17,110 I've drawn it here from studies, fairly recent studies, 649 00:46:17,110 --> 00:46:21,445 of the rodent, and these are pictures 650 00:46:21,445 --> 00:46:28,860 that [? Nauda ?] did of these structures in the human. 651 00:46:28,860 --> 00:46:31,740 OK, let's look at the rodent here. 652 00:46:31,740 --> 00:46:38,240 You see the posterior pituitary or neurohypophysis, 653 00:46:38,240 --> 00:46:43,870 that is the neural part of the pituitary, 654 00:46:43,870 --> 00:46:46,550 receiving axons from these two cell 655 00:46:46,550 --> 00:46:48,680 groups in the hypothalamus, the ventricular 656 00:46:48,680 --> 00:46:50,610 nucleus, supraoptic nucleus. 657 00:46:53,600 --> 00:46:56,775 See the axon coming in. 658 00:46:56,775 --> 00:47:03,050 And those axons that are ending in the neural pituitary, 659 00:47:03,050 --> 00:47:06,300 the neurohypophysis, aren't ending on neurons. 660 00:47:06,300 --> 00:47:08,850 They're ending on blood vessels. 661 00:47:08,850 --> 00:47:13,370 So yes, they secrete a transmitter, 662 00:47:13,370 --> 00:47:16,420 but the neurotransmitter now enters blood vessels. 663 00:47:19,900 --> 00:47:24,356 It doesn't do that to distribute throughout the body, though. 664 00:47:24,356 --> 00:47:27,250 I'm sorry, it does that because it's 665 00:47:27,250 --> 00:47:29,640 a hormone distributed throughout the body, 666 00:47:29,640 --> 00:47:31,510 and [INAUDIBLE] pituitary here. 667 00:47:34,620 --> 00:47:41,040 They come from these neurons, both of them. 668 00:47:41,040 --> 00:47:43,185 They give rise to two hormones. 669 00:47:43,185 --> 00:47:46,900 Do you remember what they are? 670 00:47:46,900 --> 00:47:55,260 Oxytocin and ADH, which means antidiuretic hormone. 671 00:47:55,260 --> 00:47:59,440 And what's the other name for antidiuretic hormone? 672 00:47:59,440 --> 00:48:01,110 Vasopressin. 673 00:48:01,110 --> 00:48:07,139 OK, because it causes vascular constriction 674 00:48:07,139 --> 00:48:08,556 and can affect blood pressure. 675 00:48:18,990 --> 00:48:21,160 An antidiuretic hormone, of course, 676 00:48:21,160 --> 00:48:25,080 is involved in food retention. 677 00:48:25,080 --> 00:48:30,360 So if someone suffers a tumor that's in this region, 678 00:48:30,360 --> 00:48:33,990 it affects the stalk of the pituitary, 679 00:48:33,990 --> 00:48:40,505 and blocks these hormones so they're no longer secreted 680 00:48:40,505 --> 00:48:47,480 into the bloodstream, a person has a pathology 681 00:48:47,480 --> 00:48:51,460 called diabetes insipidus. 682 00:48:51,460 --> 00:48:56,780 It's called diabetes because the symptoms are actually 683 00:48:56,780 --> 00:49:02,170 the same as the acute onset of diabetes mellitus, 684 00:49:02,170 --> 00:49:07,760 and the person lacks the ability to secrete insulin. 685 00:49:07,760 --> 00:49:12,870 Because when the person can't secrete insulin, 686 00:49:12,870 --> 00:49:15,360 he uses different metabolic pathways 687 00:49:15,360 --> 00:49:19,550 to get energy and get glucose into the cells of the body 688 00:49:19,550 --> 00:49:21,830 because you need insulin for that. 689 00:49:21,830 --> 00:49:23,655 So he uses other metabolic pathways 690 00:49:23,655 --> 00:49:27,550 and starts metabolising his muscle tissue. 691 00:49:27,550 --> 00:49:31,030 That produces ketone bodies in the blood 692 00:49:31,030 --> 00:49:36,000 which raise blood acidity and that can kill, of course, 693 00:49:36,000 --> 00:49:38,620 if it goes on too long. 694 00:49:38,620 --> 00:49:39,180 Sorry? 695 00:49:39,180 --> 00:49:41,210 AUDIENCE: [INAUDIBLE] 696 00:49:41,210 --> 00:49:43,470 PROFESSOR: The ketone bodies are what 697 00:49:43,470 --> 00:49:51,230 cause the thirst to get so high in acute onset diabetes. 698 00:49:51,230 --> 00:49:54,520 I experienced that for a while, and I got diabetes. 699 00:49:54,520 --> 00:49:59,640 And I felt very thirsty and was drinking a lot of fluid 700 00:49:59,640 --> 00:50:03,430 to basically get rid of the acid. 701 00:50:03,430 --> 00:50:09,730 So you have the symptoms of polyuria polydipsia. 702 00:50:09,730 --> 00:50:14,470 Polydipsia means drinking all the time, thirsty all the time. 703 00:50:14,470 --> 00:50:17,490 Polyuria causes a lot of urination, and, of course, 704 00:50:17,490 --> 00:50:19,872 you're getting rid of the acid. 705 00:50:19,872 --> 00:50:21,580 You're also getting rid of a lot of sugar 706 00:50:21,580 --> 00:50:25,370 because the blood sugar levels get high. 707 00:50:25,370 --> 00:50:30,120 Normally, ketoacidosis, that effect, 708 00:50:30,120 --> 00:50:35,130 does not occur if I just get high blood sugar today. 709 00:50:35,130 --> 00:50:38,970 It would take a long time and a lot of insulin deficiency 710 00:50:38,970 --> 00:50:40,880 for me to develop enough ketone bodies 711 00:50:40,880 --> 00:50:42,690 to cause that kind of problem. 712 00:50:42,690 --> 00:50:47,640 But that's what actually kills in diabetes. 713 00:50:50,432 --> 00:50:51,890 Unfortunately, the high blood sugar 714 00:50:51,890 --> 00:50:53,700 has a lot of other bad effects too. 715 00:50:57,600 --> 00:51:00,630 All right, so we call it diabetes insipidus 716 00:51:00,630 --> 00:51:04,566 because you get the same symptoms, polyuria, polydipsia. 717 00:51:04,566 --> 00:51:08,890 But now it's because of the lack of ADH, OK. 718 00:51:08,890 --> 00:51:12,400 They don't have normal regulation of fluid levels. 719 00:51:15,310 --> 00:51:19,690 So people with that, just like insulin diabetics 720 00:51:19,690 --> 00:51:23,215 need to be treated with insulin, people with diabetes insipidus 721 00:51:23,215 --> 00:51:25,780 need to be treated with these hormones. 722 00:51:25,780 --> 00:51:27,910 And, of course, more importantly, 723 00:51:27,910 --> 00:51:31,040 you have to deal with the tumor. 724 00:51:31,040 --> 00:51:32,720 Sometimes they can reverse the effects 725 00:51:32,720 --> 00:51:36,045 just by getting the tumor removed. 726 00:51:36,045 --> 00:51:41,000 It's very difficult surgery because of the location, OK. 727 00:51:41,000 --> 00:51:43,382 But surgeons have learned ways to get at it. 728 00:51:43,382 --> 00:51:46,100 They can actually go through the roof of the mouth 729 00:51:46,100 --> 00:51:48,440 to get at the pituitary above it. 730 00:51:48,440 --> 00:51:51,600 All right, what about the other part of the pituitary? 731 00:51:51,600 --> 00:51:54,610 I call it here the adenohypophysis. 732 00:51:54,610 --> 00:51:57,494 Adeno means glandular tissue. 733 00:51:57,494 --> 00:51:58,410 OK. 734 00:51:58,410 --> 00:52:04,720 The glandular pituitary or glandular hypophysis, 735 00:52:04,720 --> 00:52:10,990 it's also being the secretions from the adenohypophysis, 736 00:52:10,990 --> 00:52:16,080 secretions like the hormones that 737 00:52:16,080 --> 00:52:20,020 affect the gonads, hormones that affect 738 00:52:20,020 --> 00:52:24,820 the adrenal glands, the adrenocorticotropic hormone, 739 00:52:24,820 --> 00:52:26,540 OK. 740 00:52:26,540 --> 00:52:30,830 Gonadotropins, they don't secrete 741 00:52:30,830 --> 00:52:33,340 directly testosterone and estrogens. 742 00:52:33,340 --> 00:52:37,435 Those are secreted peripherally by the testes 743 00:52:37,435 --> 00:52:40,360 and by the ovaries primarily, and also 744 00:52:40,360 --> 00:52:44,410 somewhat by the adrenals, OK. 745 00:52:44,410 --> 00:52:47,930 But the hormones from the hypophysis 746 00:52:47,930 --> 00:52:53,300 here, the adenohypophysis stimulates those hormones. 747 00:52:53,300 --> 00:52:58,120 And their secretion is affected by the hypothalamus 748 00:52:58,120 --> 00:53:02,140 from neurons like those here in the median eminence region, 749 00:53:02,140 --> 00:53:07,220 this region of the hypothalamus, the arcuate nucleus where 750 00:53:07,220 --> 00:53:11,480 I show you, here, cells in that region with axons 751 00:53:11,480 --> 00:53:16,600 that are going in to the proximal part, here, 752 00:53:16,600 --> 00:53:21,400 of the neurohypophysis and also ending on blood vessels. 753 00:53:21,400 --> 00:53:24,920 But now they're ending on blood vessels that 754 00:53:24,920 --> 00:53:29,620 enter this hypophyseal artery, which 755 00:53:29,620 --> 00:53:33,420 then has many branches into the adenohypophysis. 756 00:53:33,420 --> 00:53:37,210 Those factors, they're called releasing factors, 757 00:53:37,210 --> 00:53:41,690 get to the adenohypophysis also through a vascular system. 758 00:53:41,690 --> 00:53:46,175 We call it a portal system because there are capillaries 759 00:53:46,175 --> 00:53:48,590 that pick them up, and then they go 760 00:53:48,590 --> 00:53:53,700 to a larger vessel, a portal vessel that gets them over 761 00:53:53,700 --> 00:53:55,765 to the adenohypophysis. 762 00:53:58,406 --> 00:54:03,460 Then you have another capillary bed where they're released. 763 00:54:03,460 --> 00:54:06,300 And that's shown here in humans. 764 00:54:06,300 --> 00:54:11,200 He shows the vascular system, sort of a cartoon of that here. 765 00:54:11,200 --> 00:54:15,680 So a capillary bed, a portal vessel, 766 00:54:15,680 --> 00:54:19,600 and then another capillary bed. 767 00:54:19,600 --> 00:54:23,060 I tried to change it in the text from portal vein 768 00:54:23,060 --> 00:54:24,590 to portal vessel, because I thought 769 00:54:24,590 --> 00:54:25,965 there was a regent who might want 770 00:54:25,965 --> 00:54:28,510 to call it a portal artery. 771 00:54:28,510 --> 00:54:33,300 But it's so traditional to call it a portal vein 772 00:54:33,300 --> 00:54:39,260 that copy editor changed it back to portal vein. 773 00:54:39,260 --> 00:54:42,270 So I did try to correct the language. 774 00:54:42,270 --> 00:54:43,780 Ha-ha. 775 00:54:43,780 --> 00:54:45,640 But anyway, that's the way the system works. 776 00:54:45,640 --> 00:54:47,300 It's important to know and it's very 777 00:54:47,300 --> 00:54:49,270 important in understanding human pathologies. 778 00:54:56,130 --> 00:54:58,120 So [INAUDIBLE] I already mentioned, 779 00:54:58,120 --> 00:55:01,290 I think, the major answer to question four, 780 00:55:01,290 --> 00:55:06,460 and I talked about question five, diabetes insipidus. 781 00:55:06,460 --> 00:55:09,100 So what are the homeostatic mechanisms 782 00:55:09,100 --> 00:55:12,146 associated with the hypothalamus. 783 00:55:12,146 --> 00:55:14,340 Are we already way beyond time? 784 00:55:14,340 --> 00:55:17,560 I guess we are, so we will stop, and we'll 785 00:55:17,560 --> 00:55:21,550 come back-- we're finished right here, 786 00:55:21,550 --> 00:55:23,783 we'll come back to question six. 787 00:55:23,783 --> 00:55:27,030 And it shouldn't take too long to review 788 00:55:27,030 --> 00:55:30,280 that if you've read the chapter, OK. 789 00:55:30,280 --> 00:55:32,350 So then we'll continue with the limbic system, 790 00:55:32,350 --> 00:55:35,830 and we'll begin talking about connections 791 00:55:35,830 --> 00:55:42,560 between hypothalamus, some of them by way of the thalamus, 792 00:55:42,560 --> 00:55:44,919 to the limbic system structures.