1 00:00:00,120 --> 00:00:01,800 The following content is provided 2 00:00:01,800 --> 00:00:04,030 under a Creative Commons license. 3 00:00:04,030 --> 00:00:06,880 Your support will help MIT OpenCourseWare continue 4 00:00:06,880 --> 00:00:10,740 to offer high quality educational resources for free. 5 00:00:10,740 --> 00:00:13,350 To make a donation or view additional materials 6 00:00:13,350 --> 00:00:15,810 from hundreds of MIT courses, visit 7 00:00:15,810 --> 00:00:21,200 MIT OpenCourseWare at ocw.mit.edu 8 00:00:21,200 --> 00:00:25,390 PROFESSOR: Have a little bit to finish up from last time. 9 00:00:25,390 --> 00:00:29,260 After last Wednesday's class, I had another job to do, 10 00:00:29,260 --> 00:00:35,140 and I totally forgot about this class until yesterday. 11 00:00:35,140 --> 00:00:38,280 And I realize-- thanks to the TAs-- 12 00:00:38,280 --> 00:00:40,520 that I hadn't posted the homework properly. 13 00:00:40,520 --> 00:00:43,620 It was actually in the slides, which I also hadn't posted. 14 00:00:43,620 --> 00:00:46,250 So I got all that done and delayed 15 00:00:46,250 --> 00:00:48,730 the due date until Wednesday. 16 00:00:48,730 --> 00:00:51,900 It's not a very hard homework, so you 17 00:00:51,900 --> 00:00:53,240 should have no problem with it. 18 00:00:53,240 --> 00:00:54,906 But that means Wednesday, because you've 19 00:00:54,906 --> 00:00:58,690 got that homework to do, I won't give a quiz. 20 00:00:58,690 --> 00:01:01,780 The reading this week is a little more difficult 21 00:01:01,780 --> 00:01:03,460 than what you've been doing. 22 00:01:03,460 --> 00:01:05,489 It's all posted online. 23 00:01:05,489 --> 00:01:14,015 A book by Konrad Lorenz-- The Foundations of Ethology book. 24 00:01:16,590 --> 00:01:21,440 It's still some of the best material on ethology. 25 00:01:21,440 --> 00:01:23,320 Of course, there's been recent work, 26 00:01:23,320 --> 00:01:26,780 and we will be looking at some of that online, 27 00:01:26,780 --> 00:01:28,650 as you already have. 28 00:01:28,650 --> 00:01:32,890 Now let's just finish talking about biological rhythms. 29 00:01:32,890 --> 00:01:37,300 We got started with that last time. 30 00:01:37,300 --> 00:01:41,690 We saw this measure of a hamster-- just one 31 00:01:41,690 --> 00:01:44,480 of a number of measures of hamster locomotor activity. 32 00:01:44,480 --> 00:01:46,840 And you can see this would be true 33 00:01:46,840 --> 00:01:49,370 whether you were studying rats or mice. 34 00:01:49,370 --> 00:01:53,910 But hamsters are particularly good for this kind of work, 35 00:01:53,910 --> 00:02:00,640 because their circadian rhythm is synchronized 36 00:02:00,640 --> 00:02:07,390 to the light/dark cycle-- pretty much exclusively 37 00:02:07,390 --> 00:02:09,710 by the light/dark cycle and nothing else. 38 00:02:09,710 --> 00:02:13,750 I've kept them in constant lighting conditions. 39 00:02:13,750 --> 00:02:16,730 And even though I was feeding them regularly 40 00:02:16,730 --> 00:02:18,510 at the same time every day, and there 41 00:02:18,510 --> 00:02:23,450 were noises in the hallway outside the lab, 42 00:02:23,450 --> 00:02:26,500 pretty much followed the usual human rhythm 43 00:02:26,500 --> 00:02:28,570 of activity of a workday. 44 00:02:28,570 --> 00:02:30,930 And yet they weren't affected by those things. 45 00:02:30,930 --> 00:02:33,570 It was only the light that influenced their circadian 46 00:02:33,570 --> 00:02:35,620 rhythm. 47 00:02:35,620 --> 00:02:41,960 So this is the free-running rhythm here. 48 00:02:47,110 --> 00:02:51,460 That's where they started constant light in here. 49 00:02:51,460 --> 00:02:55,160 Even with the optic tract cut, they still 50 00:02:55,160 --> 00:02:56,385 responded to the light. 51 00:02:59,546 --> 00:03:01,620 The lights were going off here. 52 00:03:01,620 --> 00:03:03,850 And you can see they began to get active 53 00:03:03,850 --> 00:03:06,830 before the lights go out. 54 00:03:06,830 --> 00:03:09,180 Hamsters are what you call a twilight animal. 55 00:03:09,180 --> 00:03:13,650 They become active when the shadows are long-- especially 56 00:03:13,650 --> 00:03:15,610 in the evening. 57 00:03:15,610 --> 00:03:19,200 And they go out and forage for food 58 00:03:19,200 --> 00:03:23,250 and then come back to their tunnels. 59 00:03:23,250 --> 00:03:24,920 And then they enter there. 60 00:03:24,920 --> 00:03:27,360 So that's when they become active. 61 00:03:27,360 --> 00:03:31,965 They stay active at least for several hours 62 00:03:31,965 --> 00:03:36,410 in the early part of the dark period. 63 00:03:36,410 --> 00:03:38,460 And then you can see they become very inactive. 64 00:03:43,400 --> 00:03:52,220 So we mentioned this proof of the endogenous clock mechanism. 65 00:03:52,220 --> 00:03:56,250 These free-running rhythms are good evidence for it. 66 00:03:56,250 --> 00:04:03,510 But the brain studies led to the discovery of a little cell 67 00:04:03,510 --> 00:04:06,520 group in the hypothalamus. 68 00:04:06,520 --> 00:04:08,910 What led to the discovery was quite simple. 69 00:04:08,910 --> 00:04:11,640 The anatomical tracing methods got better. 70 00:04:11,640 --> 00:04:14,750 They hadn't noticed with the earlier tracing methods-- 71 00:04:14,750 --> 00:04:18,200 including the earlier nodal methods-- they often 72 00:04:18,200 --> 00:04:23,120 missed this particular projection to the hypothalamus. 73 00:04:23,120 --> 00:04:25,860 And this suprachiasmatic-- this nucleus 74 00:04:25,860 --> 00:04:28,860 we abbreviate SCN-- suprachiasmatic-- right 75 00:04:28,860 --> 00:04:33,110 above the optic chiasm and the crossing of the fibers coming 76 00:04:33,110 --> 00:04:35,260 from the retina. 77 00:04:35,260 --> 00:04:37,850 And in lateral-eyed animals, most of them 78 00:04:37,850 --> 00:04:41,220 cross to the other side. 79 00:04:41,220 --> 00:04:46,660 And other people used other methods. 80 00:04:46,660 --> 00:04:48,410 They weren't all using mammals, of course. 81 00:04:48,410 --> 00:04:51,250 They were using fruit flies and many other animals. 82 00:04:51,250 --> 00:04:54,910 And these genes were initially discovered in the fruit fly. 83 00:04:54,910 --> 00:04:59,520 The period gene critical for the endogenous clock, 84 00:04:59,520 --> 00:05:03,200 but the clock gene also plays important roles. 85 00:05:03,200 --> 00:05:06,600 And this is a side view of a hamster brain 86 00:05:06,600 --> 00:05:08,790 stem where the hemisphere's removed. 87 00:05:08,790 --> 00:05:11,890 This shows the main optic tract. 88 00:05:11,890 --> 00:05:14,330 And here's where the fibers come in. 89 00:05:14,330 --> 00:05:17,700 The eyes would be out here. 90 00:05:17,700 --> 00:05:21,420 And so it's connecting with the chiasm here. 91 00:05:21,420 --> 00:05:24,430 And that little nucleus sits right there. 92 00:05:24,430 --> 00:05:29,060 This just shows what it looks like on [INAUDIBLE] stain. 93 00:05:29,060 --> 00:05:31,250 And here's a fiber-tracing study from some 94 00:05:31,250 --> 00:05:33,770 of my work with a postdoc. 95 00:05:33,770 --> 00:05:36,297 You see the fibers terminating. 96 00:05:36,297 --> 00:05:37,713 These are all coming from one eye, 97 00:05:37,713 --> 00:05:42,500 but they terminate equally on the two sides of the brain. 98 00:05:42,500 --> 00:05:46,690 It's not a specifically cross projection. 99 00:05:46,690 --> 00:05:50,685 Probably the most primitive of the retinal projections. 100 00:05:50,685 --> 00:05:52,810 And here you see what they look like on your higher 101 00:05:52,810 --> 00:05:57,620 magnification, where you see the particularly sensitive method 102 00:05:57,620 --> 00:06:00,760 of tracing allows us to see the individual axons. 103 00:06:00,760 --> 00:06:03,610 If we looked at much higher magnification, 104 00:06:03,610 --> 00:06:07,580 you can see individual terminals and individual axons 105 00:06:07,580 --> 00:06:10,430 and terminals. 106 00:06:10,430 --> 00:06:14,280 And if this is a ventral view of a human brain 107 00:06:14,280 --> 00:06:17,694 with the eyes pushed to the side there, 108 00:06:17,694 --> 00:06:18,735 there's the optic chiasm. 109 00:06:21,846 --> 00:06:23,220 This is actually a number they've 110 00:06:23,220 --> 00:06:26,700 stuck on there for instructive purposes. 111 00:06:26,700 --> 00:06:29,570 But that's the optic chiasm, and the nucleus 112 00:06:29,570 --> 00:06:31,490 sits right above that. 113 00:06:34,370 --> 00:06:35,670 So why do animals sleep. 114 00:06:35,670 --> 00:06:38,950 Why do we sleep? 115 00:06:38,950 --> 00:06:39,960 You can answer. 116 00:06:39,960 --> 00:06:43,200 As you know, we talked about "why questions." 117 00:06:43,200 --> 00:06:45,830 We first talked about Tinbergen's four questions-- 118 00:06:45,830 --> 00:06:48,470 different ways of answering that question, "Why?" 119 00:06:48,470 --> 00:06:51,370 Here we're asking a behavioral question-- why do we sleep? 120 00:06:51,370 --> 00:06:53,050 Why do animals sleep? 121 00:06:53,050 --> 00:06:54,430 They all sleep. 122 00:06:54,430 --> 00:06:57,730 First of all, there are adaptive pressures 123 00:06:57,730 --> 00:07:01,570 that made the evolution of the sleep instinct 124 00:07:01,570 --> 00:07:03,450 occur in all animals. 125 00:07:06,810 --> 00:07:09,230 It's a fixed-action pattern. 126 00:07:09,230 --> 00:07:11,980 And animals, in fact, show specific activities 127 00:07:11,980 --> 00:07:15,450 associated with preparing for sleep, going to sleep. 128 00:07:15,450 --> 00:07:18,350 They make nests-- some of them make nests every night. 129 00:07:18,350 --> 00:07:20,900 Some of them simply go to their nest. 130 00:07:20,900 --> 00:07:24,010 They engage in certain little preparatory activities-- 131 00:07:24,010 --> 00:07:30,940 humans do this, too-- and go to sleep. 132 00:07:30,940 --> 00:07:33,580 So we can talk about the adaptive pressures, 133 00:07:33,580 --> 00:07:36,400 which we'll do first. 134 00:07:36,400 --> 00:07:41,050 And this instinct depends, of course, on brain mechanisms. 135 00:07:41,050 --> 00:07:45,710 And they've discovered special roles of not 136 00:07:45,710 --> 00:07:48,870 only the suprachiasmatic nucleus in determining 137 00:07:48,870 --> 00:07:51,500 the rhythm of activity-- which affects 138 00:07:51,500 --> 00:07:56,000 the time we go to sleep-- but changes in the brain. 139 00:07:56,000 --> 00:07:59,150 Talk about the neuromodulator systems-- systems 140 00:07:59,150 --> 00:08:01,720 of very widely projecting axons, where 141 00:08:01,720 --> 00:08:03,670 the activity of one little cell group 142 00:08:03,670 --> 00:08:07,540 can make widespread changes in brain activity. 143 00:08:07,540 --> 00:08:10,960 There's a number of such systems in the brain-- probably 144 00:08:10,960 --> 00:08:13,200 at least seven. 145 00:08:13,200 --> 00:08:16,480 We talk mainly about just a few of them. 146 00:08:16,480 --> 00:08:19,280 So first of all, adaptive pressures. 147 00:08:19,280 --> 00:08:22,742 The body does need rest and recuperation. 148 00:08:22,742 --> 00:08:26,550 That is undoubtedly true, and there's 149 00:08:26,550 --> 00:08:29,352 evidence for that-- deterioration 150 00:08:29,352 --> 00:08:31,530 in bodily functions that can happen 151 00:08:31,530 --> 00:08:35,390 when you get inadequate sleep. 152 00:08:35,390 --> 00:08:37,230 Need to conserve energy stores. 153 00:08:37,230 --> 00:08:41,690 If we were using energy all the time, we would run out. 154 00:08:41,690 --> 00:08:44,660 That would vary of course with the species of animal 155 00:08:44,660 --> 00:08:48,230 and the availability of food. 156 00:08:48,230 --> 00:08:51,640 Need to avoid predators. 157 00:08:51,640 --> 00:08:55,200 Animals tend to be active in either the daylight 158 00:08:55,200 --> 00:08:59,760 or nighttime-- day-active and night-active animals. 159 00:08:59,760 --> 00:09:04,300 We're day-active animals-- except at MIT, 160 00:09:04,300 --> 00:09:05,780 where we tend to be night-active. 161 00:09:05,780 --> 00:09:10,410 But this is talking about natural behavior 162 00:09:10,410 --> 00:09:16,170 in a sort of the primitive state the way humans evolved. 163 00:09:16,170 --> 00:09:23,590 And we can evolve mechanism to avoid 164 00:09:23,590 --> 00:09:25,060 certain kinds of predators. 165 00:09:25,060 --> 00:09:27,090 It's difficult to evolve mechanisms 166 00:09:27,090 --> 00:09:28,920 to avoid all kinds of predictors. 167 00:09:28,920 --> 00:09:34,340 So most animals, by being day-active, 168 00:09:34,340 --> 00:09:39,340 need a place to sleep at night to avoid the night predators. 169 00:09:39,340 --> 00:09:43,890 And the night-active animals often became night-active. 170 00:09:43,890 --> 00:09:48,110 We think mammals evolved as nocturnal animals initially. 171 00:09:48,110 --> 00:09:49,770 All the evidence indicates that. 172 00:09:49,770 --> 00:09:52,570 It was reduction in their vision and increase 173 00:09:52,570 --> 00:09:55,280 in audition and olfaction. 174 00:09:55,280 --> 00:09:58,770 They became active at night on the forest floor avoiding 175 00:09:58,770 --> 00:10:04,340 the day-active dominant species-- the dinosaur group-- 176 00:10:04,340 --> 00:10:10,676 in particular the reptiles, which generally used vision 177 00:10:10,676 --> 00:10:11,175 to hunt. 178 00:10:14,800 --> 00:10:19,210 Another is in development. 179 00:10:19,210 --> 00:10:24,250 You may be aware that, early in development, 180 00:10:24,250 --> 00:10:30,520 babies spend a very large amount of time sleeping. 181 00:10:30,520 --> 00:10:33,280 They wake up to feed. 182 00:10:33,280 --> 00:10:37,050 Initially that's about all they're awake for. 183 00:10:37,050 --> 00:10:38,660 And then they sleep. 184 00:10:38,660 --> 00:10:45,560 And their brains are busy when they're sleeping. 185 00:10:45,560 --> 00:10:48,620 In fact, it may be a particular role of dream sleep. 186 00:10:48,620 --> 00:10:50,830 They spend a lot of their time in dream sleep. 187 00:10:50,830 --> 00:10:52,550 What are they dreaming about? 188 00:10:52,550 --> 00:10:54,970 They haven't experienced much, yet. 189 00:10:54,970 --> 00:10:58,110 Well, they have many built-in mechanisms, 190 00:10:58,110 --> 00:11:02,800 and they're not being used to guide behavior. 191 00:11:02,800 --> 00:11:08,240 The baby can't even do much, can't move all that much yet. 192 00:11:08,240 --> 00:11:12,030 But that doesn't mean the brain mechanisms aren't engaged. 193 00:11:12,030 --> 00:11:20,220 And that is one possible role of the dream sleep. 194 00:11:20,220 --> 00:11:26,490 And then, finally, discovered in more recent years-- 195 00:11:26,490 --> 00:11:29,960 there's a lot of experimental psychological work on this-- 196 00:11:29,960 --> 00:11:33,890 and the role of especially deep sleep 197 00:11:33,890 --> 00:11:36,820 period in memory consolidation. 198 00:11:36,820 --> 00:11:41,620 And I expand that a little bit, because it's undoubtedly true 199 00:11:41,620 --> 00:11:44,930 that we don't just consolidate new memories. 200 00:11:44,930 --> 00:11:48,970 We edit old ones, because the environment changes, 201 00:11:48,970 --> 00:11:53,170 and it would be maladaptive to maintain the memory for things 202 00:11:53,170 --> 00:11:57,430 that are no longer there in our current environment. 203 00:11:57,430 --> 00:12:01,420 So at least for those things we have to change the memories. 204 00:12:01,420 --> 00:12:03,280 We have to edit them. 205 00:12:03,280 --> 00:12:06,420 And that happens also during sleep. 206 00:12:06,420 --> 00:12:11,810 So then the sleep instinct we will 207 00:12:11,810 --> 00:12:13,200 call a fixed-action pattern. 208 00:12:13,200 --> 00:12:17,790 It's triggered by the endogenous clock, which is then 209 00:12:17,790 --> 00:12:20,110 trained by the light/dark cycle. 210 00:12:20,110 --> 00:12:22,620 And then the action of neuromodulator systems. 211 00:12:22,620 --> 00:12:27,710 And as I mentioned, these have widespread connections. 212 00:12:27,710 --> 00:12:30,620 The best-known ones are the ones using serotonin, 213 00:12:30,620 --> 00:12:33,680 norepinephrine, and acetylcholine. 214 00:12:33,680 --> 00:12:36,310 All of these systems have very widespread connections 215 00:12:36,310 --> 00:12:40,465 in the brain, and there are others in addition 216 00:12:40,465 --> 00:12:42,690 that have been discovered. 217 00:12:42,690 --> 00:12:49,370 And one thing that's not been investigated so much-- 218 00:12:49,370 --> 00:12:51,680 whether it's actually more difficult to study, 219 00:12:51,680 --> 00:12:54,130 but it certainly could be studied a lot more, 220 00:12:54,130 --> 00:12:57,340 and that is that there are substances 221 00:12:57,340 --> 00:13:02,620 secreted into the cerebral spinal fluid 222 00:13:02,620 --> 00:13:05,320 at the onset of sleep. 223 00:13:05,320 --> 00:13:10,330 And if you move some cerebral spinal fluid 224 00:13:10,330 --> 00:13:13,585 from a sleeping animal into an awake animal 225 00:13:13,585 --> 00:13:15,530 of the same species, you can make 226 00:13:15,530 --> 00:13:19,040 the awake animal get sleepy, too. 227 00:13:19,040 --> 00:13:21,219 And this has been known for some time, 228 00:13:21,219 --> 00:13:22,635 but it's been very little studied. 229 00:13:26,170 --> 00:13:27,860 But that concerns mechanism, which 230 00:13:27,860 --> 00:13:29,670 isn't our main concern here. 231 00:13:29,670 --> 00:13:32,470 I want to say a little bit more about the behavior-- things 232 00:13:32,470 --> 00:13:37,290 you may or may not know about in sleep schedules. 233 00:13:37,290 --> 00:13:43,920 Many humans, especially before electric lights, 234 00:13:43,920 --> 00:13:46,040 sleep biphasically. 235 00:13:46,040 --> 00:13:48,500 There's a first sleep and a second sleep. 236 00:13:48,500 --> 00:13:51,330 And they get up in between, and they're active for awhile. 237 00:13:54,030 --> 00:14:00,525 It's most common when daylight is less than 10 hours a day. 238 00:14:04,940 --> 00:14:07,655 And it has these names. 239 00:14:07,655 --> 00:14:09,140 If they're English-speaking, they 240 00:14:09,140 --> 00:14:12,080 will talk about first sleep and second sleep. 241 00:14:12,080 --> 00:14:14,910 And of course we know that in many hot countries 242 00:14:14,910 --> 00:14:17,910 a siesta is very common. 243 00:14:17,910 --> 00:14:21,190 They go to eat lunch, and the stores all close. 244 00:14:21,190 --> 00:14:24,470 They don't open again until at least 2:00 in the afternoon. 245 00:14:24,470 --> 00:14:27,540 So between 12:00 and 2:00, if you're a tourist, 246 00:14:27,540 --> 00:14:30,250 you might wander around and not find anything's open. 247 00:14:30,250 --> 00:14:33,700 Of course the tourist industry is 248 00:14:33,700 --> 00:14:38,410 adapted to Westerners not practicing the siesta. 249 00:14:38,410 --> 00:14:40,550 So they do keep more things open. 250 00:14:40,550 --> 00:14:44,100 But siestas are still very common in many countries. 251 00:14:44,100 --> 00:14:48,650 That's another kind of polyphasic sleep. 252 00:14:48,650 --> 00:14:50,200 It's very common in animals. 253 00:14:50,200 --> 00:14:54,580 So for example, if you take hamsters, 254 00:14:54,580 --> 00:14:57,060 when they enter their inactive period 255 00:14:57,060 --> 00:14:59,060 it doesn't just mean they go to sleep. 256 00:14:59,060 --> 00:15:01,890 They do go to sleep for awhile, but they're not 257 00:15:01,890 --> 00:15:06,630 sleeping the entire inactive period. 258 00:15:06,630 --> 00:15:08,900 They periodically get up. 259 00:15:08,900 --> 00:15:12,940 They do things in their nest area, in their tunnels. 260 00:15:12,940 --> 00:15:14,480 But they stay below ground. 261 00:15:14,480 --> 00:15:16,880 They don't come out and forage. 262 00:15:16,880 --> 00:15:20,270 It's when they enter their active period-- that's 263 00:15:20,270 --> 00:15:22,739 their foraging time. 264 00:15:22,739 --> 00:15:24,280 Now of course, hamsters wouldn't have 265 00:15:24,280 --> 00:15:26,020 to come out all the time-- especially, 266 00:15:26,020 --> 00:15:31,110 say, a hamster with babies might not 267 00:15:31,110 --> 00:15:33,230 have to forage for food as long as there's 268 00:15:33,230 --> 00:15:36,330 a few males around with piles of food. 269 00:15:36,330 --> 00:15:39,730 They can steal from them, because they horde food. 270 00:15:39,730 --> 00:15:42,380 But some species don't horde as much. 271 00:15:42,380 --> 00:15:44,420 Actually, mice horde, rats horde, 272 00:15:44,420 --> 00:15:47,330 but not to the extent that animals are specialized 273 00:15:47,330 --> 00:15:52,170 for it like hamsters with pouches that 274 00:15:52,170 --> 00:15:55,265 can hold a lot of food that they collect 275 00:15:55,265 --> 00:15:56,800 and bring back to their burrows. 276 00:15:59,620 --> 00:16:05,330 So what about animals that live in areas like the Arctic 277 00:16:05,330 --> 00:16:11,600 or Antarctic where there's continuous light 278 00:16:11,600 --> 00:16:15,420 or darkness for parts of the year? 279 00:16:15,420 --> 00:16:17,480 And there's been some studies of this. 280 00:16:17,480 --> 00:16:21,800 There was a study published in 2005 281 00:16:21,800 --> 00:16:25,570 on the circadian organization in reindeer. 282 00:16:25,570 --> 00:16:27,170 They studied two different groups. 283 00:16:27,170 --> 00:16:32,160 They found that they abandoned the daily rhythms of activity 284 00:16:32,160 --> 00:16:34,470 in the summer where there's continuous light-- 285 00:16:34,470 --> 00:16:37,214 both groups do. 286 00:16:37,214 --> 00:16:39,460 In at least one of the groups, they 287 00:16:39,460 --> 00:16:44,620 abandon this activity cycle in the winter 288 00:16:44,620 --> 00:16:47,370 when it's continuously dark. 289 00:16:47,370 --> 00:16:55,220 So they're not always following this hamster-like or human-like 290 00:16:55,220 --> 00:16:56,600 activity rhythm. 291 00:16:56,600 --> 00:16:59,430 Goldfish have been even more complex. 292 00:16:59,430 --> 00:17:02,940 Sometimes we like to use these organisms, 293 00:17:02,940 --> 00:17:05,829 like we like to think of them as simpler species. 294 00:17:05,829 --> 00:17:10,460 But in this case it turned out to be much more complex. 295 00:17:10,460 --> 00:17:14,670 Their activity in many of them is higher during the daytime, 296 00:17:14,670 --> 00:17:18,859 and they feed more in the nighttime. 297 00:17:18,859 --> 00:17:22,160 That is, their activity rhythm and their feeding rhythm 298 00:17:22,160 --> 00:17:24,470 can be out of sync with each other. 299 00:17:24,470 --> 00:17:29,010 And some of them, though, are just the opposite. 300 00:17:29,010 --> 00:17:34,930 They feed in daytime and they might sleep at nighttime. 301 00:17:34,930 --> 00:17:38,810 It's not so predictable with goldfish, 302 00:17:38,810 --> 00:17:40,890 and it hasn't been studied enough to know 303 00:17:40,890 --> 00:17:45,050 what are the adaptive reasons why they're shifting 304 00:17:45,050 --> 00:17:46,720 their activity patterns like this. 305 00:17:52,170 --> 00:17:54,440 And they've looked at free-running rhythms 306 00:17:54,440 --> 00:17:56,870 in the goldfish-- and they do have rhythms, 307 00:17:56,870 --> 00:17:59,890 but often the feeding rhythm and activity rhythms 308 00:17:59,890 --> 00:18:04,790 are not in sync with each other even when they're free running. 309 00:18:04,790 --> 00:18:09,710 So there have been various studies of total sleep need 310 00:18:09,710 --> 00:18:15,324 in humans, and military organizations and businesses 311 00:18:15,324 --> 00:18:16,740 have been very interested in this. 312 00:18:19,460 --> 00:18:21,090 And they've tried the experiments 313 00:18:21,090 --> 00:18:24,780 to increase efficiency of sleep-- increase 314 00:18:24,780 --> 00:18:27,100 efficiency-- of course, activities. 315 00:18:27,100 --> 00:18:31,040 And they get many different kinds of results. 316 00:18:31,040 --> 00:18:32,760 And the only thing that's really certain 317 00:18:32,760 --> 00:18:37,000 is that individuals do vary a lot. 318 00:18:37,000 --> 00:18:43,780 I had one textbook I used when I was teaching the 901 class, 319 00:18:43,780 --> 00:18:47,400 that he insisted that we never need 320 00:18:47,400 --> 00:18:48,880 more than six hour's sleep. 321 00:18:48,880 --> 00:18:51,910 He said that everything above six hours 322 00:18:51,910 --> 00:18:54,980 is just pure pleasure. 323 00:18:54,980 --> 00:18:59,910 But when you look at the actual research, 324 00:18:59,910 --> 00:19:01,300 there's not support for that. 325 00:19:01,300 --> 00:19:06,590 Some people definitely seem to need more sleep. 326 00:19:06,590 --> 00:19:10,870 If I ask you how much you sleep, it would probably average 327 00:19:10,870 --> 00:19:13,300 between eight and nine hours, and then you'd say, 328 00:19:13,300 --> 00:19:16,490 well, I need that, but I don't get it. 329 00:19:16,490 --> 00:19:17,919 Well, there are consequences. 330 00:19:17,919 --> 00:19:19,460 What's one of the things that happens 331 00:19:19,460 --> 00:19:24,210 if you fall too far below your sleep needs? 332 00:19:24,210 --> 00:19:26,130 Your immune system is affected, and you're 333 00:19:26,130 --> 00:19:28,040 more likely to get sick. 334 00:19:28,040 --> 00:19:31,060 So that is a serious thing to think about. 335 00:19:37,290 --> 00:19:39,680 I thought I was a night person for a long time, 336 00:19:39,680 --> 00:19:42,850 and then I found out I just needed more sleep. 337 00:19:42,850 --> 00:19:45,980 And I could get up and study perfectly well in the morning. 338 00:19:45,980 --> 00:19:49,240 In fact, I did a lot better job than late at night 339 00:19:49,240 --> 00:19:51,235 trying to stay awake and study. 340 00:19:54,980 --> 00:19:55,650 All right. 341 00:19:58,810 --> 00:20:00,900 Everybody does have the biological clock. 342 00:20:00,900 --> 00:20:04,250 They've not found humans that do not 343 00:20:04,250 --> 00:20:06,975 have this rhythm of sleep and waking. 344 00:20:09,840 --> 00:20:12,210 They have looked at the effects of these genes. 345 00:20:12,210 --> 00:20:18,590 For example, studied deletions of the clock gene in mice. 346 00:20:18,590 --> 00:20:20,915 Very interesting-- it causes very abnormal regulation 347 00:20:20,915 --> 00:20:23,820 of feeding and metabolism. 348 00:20:23,820 --> 00:20:27,840 If they're homozygous mutants, they 349 00:20:27,840 --> 00:20:29,880 become hyperphagic and obese just 350 00:20:29,880 --> 00:20:33,580 like they had some brain damage. 351 00:20:33,580 --> 00:20:35,940 And even though the brain damage that causes that 352 00:20:35,940 --> 00:20:40,480 doesn't seem to directly affect that gene, 353 00:20:40,480 --> 00:20:43,150 you get very high leptin levels in the blood, 354 00:20:43,150 --> 00:20:46,840 abnormal fat storage in liver cells. 355 00:20:46,840 --> 00:20:48,696 And you get some of these abnormalities even 356 00:20:48,696 --> 00:20:50,140 in the heterozygous animals. 357 00:20:56,870 --> 00:21:01,300 So now I wanted to talk about the Lorenz readings. 358 00:21:01,300 --> 00:21:02,925 I've given you three assignments. 359 00:21:06,000 --> 00:21:09,670 This will be about the first reading. 360 00:21:09,670 --> 00:21:13,175 And then on Wednesday and Friday-- Friday, 361 00:21:13,175 --> 00:21:16,280 actually, I've given you readings for Friday and Monday 362 00:21:16,280 --> 00:21:18,860 together, because the readings are longer 363 00:21:18,860 --> 00:21:21,180 and there's many more questions I want to deal with. 364 00:21:21,180 --> 00:21:27,230 So there'll be four classes looking at this Lorenz book. 365 00:21:27,230 --> 00:21:29,640 And then there will certainly be more ethology 366 00:21:29,640 --> 00:21:31,334 as the class goes on. 367 00:21:31,334 --> 00:21:33,750 We'll come back to Scott and we'll do some other readings. 368 00:21:33,750 --> 00:21:35,490 We'll come back to Tinbergen, also. 369 00:21:39,810 --> 00:21:44,300 The reading is from a section of the book in which he 370 00:21:44,300 --> 00:21:47,810 talks about fixed motor patterns. 371 00:21:47,810 --> 00:21:54,910 But he comes from a period where they used fixed-action pattern 372 00:21:54,910 --> 00:21:57,490 and fixed-motor pattern almost synonymously, 373 00:21:57,490 --> 00:21:59,370 and then they began to realize-- and he 374 00:21:59,370 --> 00:22:00,820 makes this very clear in the book, 375 00:22:00,820 --> 00:22:04,500 too-- that the meanings are somewhat different. 376 00:22:04,500 --> 00:22:06,400 So I'm calling it fixed-action pattern, 377 00:22:06,400 --> 00:22:09,580 because most of that chapter that you're reading, 378 00:22:09,580 --> 00:22:11,960 he's dealing with the more general term, 379 00:22:11,960 --> 00:22:15,990 "fixed-action pattern." 380 00:22:15,990 --> 00:22:18,470 Now when he does make it very specific 381 00:22:18,470 --> 00:22:28,470 that this has different components, the concept 382 00:22:28,470 --> 00:22:33,570 that even though it embraces these different meanings, 383 00:22:33,570 --> 00:22:35,420 they weren't separated. 384 00:22:35,420 --> 00:22:38,190 And it took them a while to realize 385 00:22:38,190 --> 00:22:39,920 what the separate components were. 386 00:22:39,920 --> 00:22:41,300 So what are they? 387 00:22:41,300 --> 00:22:44,040 If we deal with the separate components 388 00:22:44,040 --> 00:22:46,820 of a fixed-action pattern, which is the general term 389 00:22:46,820 --> 00:22:52,410 we use for an inherited pattern of movement. 390 00:22:52,410 --> 00:22:56,470 You have the actual motor pattern-- 391 00:22:56,470 --> 00:22:58,640 and that's called the fixed-motor pattern. 392 00:22:58,640 --> 00:23:01,850 And that's the most unchanging part. 393 00:23:04,980 --> 00:23:10,790 It was studying fixed-motor patterns in doves and pigeons 394 00:23:10,790 --> 00:23:20,710 and in waterfowl where Heinroth and Whitman made the discovery 395 00:23:20,710 --> 00:23:22,500 that these movement patterns are just 396 00:23:22,500 --> 00:23:24,670 like physical characteristics of the body. 397 00:23:24,670 --> 00:23:30,400 They can be used to even find homologies across species. 398 00:23:30,400 --> 00:23:33,450 You find it's the same in all members of a species, 399 00:23:33,450 --> 00:23:35,950 and so forth. 400 00:23:35,950 --> 00:23:39,150 They were looking at courtship patterns of these birds. 401 00:23:39,150 --> 00:23:41,400 Courtship patterns it's particularly clear, 402 00:23:41,400 --> 00:23:46,290 because when the fixed-motor patterns are performed, 403 00:23:46,290 --> 00:23:50,710 they're almost always performed in the very same way. 404 00:23:50,710 --> 00:23:53,200 That's not true of many fixed-action patterns, 405 00:23:53,200 --> 00:23:55,530 as we will see. 406 00:23:55,530 --> 00:23:56,520 So what else? 407 00:23:56,520 --> 00:23:57,770 There's a fixed-motor pattern. 408 00:23:57,770 --> 00:23:59,320 What else is there? 409 00:23:59,320 --> 00:24:01,410 Well, the motivational state. 410 00:24:01,410 --> 00:24:04,060 I made it clear before-- there has 411 00:24:04,060 --> 00:24:07,490 to be underlying motivational state where the motivation is 412 00:24:07,490 --> 00:24:17,660 high enough so the result of the motor pattern 413 00:24:17,660 --> 00:24:19,490 actually reduces the motivation. 414 00:24:19,490 --> 00:24:25,600 The animal is motivated to do that action. 415 00:24:25,600 --> 00:24:27,790 But we also have the stimulus, say. 416 00:24:27,790 --> 00:24:30,370 It doesn't just happen. 417 00:24:30,370 --> 00:24:32,930 It happens with a stimulus. 418 00:24:32,930 --> 00:24:36,910 So we talk about innate recognition. 419 00:24:36,910 --> 00:24:41,560 Animals do inherit-- innately they 420 00:24:41,560 --> 00:24:45,243 have the recognition of certain stimulus characteristics. 421 00:24:48,120 --> 00:24:50,180 They respond to other members of the species 422 00:24:50,180 --> 00:24:52,020 by certain characteristics of the species. 423 00:24:54,700 --> 00:24:58,800 In fact, innately they don't recognize individuals at all. 424 00:24:58,800 --> 00:25:00,275 All they need is these key stimuli. 425 00:25:03,850 --> 00:25:10,810 So here in this where I'm outlining this slide, 426 00:25:10,810 --> 00:25:14,690 I talk about the motivation or drive first. 427 00:25:14,690 --> 00:25:17,435 They have the drive to search for a certain stimulus 428 00:25:17,435 --> 00:25:17,935 situation. 429 00:25:22,750 --> 00:25:27,820 And this drive, in the Lorenz theory, 430 00:25:27,820 --> 00:25:30,455 is called an action-specific potential. 431 00:25:33,010 --> 00:25:36,690 It's the drive level-- the motivational level-- 432 00:25:36,690 --> 00:25:40,180 that builds up in the brain of the animal that 433 00:25:40,180 --> 00:25:41,900 increases the likelihood. 434 00:25:41,900 --> 00:25:43,700 The higher it gets, the more likely 435 00:25:43,700 --> 00:25:46,110 he is to show the fixed-motor pattern. 436 00:25:49,740 --> 00:25:52,600 So then the innate recognition. 437 00:25:52,600 --> 00:25:55,710 And here we talk about the innate releasing mechanism. 438 00:25:55,710 --> 00:25:58,315 So that is actually referring to a mechanism 439 00:25:58,315 --> 00:26:02,350 in the nervous system and sensory system. 440 00:26:02,350 --> 00:26:06,320 And we connect parts of the brain. 441 00:26:06,320 --> 00:26:08,980 There's innate recognition. 442 00:26:08,980 --> 00:26:10,025 The brain is tuned. 443 00:26:12,830 --> 00:26:15,260 Because of the inheritance of the animal, 444 00:26:15,260 --> 00:26:17,120 the brain is wired in a specific way, 445 00:26:17,120 --> 00:26:20,880 and he responds to a specific stimuli. 446 00:26:20,880 --> 00:26:24,960 And then, finally, the fixed-motor pattern. 447 00:26:24,960 --> 00:26:30,120 So now we've said a little bit about reflexes several times. 448 00:26:30,120 --> 00:26:33,100 We've talked about fixed-action patterns. 449 00:26:33,100 --> 00:26:38,510 Let's try to draw simple information flow models. 450 00:26:38,510 --> 00:26:40,540 And this is the way I've drawn them. 451 00:26:40,540 --> 00:26:42,610 So I show a reflex there at the top. 452 00:26:47,340 --> 00:26:51,790 I put the sensory side in green, the motor side in blue. 453 00:26:51,790 --> 00:26:56,240 And then you don't have the motivational side for a reflex, 454 00:26:56,240 --> 00:26:57,530 so there's nothing in red. 455 00:26:57,530 --> 00:26:59,000 I put that in red. 456 00:27:03,560 --> 00:27:08,340 So the reflex is simply a pathway from stimulus 457 00:27:08,340 --> 00:27:09,160 to response. 458 00:27:09,160 --> 00:27:14,310 It goes through, you could say, the sensory analysis. 459 00:27:14,310 --> 00:27:16,130 We can make the response specific 460 00:27:16,130 --> 00:27:18,420 to certain characteristics of the stimulus. 461 00:27:18,420 --> 00:27:21,770 And then on the motor side you have 462 00:27:21,770 --> 00:27:28,800 to activate in a pool of neurons that end with a motor neuron. 463 00:27:28,800 --> 00:27:32,100 Motor neuron has the fiber going right up to the muscle. 464 00:27:32,100 --> 00:27:35,060 And notice I'm showing other kinds of inputs 465 00:27:35,060 --> 00:27:38,160 that can influence it. 466 00:27:38,160 --> 00:27:42,730 These could change with motivational state, too. 467 00:27:42,730 --> 00:27:45,160 Certain reflexes might become more likely 468 00:27:45,160 --> 00:27:47,010 in certain states of motivation. 469 00:27:47,010 --> 00:27:53,300 But generally this can fluctuate a lot, these other inputs. 470 00:27:53,300 --> 00:27:56,000 But the main input is always the triggers. 471 00:27:56,000 --> 00:28:03,360 The actual response is just one. 472 00:28:03,360 --> 00:28:06,500 But for the fixed-action pattern you 473 00:28:06,500 --> 00:28:10,850 can have different stimuli that can trigger it. 474 00:28:10,850 --> 00:28:12,600 And there can be a series. 475 00:28:12,600 --> 00:28:17,390 We call them the key stimuli-- the inheritance stimuli. 476 00:28:17,390 --> 00:28:20,190 Now I'm not saying they're always fixed. 477 00:28:20,190 --> 00:28:22,170 I'm not talking yet about how these things are 478 00:28:22,170 --> 00:28:22,995 shaped by learning. 479 00:28:22,995 --> 00:28:26,091 I'm just talking about what's innate-- 480 00:28:26,091 --> 00:28:29,861 a series of stimuli that trigger the innate-releasing 481 00:28:29,861 --> 00:28:30,360 mechanisms. 482 00:28:34,600 --> 00:28:41,670 That affects the level of the action-specific potential which 483 00:28:41,670 --> 00:28:50,110 also has endogenous inputs, shown by the red arrows. 484 00:28:50,110 --> 00:28:54,890 This is why this builds up over time. 485 00:28:54,890 --> 00:28:57,370 It has durability. 486 00:28:57,370 --> 00:28:59,590 The action-specific potential goes up 487 00:28:59,590 --> 00:29:03,740 and it doesn't just go back down unless this is actually 488 00:29:03,740 --> 00:29:06,050 discharged. 489 00:29:06,050 --> 00:29:10,610 Then it connects to the motor system in a very interesting 490 00:29:10,610 --> 00:29:14,500 way, because many fixed-motor patterns are actually 491 00:29:14,500 --> 00:29:17,010 a series of actions. 492 00:29:17,010 --> 00:29:21,940 The lowest threshold is usually search behavior. 493 00:29:24,670 --> 00:29:27,330 The right stimulus isn't there for eliciting 494 00:29:27,330 --> 00:29:31,020 all of these components of the fixed-motor pattern. 495 00:29:31,020 --> 00:29:34,800 So the only thing you get is search. 496 00:29:34,800 --> 00:29:38,560 And then, at the higher thresholds, 497 00:29:38,560 --> 00:29:41,400 the thresholds change for eliciting 498 00:29:41,400 --> 00:29:42,590 the various components. 499 00:29:42,590 --> 00:29:45,860 It's often a chain of movements that 500 00:29:45,860 --> 00:29:50,440 are all part of the same fixed-action pattern. 501 00:29:50,440 --> 00:29:51,240 All right. 502 00:29:51,240 --> 00:29:55,980 So that's a simple way to characterize it. 503 00:29:55,980 --> 00:29:59,080 So to learn more about this, it's 504 00:29:59,080 --> 00:30:01,880 interesting to go through some of the other Lorenz concepts. 505 00:30:01,880 --> 00:30:05,360 He talks about intention movements. 506 00:30:05,360 --> 00:30:07,920 So what are intention movements? 507 00:30:07,920 --> 00:30:11,030 You should be able to think of examples from animal behavior 508 00:30:11,030 --> 00:30:13,060 and from human behavior. 509 00:30:16,720 --> 00:30:24,760 If your level of hunger-- the action-specific potential 510 00:30:24,760 --> 00:30:30,520 of that particular pattern of that particular effect-- 511 00:30:30,520 --> 00:30:34,130 the fixed-action pattern of eating-- is high, 512 00:30:34,130 --> 00:30:37,360 you will show intention movements 513 00:30:37,360 --> 00:30:40,190 when there's actually not even any food around. 514 00:30:40,190 --> 00:30:42,110 And if there is food around, in fact 515 00:30:42,110 --> 00:30:44,360 you will show intention movements before you start 516 00:30:44,360 --> 00:30:48,300 to eat, because you'll be affected by the timing 517 00:30:48,300 --> 00:30:49,720 by other people around you you're 518 00:30:49,720 --> 00:30:51,310 going to eat with and so forth. 519 00:30:51,310 --> 00:30:55,890 What is an intention movement here? 520 00:30:55,890 --> 00:30:57,770 Well, people lick their lips. 521 00:30:57,770 --> 00:31:03,140 They salivate. 522 00:31:03,140 --> 00:31:10,220 They do various things that give away their intention to eat. 523 00:31:10,220 --> 00:31:14,500 What do you do when you're motivated to leave this room, 524 00:31:14,500 --> 00:31:19,850 and I'm starting to go over time a little bit? 525 00:31:19,850 --> 00:31:22,750 I see all kinds of intention movements out there. 526 00:31:22,750 --> 00:31:26,185 I see you packing your bags, I see you shifting in your seat. 527 00:31:26,185 --> 00:31:30,030 I mean, these are all intention movements. 528 00:31:30,030 --> 00:31:33,330 They're anticipatory movements that 529 00:31:33,330 --> 00:31:36,605 in most fixed-action patterns occur. 530 00:31:40,390 --> 00:31:46,900 An animal like a goose, when he intends to fly, 531 00:31:46,900 --> 00:31:49,640 always goes through these series of moments. 532 00:31:52,770 --> 00:31:55,960 Cranes his neck and emits a call. 533 00:31:55,960 --> 00:31:57,455 He shakes his bill. 534 00:32:00,400 --> 00:32:04,720 Then he will start to unfurl his feathers. 535 00:32:04,720 --> 00:32:07,110 But that's only the third stage. 536 00:32:07,110 --> 00:32:11,260 Stage five is when he actually leaps into the air. 537 00:32:11,260 --> 00:32:15,280 He goes through the series of movements every time. 538 00:32:15,280 --> 00:32:17,060 Well, the initial movements can be 539 00:32:17,060 --> 00:32:18,666 considered intention movements. 540 00:32:23,100 --> 00:32:27,570 And it's interesting, because they can evolve on their own, 541 00:32:27,570 --> 00:32:33,550 so to speak, because they can serve important social signals. 542 00:32:33,550 --> 00:32:38,040 just think of the intention movements to mate. 543 00:32:38,040 --> 00:32:42,700 Animals make these intention movements 544 00:32:42,700 --> 00:32:47,020 before they mate-- preparatory movements. 545 00:32:47,020 --> 00:32:49,090 But those can evolve, too. 546 00:32:49,090 --> 00:32:53,395 So they serve as signals to other members of the species. 547 00:32:56,140 --> 00:33:01,010 And that was clear in the studies 548 00:33:01,010 --> 00:33:04,610 of even back early in the 20th century, 549 00:33:04,610 --> 00:33:12,580 when Heinroth and Whitman were studying fixed-action patterns 550 00:33:12,580 --> 00:33:16,300 in geese and pigeons and doves. 551 00:33:16,300 --> 00:33:19,060 Some of the things they were looking at 552 00:33:19,060 --> 00:33:24,270 had in fact evolved as signals that were closely related 553 00:33:24,270 --> 00:33:30,760 to the actual fixed-action pattern that they evolved from. 554 00:33:30,760 --> 00:33:32,300 But they become separate. 555 00:33:32,300 --> 00:33:36,160 They become signals important in social life. 556 00:33:36,160 --> 00:33:38,860 And that's particularly obvious when 557 00:33:38,860 --> 00:33:41,750 we deal with aggressive behavior. 558 00:33:41,750 --> 00:33:50,940 And many aggressive encounters in animals are ritualized. 559 00:33:50,940 --> 00:33:54,000 It doesn't mean they're actually going to attack, 560 00:33:54,000 --> 00:33:57,986 but the threat movements they make 561 00:33:57,986 --> 00:34:00,930 that usually don't lead to an actual attack 562 00:34:00,930 --> 00:34:05,480 are signals to the other animals of the aggressive intent 563 00:34:05,480 --> 00:34:06,810 of the animal. 564 00:34:06,810 --> 00:34:09,830 And so studies of aggressive behavior 565 00:34:09,830 --> 00:34:14,780 have been particularly helpful in understanding 566 00:34:14,780 --> 00:34:18,760 this evolution of signaling functions. 567 00:34:18,760 --> 00:34:21,790 And a lot of courtship patterns which 568 00:34:21,790 --> 00:34:24,810 have become quite elaborate in many species-- 569 00:34:24,810 --> 00:34:29,199 particularly birds-- are like this. 570 00:34:29,199 --> 00:34:33,440 They're elaborate methods of communicating intention 571 00:34:33,440 --> 00:34:34,369 to mate. 572 00:34:34,369 --> 00:34:39,190 In fact, during that whole time at any time the male is 573 00:34:39,190 --> 00:34:46,000 displaying his intention to mate via the courtship 574 00:34:46,000 --> 00:34:48,424 dances that he's doing, the female can change her mind 575 00:34:48,424 --> 00:34:49,325 and fly away. 576 00:34:52,164 --> 00:34:54,330 But if she doesn't change her mind, then, of course, 577 00:34:54,330 --> 00:34:57,100 eventually it will lead to mating. 578 00:34:57,100 --> 00:35:00,200 And remember, we talked about jackdaws and kittiwakes. 579 00:35:00,200 --> 00:35:02,380 We talked about the kittiwakes, how much 580 00:35:02,380 --> 00:35:04,500 of their aggressive behavior does not 581 00:35:04,500 --> 00:35:06,925 lead to actual attacks, but they showed 582 00:35:06,925 --> 00:35:10,560 a lot of ritualized aggressive behavior. 583 00:35:10,560 --> 00:35:13,150 And you see that in jackdaws as well. 584 00:35:13,150 --> 00:35:17,090 It's rare when they actually attack. 585 00:35:17,090 --> 00:35:19,305 And when they do, the whole colony responds. 586 00:35:19,305 --> 00:35:21,350 It becomes confused. 587 00:35:21,350 --> 00:35:25,720 And pretty much everything gets toned down 588 00:35:25,720 --> 00:35:27,890 without much damage being done. 589 00:35:31,420 --> 00:35:35,910 So if a lot of these fixed-action patterns 590 00:35:35,910 --> 00:35:39,330 are actually not like these simple courtship movements that 591 00:35:39,330 --> 00:35:42,390 always are executed about the same way, 592 00:35:42,390 --> 00:35:45,310 but they actually are a series of moments-- 593 00:35:45,310 --> 00:35:49,660 how do you know you're dealing with the same fixed-action 594 00:35:49,660 --> 00:35:51,940 pattern if it's a series of different movements? 595 00:35:54,850 --> 00:36:00,310 Lorenz goes through an elaborate discussion of this, 596 00:36:00,310 --> 00:36:04,630 because people that are just getting into ethology 597 00:36:04,630 --> 00:36:09,650 and studying animal behavior find this very confusing, 598 00:36:09,650 --> 00:36:13,480 and it takes a long time in studying an animal when 599 00:36:13,480 --> 00:36:22,290 you learn which behaviors belong to a specific sequence 600 00:36:22,290 --> 00:36:24,420 and will lead to a certain fixed-action 601 00:36:24,420 --> 00:36:27,650 or fixed-motor pattern. 602 00:36:27,650 --> 00:36:32,300 The first one he points out is predictability-- 603 00:36:32,300 --> 00:36:36,520 that someone that's studying the behavior 604 00:36:36,520 --> 00:36:42,125 finds that one little behavior always leads to another. 605 00:36:44,710 --> 00:36:46,865 So a good ethologist, if he's experienced, 606 00:36:46,865 --> 00:36:51,350 he can reliably predict the next movement in a series. 607 00:36:51,350 --> 00:36:56,980 That was true of Seitz's studies in the cichlid fighting 608 00:36:56,980 --> 00:36:59,270 behavior of the fighting fish. 609 00:36:59,270 --> 00:37:03,990 It was true of Lorenz's studies of geese and of ducks, 610 00:37:03,990 --> 00:37:09,570 and it's true of the studies of doves and pigeons by Whitman. 611 00:37:09,570 --> 00:37:19,190 And when the intensity of the motivation increases, 612 00:37:19,190 --> 00:37:22,940 the behavior shifts. 613 00:37:22,940 --> 00:37:25,110 But it never shifts. 614 00:37:25,110 --> 00:37:27,050 They tend to go through certain stages. 615 00:37:27,050 --> 00:37:28,830 Like I mentioned, there's five stages 616 00:37:28,830 --> 00:37:33,800 in the flight take-off by a goose. 617 00:37:33,800 --> 00:37:39,180 He never jumps from stage one directly to stage five. 618 00:37:39,180 --> 00:37:43,860 You can tell where he is in the sequence. 619 00:37:43,860 --> 00:37:48,520 And in fact if he's not really going to fly, 620 00:37:48,520 --> 00:37:50,290 he'll never reach stage five. 621 00:37:57,020 --> 00:37:57,980 But wait a minute. 622 00:37:57,980 --> 00:38:02,650 Can't the animal just switch to another motivational state? 623 00:38:02,650 --> 00:38:04,230 And maybe that's all he's doing when 624 00:38:04,230 --> 00:38:05,920 you see a different movement. 625 00:38:05,920 --> 00:38:09,690 Well, animals do switch motivations. 626 00:38:09,690 --> 00:38:14,960 But think of an animal that's motivated to attack 627 00:38:14,960 --> 00:38:18,710 and he's motivated to feed. 628 00:38:18,710 --> 00:38:21,670 Can he switch suddenly from one to the other? 629 00:38:21,670 --> 00:38:23,550 Generally not. 630 00:38:23,550 --> 00:38:28,300 Think of an angry human that's also hungry. 631 00:38:28,300 --> 00:38:30,421 Does he switch suddenly and sit down and eat? 632 00:38:30,421 --> 00:38:30,920 No. 633 00:38:30,920 --> 00:38:33,750 It takes them a while to calm down. 634 00:38:33,750 --> 00:38:38,200 You don't you shift your motivational state so rapidly. 635 00:38:38,200 --> 00:38:42,110 But if you're dealing with a sequence of different movements 636 00:38:42,110 --> 00:38:45,830 that all have the same drive behind them, 637 00:38:45,830 --> 00:38:48,390 then you do switch. 638 00:38:48,390 --> 00:38:51,900 But just not from stage one to stage five, but stage one 639 00:38:51,900 --> 00:38:54,830 to stage two, stage two to stage three, and so forth. 640 00:38:54,830 --> 00:38:57,332 Or you might drop down one level if the motivation 641 00:38:57,332 --> 00:38:57,915 is decreasing. 642 00:39:04,680 --> 00:39:10,160 I point out here that first of all the same stimulus that 643 00:39:10,160 --> 00:39:15,600 elicits all the different behaviors in a sequence-- these 644 00:39:15,600 --> 00:39:19,360 are the key stimuli that increase the motivation to do 645 00:39:19,360 --> 00:39:22,550 a certain behavior. 646 00:39:22,550 --> 00:39:25,380 It's the same stimulus that elicits all the patterns, 647 00:39:25,380 --> 00:39:27,790 whereas different stimuli are involved 648 00:39:27,790 --> 00:39:30,515 if it's a different fixed-action pattern. 649 00:39:36,820 --> 00:39:39,530 So Number 5 here is just similar. 650 00:39:39,530 --> 00:39:46,680 It's spelling out details of this readiness 651 00:39:46,680 --> 00:39:53,530 to perform that's fluctuating as a single thing 652 00:39:53,530 --> 00:39:56,490 determining what patterns you're actually seeing. 653 00:39:56,490 --> 00:39:59,740 That unity that ethologists observe, 654 00:39:59,740 --> 00:40:04,040 though, isn't always so apparent in baby animals. 655 00:40:04,040 --> 00:40:08,130 It does have to develop in many of them. 656 00:40:08,130 --> 00:40:10,370 Experience can be very important in the way 657 00:40:10,370 --> 00:40:11,305 these things develop. 658 00:40:14,060 --> 00:40:16,040 Now this is a difficult concept, but let 659 00:40:16,040 --> 00:40:18,270 me try to go through it anyway, because Seitz 660 00:40:18,270 --> 00:40:21,240 was very important in working out 661 00:40:21,240 --> 00:40:25,980 some of the principles of ethological investigation 662 00:40:25,980 --> 00:40:30,680 and the principles of ethology that Lorenz was talking about. 663 00:40:30,680 --> 00:40:33,680 He was an ethologist who, together 664 00:40:33,680 --> 00:40:37,000 with Lorenz and a number of others, 665 00:40:37,000 --> 00:40:41,190 were working on these things we're talking about. 666 00:40:41,190 --> 00:40:43,110 And he had this method he called the method 667 00:40:43,110 --> 00:40:44,600 of dual qualification. 668 00:40:44,600 --> 00:40:50,290 It was used to assess how effective a dummy stimulus is. 669 00:40:50,290 --> 00:40:52,630 How do you determine how effective 670 00:40:52,630 --> 00:40:55,904 a stimulus is when the animals you're studying 671 00:40:55,904 --> 00:40:57,570 have all different levels of motivation? 672 00:41:01,460 --> 00:41:06,670 It's not an easy thing, because a highly motivated animal 673 00:41:06,670 --> 00:41:09,960 could respond to a dummy stimulus that's really 674 00:41:09,960 --> 00:41:15,670 not the most effective dummy-- not the most effective stimulus 675 00:41:15,670 --> 00:41:17,900 pattern. 676 00:41:17,900 --> 00:41:19,760 But an animal less motivated might not 677 00:41:19,760 --> 00:41:21,735 respond much at all to that. 678 00:41:21,735 --> 00:41:23,790 A very highly motivated animal, he 679 00:41:23,790 --> 00:41:26,970 will respond to the less-effective stimulus. 680 00:41:26,970 --> 00:41:32,990 Well, how do you know that the difference between two stimuli 681 00:41:32,990 --> 00:41:35,980 isn't just due to having animals with different motivational 682 00:41:35,980 --> 00:41:37,020 level? 683 00:41:37,020 --> 00:41:41,110 So Seitz realized that what he had to do 684 00:41:41,110 --> 00:41:46,790 was expose the animal to the dummy stimulus first, 685 00:41:46,790 --> 00:41:49,710 and then, immediately afterwards, 686 00:41:49,710 --> 00:41:52,195 what happens if he executes the motor pattern? 687 00:41:55,780 --> 00:41:57,460 His motivational level goes down. 688 00:42:00,590 --> 00:42:06,120 Every time the animal executes-- the fixed-action, fixed-motor 689 00:42:06,120 --> 00:42:11,050 pattern-- becomes less motivated to do it. 690 00:42:11,050 --> 00:42:16,510 So show him the dummy stimulus, see how he responds, 691 00:42:16,510 --> 00:42:19,200 record the response, and now expose him 692 00:42:19,200 --> 00:42:23,450 to the most effective stimulus, which is usually, 693 00:42:23,450 --> 00:42:26,360 if you're studying aggressive behavior, 694 00:42:26,360 --> 00:42:32,820 another male of the same species in full fighting colors. 695 00:42:32,820 --> 00:42:35,060 And see what response you get there. 696 00:42:35,060 --> 00:42:37,410 Well, if the dummy stimulus had been very effective, 697 00:42:37,410 --> 00:42:41,660 he would respond much less to that most effective stimulus. 698 00:42:41,660 --> 00:42:46,340 If it weren't very effective, he will respond much more. 699 00:42:46,340 --> 00:42:49,680 And by looking at the difference between those two, 700 00:42:49,680 --> 00:42:53,660 he could judge much better the effectiveness 701 00:42:53,660 --> 00:42:55,930 of the dummy stimulus. 702 00:42:55,930 --> 00:42:58,270 So that's why you've got to realize 703 00:42:58,270 --> 00:43:03,430 there's two variables here-- the action-specific potential 704 00:43:03,430 --> 00:43:08,520 level-- the level of drive, which decreases every time he 705 00:43:08,520 --> 00:43:12,420 sort of forms the movement, and then 706 00:43:12,420 --> 00:43:16,490 varying effectiveness of those stimuli 707 00:43:16,490 --> 00:43:18,337 represented by the dummy stimulus. 708 00:43:21,530 --> 00:43:23,280 So this is just what I went over. 709 00:43:27,490 --> 00:43:30,110 It's not easy, of course, to apply, 710 00:43:30,110 --> 00:43:34,550 but it does increase the ability to judge dummy stimuli. 711 00:43:34,550 --> 00:43:38,070 And one of the things that Seitz discovered in doing all this 712 00:43:38,070 --> 00:43:40,890 is something about the stimuli. 713 00:43:40,890 --> 00:43:44,970 Stimuli usually consisted of a number of key stimuli. 714 00:43:44,970 --> 00:43:46,760 It wasn't usually just one thing, 715 00:43:46,760 --> 00:43:49,010 but various properties of the stimulus 716 00:43:49,010 --> 00:43:52,340 were effective in eliciting the stimulus. 717 00:43:52,340 --> 00:43:56,540 But what we discovered was that each key stimulus sort of 718 00:43:56,540 --> 00:44:00,430 summated with the others. 719 00:44:00,430 --> 00:44:03,100 So you could show it in a flow diagram like this. 720 00:44:06,030 --> 00:44:10,490 The innate releasing mechanism was triggered, 721 00:44:10,490 --> 00:44:14,535 so the drive increased and the likelihood of the response 722 00:44:14,535 --> 00:44:15,035 increased. 723 00:44:18,550 --> 00:44:23,700 If these were key stimuli, their effect summated. 724 00:44:23,700 --> 00:44:24,700 Two are better than one. 725 00:44:24,700 --> 00:44:30,180 All three is better than two, and so forth. 726 00:44:30,180 --> 00:44:34,350 And often stimulus three was just 727 00:44:34,350 --> 00:44:36,420 as effective as stimulus one. 728 00:44:36,420 --> 00:44:41,640 But the two together, their effects summated. 729 00:44:41,640 --> 00:44:44,920 And he called that the law of heterogeneous summation, 730 00:44:44,920 --> 00:44:48,450 because the stimuli could seem very different with each other, 731 00:44:48,450 --> 00:44:54,110 but they still, as far as this response, 732 00:44:54,110 --> 00:44:56,990 they simply summated in their effectiveness. 733 00:44:59,930 --> 00:45:00,980 All right. 734 00:45:00,980 --> 00:45:06,810 So the effectiveness of stimuli, though, can change over time. 735 00:45:06,810 --> 00:45:12,750 We already know that when you elicit a fixed-action pattern, 736 00:45:12,750 --> 00:45:15,980 the animal-- you've reduced his level of motivation. 737 00:45:15,980 --> 00:45:18,410 Now he's a little less likely now. 738 00:45:18,410 --> 00:45:21,280 And some things he's a lot less likely. 739 00:45:21,280 --> 00:45:22,680 Some he's a little less likely. 740 00:45:22,680 --> 00:45:26,100 That varies with what fixed-action pattern 741 00:45:26,100 --> 00:45:27,520 you're dealing with. 742 00:45:27,520 --> 00:45:31,000 So they coined the term "action-specific fatigue" 743 00:45:31,000 --> 00:45:35,670 to talk about this decrease in motivation. 744 00:45:35,670 --> 00:45:38,240 It seemed like it was a fatigue. 745 00:45:38,240 --> 00:45:40,770 It was not a very good term. 746 00:45:40,770 --> 00:45:44,660 And the problem with thinking about this, 747 00:45:44,660 --> 00:45:46,900 or interpreting the behavior, was 748 00:45:46,900 --> 00:45:53,990 what about stimulus-side changes they were habituating to? 749 00:45:53,990 --> 00:46:00,370 So this guy [? Precktal ?] actually studied this a lot, 750 00:46:00,370 --> 00:46:03,460 and he showed you could get separate effects on the motor 751 00:46:03,460 --> 00:46:08,720 side and the stimulus side-- or he called it the receptor side. 752 00:46:08,720 --> 00:46:11,985 He was studying gaping reactions in birds. 753 00:46:18,190 --> 00:46:22,040 This is what I just said-- that action-specific fatigue is not 754 00:46:22,040 --> 00:46:24,650 such a good term, because it looks like fatigue, 755 00:46:24,650 --> 00:46:26,500 but it's not really fatigue at all. 756 00:46:26,500 --> 00:46:29,430 It's just less motivation. 757 00:46:29,430 --> 00:46:33,510 Let's talk about an animal I study so much-- 758 00:46:33,510 --> 00:46:36,410 the Syrian hamster-- and talk about, say, 759 00:46:36,410 --> 00:46:38,390 the orienting movements he makes. 760 00:46:38,390 --> 00:46:41,880 Now the hamster is always motivated 761 00:46:41,880 --> 00:46:43,200 to get sunflower seeds. 762 00:46:49,520 --> 00:46:52,210 I've not been there, but suddenly I show up, 763 00:46:52,210 --> 00:46:53,860 and I show him the sunflower seeds, 764 00:46:53,860 --> 00:46:55,620 and he makes an orienting movement. 765 00:46:55,620 --> 00:46:58,750 But I don't give it to him. 766 00:46:58,750 --> 00:47:01,760 If I keep showing him the seed in the same part 767 00:47:01,760 --> 00:47:03,260 of the visual field, he habituates. 768 00:47:03,260 --> 00:47:07,410 He will respond a few times, and then he stops. 769 00:47:07,410 --> 00:47:08,790 He's habituated. 770 00:47:08,790 --> 00:47:11,260 If I show him another part of the field, 771 00:47:11,260 --> 00:47:14,860 he would be more likely to respond. 772 00:47:14,860 --> 00:47:16,810 And eventually he's habituated. 773 00:47:16,810 --> 00:47:18,720 It recovers over time. 774 00:47:18,720 --> 00:47:22,270 If I just wait awhile, I can get them to respond again. 775 00:47:22,270 --> 00:47:25,750 Now sure if I reward him, then he's going to keep responding. 776 00:47:25,750 --> 00:47:27,990 I'm just talking about what he does 777 00:47:27,990 --> 00:47:30,550 when the stimulus is novel, and what 778 00:47:30,550 --> 00:47:34,680 he does when the stimulus becomes less novel. 779 00:47:34,680 --> 00:47:38,030 He'll keep responding only if he's rewarded. 780 00:47:38,030 --> 00:47:41,880 So let's take another behavior. 781 00:47:41,880 --> 00:47:43,860 But this is even more dramatic, because there's 782 00:47:43,860 --> 00:47:48,130 no real reward except that he's still alive. 783 00:47:48,130 --> 00:47:50,950 It's anti-predator behavior. 784 00:47:50,950 --> 00:47:57,840 Say I've built an artificial living situation where 785 00:47:57,840 --> 00:48:00,650 he lives in an underground tunnel. 786 00:48:00,650 --> 00:48:04,070 But he has to come out to get water or food. 787 00:48:04,070 --> 00:48:06,510 And so I know when he's going to come out, 788 00:48:06,510 --> 00:48:09,270 because I know his rhythm of behavior. 789 00:48:09,270 --> 00:48:13,590 He'll come out about the time the lights are going off. 790 00:48:13,590 --> 00:48:15,540 I have them going out fairly rapidly, 791 00:48:15,540 --> 00:48:18,280 so I know more precisely when he's going to come out. 792 00:48:21,380 --> 00:48:23,050 So he comes out. 793 00:48:23,050 --> 00:48:24,040 He's very cautious. 794 00:48:24,040 --> 00:48:27,030 He's very afraid of predators. 795 00:48:27,030 --> 00:48:30,310 I have it so that he has to cross an open area. 796 00:48:30,310 --> 00:48:31,540 So here comes the hamster. 797 00:48:31,540 --> 00:48:34,610 And he's cautiously hugging the ground, 798 00:48:34,610 --> 00:48:37,780 moving across the open area towards the food and water I 799 00:48:37,780 --> 00:48:41,850 have in the opposite corner of this field area. 800 00:48:41,850 --> 00:48:44,020 Now I make a noise. 801 00:48:44,020 --> 00:48:46,220 I take a piece of paper and crush it. 802 00:48:46,220 --> 00:48:48,660 Crunch! 803 00:48:48,660 --> 00:48:50,830 The animal runs. 804 00:48:50,830 --> 00:48:55,340 You think hamsters can't move fast, but in this situation 805 00:48:55,340 --> 00:48:56,980 they move very, very fast. 806 00:48:56,980 --> 00:48:58,830 And they run back to the tunnel. 807 00:48:58,830 --> 00:49:02,580 In fact they run down the tunnel-- 808 00:49:02,580 --> 00:49:05,630 sometimes all the way to their nest. 809 00:49:05,630 --> 00:49:06,790 So I'm patient. 810 00:49:06,790 --> 00:49:08,710 I wait. 811 00:49:08,710 --> 00:49:12,310 And the animal eventually, of course-- usually fairly soon, 812 00:49:12,310 --> 00:49:17,580 because he's got to forage for food and water-- 813 00:49:17,580 --> 00:49:22,230 he comes up again, and he starts the whole process again. 814 00:49:22,230 --> 00:49:25,370 I let him get out in the middle of the field, 815 00:49:25,370 --> 00:49:29,730 crush the paper again, and he runs back to the tunnel. 816 00:49:29,730 --> 00:49:34,590 But this time he doesn't go very far in the tunnel, 817 00:49:34,590 --> 00:49:39,290 and he turns around, and he comes back a lot sooner. 818 00:49:39,290 --> 00:49:42,200 If I do it a third time, he runs over 819 00:49:42,200 --> 00:49:44,000 towards the tunnel entrance and stops. 820 00:49:44,000 --> 00:49:45,700 He doesn't even go in the tunnel. 821 00:49:49,120 --> 00:49:54,287 If I do it a fourth time, he stops and pricks up his ears. 822 00:49:54,287 --> 00:49:55,120 So what's happening? 823 00:49:55,120 --> 00:49:58,610 He's habituating to that noise. 824 00:49:58,610 --> 00:50:01,360 So the next time he comes out, now 825 00:50:01,360 --> 00:50:04,280 if I use that same stimulus, he will continue on 826 00:50:04,280 --> 00:50:07,160 and get his food or water. 827 00:50:07,160 --> 00:50:12,020 But if I change the sound-- say I jingle some keys 828 00:50:12,020 --> 00:50:17,900 or I take my fingernails and scratch a piece of wood-- 829 00:50:17,900 --> 00:50:20,880 it can be fairly soft sound, but the hamster can hear it very, 830 00:50:20,880 --> 00:50:24,740 very well-- I get the full-blown response again-- running 831 00:50:24,740 --> 00:50:26,750 back to the tunnel just from the novel. 832 00:50:26,750 --> 00:50:30,500 And again, I can selectively habituate the animal 833 00:50:30,500 --> 00:50:31,725 to one sound or another. 834 00:50:35,510 --> 00:50:38,720 Let's say he's responding to this novel sound. 835 00:50:38,720 --> 00:50:43,420 If in the very next time I use the crushing paper again, 836 00:50:43,420 --> 00:50:44,990 he retains his habituation. 837 00:50:44,990 --> 00:50:46,430 It's very specific. 838 00:50:46,430 --> 00:50:48,980 He's learned specifically which sounds 839 00:50:48,980 --> 00:50:51,750 are novel, which are not novel. 840 00:50:54,390 --> 00:50:57,054 It's only the novel sounds that he's afraid of, because they 841 00:50:57,054 --> 00:50:57,970 could mean a predator. 842 00:51:00,530 --> 00:51:05,942 Now what he's doing when he freezes or runs 843 00:51:05,942 --> 00:51:07,620 is he's looking for predators. 844 00:51:07,620 --> 00:51:11,180 In fact, when he comes back from his tunnel, 845 00:51:11,180 --> 00:51:13,190 his head pops out of the tunnel. 846 00:51:13,190 --> 00:51:14,980 He doesn't just run out. 847 00:51:14,980 --> 00:51:20,100 He spends a lot of time scanning for predators on the horizon 848 00:51:20,100 --> 00:51:20,745 and above. 849 00:51:23,900 --> 00:51:28,960 So that's selective stimulus habituation. 850 00:51:32,090 --> 00:51:33,405 And it depends on novelty. 851 00:51:36,480 --> 00:51:38,420 So the stimulus becomes less and less 852 00:51:38,420 --> 00:51:40,110 effective with repetitions. 853 00:51:44,580 --> 00:51:47,100 And it's affected by the modality. 854 00:51:47,100 --> 00:51:48,920 We'll come back to this next time. 855 00:51:48,920 --> 00:51:53,520 I'll start by talking about what Lorenz calls tool activities-- 856 00:51:53,520 --> 00:51:56,530 the multi-purpose action patterns.