The powers of Hide seemed to have grown with the sickliness of Jackyal, and certainly the hate that now divided them was equal on each side. With Jekyll, it was a thing of vital instinct. He had now seen the full deformity of that creature that shared with him some of the phenomena of consciousness, and was co heir with him to death and beyond these links of community, which in themselves made the most poignant part of his distress. He thought of Hide for all his energy of life, as of something not only hellish but inorganic. This was the shocking thing that the slime of the pit seemed to utter, cries and voices, that the amorphous dust gesticulated and sinned, that what was dead and had no shape should usurp the offices of life. Welcome to stuff to Blow your mind from How Stuff Works dot Com. Hey you welcome to up to blow your mind. My name is Robert Lamb and I'm Joe McCormick and Robert. Why are you reading Robert Louis Stevenson at us Oh, Because that's from the Strange Case of Dr Jackel and Mr Hyde from eighteen eighty six, and it concerns the idea of there being two entities within the human skull, two entities within the mind, indeed two minds within the brain. And I think this is an interesting place to start because while it presents a very erroneous vision of the lateralization of human brain function, it also, uh, it gets some of the same like hair standing up on the back of the neck, that the actual research we're gonna be talking about today does, at least for me. Oh yeah, I mean, Robert Louis Stevenson was a fabulous writer and he's he's one of those authors that you can read today and it holds up so well. Did they ever make a good Jackal and Hyde movie. It's been a very long time since I've saw it, but there was an adaptation. It may have been a TV adaptation with Michael Caine Michael Kine. Yeah, And I remember really loving that and being quite disturbed by it as a child. Now, I was thinking there had to be a Jekyl and Hyde with Tim Curry as Jackal and Hyde. But I think maybe I'm confusing that with the Muppet Treasure Island, where he's You're thinking of the Muppet Jacky and High he's long John silver Man, that scene where he tramples Kermit to death is brutal. Well, yeah, so so we are we are beginning with kind of an erroneous model. But but I think helpful and because it is often easy to think of the brain as the thing itself, right, we fall into this center, our mode of of of of you know, the thinking of the brain body relationship as being a rider and its horse, when instead it is more this idea of a centaur, this this this one single entity, um, you know, and honestly, we see this reflected in so many real and fictional scenarios. Uh. Take for instance, the late physicist Stephen Hawking a brilliant brain within a body that was gradually paralyzed by motor neuron disease. Or just look to our dreams in which the inner world of the brain runs wild while the body goes un lockdown own. Uh you know, think of our imaginings, our inner thoughts versus our outer smile. And then there are all those disembodied brains and science fiction right from Crying and his robot body and teenaging Ninja Turtles to the Brain that Wouldn't Die Cane and RoboCop to one of the best I know that's one of one of your favorites as well, greatest of all time lovecrafts, The Whisper and Darkness, and so many Doctor Who characters, especially the Daleks brain guy from MST three Ky. We just keep keep coming up with these these visions of the brain as the just sort of the central human thought experience. You know, I never thought of this until now, but actually the brain guy from Mystery Science Theater is kind of a great illustration of Daniel Dennett's short story thought Experiment where am I I wonder if there was any connection there. Someone have to have to have to reach out to the the MST guys on that, you know, there are those like plot lines where his brain gets separated from him and somewhere else. Um. Of course, we know that things are not this simple. No brain is an island. It's affected by a host of outside influences, including all sorts of environmental nervous stimuli. And we're learning more and more about the role of our microbiome and various parasites in human cognition. But even if we're to just strip away all of that, if we're actually to become a brain and a tank, you know, Kane's brain in RoboCop two or or any of these sci fi visions take out all that external stuff, just the brain. We still have to contend with the fact that the brain, like a government, is composed of different houses. The brain consists of two cerebral hemispheres connected by the corpus colossum uh, each each hemisphere with many different modules, all of these acting in concert with each other, all of it interconnected. Yeah. One comparison I've seen in some of the neuroscience research we're looking at today is that the brain is often described as a computer, you know, or by the metaphor of a computer. You know. It's not that it is a computer, but that Yeah, there's the analogy that the brain is like a computer in the different parts of the brain and are maybe sort of like different programs that run on that computer. But at least one researcher we were reading I said, maybe it's more accurate to think of the brain not as a computer running different software, but as a vast network of computers that are each capable of operating independently, but most of the time operate in in tandem. It's right. This is an example where if you don't really have much of an understanding of how computer works, the the the idea of thinking of the human mind as a computer as technology is is more harmful. But if you have, if you have a better understanding of how computer actually works, it could perhaps be a more helpful metaphor cuttle cats cuttle fish to the second oil age and kingdom with or of darkness. I don't dispute the eurostata, but if he's down here, we know not blood but darkness, the earth's black riches. No I could taste it on my lips. Today, I want to talk to you about the science of transgenesis tens genesis dot show now I wanted to to I think it would be helpful to just go ahead and consider one particular question right up top now. And we've certainly received questions like this following episodes in which brain hemispheres are discussed, such as our discussions on the bicameral mind hypothesis or the alphabet in the Goddess. Because there's this kind of pop understanding, right that each side of our brain controlled certain aspects of being, and that certain individuals have certain leanings that you know you have, right brain people left brain people, and that when that we can reconnect with our less favored hemisphere. Now, there certainly are some pieces of evidence that we're gonna look at in this episode that certain functions of human life are strongly lateralized in one half of the brain or the other, but they're not necessarily these functions or personality traits that are understood in popular consciousness like logic and creativity, right like taking or that you're gonna take some sort of a quiz online and find out if you're a right or lefty in terms of your brain. Now, a lot of these ideas apparently were popularized by nineteen seventy nine book title Drawing on the Right Side of the Brain by Betty Edwards. Uh, and the downstream myth that kind of uh, you know, took over a popular culture for a little bit. There is that, yeah, you had left side logic, right side creativity. And even in people who know better people, we still talk like this. I've noticed that I use this metaphor even though I know it's wrong, Like I will sometimes think of people as being very right brained or very left brained, even though that I know that that I've read before about how that's not correct. Well, likewise, if I hear it mentioned saying a yoga class, I'm gonna be less inclined. I'm not going to be the jerk in the yoga class that like perks up and says act l A, there's some interesting you know, I'm I'm gonna set back and enjoy the class because because it's one of those things that can can feel true. Right. But the idea goes back further than this particular book here. I mean, it goes back to some of the earlier discoveries that we're going to discuss here about hemispheric division. UM. You know, the ideas of neurologist Paul Broca who lived eighteen four through eighty French neurologist or Carl Vernica who lived who lived eighteen forty eight through nineteen o five, a German. They studied patients who had communication troubles due to brain injury UM, such as you know, left temporal lobe injuries, and they figured that this was the language center. Thus language was left hemisphere focus. And this is one thing that actually has been more born out by good research in in the history of neuroscience, is that one thing it's very clear the left hemisphere of the brain does, is it is dominant in language function. It's not that the right brain can't do any language, but it can't do a whole lot of language certainly can't do what the left hemisphere can do. Right Uh now we we kicked off the episode with reading from Robert Louis Stevenson against Scottish author He lived eighteen fifty eight and according to neuroscientist Elizabeth Waters, who's put together some you know, wonderful ted talks and ted ed videos about this, uh this, this, uh this topic, she points out that Robert Lewis Stevenson, in his book Strange Case of Dr Checkl and Mr Hyde, presented the notion of a logical left hemisphere that is in combat in you know, in in in in this uh this struggle with an emotional right hemisphere, and uh it's It's also worth noting that Robert Lewis Stevenson was also inspired by two popular French cases of individuals who exhibited dual personalities, uh their name. They were credited as being uh Felida X and Sergeant Fay. And these were apparently cases that were really you know, well covered in French and British press at the time. You know, it's kind of popular science influencing, uh, popular science fiction. Do you have any sense of whether what was presented to the public about these cases was largely accurate or was compleating. I don't, but I'd love to go back and look at it, because you know, this is a case where you can the science influences the science fiction, and the science fiction influences, uh to a certain extent, how the public thinks about a given topic. Now, other another influence on Robert Louis Stevenson. Apparently he had a just a terribly high fever, uh at one point during which he claimed to have experienced a split into which he experienced quote myself and quote that other fellow. Yeah, so this apparently had a big influence on him. An according to biograph for Claire Harmon, author of Myself and the Other Fellow, duality and the idea of the double self turn up again and again in Robert Louis Stevenson's work. Well, maybe I'm over interpreting here, and this could be just kind of a mundane parallel, but I mean I see stuff like that even in Treasury, and you know, his Space Adventure where long John Silver is at the same time a a patient and sort of good father figure and also an evil pirate. Yeah. Yeah, this is the the argument here is, Yeah, that this is the type of duality that that he was obsessed with and and so much of it, so many of his works, I mean essentially had a fever induced psychedelic experience and then this lining up with various elements of his of his life. I mean, that is the meat he chewed upon. But of course, this popular understanding of the left right division. You know that that like the side ruled by passion and the right brain and the side ruled by logic and reason and the left brain. That's not exactly right, right. You know, as we'll explore, doctors actually looked to patients with missing brain hemispheres or separated hemispheres and is appealing as this notion, maybe it didn't really hold up. I mean, they were all still logical and creative beings. You didn't just end up with us, you know, as a Spock or whatever the opposite of Spock would be in the Star Trek universe. To be clear, though, Yeah, the brain is divided into two hemispheres in internal regions like the striatum, the hypothalamus, the thalamus, and the brain stem. They're also organized with left and right sides as well, despite appearing to be continuous when you when you sort of look at illustrations of them. Yeah, and for the rest of this episode, in fact, this is gonna be the first of two episodes we're going to be looking at ways that despite this, uh, this like emotional versus logical split being wrong, there are very interesting ways that the brain hemispheres are different and do different things. In fact, well, we can start with the mundane ones I guess, right, like mundane motor control differences. Exactly. We can look to the two two arms and legs. For instance, the right hemisphere of the brain controls the left arm and leg, the left hemisphere controls the right arm and leg. Now I have read that in a way like both hemispheres can in some way to some degree control both arms. But that when it gets done to like fine motor control of like controlling the actions of the hand and especially that's where he gets really lateralized and like it's really going to be your right brain that's controlling what your left hand does with its fingers. Now, a more complex example is, but one it's extremely important is each eye has a left and right visual field, with the left visual field sent to the right hemisphere and the right field sent to the left hemisphere. Now this can also be misunderstood because I've seen it represented in the press in places that where like the left eye goes to the right hemisphere and the right eye goes to the left hemisphere. And that's not quite right either, because both hemispheres can get some information from both eyes. But it has to do with the side of the visual field that you're talking about. So like stuff that you perceive over to the left part of what you're looking at that goes to the right hemisphere, and stuff you perceive over in the right area of what you're looking at to the right of your center of vision that goes to the left hemisphere. And then our visual experience of reality it comes together from these two feeds. Movement and vision depend then on this uni hemispheric relationship. Now, why do our brains work this way? Yeah? Why the crossover? Why don't we just go straight up parallel? It's one of those things about the human vice seems needlessly complicated, right, um, And the thing is we're not entirely sure. One theory that has been discussed is that animals developed more as as animals developed more advanced nervous systems, there was an advantage in escaping to the right if something came at you from the left. So these are examples where we can actually look to specific hemispheres and say here, here, here's where they are most active. But we can't easily extend this idea to other aspects of cognition, and certainly not to the overall human experience or things like pure logical thinking or creativity. No, not that, But there are some cognitive functions that do appear to be pretty strongly lateralized in one way or another, And one of them, obviously is language. We mentioned this, Yeah, that's localized to the left, especially complex language and the power of speech. There's some research indicating that like the right brain might be able to have a sort of simple lexicon or understand very simple bits of language, but if you want to generate a sentence like speak one out loud, or understand complex instructions in language, this is usually going to be dominated by processes in the left hemisphere. Oh and we should also say that everything we say about hemispheres in this episode is going to be for most cases. There there cases where this is reversed, where people have like the switching of which hemisphere is dominant, but we're talking about the majority of cases here right now. Meanwhile, attention, we see that more localized to the right hemisphere. Yeah, and this would be especially things like visual and spatial reasoning, Like the right hemisphere is going to be very important if you need to imagine a map in order to give directions. So, brain activity unbalancing, where one one side is more active in a given task than another. This this occurs based on which system is being employed in a given task, rather than anything about an individual or their background. Of This is all, of course, assuming a healthy brain. Obviously, if one side of your brain is missing, there's going to be more activity beside it's there. Now, no evidence suggests that individual individuals have truly dominant sides of the brain when it comes to their you know, their personality makeup right, you're not like creative right brained or logical left brain right and likewise that the logic and creativity split idea. Uh, you know again, you'll have individuals that are certainly more logical, perhaps or more creative. But as as neuroscientist Elizabeth Waters has pointed out among many others, logic and creativity are not these two distinct notions, you know, they're deeply interlinks, Like being good at logic is in many cases being a certain type of creative. Yeah. I mean, what you might dismiss is just a really logical exercise, like safe solving a complex math problem that may well require that will require some creative thinking. Likewise, a creative endeavor like say, writing a poem, finishing a novel, coming up with a cool joke, whatever, you know, those are gonna gonna be activities that also involve logic. In fact, some of what we're going to discuss in this pair of episodes in in the neuroscience research turns this whole thing on its head in a way, because the left part of the brain that's more dominant in exercises involving speech and language often tends to be the more creative one in explaining behaviors. Right it's the one that tends to interpret and come up with explanations for things as will as we'll talk about later on, which is a creative exercise. Whereas the right brain tends to more often be the part of the brain that records experiences accurately without creating explanations for them exactly. And but but certainly, if I'm gonna you know, drive home anything, we want to point out that that the creativity law, anything that employs these these two loose idea, you know, buckets of of of of cognition. You know, these are going to be products of whole brain cognition. Like our our the brain is all these areas of the brain are working together, uh to create this effect. Now, ultimately in this episode, we're going to be asking what happens when you cut those two hemispheres of the brain apart. Yes, but I guess we'll have to get to that after a break. All Right, we're back now. Before we get to the idea of severing the brain hemispheres, we should probably talk about a little more about Broca and Vernica. Yeah, these are just two really key individuals to this whole discussion and even just the idea of understanding the human brain. Um So Paul Broca will start with him again eighteen eighty He was a French surgeon, neurologist and anthropologists and he is also for anyone who hasn't read the book but has seen the title. He is the namesake for Karl Sagan's book Broke His Brain. Sagan describes at one point point holding a jar containing the noted scientist's brain. Wait, like imagining doing this literally doing literally doing it? Okay, holding holding the jar that contains his brain and thinking about like what you know, talking he talks a bit about Broca and and and you know, his his work, his personality, but also just sort of meditates on what you're doing when you when you hold this brain in your hands. I want to imagine that, having not read this book, it is in fact just like a caper story with Broker's brain as the MacGuffin and it gets traded around and their car chases. Sagan is trying to get it back from the KGB spies. Uh no, not quite, but Dante Skull shows up as well. O nice So brokea though he made important contributions to our understanding of cancer, the treatment of aneurysms and aphasia and his Sagan pointed out, Broca was also quite concerned with the medical care of the poor. He was you know, he was he was a free thinker. He was a strong Darwin supporter, and above just about everything, he was the founder of modern brain surgery, and Broco was influential in identifying regions of the brain as being especially responsible for certain cognitive functions. Right. Yeah, he investigated the rheinan cephalon the smell brain. But his name actually goes to a small region in the left frontal lobe of the cerebral cortex what we call Broca's area. Uh. This is left hemisphere, third frontal convolution. To be specific, this is the area where articulate speech is largely localized and controlled. And his Segan pointed out, given the importance of language and articulate speech and human evolution, this portion of the human brain may be considered, in Sagan's words, the seat of our humanity and some respects. And it's also something anatomists have looked for in the remains of our hominid ancestors, such as Homo habilish. Columbia University anthropologist Ralph Holloway Sagan sided Uh's you know, studied and claimed to have found evidence for its development of a Broca's area some two million years ago, and this would have been around the time early tool use was beginning uh. Also South African palaeo anthropologist Philip Tobias also made this claim, though according to Susanne Kemer, Associate professor of Linguistics at Rice University, quote, these claims have been controversial. Many see no regular impressions that could be ascribed to brain structure here, and I can imagine it's probably difficult to just look at skulls and figure out what brain regions were evolved when, right, but broke as a discovery here broke a's namesake here is the first of many discoveries that illuminated hemispheric separation of function in the brain. And you know, and really driving home the idea of that specific brain functions might be isolated to specific parts of the brain. Yeah, if there's a certain part in the left hemisphere that seems especially important for language, what else could be lateralized? Right now is to throw in the Nowadays, you hear more talk of networks as opposed to regions. You know, again getting into this idea that that that that we're looking at at a network of of of different systems and not individual areas that are just doing all the heavy lifting. Your brain is less like a computer. Maybe in more like the Internet, right, but a conscious Internet. That's scary. Uh so horror movie pitch the conscious Internet. Uh yeah, and then it takes physical form via three D printers. Right, But let's also talk about about the German Carl Vernica okay live eight five a German? Yeah, Well, thus the Vernica uh he was. He has another area of the brain's name for him, the Vernica area, and he first described this area in eighteen seventy four, and it's found in the posterior third of the upper temporal convolution of the left hemisphere of the brain. It's close to the auditory cortex and seems to play a unique role in the comprehension of sound and language reception and comprehension. So the stage is set to discuss the lateralization of certain brain functions. But we mentioned earlier that this episode was really gonna end up focusing on cutting brains in half. And I know you're out there saying, when are you going to cut the brain in half? Robert, I think it's time. We've got to make the incision, that's right, And what better time to just slice the human brain in half than the nineteen sixties and seventies it's really really perfect. I mean, you could really almost it's tempting to just want to think like a left brain, right brain, old fashioned idea and have like the nineteen sixties hemisphere, in the nineteen seventies hemisphere. Right, there's just something something perfect about the post revolutionary hemisphere. Uh no, no, So we're gonna be talking about the research of neuroscientists named Roger Sperry and Michael Gazzaniga, and so actually the brain cutting started in the nineteen forties, but it was in the nineteen sixties that the research on people with severed hemispheres really got going, that's right. And they they discovered something that's that was seemingly amazing that if you split the brain, you you essentially split the person as well in a certain sense and not in another sense. And well we'll have to define that as we go on. But but but just think about it for a second. Just the the the promise that the you know, the tease of this idea that there would be one person per hemisphere of the brain, this division of the self. Getting back to this idea in a certain sense of myself and the other guy, right, yeah, oh, that's right. Uh, the Robert Louis Stevenson and h and this was work they would have eventually earned Sperry the Nobel Prize in Medicine in now. During this this these decades of research, Sperry performed experiments on cats, monkeys, and humans and focus a lot of attention on the neuron packed corpus colossum that bridges the hemispheres. This is often described as sort of like a broadband Internet cable, like an Internet backbone, fiber optic or something that connects the two hemispheres together and enables most of the exchange of information between them. Right now, with non human animals, he surgically split the brains, producing what he called a split brain, in which each side seemed to function independently of the other. And he also found that an animal with a split brain could memorize double the information. Oh I didn't read that. Yeah, that was a tidbit I ran across creepy now obviously him not being a mad scientist villain in like a serial in a comic book or something. He didn't split human brains just for experiment, that's right. Fortunately for him, there were already humans walking around with split brains because they had had because there were patients who had their corpus colossum separated uh severed as a treatment for epilepsy, and so he was able to get a number of these individuals to volunteer for his experiments. Yes, so this procedure was not done for experiments, obviously, it was done as a medical treatment, and it's known as a corpus callosodomy, and so the theory behind it is that an epileptic seizure is sort of like a storm of activity in the brain with too many neurons firing and triggering chaotic activity all throughout both hemispheres. And the idea was if you cut the corpus colosum, if you sever that broadband internet connection between the two hemispheres of the brain, you limit the ability of one of these seizures to spread from one hemisphere of the brain to the other. And in many cases where severe epilepsy could not be treated by any other means, the surgery actually was considered effective, I think, especially later versions of the surgery, less so in the forties, more so I think in like the sixties on. But this surgery generally isn't used today because we have on on the whole safer, better, less radical treatments for epilepsy. Now they're they're drugs that are pretty effective, and there are less radical surgeries you can do. And it's not known exactly how many patients ever received a corpus colisotomy and history I've seen estimates including somewhere between fifty and a hundred total patient. I read Michael Gazaniga estimated that there were over a hundred patients who had received one. Now, obviously not all of these patients volunteered for split brain neurology research, but some did. And one of the really interesting things to point out is that we'll have to keep coming back to this is that despite the radical nature of this surgical intervention, cutting the two hemispheres apart and basically preventing them from communicating with one another, most patients reported that their lives were generally normal after the surgeries. Their families did not usually report any major changes in behavior, personality, or cognitive ability. Uh. Michael Gazaniga says that generally, quote, you wouldn't know it if you were talking to such a patient. Yeah, I've read that the really the only notable results of this outside of you know, perhaps some experimental stuff that's gonna come up, was that they didn't have the seizures anymore. Yeah, like that. That was the goal, and that was the the the primary experiential difference. By and large, people underwent this procedure. It cut the two halves of their brain apart, and they seemed mostly unchanged. Now. On the other hand, I have read some anecdotes about changes certain patients faced, especially right after the surgery, during like an adaptation period. For example, a article in Nature News by David Woolman recounts the experiences of a patient named Vicky, who received a calisotomy in nineteen seventy nine to treat terrible caesar she was having. There's a story that her seizures were so bad that one time she like fell on a stove and burned her back while she was having one. Um And so she says that for the first few months after her surgery, she would stand in the grocery store trying to pick items off of the shelf, but having severe difficulty just picking up items. She says, quote, I'd reach with my right right hand for the thing I wanted, but the left would come in and they'd kind of fight almost like repelling magnets. Uh. And she would apparently have similar troubles when trying to get dressed in the morning. Woolman writes, quote, Vicky couldn't reconcile what she wanted to put on with what her hands were doing. Sometimes she ended up wearing three outfits at once. And then Vicky says, quote, I'd have to dump all the clothes on the bed to catch my breath and start again. And I've read other accounts along these lines that a few split brain patients described things like that this was one image one hand buttoning up a shirt and the other hand following immediately behind it and unbutton ing all the buttons. But these kinds of these type of descriptions are apparently not typical. Most reports indicate that people's behavior, cognitive ability, personality, all that is mostly unchanged. And even in Vicky's case, after about a year, she was mostly back to normal in terms of everyday activities. She says, she could, you know, slice vegetables, to cook and and operate machines and all that. And this is in line with other reports. Amazingly, you can completely sever the connection between the two hemispheres of the brain and most of the people you do this to function normally in day to day life afterwards, before we even get to the other strange stuff we're talking about that in itself seems crazy. Yeah, I am just always amazed when you when you hear about the things that can be done to the brain and the ways that the brain can can can bounce back and and behave just relatively normally or just or seemingly completely normally. Even in the face of catastrophic injuries. The brain can often find a way. The mind, uh finds a way. But of course, despite these reports that people are generally unchanged, what we're about to talk about is that if you and what Sparry and Kazaniga discovered is if you apply some special conditions in the lab, you can see some really strange and thrilling things at work in the split brain patients. Yeah, the crux of this comes down to the very visual processing we discussed earlier. Left visual field, right side of the brain, right visual field, left side of the brain. So in a split brain, the left side of the brain can't see the left field of vision and the right side of the brain can't see the right visual field, or generally can't generally yeah, generally speaking, and we'll we'll get into the meat of this in a minute. But but it's going to lead to split brain cats with eye patches and split brain monkeys with memorization, because, as we mentioned again, he did conduct animal experiments to see how this uh to to to reveal what was going on, and the animal experiments were very they produced very strange and fascinating results. But you always wonder, well, okay, you know, animal brains are just different than human brains, so so what happens with the actual human So I was reading an account of their very first patients, very in Gazaniga's very first split brain patient, uh in that that David Wollman article, and it was a man known as w J. A lot of times these patients are known just by a first name or by initials, you know, to protect their their identity. And apparently w J. Had served as a paratrooper in World War two and he suffered a head engine read during the fighting, a Nazi had smashed him in the head with the rifle butt, and afterwards he experienced severe seizures and was treated with the callistotomy. And so in nineteen sixty two after the surgery, Becazanega ran visual field experiments with w J. And what he found was amazing. So the standard set up of one of these experiments is that you have the patient focus on a dot in the middle of a screen and then you flash a visual stimulus in the peripheral visual field on one side or the other. And the scientists knew from previous research that this would mean stimuli shown to the left visual field, as we've been saying, would usually be perceived only by the right hemisphere, and stuff shown in the right visual field would be perceived only by the left hemisphere. But now that the hemispheres can't talk to each other anymore, what happens? So w J was shown images in his left or right visual fields and then asked to press a button and then asked to say what he saw. And when an image was shown to his left hemisphere, the part we know is primarily responsible for language, he had no problems at all. Right, you show the left brain whatever you want, a cat or you know, show him RoboCop, and then they'll press the button to indicate they saw something, and he'll say, I saw robo cop. But when they showed an image to w j's right hemisphere. What he said was that he saw nothing, but strangely enough, his left hand, which remember, of course, the left hand is connected to the right hemisphere. His left hand pressed the button when he saw the image, even though the part of his brain responsible for speech was saying out loud, I don't see anything. I mean, take take a second to think about that. Like when I first read that, I was like, oh, okay, oh, and then it hit me and I got the chills. I mean, you know, the hair stands up on the back of my neck. Literally. Yeah, Because what we're we're imagining here is we we read this and discussed it is. It's not a complete sle like separation of self, but it's like a temporary, very duality, like a flash of duality, where in the very place where we we want and expect to find some sort of continuity of self, well, it's yeah, it's like peeking in and seeing a quick glimpse of a reality that may be far more true and accurate a description of how the brain is than we would like to admit, or that normally seems true to us. Because again, we always feel unified and the split brain patients feel unified will revisit this a little more, but they don't report feeling like two different people. They just feel normal. This is just how I am. And yet from an objective outsider's point of view, it's almost as if you've got two different people taking the test at the same time. One is registering I see something with a hand and the other is saying he doesn't see anything. And yet it only seems this way under certain conditions, and only from the outside. Now, if you want to see an example of this, you can actually see one of these experiments demonstrated on film. And there's like a short documentary segment feature that I think he's up on YouTube. Still there's a patient name to Joe who is working with Kazanega and this looks like it's the nineties or so, and uh, it demonstrates a typical experiment. So you show either words or pictures to the left brain only, and Joe can name them out loud just fine. So he you know, you show him the word car or a picture of a car. He says car. Show him the word grapes or picture of grapes. He says grapes. Everything seems normal because it's all going to the left hemisphere, and that's the hemisphere that talks. You show a word to the right brain, only in this case, the word pan flashes on the far left side of the screen, and suddenly Joe is stumped. Uh just based on my read, it looks to me like he seems to be aware that he saw something, Like there's a kind of recognition that it looks to me at least like he is aware something appeared but can't say what it is. And with a little shrug and a shaking of his head, he says, I didn't see it. But then Gazzaniga has him close his eyes and draw with his left hand, which is controlled mostly by the right hemisphere, and his left hand draws a pan. Again legitimate chills, And of course, after he draws it and looks at it with both eyes, he can say, yeah, I saw a pan, But the part of his brain that talks didn't seem to know he'd seen a pan until after his left hand drew it. Another type of experiment they carried out. You take a split brain patient and simultaneously show two different pictures on the two to the two different hemispheres. You show a hammer to the left hemisphere and you show a saw to the right hemisphere and you ask what did you see. Of course, the speaking part of the brain says hammer. The person says I saw a hammer. But then when asked to draw with the left hand, the patient draws a saw and you ask them why did you do that, and the patient in this one case, the case of Joe, says I don't know. Now. In other cases like this version of this test, sometimes the speaking part of the brain will not just say I don't know, but will actually seem to make up stories about why their brain produced a certain output that the left part of the brain, the speaking part, doesn't seem to understand, and they'll just confabulate an explanation. Well, you know, they might say, well, because you know, I I was thinking about this other thing, or because you said this thing earlier, or something, well that makes sense. I mean, it's almost like a supernatural experience, right, and uh. And you know, logically you can, you know, try and find some sort of answer to it. But the answer you give, and apparently the I mean, there's no indication that these people were just consciously lying about their motivations. The answer you give, and apparently the answer you seem to believe is not true. It is just like you. You can come up with explanations for your own behavior that are completely wrong, and we can show why they're wrong, but you are not aware that they're wrong. You can be wrong about your own mind. And even without a split brain, of course, humans are are very capable of of of coming up with false reasons for whatever they believe or whatever they did. Oh, absolutely, yeah, I think that's entirely correct. And that's sort of what I what I'm thinking we might be able to extrapolate here. So one of the most amazing things to me about this kind of research is uh is that this can happen to the brain. For the most part, nobody seems to notice. It takes a lab experiment like this to draw it out. Like not the people who interact with the split brain patient. Remember that family members usually report no major changes in personality or cognitive ability. As David Wollman points out in his Nature article, the patients themselves say they quote never reported feeling anything less than whole, and in the words of Michael Gazzaniga, the severed hemispheres do not seem to notice that they have been severed. And they don't report missing each other. So this raises so many questions. First of all, why are they connected in the first place If they can be severed like this and not seem to notice that, that's an interesting thing, Like, what's the reason for this this connection? Second, how is this possible? Like, how is it possible to cut a brain in half and have it not seem to notice anything's different and not behave much different? Indeed, I mean, even in a light of everything we've talked about, it seems it seems kind of impossible. It seems seems like it's a like like like it's a magic trick, a grotesque magic trick, but a magic trick in the west. Well, maybe we should discuss a possible explanation for this after a break, thank thank Alright, we're back. Okay, So we're asking the question of how is it possible given these split brain experiments where uh, you sever the corpus closum, the two hemispheres of the brain are separated, and now functions that are dominated by one hemisphere of the brain or the other can can take place, can go on independently without the other part of the brain seeming to be aware and This even leads to stuff like the right brain being aware of a piece of information that motivates action. Like say you show the right brain a picture, the left hand, which is mainly controlled by the right brain, can draw a picture of that thing, and the left brain doesn't know why it happened, and the person speaking gives a maybe a made up explanation of where that image came from. How is this kind of thing possible? Gazanica explains it in terms of what he sort of calls interpreter theory. The interpreter is the idea of the part of your brain. Gazaniga thinks this is localized in the left hemisphere that comes up with this contrived explanation for why your your brain did something that it doesn't actually understand. Uh. And we can know in many cases that this explanation is bunk because we know where the actual stimulus for the behavior came from. It was shown to the other half of the brain that the speaking part of the brain doesn't know about. And so Gazanica's idea is that this interpreter function, its main role is to create a sense of self, to sort of weave an autobiographical narrative about the self that makes sense, even if it makes sense in a completely false way, that does not actually explain the real things that happened in the real motivations for behavior. It just comes up with post talk explanations for behaviors. And you know, this reminds me of Um, I'm sure you've read about this before. There's a metaphor that's often used. I don't know where it comes from in the first place, but sometimes the psychologist Jonathan Height invokes it of the elephant and the rider, you know, to explain the conscious and unconscious brain. So in the case of the unconscious versus the conscious brain, the conscious mind is a person is like a person riding on top of an elephant, and the elephant is the unconscious mind. And the writer thinks they are driving, steering the elephant around, but actually the elephant goes where it wants, and the writer is just writing right there along for the ride wherever the elephant goes. Nevertheless, the writer will always be able to come up with some explanation for why they meant to steer the elephant in the direction it went right, Like oh yeah, yeah, I actually wanted to go over to that mud hole and get showered in mud because because I was hot and the mud is cooling me off. Now. But in this scenario, the elephant, of course is the one calling the shots, actually right, I mean, yeah, elephants love mud holes right now. Of course, not to be a stickler here to complicate the issue, but you could have a mahoot in there. I believe the term is is mahoot the individual who who will sometimes stand to the side and using a stick to touch different parts of the elephant, um naked go where it needs to go. Oh well, we know quite well that often the unconscious mind of a person can be controlled by manipulation from the outside without the rider being aware that they're not driving. I mean, think about the ways people are are manipulated in their unconscious drives and desires by advertising, by media, by drugs, by so all of these things are the stick of the mahoot, which I'm sure has a particular name that I'm not aware of. And then the mahoot is it represents the interests of corporations and governments and uh and religious groups, etcetera. It's driving somebody's unconscious mind around while they think they're the driver. I mean, no matter you know, the elephant is going to be calling the shots. See whether it's being manipulated or it's just following its nature. But either way, the driver is always going to be able to come up with the story saying, yeah, this is why we went over here. I have planned it this way all along. I wanted to buy this product. Now, this is a kind of different case, But the analogy here is that the talking, explaining, interpreting part of the left brain, according to Gazaniga's theory, is making up stories about why the now alien right brain does what it does, which, of course, it still shares a body so it controls some of the same limbs and stuff, when the interpreter really has no idea why the other part of the brain did what it did. Now, I think we should probably take a minute to emphasize like the drawbacks and limitations of split brain research. One of them is that, as riveting as I feel like, this kind of thing is um I think, for one thing, due to the necessity of the small sample sizes and the unusual history of the patients involved, this is the kind of research that's better thought of as a jumping off point to inspire questions and hypotheses that you should really try to prove through other means if possible. Like a lot of modern neuroscientists would probably say that you can learn more with more confidence from brain imaging studies like f m R I and stuff, then you can from a very small cohort of people with calls. Otomy's right, right, But at the same time that that may be true. But I do think there's real value in these kind of experiments, specifically mainly because you can see it, like you can see the human behavior in reality. You can see the implications of a strange discovery in neuroscience instantiated in the real world. It's one thing to learn through fmr I. That's something like different brain reach can function somewhat independently of one another, almost as multiple brains within the same head that don't understand what the other one is doing. You could probably show that in some ways through fm R I, But the split brain experiments show you the texture and the drama of the experience of a real person dealing with these facts about the brain. Other studies could probably find ways of indicating this, but but it is I think valuable how these experiments showed the experience of it right, like you can actually see somebody in real time dealing with the fact that they don't understand why their left hand just did what it did. I was reading a little a little bit about this. I ran across uh some material written by a cognitive psychologist, Year Pinto, an assistant professor at the Psychology department of the University of Amsterdam in the Netherlands. And uh Pinto and their team tested to split brain patients in to see if they could respond accurately to objects in the left visual field perceived by the right brain while also responding verbally or with the right hand controlled by the left brain. And Pinto uh Pinto also wrote about this in a piece for Ian magazine as well. So Pinto and the and and the team found that they could be that the individual could perceive stimuli and presence in either side of the visual field, but that they couldn't compare stimuli across the midline of the visual field. When the stimulus appeared in the left field, they were better at indicating its visual properties attention, and when it appeared in the right visual field, they were better at labeling it. So, you know, coming back to a language, here's how Pinto summed it up in Ian magazine. I just want to read a passage from this because I think it it punctuates a lot of what we're talking about here. Quote. Based on these findings, we have proposed a new model of the split brain syndrome. When you split the brain, you still end up with only one person. However, this person experiences two streams of visual information, one for each visual field, and that person is unable to integrate the two streams. It is as if he watches an out of sync movie, but not with the audio and video out of sync. Rather, the two UNSYNCD streams are both video. And there's more. While the previous model provided strong evidence for materialism, split the brain, split the person, the current understanding seems to only deepen the mystery of consciousness. You split the brain into two halves, and yet you still have only one person. How does a brain consisting of many modules create just one person? And how do split brainers operate as one when these parts are not even talking to each other. Now, this study, I think, does add some interesting nuance to what we've been talking about before. One thing, I feel like I don't maybe I'm just missing something. I feel like Pinto is setting up this model as like, uh, as like a counterpoint to the idea of of what Spery and Gazzaniga discovered. But it seems actually to me kind of in line with what they discovered, like the idea that that our consciousness is very mysterious. I mean, I think Spery Gazaniga would say that despite being able to produce these behaviors that look from the outside like as if they're from two different people. Uh, the experience of the patient, as they've always reported, is that they feel like a normal, whole person that nothing seems to have changed to them, right. I think in both cases though, it just you end up in this weird conundrum almost, this paradox, this idea that the single person we feel that we are is in some ways too And in these cases where we see evidence of of seem to see two evidence of what you could you know, call two minds within one brain, they're still functioning as one. They are still one. And so yeah, the paradox of that which is one seems too and that which is too seems one or more than two. Yeah, I mean that we've got the two hemispheres of the brain but remember that the hemispheres are each full of you know, modules, and like they're full of millions of neurons and they're that are working in different networks and jules to accomplish different goals. And so I think one of the lessons is that definitely different parts of the brain can behave and generate behaviors independently. And somehow you are here and you end up thinking I am a person. There's one of me, but there's a lot of different independent stuff going on inside whatever makes you. Yeah, I come back to that Hunter S. Thompson Warren Yvon quote, you're a whole different person when you're scared. Uh and in because in some because in to some extent, as we've discussed, you are a different person. You're at least a different version of the person. Uh So, yeah, how many how many us are there? Really? Well? I think we can explore this more in the second episode, but this really should give us some questions to think about, questions about whether our idea of a person or a self is really an accurate understanding of what brains are like, or is it just a is it just a convenient illusion? And that is some stuff to blow your mind or minds if you will. Hey, if you want to check out more episodes of the show while you're waiting for the next episode to drop, head on over to Stuff to Blow your Mind dot com. That's where we'll find them all. That's what we'll find links to our various social media accounts. Hey, and I want to mention again check out Invention at invention pod dot com. That is our other show that comes out on Mondays where we discuss the crazy inventions and sometimes it seemingly very mundane inventions that change the way we live our lives, that changed the world. 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