WEBVTT - The Dark Side of Neuroplasticity 0:00:00.440 --> 0:00:03.480 Show Dr josup. Do you expect me to talk? Oh? 0:00:03.600 --> 0:00:08.920 This this isn't a standard interrogation. Inject him? Watch this now, 0:00:09.119 --> 0:00:13.080 poison truth Cerro, None of the above. No, this is 0:00:13.119 --> 0:00:17.800 something far more experimental. But perhaps a notorious secret agents 0:00:17.840 --> 0:00:23.120 such as yourself has heard of induced neuroplasticity. What you're 0:00:23.160 --> 0:00:29.000 talking of experimental neurotherapy drugs your math? Oh, neuroplasticity is 0:00:29.080 --> 0:00:31.800 far more than that. Yes, yes, this, this sort of 0:00:32.040 --> 0:00:35.800 treatment will soon revolutionize the way we deal with addictions 0:00:35.840 --> 0:00:39.680 and brain disease. It will allow adults of any age 0:00:39.760 --> 0:00:42.479 to learn new languages with the aptitude of a young child. 0:00:42.840 --> 0:00:45.960 But that's not why I've injected you with it. No, 0:00:46.200 --> 0:00:50.840 we've we've romanticized neuroplasticity. You see, we forget the importance 0:00:50.880 --> 0:00:55.320 of neuro stability. As children, we have an amazing ability 0:00:55.360 --> 0:00:58.400 to adapt to any environment, any language, were open to 0:00:58.440 --> 0:01:02.400 the world. We're also open to trauma. But then everything 0:01:02.480 --> 0:01:05.360 has to settle. We put aside those childish things and 0:01:05.400 --> 0:01:09.760 we become by a man doctors, secret agents. What do 0:01:09.800 --> 0:01:12.639 you want from me? Why? I want to change your life? 0:01:13.080 --> 0:01:16.800 Hans Rob the film Weight What what are you showing me? 0:01:16.920 --> 0:01:23.120 Jessup a YouTube playlist. Oh please, hours upon hours of 0:01:23.520 --> 0:01:27.959 let's call it informative content from some of the platforms 0:01:28.160 --> 0:01:33.520 leading personality No, not thish influencers. I'll tell you anything. 0:01:33.520 --> 0:01:44.560 For medians, no commentates, unboxes. No. Welcome to Stuff to 0:01:44.600 --> 0:01:53.400 Blow your Mind from how Stuff Works dot com. Hey, 0:01:53.560 --> 0:01:55.360 welcome to Stuff to blow your mind. My name is 0:01:55.440 --> 0:01:58.320 Robert Lamb and I'm Joe McCormick. And today we're gonna 0:01:58.320 --> 0:02:01.280 be talking about another topic, sort of a follow up 0:02:01.320 --> 0:02:04.080 from Robert's visit this year to the World Science Festival. 0:02:04.200 --> 0:02:08.280 We're gonna be talking about neuroplasticity. That's right. This, uh, 0:02:08.360 --> 0:02:11.240 this particular panel that that I attended, and this one 0:02:11.280 --> 0:02:13.440 is also available online. Will make sure there's a link 0:02:13.480 --> 0:02:16.200 to the YouTube video on the landing page for this 0:02:16.200 --> 0:02:18.680 episode Acceptable in your Mind dot com. Uh. The particular 0:02:18.680 --> 0:02:21.320 panel was called Nuts and Bolts of Better Brains. It 0:02:21.400 --> 0:02:28.440 was hosted by Guy mccon, neurosurgeon, neuroscientist, Alvero Pascal Leoni, neuroscientist, 0:02:28.720 --> 0:02:33.800 uh Nim Tottenham developmental or psychologist, and Carlas Shots, a neuroscientist, 0:02:34.120 --> 0:02:36.839 and they discussed neuroplasticity, which is something that we've we've 0:02:36.880 --> 0:02:39.080 touched on on the show before, and I think a 0:02:39.120 --> 0:02:42.800 lot of people have kind of a general concept of Yeah, 0:02:42.919 --> 0:02:45.560 neuroplasticity is one of those words that I think has 0:02:45.639 --> 0:02:50.400 suffered a lot of abuse in the press um because 0:02:50.560 --> 0:02:53.440 I mean, there are words that have a good meaning 0:02:53.800 --> 0:02:56.760 in science, and there's nothing wrong with the concept itself. 0:02:57.080 --> 0:03:01.000 But in today's neuroscience, neuroplasticity does have a meaning, and 0:03:01.040 --> 0:03:04.000 it does have a useful meaning. But you see it 0:03:04.400 --> 0:03:09.280 in a lot of hype and bs on the internet. Yeah, 0:03:09.320 --> 0:03:11.200 Like I noticed, when when you do a search for 0:03:11.240 --> 0:03:14.280 neuroplasticity you want to read things about it, you get 0:03:14.320 --> 0:03:18.239 mostly content at one of two levels. Either content for 0:03:18.600 --> 0:03:22.440 experts and neuroscientists, like actual scientific literature that the average 0:03:22.440 --> 0:03:25.880 reader can't penetrate, and then you get also a whole 0:03:25.919 --> 0:03:29.480 lot of hype and bs that is telling you about 0:03:29.760 --> 0:03:31.840 I don't know, about how you're going to revolutionize your 0:03:31.880 --> 0:03:34.280 brain and you'll become like a child again and become 0:03:34.280 --> 0:03:36.800 a master of your own abilities. Yeah, I mean it's 0:03:36.840 --> 0:03:38.960 already become something of a buzzword, for instance, with with 0:03:39.000 --> 0:03:46.280 certain uh like supplement manufacturers, and take this neuroplasticity vitamin Yeah, okay, thanks, 0:03:47.000 --> 0:03:50.120 But but the neuroplasticity is a real thing. It is 0:03:50.240 --> 0:03:52.720 you can think of it simply as the brain's ability 0:03:52.760 --> 0:03:57.480 to adapt, and humans most incredible powers of neuroplasticity, especially 0:03:57.560 --> 0:04:01.400 during the so called critical periods of early childhood. Yeah. 0:04:01.440 --> 0:04:03.480 One of the things to think about this kind of 0:04:03.520 --> 0:04:10.280 weird is um how well humans adapt to such different 0:04:10.480 --> 0:04:16.160 life conditions. Like if you take most animals out of 0:04:16.200 --> 0:04:19.480 the environment and condition conditions that they're best adapted to, 0:04:19.920 --> 0:04:23.120 they don't do very well. There are some exceptions, but 0:04:23.200 --> 0:04:25.760 most of the time an animal has evolved to have 0:04:25.839 --> 0:04:30.320 certain instincts. It's got sort of like pretty hardwired behaviors. 0:04:30.440 --> 0:04:33.080 It can live, you know, it can be born where 0:04:33.120 --> 0:04:36.160 it is supposed to be born and live encountering the 0:04:36.240 --> 0:04:39.359 kind of stimuli it would normally encounter, and you know, 0:04:39.560 --> 0:04:41.719 it can do its thing that nature has shaped it for. 0:04:42.000 --> 0:04:45.479 But humans can do all kinds of stuff. We can 0:04:45.520 --> 0:04:47.760 live in the snow, we can live in the desert, 0:04:47.880 --> 0:04:51.360 we can live in cities, we can live in it plans. 0:04:51.480 --> 0:04:54.040 We can be farmers, we can be doctors. We can 0:04:54.080 --> 0:04:57.240 do so many different kinds of things with our brains. 0:04:57.560 --> 0:05:00.760 And there are no other animals like this really. Yeah, 0:05:00.800 --> 0:05:02.680 the in the talk, they brought up the example of 0:05:02.720 --> 0:05:05.359 the loggerhead turtle as an example of a creature that 0:05:05.440 --> 0:05:09.520 is not a paragon of neuroplasticity but neuro stability. A 0:05:09.560 --> 0:05:13.200 creature that, upon birth is just ready to go and 0:05:13.240 --> 0:05:16.599 do a very specific thing exceedingly well in a very 0:05:16.640 --> 0:05:20.240 specific environment. But if you put some major obstacles in 0:05:20.279 --> 0:05:23.520 that turtle's way, the turtle probably would not find a 0:05:23.560 --> 0:05:26.800 way to adapt to those obstacles and survive around them. 0:05:26.800 --> 0:05:29.480 It would probably just not survive to adulthood, right, I 0:05:29.480 --> 0:05:31.320 mean in the turtle is a good example of that, 0:05:31.360 --> 0:05:33.880 because I mean with with with various sea turtles, we've 0:05:33.880 --> 0:05:38.080 seen examples of how just artificial lighting can screw up 0:05:38.160 --> 0:05:42.320 a very particular approach to going about its life cycle. Yeah, 0:05:42.360 --> 0:05:45.240 but so your brain. One of the reasons your brain 0:05:45.360 --> 0:05:48.600 is so powerful compared to the brains of animals is 0:05:48.680 --> 0:05:52.000 that it can be adapted to so many different scenarios 0:05:52.000 --> 0:05:55.440 and so many different types of tasks depending on what 0:05:55.560 --> 0:05:59.560 sorts of environments you're exposed to when you're very young. Yeah, 0:06:00.040 --> 0:06:02.120 language is of course one of the great examples, and 0:06:02.120 --> 0:06:04.919 I think everyone has at least some awareness of this. 0:06:05.440 --> 0:06:07.840 Certainly anybody out there who's a parent has has read 0:06:07.839 --> 0:06:10.520 about this or experience this with their own children. Is 0:06:10.520 --> 0:06:15.120 that during certain critical periods, they have an amazing ability 0:06:15.160 --> 0:06:17.080 to not only pick up a language, but to just 0:06:17.200 --> 0:06:20.760 perfectly pick it up, to just breathe it in and 0:06:20.760 --> 0:06:24.359 and and become fluent in it without without any of 0:06:24.400 --> 0:06:28.960 the challenges that are generally encountered by adults trying to 0:06:29.040 --> 0:06:30.920 learn a second language. I mean, one of the ways 0:06:31.000 --> 0:06:34.040 that it's often put is that with great effort, and 0:06:34.160 --> 0:06:37.599 adult can learn to speak a language they don't already speak, 0:06:37.680 --> 0:06:40.000 but they will pretty much always speak it with an accent. 0:06:40.680 --> 0:06:43.120 Children can learn to speak all kinds of and can 0:06:43.200 --> 0:06:45.400 learn to speak multiple languages at the same time, and 0:06:45.440 --> 0:06:48.520 can generally learn to speak them without an accent. But then, 0:06:48.520 --> 0:06:50.640 of course it goes beyond this too, because there there's 0:06:50.680 --> 0:06:53.760 so many other things that are being absorbed during childhood, 0:06:53.800 --> 0:06:57.280 you know, the social norms, cultural norms, just how one 0:06:57.400 --> 0:07:01.159 interacts with your environment, and that has enabled humans to 0:07:01.240 --> 0:07:05.160 thrive all over the world, you know, obviously with technological 0:07:05.600 --> 0:07:10.080 aids in many cases, but still it it underlies the 0:07:10.160 --> 0:07:13.560 diversity and success of our species. Then again, there are 0:07:13.600 --> 0:07:16.800 some reasons to think that you don't want the brain 0:07:16.920 --> 0:07:20.600 to be sort of infinitely plastic, right, because if we 0:07:21.000 --> 0:07:24.440 consider plasticity the ability of the brain to adapt to 0:07:24.480 --> 0:07:28.040 new scenarios and change itself to work better, you also 0:07:28.080 --> 0:07:30.240 need cases where the brain knows what to do and 0:07:30.280 --> 0:07:34.240 does it instead of keeps being influenced and changing right right, 0:07:34.280 --> 0:07:36.480 and knows where to where to where to stop. You 0:07:36.520 --> 0:07:40.120 know what, what avenues to stop exploring because basically what 0:07:40.120 --> 0:07:42.720 happens is their neural circuitry branches out to master the 0:07:42.760 --> 0:07:46.280 skills necessary for survival. And then uh, and then after 0:07:46.320 --> 0:07:48.080 it does this, after you know, some of the branches 0:07:48.120 --> 0:07:50.560 have been prune back. Uh. You can think of it 0:07:50.640 --> 0:07:52.920 like a you know, like one of those shrub sculptures 0:07:52.920 --> 0:07:56.000 from the Shining from you know, the original novel. If 0:07:56.000 --> 0:07:58.760 you've read that, you know you you you prune everything down, 0:07:58.760 --> 0:08:01.480 cut it away until it's the appropriate shape. Yeah. It's 0:08:01.480 --> 0:08:03.560 an interesting thing that the speakers in this event talk 0:08:03.600 --> 0:08:06.400 about is that the idea of pruning in childhood, how 0:08:06.840 --> 0:08:09.440 it starts off with way more connections than it needs, 0:08:09.760 --> 0:08:12.640 and then through this process it sort of pairs back 0:08:12.760 --> 0:08:14.560 the stuff that says, Okay, it looks like I'm not 0:08:14.600 --> 0:08:16.360 going to need that in life. We can just sever 0:08:16.400 --> 0:08:19.240 all those Yeah, I mean it kind of matches up 0:08:19.280 --> 0:08:22.040 with the cliche of the child who can grow up 0:08:22.040 --> 0:08:25.360 to be anything, right, which you know, obviously any given 0:08:25.400 --> 0:08:28.040 child can't grow up to be absolutely anything. But there 0:08:28.160 --> 0:08:29.840 is a there. There is a lot of room for 0:08:29.880 --> 0:08:33.199 specialization and and and and diverse growth there. Yeah, we 0:08:33.559 --> 0:08:36.760 have natural tendencies and natural potentials, and some of that 0:08:36.880 --> 0:08:41.920 is genetic. But then also we were extremely adaptable as children, right. 0:08:42.200 --> 0:08:44.840 But then of course in neural stability has to kick in. 0:08:44.960 --> 0:08:49.960 That's important too, a necessary balance in the human brain. Um, 0:08:50.040 --> 0:08:52.360 you're going to grow up and become this thing we 0:08:52.400 --> 0:08:55.920 call an adult. But what if I am Peter Pan 0:08:56.120 --> 0:08:57.800 and I don't want to grow up and be an 0:08:57.800 --> 0:09:00.600 adult because growing up and being in a delt and 0:09:00.679 --> 0:09:04.520 having neuro stability limits my potential. What if I decide 0:09:04.640 --> 0:09:07.600 I don't want to be somebody who only speaks English. 0:09:07.640 --> 0:09:11.400 I want to be somebody who speaks Chinese and speaks 0:09:11.400 --> 0:09:15.160 French and speaks the click languages. And you know what 0:09:15.440 --> 0:09:17.959 if I want to speak all those languages without an accent, 0:09:18.080 --> 0:09:20.560 why can't I do that. Yeah, I want to have 0:09:20.600 --> 0:09:23.640 infinite potential again. I want to go back to I 0:09:23.640 --> 0:09:25.400 want to be able to grow up to be anything. 0:09:25.880 --> 0:09:27.680 You know. I think we've all had moments like that 0:09:27.720 --> 0:09:30.800 where we we we we look at where we are 0:09:30.800 --> 0:09:32.920 and we think, well, if I could go back and 0:09:32.960 --> 0:09:35.440 open myself up to this language or this ability or 0:09:35.440 --> 0:09:37.400 what have you, then I would love to do that, 0:09:37.480 --> 0:09:39.640 you know, or or just the idea that nobody wants to. 0:09:40.000 --> 0:09:41.840 You don't want to feel stagnant. You want to feel 0:09:41.880 --> 0:09:44.760 like you're continuing to grow and uh and you know, 0:09:44.880 --> 0:09:48.160 keep up with the young ones. And so scientists have 0:09:48.280 --> 0:09:55.040 continually looked to possible ways of essentially rewidening the doorways 0:09:55.080 --> 0:09:59.040 of of neuroplasticity. That's one of the metaphors it's often used, right, 0:09:59.120 --> 0:10:01.800 is that when you're a child out the door is open, 0:10:01.840 --> 0:10:05.240 the window is open for you to grasp onto anything. 0:10:05.600 --> 0:10:08.439 But then depending on who's throwing the metaphor round, you 0:10:08.440 --> 0:10:10.240 can say, well it closes when you become an adult, 0:10:10.320 --> 0:10:13.120 but it doesn't really closes. It gets sort of like 0:10:13.240 --> 0:10:18.240 it gets almost closed, right, it narrows, And so we've 0:10:18.240 --> 0:10:22.120 looked to ways to to widen it in adulthood, and 0:10:22.120 --> 0:10:25.680 and it goes beyond this mirror um, you know, intellectual 0:10:26.880 --> 0:10:29.600 vanity as well. Right, it's not just Peter Pan saying 0:10:29.640 --> 0:10:32.120 I want this, I want that. There's also the idea 0:10:32.200 --> 0:10:36.560 of treating problems in the adult brain by reintroducing plasticity, right, 0:10:36.600 --> 0:10:38.960 it would it would give us a way to treat 0:10:39.240 --> 0:10:45.440 various neurodegenerative disorders, anxiety, depression, even post traumatic stress disorder. 0:10:45.520 --> 0:10:48.040 Like anytime there's a there's a potential for for growth 0:10:48.040 --> 0:10:50.480 and change, positive growth and change in the brain to 0:10:50.720 --> 0:10:54.000 help with a given condition. Neuroplasticity is often brought up 0:10:54.000 --> 0:10:56.960 as a as a potential cure. But it's a challenge 0:10:57.040 --> 0:10:59.720 to do this sort of thing. As a Columbia University 0:10:59.760 --> 0:11:03.679 develop antal psychologist Dr Nim Totenham, who we were referenced already, 0:11:03.920 --> 0:11:06.559 as she stated in the in that World Science Festival discussion, 0:11:06.720 --> 0:11:10.240 the brain actually extends, expends a lot of energy to 0:11:10.360 --> 0:11:14.200 keep critical periods from reopening. Yeah, we there there seems 0:11:14.240 --> 0:11:17.880 to be some logic underlying this, this move the evolution 0:11:17.920 --> 0:11:20.280 took right, it says, you know, you don't stay a 0:11:20.320 --> 0:11:23.160 plastic child forever. At some point the brain needs to 0:11:23.440 --> 0:11:25.839 figure out what to be and be that right. And 0:11:26.280 --> 0:11:29.520 that's one of the reasons we're calling this episode the 0:11:29.559 --> 0:11:33.160 Dark Side of neuroplasticity. Not that neuroplasticity he necessarily has 0:11:33.160 --> 0:11:36.800 this deep, dark underbelly, but the sort of public awareness 0:11:37.000 --> 0:11:40.160 tends to lean so heavily towards neuroplastics is just an 0:11:40.200 --> 0:11:42.280 absolute good. I want as much of it as I 0:11:42.280 --> 0:11:46.240 can get. We want to counter the hype. Neuroplasticity is 0:11:46.240 --> 0:11:48.880 a good thing, but it's also not in uh, it's 0:11:48.920 --> 0:11:52.040 not a good thing in every possible case, in every 0:11:52.080 --> 0:11:54.720 possible sense. Right, And towards the end of the episode, 0:11:54.760 --> 0:11:58.160 Will will speculate a little bit and look at some 0:11:58.160 --> 0:12:01.400 some speculation from experts about some of the possible pitfalls 0:12:01.440 --> 0:12:03.320 could be. What are some and even what are some 0:12:03.360 --> 0:12:08.520 of the black mirror esque possibilities in a world full 0:12:08.559 --> 0:12:13.000 of neuroplasticity inducing drugs? Yeah, now the question about these drugs, though, 0:12:13.080 --> 0:12:16.280 is still wide open. I mean it's sort of uh. 0:12:16.400 --> 0:12:18.280 I hate to use the metaphor the wild West. What's 0:12:18.280 --> 0:12:21.240 a better metaphor for an arena in which there is 0:12:21.280 --> 0:12:24.559 still much much new ground being forged? Welcome to the 0:12:24.640 --> 0:12:29.640 jungle Baby. How about some spelunking. We're spelunking. Yeah, those 0:12:29.640 --> 0:12:32.400 are close confines, though, I guess okay, I think I 0:12:32.440 --> 0:12:36.080 think wild West is still pretty good. Well whatever it is. 0:12:36.120 --> 0:12:39.080 I mean, we're still trying to figure out what kinds 0:12:39.080 --> 0:12:42.120 of drugs might do this, what side effects they might have, 0:12:42.240 --> 0:12:44.280 if they are effective at doing it, And we'll talk 0:12:44.320 --> 0:12:46.920 more later in the episode about what some of these 0:12:46.920 --> 0:12:50.319 specific drugs might be. Yeah, because to master neuroplus this day, 0:12:50.320 --> 0:12:52.520 we're going to have to establish the molecules that close 0:12:52.600 --> 0:12:55.400 the doors. I mean, the thing is, it is possible 0:12:55.440 --> 0:12:58.880 to extend critical periods and manipulate them, and experts do, 0:12:59.000 --> 0:13:01.000 in fact think that we'll one day be able to 0:13:01.040 --> 0:13:03.959 do this with a pill, with some sort of medication. 0:13:04.040 --> 0:13:06.000 So it's not a question of of if. It's a 0:13:06.080 --> 0:13:10.280 question of when the groundwork is already being laid for this. Uh, 0:13:10.360 --> 0:13:12.120 it's just how are we gonna be ready for it 0:13:12.160 --> 0:13:14.120 when it happens. Well, I think we should take a 0:13:14.200 --> 0:13:15.840 quick break and then when we come back we will 0:13:16.000 --> 0:13:18.240 discuss a few things about the history of the idea 0:13:18.280 --> 0:13:24.280 of neuroplasticity. Than alright, we're back. So Charles Darwin actually 0:13:24.280 --> 0:13:28.040 offered some thoughts about how the brain changes in response 0:13:28.080 --> 0:13:30.720 to the environment. In his book The Descent of Man, 0:13:30.800 --> 0:13:33.920 which published in eighteen seventy four, and though we should 0:13:33.960 --> 0:13:36.960 note that he did not use the term plasticity, he 0:13:37.000 --> 0:13:39.520 did sort of write about the idea of of the 0:13:39.559 --> 0:13:42.880 brain adapting. He wrote, quote, I have shown that the 0:13:42.880 --> 0:13:46.920 brains of domestic rabbits are considerably reduced in bulk in 0:13:47.040 --> 0:13:50.480 comparison with those of the wild rabbit or hair, and 0:13:50.520 --> 0:13:53.599 this may be attributed to their having been closely confined 0:13:53.679 --> 0:13:59.120 during many generations, so that they have exerted their intellect, instincts, senses, 0:13:59.160 --> 0:14:03.880 and voluntary movements. But little uh note that he's imagining 0:14:03.920 --> 0:14:07.679 this adaptation of the brain taking place over multiple generations 0:14:07.760 --> 0:14:10.520 through inheritance, which is very different from the kind of 0:14:10.520 --> 0:14:13.520 plasticity that we're talking about, which takes place within a 0:14:13.559 --> 0:14:16.520 single body within a single lifetime. But he is at 0:14:16.559 --> 0:14:19.160 least offering an image they're of saying like, Okay, maybe 0:14:19.200 --> 0:14:22.360 the brain can kind of be molded to what it 0:14:22.560 --> 0:14:27.000 best does given its environmental circumstances. Right if you if 0:14:27.040 --> 0:14:29.120 you're a wild hair, and you need to be crafty 0:14:29.160 --> 0:14:31.720 and wily and use all your senses to survive out 0:14:31.720 --> 0:14:35.480 in the brush. Uh, you you will grow these bulky brains. 0:14:35.520 --> 0:14:37.680 But if you're a domestic hair and all you do 0:14:37.760 --> 0:14:40.600 is sit around and get fed, then you don't need 0:14:40.600 --> 0:14:43.320 all that stuff and the brain will adapt. This touches 0:14:43.360 --> 0:14:45.120 on a fact that we've discussed before, and that is 0:14:45.200 --> 0:14:47.760 that that the that the brain like evolution is a 0:14:47.800 --> 0:14:50.760 miser and that's cheap. Yeah, it's it's cheap. It wants 0:14:50.800 --> 0:14:54.160 the most economic model for functionality. It is. It is 0:14:54.200 --> 0:14:57.520 the Ebenezer Scrooge of the body. No, the whole body 0:14:57.600 --> 0:14:59.840 is cheap. Actually, you know it makes sense. You don't 0:14:59.840 --> 0:15:03.640 want wasting energy in an environment where energy is hard 0:15:03.640 --> 0:15:07.600 to come by. Living in a world of technology and abundance. Uh, 0:15:07.800 --> 0:15:09.840 you know, we should stop to think, how, you know, 0:15:09.920 --> 0:15:11.960 if if you have food to eat, if you're not 0:15:12.000 --> 0:15:14.080 wondering where your next meal comes from, you should think 0:15:14.080 --> 0:15:16.120 about how lucky you are. But you should also think 0:15:16.120 --> 0:15:19.000 about how, in many ways your body and the bodies 0:15:19.040 --> 0:15:21.520 of every other creature in the world, we're sort of 0:15:21.560 --> 0:15:24.760 designed for scenarios where you would be constantly living on 0:15:24.760 --> 0:15:28.000 the edge of starvation. But back to neuro plasticity. So 0:15:28.240 --> 0:15:32.479 the term plasticity emerged from the work of American psychologist 0:15:32.520 --> 0:15:35.400 William James who lived eighteen forty two to nineteen ten, 0:15:36.000 --> 0:15:38.960 and James defined it the following way. He said, it's 0:15:39.040 --> 0:15:43.000 quote the possession of a structure weak enough to yield 0:15:43.080 --> 0:15:47.560 an influence, but strong enough not to yield all at once. Yeah, 0:15:47.640 --> 0:15:51.240 I mean that makes sense. It's ideal for a young 0:15:51.360 --> 0:15:53.480 child to be open to their environment and not so 0:15:53.520 --> 0:15:56.720 open that they're just completely overwhelmed. Right, So I want 0:15:56.720 --> 0:16:00.240 to read a quote from William James from his from 0:16:00.280 --> 0:16:03.760 his seminal work on psychology, where he started deposit that 0:16:03.800 --> 0:16:06.880 the brain might have some kind of might have some 0:16:06.960 --> 0:16:11.320 kind of like changeable structure. So he says, quote, if 0:16:11.320 --> 0:16:15.320 habits are due to the plasticity of materials to outward agents, 0:16:15.520 --> 0:16:19.600 we can immediately see to what outward influences, if to any, 0:16:19.720 --> 0:16:24.360 the brain matter is plastic, not too mechanical pressures, not 0:16:24.520 --> 0:16:27.800 to thermal changes, not to any of the forces to 0:16:27.840 --> 0:16:30.640 which all the other organs of our body are exposed. 0:16:30.920 --> 0:16:34.440 For nature has so blanketed and wrapped the brain about 0:16:34.720 --> 0:16:37.360 that the only impressions that can be made upon it 0:16:37.720 --> 0:16:40.480 are through the blood on the one hand, and the 0:16:40.560 --> 0:16:43.920 sensory nerve roots on the other. And it is to 0:16:44.000 --> 0:16:47.720 the infinitely attenuated currents that pour in through these latter 0:16:47.880 --> 0:16:52.000 channels that the hemispherical cortex shows itself to be so 0:16:52.160 --> 0:16:57.040 peculiarly susceptible. The currents, once in, must find a way out. 0:16:57.480 --> 0:17:00.560 In getting out, they leave their traces in the paths 0:17:00.640 --> 0:17:04.480 which they take. The only thing they can do, in short, 0:17:04.960 --> 0:17:07.840 is to deepen old paths or to make new ones. 0:17:08.240 --> 0:17:11.479 And the whole plasticity of the brain sums itself up 0:17:11.520 --> 0:17:14.159 in two words when we call it an organ in 0:17:14.160 --> 0:17:17.560 which currents pouring in from the sense organs make with 0:17:17.640 --> 0:17:23.040 extreme facility paths which do not easily disappear. For, of course, 0:17:23.119 --> 0:17:26.520 a simple habit, like every other nervous event, the habit 0:17:26.560 --> 0:17:30.240 of snuffling, for example, or putting one's hands into one's 0:17:30.280 --> 0:17:35.000 pockets or biting one's nails, is mechanically nothing but a 0:17:35.080 --> 0:17:39.760 reflex discharge, and its anatomical substratum must be a path 0:17:40.000 --> 0:17:43.480 in the system. The most complex habits, as we shall 0:17:43.560 --> 0:17:46.520 presently see more fully, are from the same point of view, 0:17:46.600 --> 0:17:50.720 nothing but concatenated discharges of the nerve centers, due to 0:17:50.720 --> 0:17:56.000 the presence there of systems of reflex paths so organized 0:17:56.040 --> 0:18:00.000 as to wake each other up successively, the impression produced 0:18:00.119 --> 0:18:03.480 by one muscular contraction serving as a stimulus to provoke 0:18:03.520 --> 0:18:07.880 the next, until a final impression inhibits the process and 0:18:07.960 --> 0:18:11.960 closes the chain. So that was very forward thinking on 0:18:12.000 --> 0:18:16.280 William James's part. He's so, he's got a very rudimentary 0:18:16.440 --> 0:18:20.120 nineteenth century understanding of brain function here, but it does 0:18:20.160 --> 0:18:23.720 get some some interesting basic insights right. One of them 0:18:24.280 --> 0:18:26.919 is that habits or tendencies of the brain consist of 0:18:26.920 --> 0:18:31.520 a kind of reinforcing of pathways of activities. Another is 0:18:31.560 --> 0:18:34.879 that complex brain functions are built out of many less 0:18:34.880 --> 0:18:38.760 complex brain functions happening together in sequence. Another is that 0:18:38.800 --> 0:18:43.000 the potential and predispositions of an individual brain like your brain, 0:18:43.600 --> 0:18:47.960 can be changed based on repeated interaction with chemicals in 0:18:47.960 --> 0:18:51.000 the blood or with the data of the senses. And 0:18:51.040 --> 0:18:53.119 that last part is just as a tangent one of 0:18:53.119 --> 0:18:56.639 those utterly mundane facts that I often have to stop 0:18:56.680 --> 0:19:00.159 and force myself to be amazed by over and over again, Like, 0:19:00.200 --> 0:19:03.920 think about this. It sounds kind of stupid to say, 0:19:03.960 --> 0:19:07.679 but by making acoustic vibrations in the air with my 0:19:07.840 --> 0:19:11.040 mouth that you can hear or by like drawing a 0:19:11.080 --> 0:19:13.639 picture on a chalkboard and putting it in front of 0:19:13.640 --> 0:19:18.040 your eyes. I can literally change the physical configuration of 0:19:18.080 --> 0:19:22.480 your brain. I make changes inside your skull by doing 0:19:22.520 --> 0:19:25.520 things you can see in here. Isn't that bizarre? Yeah? 0:19:25.560 --> 0:19:27.080 I mean if you and if you extend it to 0:19:27.280 --> 0:19:31.400 written language, you can think, oh, well, somebody who wrote something, uh, 0:19:31.480 --> 0:19:35.920 inscribed something down a thousand, two thousand, three thousand years ago. 0:19:36.640 --> 0:19:40.920 They can speak across all those uh, those dead millennia, 0:19:41.240 --> 0:19:43.160 and they can speak right to our brain and make 0:19:43.240 --> 0:19:46.439 changes in it. It's unbelievable. Now. I mentioned earlier that 0:19:46.480 --> 0:19:49.600 the term plasticity in the context of neuroscience had been 0:19:49.680 --> 0:19:51.639 used to mean a lot of different things. There was 0:19:51.680 --> 0:19:55.080 one particular paper I looked at about this by Giovanni 0:19:55.119 --> 0:19:58.439 Berluki and Henry book Tool from two thousand nine and 0:19:58.520 --> 0:20:01.400 Experimental Brain Research, and they talk about how the term 0:20:01.440 --> 0:20:04.560 plasticity has been used over the past century to refer 0:20:04.600 --> 0:20:07.919 to quote changes in neural organization, which may account for 0:20:08.080 --> 0:20:12.320 various forms of behavioral modifiability, either short lasting or enduring, 0:20:12.440 --> 0:20:18.080 including maturation, adaptation to a mutable environment, specific and unspecific 0:20:18.160 --> 0:20:22.560 kinds of learning, and compensatory adjustments in response to functional 0:20:22.600 --> 0:20:26.119 losses from aging or brain damage. So that that's a 0:20:26.119 --> 0:20:29.760 lot of different meanings encompassed in the idea of plasticity, 0:20:29.800 --> 0:20:32.240 but it does sort of apply to all of those, 0:20:32.520 --> 0:20:35.560 so it's subject to generalization. But then also is sort 0:20:35.600 --> 0:20:37.840 of uh is a turn It sort of refers to 0:20:37.960 --> 0:20:40.879 general change in the brain. Yeah, a kind of adaptation 0:20:40.920 --> 0:20:43.560 that has come to be associated with pressures put on 0:20:43.600 --> 0:20:47.000 the brain from the environment. Right, So, with modern techniques, 0:20:47.040 --> 0:20:49.720 we've discovered that the way these pathways are forged and 0:20:49.760 --> 0:20:54.160 reinforced in the brain depends largely on the crucial element 0:20:54.280 --> 0:20:56.879 of the synapps or you know, the bridge of space 0:20:56.960 --> 0:21:00.359 that connects to nerve cells and allows impulses to pass 0:21:00.440 --> 0:21:05.119 between the cells. And in eighteen three, the Italian neuropsychiatrist 0:21:05.200 --> 0:21:10.080 Eugenio Tanzi first proposed that the basis of practiced based 0:21:10.200 --> 0:21:15.240 learning and associative memory was these connections between nerve cells 0:21:15.240 --> 0:21:18.280 in the brain. Because Tanzi knew that there are other 0:21:18.320 --> 0:21:21.760 scientists who had observed the slowing of the passage of 0:21:21.840 --> 0:21:24.960 nerve impulses through the gray matter in the brain, and 0:21:25.000 --> 0:21:27.679 so he hypothesized that maybe what's going on in that 0:21:27.840 --> 0:21:32.320 slow down is that there's difficulty for the impulses to 0:21:32.480 --> 0:21:35.880 cross the gaps between neurons, these gaps that we now 0:21:35.920 --> 0:21:39.800 call synapses or synaptic fissures. And based on that assumption, 0:21:40.200 --> 0:21:43.200 Tansi argued that the way the brain adapts, the way 0:21:43.240 --> 0:21:47.639 it learns through practice and creates associations between things, the 0:21:47.680 --> 0:21:51.119 way it sort of enacts its plastic potential is by 0:21:51.119 --> 0:21:55.240 a kind of exercise. When you perform a repetitious activity 0:21:55.280 --> 0:21:59.480 in the brain, the same pathways of neurons repeatedly communicate 0:21:59.520 --> 0:22:01.960 with each other, and by doing this you cause a 0:22:02.080 --> 0:22:05.480 kind of hypertrophy or strengthening of the connections between those 0:22:05.520 --> 0:22:08.280 specific neurons. The more you do a certain thing in 0:22:08.320 --> 0:22:11.399 the brain, the easier than that thing becomes to do 0:22:11.560 --> 0:22:15.000 in the brain. And then the next year, in eighteen 0:22:15.040 --> 0:22:19.960 ninety four, the Spanish neuroscientists Santiago Ramonikahal, who I've thought 0:22:20.000 --> 0:22:21.800 before we should do a whole episode on this guy. 0:22:21.840 --> 0:22:25.479 Perhaps he also speculated that learning was based on the 0:22:25.480 --> 0:22:29.679 creation and strengthening of connections between neurons. I feel like 0:22:29.720 --> 0:22:32.640 this is something that has been I think over the years, 0:22:32.640 --> 0:22:36.280 it's just been so well demonstrated or not really demonstrated, 0:22:36.280 --> 0:22:40.600 but illustrated with animations and and uh and and art 0:22:40.760 --> 0:22:43.200 that I have it like well ingrained in my head. 0:22:43.320 --> 0:22:47.639 Like when people talk start talking about synapses firing, I 0:22:47.760 --> 0:22:50.280 picture it. And maybe I also kind of think of 0:22:50.320 --> 0:22:52.919 it in terms of of playing an instrument, like the 0:22:52.960 --> 0:22:57.119