WEBVTT - Split Brain, Part 1 0:00:00.040 --> 0:00:02.240 The powers of Hide seemed to have grown with the 0:00:02.279 --> 0:00:05.600 sickliness of Jackyal, and certainly the hate that now divided 0:00:05.640 --> 0:00:08.840 them was equal on each side. With Jekyll, it was 0:00:08.880 --> 0:00:11.760 a thing of vital instinct. He had now seen the 0:00:11.800 --> 0:00:14.560 full deformity of that creature that shared with him some 0:00:14.760 --> 0:00:18.119 of the phenomena of consciousness, and was co heir with 0:00:18.239 --> 0:00:21.599 him to death and beyond these links of community, which 0:00:21.640 --> 0:00:25.080 in themselves made the most poignant part of his distress. 0:00:25.079 --> 0:00:28.360 He thought of Hide for all his energy of life, 0:00:28.640 --> 0:00:32.680 as of something not only hellish but inorganic. This was 0:00:32.760 --> 0:00:35.760 the shocking thing that the slime of the pit seemed 0:00:35.760 --> 0:00:39.640 to utter, cries and voices, that the amorphous dust gesticulated 0:00:39.680 --> 0:00:43.000 and sinned, that what was dead and had no shape 0:00:43.040 --> 0:00:50.400 should usurp the offices of life. Welcome to stuff to 0:00:50.440 --> 0:00:59.280 Blow your mind from How Stuff Works dot Com. Hey 0:00:59.360 --> 0:01:01.200 you welcome to up to blow your mind. My name 0:01:01.240 --> 0:01:03.920 is Robert Lamb and I'm Joe McCormick and Robert. Why 0:01:03.960 --> 0:01:07.080 are you reading Robert Louis Stevenson at us Oh, Because 0:01:07.080 --> 0:01:09.360 that's from the Strange Case of Dr Jackel and Mr 0:01:09.440 --> 0:01:13.280 Hyde from eighteen eighty six, and it concerns the idea 0:01:13.360 --> 0:01:17.759 of there being two entities within the human skull, two 0:01:17.880 --> 0:01:21.399 entities within the mind, indeed two minds within the brain. 0:01:21.800 --> 0:01:23.679 And I think this is an interesting place to start 0:01:23.720 --> 0:01:27.640 because while it presents a very erroneous vision of the 0:01:27.720 --> 0:01:33.000 lateralization of human brain function, it also, uh, it gets 0:01:33.000 --> 0:01:34.959 some of the same like hair standing up on the 0:01:35.000 --> 0:01:37.520 back of the neck, that the actual research we're gonna 0:01:37.520 --> 0:01:39.880 be talking about today does, at least for me. Oh yeah, 0:01:39.920 --> 0:01:42.440 I mean, Robert Louis Stevenson was a fabulous writer and 0:01:42.440 --> 0:01:44.400 he's he's one of those authors that you can read 0:01:44.400 --> 0:01:46.640 today and it holds up so well. Did they ever 0:01:46.680 --> 0:01:49.080 make a good Jackal and Hyde movie. It's been a 0:01:49.200 --> 0:01:51.080 very long time since I've saw it, but there was 0:01:51.080 --> 0:01:53.480 an adaptation. It may have been a TV adaptation with 0:01:53.520 --> 0:01:57.880 Michael Caine Michael Kine. Yeah, And I remember really loving 0:01:57.920 --> 0:02:00.680 that and being quite disturbed by it as a child. Now, 0:02:00.720 --> 0:02:03.360 I was thinking there had to be a Jekyl and 0:02:03.440 --> 0:02:06.080 Hyde with Tim Curry as Jackal and Hyde. But I 0:02:06.120 --> 0:02:08.840 think maybe I'm confusing that with the Muppet Treasure Island, 0:02:08.880 --> 0:02:11.440 where he's You're thinking of the Muppet Jacky and High 0:02:11.600 --> 0:02:15.680 he's long John silver Man, that scene where he tramples 0:02:15.760 --> 0:02:20.160 Kermit to death is brutal. Well, yeah, so so we 0:02:20.200 --> 0:02:22.400 are we are beginning with kind of an erroneous model. 0:02:22.400 --> 0:02:25.120 But but I think helpful and because it is often 0:02:25.120 --> 0:02:28.240 easy to think of the brain as the thing itself, right, 0:02:28.760 --> 0:02:31.359 we fall into this center, our mode of of of 0:02:31.440 --> 0:02:34.399 of you know, the thinking of the brain body relationship 0:02:34.440 --> 0:02:36.720 as being a rider and its horse, when instead it 0:02:36.840 --> 0:02:39.519 is more this idea of a centaur, this this this 0:02:39.639 --> 0:02:43.119 one single entity, um, you know, and honestly, we see 0:02:43.120 --> 0:02:46.680 this reflected in so many real and fictional scenarios. Uh. 0:02:46.960 --> 0:02:50.000 Take for instance, the late physicist Stephen Hawking a brilliant 0:02:50.000 --> 0:02:53.359 brain within a body that was gradually paralyzed by motor 0:02:53.440 --> 0:02:56.679 neuron disease. Or just look to our dreams in which 0:02:56.720 --> 0:02:58.880 the inner world of the brain runs wild while the 0:02:58.880 --> 0:03:01.320 body goes un lockdown own. Uh you know, think of 0:03:01.360 --> 0:03:04.880 our imaginings, our inner thoughts versus our outer smile. And 0:03:04.919 --> 0:03:07.799 then there are all those disembodied brains and science fiction 0:03:07.960 --> 0:03:11.840 right from Crying and his robot body and teenaging Ninja 0:03:11.880 --> 0:03:15.120 Turtles to the Brain that Wouldn't Die Cane and RoboCop 0:03:15.160 --> 0:03:16.640 to one of the best I know that's one of 0:03:16.840 --> 0:03:19.880 one of your favorites as well, greatest of all time lovecrafts, 0:03:19.919 --> 0:03:22.600 The Whisper and Darkness, and so many Doctor Who characters, 0:03:22.880 --> 0:03:26.200 especially the Daleks brain guy from MST three Ky. We 0:03:26.240 --> 0:03:28.720 just keep keep coming up with these these visions of 0:03:28.760 --> 0:03:32.480 the brain as the just sort of the central human 0:03:32.480 --> 0:03:34.880 thought experience. You know, I never thought of this until now, 0:03:34.920 --> 0:03:37.760 but actually the brain guy from Mystery Science Theater is 0:03:37.800 --> 0:03:40.720 kind of a great illustration of Daniel Dennett's short story 0:03:40.720 --> 0:03:43.320 thought Experiment where am I I wonder if there was 0:03:43.360 --> 0:03:46.080 any connection there. Someone have to have to have to 0:03:46.120 --> 0:03:48.600 reach out to the the MST guys on that, you know, 0:03:48.640 --> 0:03:50.640 there are those like plot lines where his brain gets 0:03:51.120 --> 0:03:56.240 separated from him and somewhere else. Um. Of course, we 0:03:56.320 --> 0:03:58.520 know that things are not this simple. No brain is 0:03:58.560 --> 0:04:01.400 an island. It's affected by a host of outside influences, 0:04:01.440 --> 0:04:04.720 including all sorts of environmental nervous stimuli. And we're learning 0:04:04.760 --> 0:04:07.680 more and more about the role of our microbiome and 0:04:07.760 --> 0:04:12.080 various parasites in human cognition. But even if we're to 0:04:12.360 --> 0:04:14.320 just strip away all of that, if we're actually to 0:04:14.400 --> 0:04:18.239 become a brain and a tank, you know, Kane's brain 0:04:18.320 --> 0:04:20.680 in RoboCop two or or any of these sci fi 0:04:20.839 --> 0:04:23.480 visions take out all that external stuff, just the brain. 0:04:23.600 --> 0:04:26.240 We still have to contend with the fact that the brain, 0:04:26.839 --> 0:04:29.800 like a government, is composed of different houses. The brain 0:04:29.880 --> 0:04:35.479 consists of two cerebral hemispheres connected by the corpus colossum uh, 0:04:35.640 --> 0:04:39.159 each each hemisphere with many different modules, all of these 0:04:39.200 --> 0:04:43.040 acting in concert with each other, all of it interconnected. Yeah. 0:04:43.080 --> 0:04:46.000 One comparison I've seen in some of the neuroscience research 0:04:46.080 --> 0:04:48.560 we're looking at today is that the brain is often 0:04:48.600 --> 0:04:52.400 described as a computer, you know, or by the metaphor 0:04:52.440 --> 0:04:54.280 of a computer. You know. It's not that it is 0:04:54.320 --> 0:04:57.240 a computer, but that Yeah, there's the analogy that the 0:04:57.279 --> 0:04:59.640 brain is like a computer in the different parts of 0:04:59.640 --> 0:05:02.400 the brain and are maybe sort of like different programs 0:05:02.440 --> 0:05:06.240 that run on that computer. But at least one researcher 0:05:06.360 --> 0:05:08.680 we were reading I said, maybe it's more accurate to 0:05:08.839 --> 0:05:12.360 think of the brain not as a computer running different software, 0:05:12.400 --> 0:05:16.400 but as a vast network of computers that are each 0:05:16.560 --> 0:05:20.600 capable of operating independently, but most of the time operate 0:05:20.760 --> 0:05:23.719 in in tandem. It's right. This is an example where 0:05:24.120 --> 0:05:26.520 if you don't really have much of an understanding of 0:05:26.560 --> 0:05:29.680 how computer works, the the the idea of thinking of 0:05:29.720 --> 0:05:33.920 the human mind as a computer as technology is is 0:05:33.960 --> 0:05:36.680 more harmful. But if you have, if you have a 0:05:36.720 --> 0:05:39.279 better understanding of how computer actually works, it could perhaps 0:05:39.320 --> 0:05:43.560 be a more helpful metaphor cuttle cats cuttle fish to 0:05:43.640 --> 0:05:48.360 the second oil age and kingdom with or of darkness. 0:05:48.360 --> 0:05:53.160 I don't dispute the eurostata, but if he's down here, 0:05:52.480 --> 0:05:57.440 we know not blood but darkness, the earth's black riches. 0:05:59.160 --> 0:06:04.640 No I could taste it on my lips. Today, I 0:06:04.720 --> 0:06:09.480 want to talk to you about the science of transgenesis 0:06:13.839 --> 0:06:18.760 tens genesis dot show now I wanted to to I 0:06:18.760 --> 0:06:20.479 think it would be helpful to just go ahead and 0:06:20.520 --> 0:06:24.599 consider one particular question right up top now. And we've 0:06:24.600 --> 0:06:28.679 certainly received questions like this following episodes in which brain 0:06:28.760 --> 0:06:33.160 hemispheres are discussed, such as our discussions on the bicameral 0:06:33.160 --> 0:06:36.720 mind hypothesis or the alphabet in the Goddess. Because there's 0:06:36.760 --> 0:06:39.960 this kind of pop understanding, right that each side of 0:06:39.960 --> 0:06:43.520 our brain controlled certain aspects of being, and that certain 0:06:43.520 --> 0:06:46.560 individuals have certain leanings that you know you have, right 0:06:46.560 --> 0:06:48.880 brain people left brain people, and that when that we 0:06:48.960 --> 0:06:53.279 can reconnect with our less favored hemisphere. Now, there certainly 0:06:53.320 --> 0:06:56.400 are some pieces of evidence that we're gonna look at 0:06:56.480 --> 0:07:00.479 in this episode that certain functions of human life are 0:07:00.920 --> 0:07:03.960 strongly lateralized in one half of the brain or the other, 0:07:04.240 --> 0:07:07.479 but they're not necessarily these functions or personality traits that 0:07:07.520 --> 0:07:12.280 are understood in popular consciousness like logic and creativity, right 0:07:12.360 --> 0:07:14.320 like taking or that you're gonna take some sort of 0:07:14.360 --> 0:07:16.040 a quiz online and find out if you're a right 0:07:16.120 --> 0:07:18.800 or lefty in terms of your brain. Now, a lot 0:07:18.840 --> 0:07:22.480 of these ideas apparently were popularized by nineteen seventy nine 0:07:22.560 --> 0:07:24.880 book title Drawing on the Right Side of the Brain 0:07:25.000 --> 0:07:29.240 by Betty Edwards. Uh, and the downstream myth that kind 0:07:29.240 --> 0:07:31.720 of uh, you know, took over a popular culture for 0:07:31.720 --> 0:07:33.800 a little bit. There is that, yeah, you had left 0:07:33.880 --> 0:07:36.880 side logic, right side creativity. And even in people who 0:07:36.960 --> 0:07:40.280 know better people, we still talk like this. I've noticed 0:07:40.320 --> 0:07:43.280 that I use this metaphor even though I know it's wrong, 0:07:43.680 --> 0:07:46.200 Like I will sometimes think of people as being very 0:07:46.280 --> 0:07:49.040 right brained or very left brained, even though that I 0:07:49.120 --> 0:07:52.800 know that that I've read before about how that's not correct. Well, likewise, 0:07:52.800 --> 0:07:55.560 if I hear it mentioned saying a yoga class, I'm 0:07:55.600 --> 0:07:57.320 gonna be less inclined. I'm not going to be the 0:07:57.400 --> 0:07:59.400 jerk in the yoga class that like perks up and 0:07:59.400 --> 0:08:02.600 says act l A, there's some interesting you know, I'm 0:08:02.640 --> 0:08:05.720 I'm gonna set back and enjoy the class because because 0:08:05.720 --> 0:08:08.160 it's one of those things that can can feel true. Right. 0:08:08.840 --> 0:08:11.840 But the idea goes back further than this particular book here. 0:08:11.920 --> 0:08:13.520 I mean, it goes back to some of the earlier 0:08:13.560 --> 0:08:18.119 discoveries that we're going to discuss here about hemispheric division. UM. 0:08:18.440 --> 0:08:22.480 You know, the ideas of neurologist Paul Broca who lived 0:08:22.480 --> 0:08:29.280 eighteen four through eighty French neurologist or Carl Vernica who 0:08:29.280 --> 0:08:32.079 lived who lived eighteen forty eight through nineteen o five, 0:08:32.160 --> 0:08:35.600 a German. They studied patients who had communication troubles due 0:08:35.640 --> 0:08:39.640 to brain injury UM, such as you know, left temporal 0:08:39.720 --> 0:08:43.079 lobe injuries, and they figured that this was the language center. 0:08:43.160 --> 0:08:46.720 Thus language was left hemisphere focus. And this is one 0:08:46.720 --> 0:08:49.880 thing that actually has been more born out by good 0:08:49.920 --> 0:08:52.800 research in in the history of neuroscience, is that one 0:08:52.880 --> 0:08:55.960 thing it's very clear the left hemisphere of the brain does, 0:08:56.400 --> 0:08:59.760 is it is dominant in language function. It's not that 0:08:59.800 --> 0:09:02.360 the right brain can't do any language, but it can't 0:09:02.400 --> 0:09:04.520 do a whole lot of language certainly can't do what 0:09:04.559 --> 0:09:08.040 the left hemisphere can do. Right Uh now we we 0:09:08.240 --> 0:09:11.480 kicked off the episode with reading from Robert Louis Stevenson 0:09:11.679 --> 0:09:15.720 against Scottish author He lived eighteen fifty eight and according 0:09:15.720 --> 0:09:18.960 to neuroscientist Elizabeth Waters, who's put together some you know, 0:09:19.200 --> 0:09:23.079 wonderful ted talks and ted ed videos about this, uh this, this, 0:09:23.280 --> 0:09:26.480 uh this topic, she points out that Robert Lewis Stevenson, 0:09:26.760 --> 0:09:29.520 in his book Strange Case of Dr Checkl and Mr Hyde, 0:09:29.520 --> 0:09:33.280 presented the notion of a logical left hemisphere that is 0:09:33.320 --> 0:09:36.080 in combat in you know, in in in in this 0:09:36.240 --> 0:09:40.199 uh this struggle with an emotional right hemisphere, and uh 0:09:40.200 --> 0:09:43.440 it's It's also worth noting that Robert Lewis Stevenson was 0:09:43.440 --> 0:09:46.800 also inspired by two popular French cases of individuals who 0:09:46.800 --> 0:09:50.320 exhibited dual personalities, uh their name. They were credited as 0:09:50.360 --> 0:09:55.319 being uh Felida X and Sergeant Fay. And these were 0:09:55.320 --> 0:09:57.960 apparently cases that were really you know, well covered in 0:09:58.000 --> 0:09:59.920 French and British press at the time. You know, it's 0:10:00.040 --> 0:10:04.560 kind of popular science influencing, uh, popular science fiction. Do 0:10:04.600 --> 0:10:07.160 you have any sense of whether what was presented to 0:10:07.200 --> 0:10:10.640 the public about these cases was largely accurate or was compleating. 0:10:10.760 --> 0:10:12.120 I don't, but I'd love to go back and look 0:10:12.120 --> 0:10:13.720 at it, because you know, this is a case where 0:10:13.760 --> 0:10:16.640 you can the science influences the science fiction, and the 0:10:16.679 --> 0:10:20.880 science fiction influences, uh to a certain extent, how the 0:10:20.880 --> 0:10:25.200 public thinks about a given topic. Now, other another influence 0:10:25.240 --> 0:10:27.440 on Robert Louis Stevenson. Apparently he had a just a 0:10:27.520 --> 0:10:30.960 terribly high fever, uh at one point during which he 0:10:31.000 --> 0:10:35.120 claimed to have experienced a split into which he experienced 0:10:35.520 --> 0:10:40.600 quote myself and quote that other fellow. Yeah, so this 0:10:40.679 --> 0:10:42.600 apparently had a big influence on him. An according to 0:10:42.600 --> 0:10:46.600 biograph for Claire Harmon, author of Myself and the Other Fellow, 0:10:46.960 --> 0:10:50.000 duality and the idea of the double self turn up 0:10:50.000 --> 0:10:53.560 again and again in Robert Louis Stevenson's work. Well, maybe 0:10:53.600 --> 0:10:55.480 I'm over interpreting here, and this could be just kind 0:10:55.480 --> 0:10:58.600 of a mundane parallel, but I mean I see stuff 0:10:58.640 --> 0:11:00.760 like that even in Treasury, and you know, his Space 0:11:00.800 --> 0:11:03.839 Adventure where long John Silver is at the same time 0:11:03.960 --> 0:11:07.440 a a patient and sort of good father figure and 0:11:07.520 --> 0:11:10.480 also an evil pirate. Yeah. Yeah, this is the the 0:11:10.640 --> 0:11:12.199 argument here is, Yeah, that this is the type of 0:11:12.280 --> 0:11:15.040 duality that that he was obsessed with and and so 0:11:15.120 --> 0:11:16.719 much of it, so many of his works, I mean 0:11:16.840 --> 0:11:19.800 essentially had a fever induced psychedelic experience and then this 0:11:19.920 --> 0:11:22.439 lining up with various elements of his of his life. 0:11:22.760 --> 0:11:25.640 I mean, that is the meat he chewed upon. But 0:11:25.760 --> 0:11:29.000 of course, this popular understanding of the left right division. 0:11:29.080 --> 0:11:32.040 You know that that like the side ruled by passion 0:11:32.120 --> 0:11:34.400 and the right brain and the side ruled by logic 0:11:34.440 --> 0:11:37.680 and reason and the left brain. That's not exactly right, right. 0:11:37.880 --> 0:11:40.920 You know, as we'll explore, doctors actually looked to patients 0:11:40.960 --> 0:11:44.520 with missing brain hemispheres or separated hemispheres and is appealing 0:11:44.520 --> 0:11:47.720 as this notion, maybe it didn't really hold up. I mean, 0:11:47.720 --> 0:11:51.199 they were all still logical and creative beings. You didn't 0:11:51.240 --> 0:11:53.440 just end up with us, you know, as a Spock 0:11:54.000 --> 0:11:56.200 or whatever the opposite of Spock would be in the 0:11:56.240 --> 0:11:59.040 Star Trek universe. To be clear, though, Yeah, the brain 0:11:59.280 --> 0:12:03.440 is divided into two hemispheres in internal regions like the striatum, 0:12:03.559 --> 0:12:07.360 the hypothalamus, the thalamus, and the brain stem. They're also 0:12:07.520 --> 0:12:11.319 organized with left and right sides as well, despite appearing 0:12:11.360 --> 0:12:13.319 to be continuous when you when you sort of look 0:12:13.320 --> 0:12:15.400 at illustrations of them. Yeah, and for the rest of 0:12:16.040 --> 0:12:17.760 this episode, in fact, this is gonna be the first 0:12:17.760 --> 0:12:19.880 of two episodes we're going to be looking at ways 0:12:19.920 --> 0:12:23.880 that despite this, uh, this like emotional versus logical split 0:12:24.000 --> 0:12:27.640 being wrong, there are very interesting ways that the brain 0:12:27.679 --> 0:12:31.480 hemispheres are different and do different things. In fact, well, 0:12:31.600 --> 0:12:33.800 we can start with the mundane ones I guess, right, 0:12:33.840 --> 0:12:38.080 like mundane motor control differences. Exactly. We can look to 0:12:38.200 --> 0:12:41.120 the two two arms and legs. For instance, the right 0:12:41.160 --> 0:12:43.880 hemisphere of the brain controls the left arm and leg, 0:12:44.240 --> 0:12:47.040 the left hemisphere controls the right arm and leg. Now 0:12:47.040 --> 0:12:50.439 I have read that in a way like both hemispheres 0:12:50.559 --> 0:12:54.480 can in some way to some degree control both arms. 0:12:54.920 --> 0:12:57.280 But that when it gets done to like fine motor 0:12:57.320 --> 0:13:00.040 control of like controlling the actions of the hand and 0:13:00.720 --> 0:13:04.080 especially that's where he gets really lateralized and like it's 0:13:04.080 --> 0:13:06.640 really going to be your right brain that's controlling what 0:13:06.760 --> 0:13:10.480 your left hand does with its fingers. Now, a more 0:13:10.559 --> 0:13:14.839 complex example is, but one it's extremely important is each 0:13:14.960 --> 0:13:18.600 eye has a left and right visual field, with the 0:13:18.720 --> 0:13:21.320 left visual field sent to the right hemisphere and the 0:13:21.480 --> 0:13:24.280 right field sent to the left hemisphere. Now this can 0:13:24.320 --> 0:13:26.920 also be misunderstood because I've seen it represented in the 0:13:26.960 --> 0:13:30.520 press in places that where like the left eye goes 0:13:30.600 --> 0:13:32.800 to the right hemisphere and the right eye goes to 0:13:32.840 --> 0:13:35.320 the left hemisphere. And that's not quite right either, because 0:13:35.720 --> 0:13:38.839 both hemispheres can get some information from both eyes. But 0:13:38.920 --> 0:13:41.959 it has to do with the side of the visual 0:13:42.120 --> 0:13:45.160 field that you're talking about. So like stuff that you 0:13:45.240 --> 0:13:48.839 perceive over to the left part of what you're looking 0:13:48.880 --> 0:13:52.040 at that goes to the right hemisphere, and stuff you 0:13:52.200 --> 0:13:55.160 perceive over in the right area of what you're looking 0:13:55.200 --> 0:13:57.640 at to the right of your center of vision that 0:13:57.720 --> 0:14:00.480 goes to the left hemisphere. And then our visual experience 0:14:00.480 --> 0:14:03.840 of reality it comes together from these two feeds. Movement 0:14:03.880 --> 0:14:09.480 and vision depend then on this uni hemispheric relationship. Now, 0:14:09.480 --> 0:14:11.920 why do our brains work this way? Yeah? Why the crossover? 0:14:11.920 --> 0:14:13.760 Why don't we just go straight up parallel? It's one 0:14:13.760 --> 0:14:16.920 of those things about the human vice seems needlessly complicated, right, um, 0:14:17.720 --> 0:14:20.400 And the thing is we're not entirely sure. One theory 0:14:20.520 --> 0:14:23.520 that has been discussed is that animals developed more as 0:14:23.680 --> 0:14:26.480 as animals developed more advanced nervous systems, there was an 0:14:26.480 --> 0:14:29.760 advantage in escaping to the right if something came at 0:14:29.800 --> 0:14:32.680 you from the left. So these are examples where we 0:14:32.680 --> 0:14:36.040 can actually look to specific hemispheres and say here, here, 0:14:36.040 --> 0:14:38.400 here's where they are most active. But we can't easily 0:14:38.400 --> 0:14:41.240 extend this idea to other aspects of cognition, and certainly 0:14:41.240 --> 0:14:44.360 not to the overall human experience or things like pure 0:14:44.400 --> 0:14:47.680 logical thinking or creativity. No, not that, But there are 0:14:47.760 --> 0:14:51.880 some cognitive functions that do appear to be pretty strongly 0:14:51.960 --> 0:14:54.600 lateralized in one way or another, And one of them, 0:14:54.640 --> 0:14:57.960 obviously is language. We mentioned this, Yeah, that's localized to 0:14:58.000 --> 0:15:01.640 the left, especially complex language and the power of speech. 0:15:02.080 --> 0:15:04.720 There's some research indicating that like the right brain might 0:15:04.720 --> 0:15:08.160 be able to have a sort of simple lexicon or 0:15:08.280 --> 0:15:11.800 understand very simple bits of language, but if you want 0:15:11.840 --> 0:15:15.720 to generate a sentence like speak one out loud, or 0:15:15.960 --> 0:15:19.720 understand complex instructions in language, this is usually going to 0:15:19.800 --> 0:15:22.600 be dominated by processes in the left hemisphere. Oh and 0:15:22.640 --> 0:15:25.200 we should also say that everything we say about hemispheres 0:15:25.680 --> 0:15:28.680 in this episode is going to be for most cases. 0:15:28.760 --> 0:15:31.680 There there cases where this is reversed, where people have 0:15:31.840 --> 0:15:34.720 like the switching of which hemisphere is dominant, but we're 0:15:34.720 --> 0:15:38.600 talking about the majority of cases here right now. Meanwhile, attention, 0:15:38.960 --> 0:15:41.720 we see that more localized to the right hemisphere. Yeah, 0:15:41.760 --> 0:15:45.400 and this would be especially things like visual and spatial reasoning, 0:15:45.600 --> 0:15:48.560 Like the right hemisphere is going to be very important 0:15:48.600 --> 0:15:51.640 if you need to imagine a map in order to 0:15:51.760 --> 0:15:57.720 give directions. So, brain activity unbalancing, where one one side 0:15:57.760 --> 0:16:01.080 is more active in a given task than another. This 0:16:01.080 --> 0:16:04.080 this occurs based on which system is being employed in 0:16:04.120 --> 0:16:08.000 a given task, rather than anything about an individual or 0:16:08.000 --> 0:16:10.600 their background. Of This is all, of course, assuming a 0:16:10.640 --> 0:16:14.360 healthy brain. Obviously, if one side of your brain is missing, 0:16:14.440 --> 0:16:17.920 there's going to be more activity beside it's there. Now, 0:16:18.280 --> 0:16:21.880 no evidence suggests that individual individuals have truly dominant sides 0:16:21.920 --> 0:16:23.800 of the brain when it comes to their you know, 0:16:23.800 --> 0:16:27.360 their personality makeup right, you're not like creative right brained 0:16:27.440 --> 0:16:30.880 or logical left brain right and likewise that the logic 0:16:31.000 --> 0:16:35.440 and creativity split idea. Uh, you know again, you'll have 0:16:35.480 --> 0:16:39.000 individuals that are certainly more logical, perhaps or more creative. 0:16:39.320 --> 0:16:43.000 But as as neuroscientist Elizabeth Waters has pointed out among 0:16:43.200 --> 0:16:47.600 many others, logic and creativity are not these two distinct notions, 0:16:47.680 --> 0:16:52.160 you know, they're deeply interlinks, Like being good at logic 0:16:52.320 --> 0:16:56.400 is in many cases being a certain type of creative. Yeah. 0:16:56.440 --> 0:16:59.920 I mean, what you might dismiss is just a really 0:17:00.000 --> 0:17:03.400 logical exercise, like safe solving a complex math problem that 0:17:03.480 --> 0:17:07.520 may well require that will require some creative thinking. Likewise, 0:17:07.520 --> 0:17:10.960 a creative endeavor like say, writing a poem, finishing a novel, 0:17:11.359 --> 0:17:14.320 coming up with a cool joke, whatever, you know, those 0:17:14.359 --> 0:17:17.720 are gonna gonna be activities that also involve logic. In fact, 0:17:17.760 --> 0:17:19.360 some of what we're going to discuss in this pair 0:17:19.400 --> 0:17:22.359 of episodes in in the neuroscience research turns this whole 0:17:22.359 --> 0:17:25.320 thing on its head in a way, because the left 0:17:25.359 --> 0:17:28.520 part of the brain that's more dominant in exercises involving 0:17:28.560 --> 0:17:32.280 speech and language often tends to be the more creative 0:17:32.359 --> 0:17:35.280 one in explaining behaviors. Right it's the one that tends 0:17:35.320 --> 0:17:39.240 to interpret and come up with explanations for things as 0:17:39.280 --> 0:17:41.760 will as we'll talk about later on, which is a 0:17:41.800 --> 0:17:45.639 creative exercise. Whereas the right brain tends to more often 0:17:45.680 --> 0:17:49.840 be the part of the brain that records experiences accurately 0:17:49.960 --> 0:17:54.640 without creating explanations for them exactly. And but but certainly, 0:17:54.800 --> 0:17:57.160 if I'm gonna you know, drive home anything, we want 0:17:57.200 --> 0:18:01.399 to point out that that the creativity law, anything that 0:18:01.480 --> 0:18:05.919 employs these these two loose idea, you know, buckets of 0:18:05.920 --> 0:18:08.280 of of of cognition. You know, these are going to 0:18:08.320 --> 0:18:11.359 be products of whole brain cognition. Like our our the 0:18:11.440 --> 0:18:14.600 brain is all these areas of the brain are working together, 0:18:15.080 --> 0:18:19.040 uh to create this effect. Now, ultimately in this episode, 0:18:19.080 --> 0:18:22.359 we're going to be asking what happens when you cut 0:18:22.400 --> 0:18:26.119 those two hemispheres of the brain apart. Yes, but I 0:18:26.160 --> 0:18:30.800 guess we'll have to get to that after a break. 0:18:31.320 --> 0:18:33.960 All Right, we're back now. Before we get to the 0:18:34.000 --> 0:18:36.600 idea of severing the brain hemispheres, we should probably talk 0:18:36.600 --> 0:18:39.920 about a little more about Broca and Vernica. Yeah, these 0:18:39.960 --> 0:18:43.240 are just two really key individuals to this whole discussion 0:18:43.240 --> 0:18:45.760 and even just the idea of understanding the human brain. 0:18:46.280 --> 0:18:50.760 Um So Paul Broca will start with him again eighteen 0:18:50.840 --> 0:18:54.760 eighty He was a French surgeon, neurologist and anthropologists and 0:18:54.840 --> 0:18:57.200 he is also for anyone who hasn't read the book 0:18:57.280 --> 0:18:59.600 but has seen the title. He is the namesake for 0:18:59.680 --> 0:19:03.960 Karl Sagan's book Broke His Brain. Sagan describes at one 0:19:03.960 --> 0:19:07.880 point point holding a jar containing the noted scientist's brain. Wait, 0:19:08.080 --> 0:19:12.000 like imagining doing this literally doing literally doing it? Okay, 0:19:12.119 --> 0:19:15.040 holding holding the jar that contains his brain and thinking 0:19:15.119 --> 0:19:17.399 about like what you know, talking he talks a bit 0:19:17.400 --> 0:19:20.840 about Broca and and and you know, his his work, 0:19:20.920 --> 0:19:25.040 his personality, but also just sort of meditates on what 0:19:25.080 --> 0:19:28.320 you're doing when you when you hold this brain in 0:19:28.359 --> 0:19:31.880 your hands. I want to imagine that, having not read 0:19:31.920 --> 0:19:34.240 this book, it is in fact just like a caper 0:19:34.320 --> 0:19:37.400 story with Broker's brain as the MacGuffin and it gets 0:19:37.400 --> 0:19:40.000 traded around and their car chases. Sagan is trying to 0:19:40.000 --> 0:19:43.120 get it back from the KGB spies. Uh no, not quite, 0:19:43.200 --> 0:19:46.400 but Dante Skull shows up as well. O nice So 0:19:46.840 --> 0:19:50.840 brokea though he made important contributions to our understanding of cancer, 0:19:51.040 --> 0:19:55.200 the treatment of aneurysms and aphasia and his Sagan pointed out, 0:19:55.359 --> 0:19:57.639 Broca was also quite concerned with the medical care of 0:19:57.680 --> 0:19:59.639 the poor. He was you know, he was he was 0:19:59.680 --> 0:20:02.760 a free thinker. He was a strong Darwin supporter, and 0:20:03.280 --> 0:20:05.840 above just about everything, he was the founder of modern 0:20:05.880 --> 0:20:10.520 brain surgery, and Broco was influential in identifying regions of 0:20:10.560 --> 0:20:14.520 the brain as being especially responsible for certain cognitive functions. Right. Yeah, 0:20:14.600 --> 0:20:18.600 he investigated the rheinan cephalon the smell brain. But his 0:20:18.800 --> 0:20:22.240 name actually goes to a small region in the left 0:20:22.280 --> 0:20:27.199 frontal lobe of the cerebral cortex what we call Broca's area. Uh. 0:20:27.320 --> 0:20:31.200 This is left hemisphere, third frontal convolution. To be specific, 0:20:31.640 --> 0:20:35.240 this is the area where articulate speech is largely localized 0:20:35.240 --> 0:20:38.480 and controlled. And his Segan pointed out, given the importance 0:20:38.480 --> 0:20:42.199 of language and articulate speech and human evolution, this portion 0:20:42.240 --> 0:20:45.680 of the human brain may be considered, in Sagan's words, 0:20:45.720 --> 0:20:48.960 the seat of our humanity and some respects. And it's 0:20:48.960 --> 0:20:52.000 also something anatomists have looked for in the remains of 0:20:52.040 --> 0:20:57.800 our hominid ancestors, such as Homo habilish. Columbia University anthropologist 0:20:57.880 --> 0:21:01.760 Ralph Holloway Sagan sided Uh's you know, studied and claimed 0:21:01.760 --> 0:21:04.639 to have found evidence for its development of a Broca's 0:21:04.680 --> 0:21:07.560 area some two million years ago, and this would have 0:21:07.560 --> 0:21:10.840 been around the time early tool use was beginning uh. 0:21:11.080 --> 0:21:15.879 Also South African palaeo anthropologist Philip Tobias also made this claim, 0:21:16.119 --> 0:21:20.199 though according to Susanne Kemer, Associate professor of Linguistics at 0:21:20.280 --> 0:21:23.800 Rice University, quote, these claims have been controversial. Many see 0:21:23.880 --> 0:21:27.680 no regular impressions that could be ascribed to brain structure here, 0:21:28.119 --> 0:21:31.200 and I can imagine it's probably difficult to just look 0:21:31.200 --> 0:21:34.639 at skulls and figure out what brain regions were evolved when, right, 0:21:35.440 --> 0:21:39.160 but broke as a discovery here broke a's namesake here 0:21:39.480 --> 0:21:43.480 is the first of many discoveries that illuminated hemispheric separation 0:21:43.600 --> 0:21:46.400 of function in the brain. And you know, and really 0:21:46.480 --> 0:21:49.000 driving home the idea of that specific brain functions might 0:21:49.080 --> 0:21:52.360 be isolated to specific parts of the brain. Yeah, if 0:21:52.680 --> 0:21:55.240 there's a certain part in the left hemisphere that seems 0:21:55.280 --> 0:21:58.880 especially important for language, what else could be lateralized? Right 0:21:59.320 --> 0:22:02.640 now is to throw in the Nowadays, you hear more 0:22:02.640 --> 0:22:06.920 talk of networks as opposed to regions. You know, again 0:22:06.960 --> 0:22:10.160 getting into this idea that that that that we're looking 0:22:10.200 --> 0:22:13.159 at at a network of of of different systems and 0:22:13.200 --> 0:22:16.720 not individual areas that are just doing all the heavy lifting. 0:22:17.000 --> 0:22:19.320 Your brain is less like a computer. Maybe in more 0:22:19.359 --> 0:22:23.840