[MUSIC, Title: "Children's Changing Brains"] [Beth] Simona is an incredible skateboarder. After years of practice, she makes it all look easy. She's practically a ballerina on wheels. Her little sister, Olivia, however, doesn't have it as easy. As she is first learning to skateboard, all she seems to do is fall down. Although she wears a helmet and has padded knees, she still somehow manages to get scrapes and cuts. Learning to skateboard has become a continuing litany of bruises and bandages. But Olivia keeps right on trying through all the discomfort and pain. Despite the fact that Olivia has always been a little clumsier than Simona, she keeps at it anyway. Why? Because she can see how enjoyable it can be to skateboard! Her big sister's glee at skateboarding and her breathless retelling of what she did with her friends that day provide all the motivation Olivia needs. Even if Olivia may not grow up to be as skilled a skateboarder as Simona, she can still skateboard faster than she can walk, and she can still get a lot of enjoyment out of it. The key idea here is that eventually Olivia learns how to skateboard, and she never said to herself, "Gee, I guess I don't have the gene for skateboarding." Despite the frequent wobbles and falls, Olivia kept practicing day by day through the summer, until at the end of the summer she was floating along. Not as naturally as her big sister, but comfortably and well. Why can some students endure a lot of discomfort and even pain to learn something like skateboarding, while they can't seem to endure something far less physically painful— like learning how to read? Why do some kids happily keep trying to learn to skateboard when they can clearly see they're not as good as other kids? But when it comes to reading or math or any other subject, they see other kids doing better and give up— like Barb did when trying to learn math as a child. [Barb] There are many more questions when it comes to learning. Babies can pick up their native language with ease just by listening to the people around them— unlike adults who can spend years of focused study to learn the complex nuances of another language's grammar. I remember being amazed at how a five year old who moved to Russia could soon be speaking Russian far better than I could after two years of intensive study of the language. [Russian-speaking child looking at the MOOC Learning How to Learn: "What is this? It looks interesting! Can I try it?" ]
[Barb] How can that happen? Another question. Why is learning to speak a language so very different from learning to read? Put a toddler around a stack of books and they'll just toddle around the books, and maybe even chew on them—they can't learn to read without some kind of specific instruction related to reading. And why do many more students have problems such as dyslexia when it comes to reading—but there are far fewer such disorders when it comes to being able to learn to speak their native language? To answer these questions, we need to explore how the brain develops as infants mature. [MUSIC Title: "Pruning—The Good and the Bad"] [Terry] So it's time to talk about pruning. No, not THIS kind of pruning! THIS kind of pruning, in the neocortex. Let me explain. Recall that earlier in our course we talked about the neocortex, that dinner- napkin-size repository for the neural links in our long term memory. Well, let's take a look inside the cortex, along the thin edge of the napkin. Here I am inside the thin layer of the neocortex, which is called the "neuropil"—it's almost like a sheet of neural felt. You can see the neurons and dendrites all around me. When babies are young and the neurons are newly born, they flock toward the neuropil of the neocortex, almost like migratory birds. They know where they're supposed to roost. They roost at their neural home in the neuropil. Their axons reach out to almost connect with the dendritic spines of other neurons. The incredibly thin gaps that helped form the connections between the axon of one neuron and the dendritic spine of the next. These are called synapses. And neurons speak to one another through these synapses. By the time a toddler is two years old, most of the neurons and connections that the toddler will ever have are already in place. It's like toddlers have a headgear that enables them to learn pretty much anything that the world throws at them. But keeping these neurons connected is metabolically costly. Metaphorically speaking, it's almost like the brains of babies are gas guzzlers, needing twice as much energy as an adult brain. It's a good thing to have all those extra connections to start with, after all, a baby never knows what to expect. But as babies get more familiar with the world, it makes sense to start focusing on the important connections and losing some of the connections that are just hanging around using up energy. So those unused neural connections gradually begin to fall away— a process called pruning. [Barb] This is why a two or three year old child growing up in a culture that rolls their r's, can roll their r's just fine. But their aunt from a culture where the r's are not rolled, just can't roll their r's very well. Oftentimes not even after lots and lots of practice. [Child] Ferrocarril [Aunt] Ferocaril [said with poor accent] [Child] No, es ferrocarril. [Barb] Yeah. The neural connections that help allow for rolling the r, "rrrrrr" have been pruned away because they weren't used as their aunt was growing up. Actually, it turns out that having trouble with various forms of r are so common, that one research paper was cleverly titled "To 'r' is human." [A pun on "err," meaning erroneous.] [Beth] If a child grows up in a healthy, varied environment, a broader range of neural connections can stay in place. But a limited environment during the early years can mean that a child can have too many connections pruned while they are growing up. There's not much around to be learning. This explains the unfortunate cases of children who have been discovered growing up in environments with very little social interaction or stimulation. Like the Romanian orphans, who were often housed, virtually abandoned in overwhelmed orphanages during Ceaușescu's dictatorial regime. Or rare children kept in closets virtually all their lives. These children often simply can't recover and learn normally because by the time they'd arrived in an enriched environment, they'd already gone through the stage where pruning takes place. Since little was being used, a lot of connections got pruned away. [Terry] Interestingly, some forms of dyscalculia may arise, not because children have too LITTLE connectivity between their neurons and between brain regions, but because there is too MUCH connectivity. It's like a cook who while trying to make a chocolate souffle, puts in too much chocolate, and the souffle ends up a brick of chocolate. Too much of a good thing. With so many regions of the brain being activated at once, it's no wonder the child is confused. In these cases, it's not as if the child can't see the obvious. It may instead be that they look at what seems obvious to the teacher, and yet they see many possibilities— so many that they can't find the proper pathway to understanding. What you see and what you hear are processed in the back parts of your brain. These back parts mature first in early childhood. By maturing, we mean massive pruning has ended, and the cortex has lost some of its flexibility. The maturation and accompanying pruning gradually move toward the front of the brain. The last part of the brain to mature in early adulthood is the prefrontal cortex where planning and judgment take place. This slow prefrontal maturation explains why middle and high school students can sometimes act in such surprisingly immature ways. But when maturity rolls around, people can still adjust their neural connections—just not quite as easily as during childhood. But rest assured people continue to make new synaptic connections and prune unused connections throughout their lifetimes. And your oldest memories are the most permanent. [MUSIC Title: "The Expectations of Your Culture or Your Discipline"] [Barb] As children mature, neural pathways related to the expectations of their culture strengthen with repeated use. For example, what may seem obvious, good manners to you may be considered unspeakably rude in another culture. But you can become so used to the habitual neural pathways of your own culture that it may be hard for you to take another perspective. Your own way of doing things, whether it be greeting a person, for example, by kissing on both cheeks, as do the Spaniards or shaking hands, as with traditional Western cultures, or pressing one's hands together, as in India—each way, if you've been raised that way, seems to become the right way. The good thing of forming familiar habitual neural pathways is that you react appropriately in your usual surroundings without having to think about things. But the bad thing is your neural pathways can also lock you into what you've grown up with, making it difficult for you to see new or different perspectives. Neural pathways can also become fixed, related to the ideas of your discipline and how to teach that discipline. Famous historian of science Thomas Kuhn wrote that in general, only two types of people seem to be able to make breakthrough paradigm shifts— that is, major changes in science. The same "two types of people" idea seems to apply more generally to major changes in many disciplines. The first type of paradigm shifters are young people who have not yet had the chance for their neural pathways to become locked into place through many years of looking through the lens of the dogma they have originally been trained in. The second paradigm shifters are older people who were originally trained in a different discipline. Looking at the new discipline with their very different backgrounds allows them to look with fresh perspectives. Terry, for example, was originally trained as a physicist, which gave him the ability to look with fresh eyes at neuroscience. [Beth] This is why it can be very important for disciplines, including education and neuroscience, to consider perspectives from other disciplines. Both neuroscientists and teachers can take in ideas from those people originally trained in different disciplines, as well as from young people who have not grown used to the usual way of doing things. For example, educators used to think that drill meant kill. But now, with insights from neuroscience, we know that well done drill leads to SKILL, in other words drill to skill. This has important implications for all of education and involves a paradigm shift in how we teach. Next up, we'll learn why some things are easy for the brain to learn, while other things are much more difficult. [Beth] I'm Beth Rogowsky. [Barb] I'm Barb Oakley. [Terry] I'm Terry Sejnowski. [All] Learn it, link it, let's do it! [Child] Ferrocarril [Aunt] Ferocaril [with a decidely poor accent] [Child] Ferro...[Laughter] [Aunt] Ya bebe, entonces va ser así: usted va a decir ferrocarril, (Okay baby, so it is going to go like this. You are going to say railway,) yo lo voy a decir mal. Usted me a va a decir “no” y decirlo bien. (and I will say it incorrectly. You will then tell me “no” and say it correctly.) Ya? Otra vez. Ya? Como que me esta enseñando. Ya? Entiende? (Okay? Again. Okay? As if you are teaching me. Okay? Do you understand?) [Child] Mmm hmm. [Aunt] Toma bebe, puede morderlo? (Take this little one. Can you bite it?) [Uncle] You picked a too big book. [Aunt] I know. Este mejor. Puede morderlo? (Better this one, can you bite it?.) [Uncle] It's too big, too. [Barb] Let her pick it up. [Uncle] Guardalo. (Put it back.) [All] Muy bien! A ver de nuevo. (Very good! Let’s try again.) [Barb] Should she look at the camera when she's doing it? Kevin, should she look at you? [All] Ay may bien. (Oh, very good!) [LAUGHTER]
