The Adolescent Brain: A Work in Progress

Presenter: Pat Wolfe, Mind Matters, Inc., Napa, CA

This session is presented in separate parts. Use the buttons at the end of the transcription to navigate between each part.

Part Two

PAT WOLFE: We are going to talk about three major changes that take place in the adolescent brain. You had to have this background to understand that.

So, change one is this: Evidently, bigger is not better. Because during adolescence -- well, first of all, let's start a little bit before adolescence. Between seven and 11, the brain undergoes another huge spurt of growth of connections just like they were doing around 18 months to two. And it is interesting that most of this growth is in the temporal lobes and in the parietal lobes. Now, the temporal lobes, I told you, handle auditory information. But deep down within the temporal lobes is a structure called the hippocampus, and it is responsible for memory.

So, the part of the brain between, seven and 11, that works really efficiently and is growing a lot and developing a lot is the part of the brain that handles memory. Tremendous growth. This is probably why this is a prime time to learn a second language, because you are getting this tremendous growth in the temporal lobes in the part of the brain that hears those sounds and remembers them.

The other place that this tremendous spurt is taking place is in the parietal lobes, which handles a lot of your integration of sensory data and movement. And some of the researchers think this is also a prime time perhaps for learning to use or play a musical instrument or sports.

The frontal lobes start losing tissue. In fact, during adolescence -- well, first of all, this growth peaks around 11 in girls and 12 in boys. You do know that girls reach puberty about a year before. That is a real generalization, or over-generalization, but this is going to occur first. And then a selective pruning takes place, just like in that two-year-old brain, but most of this pruning is taking place in the frontal lobes. And your adolescent loses approximately 3 percent of the gray matter in the frontal lobes.

And this is a natural process and you do not want to stop it. You are not going to get a program out here out that says how to stop the loss of tissue in the adolescent brain by our program. No.

Think of it this way. And I got this from researcher Jay Giedd and he says, think of Michelangelo, with this block of marble. He begins to sculpt away until David emerges. And this is precisely what is going on in the adolescent brain, starting around 11. The brain is pruning away, sculpting away excess material, excess connections, to make a more refined, more efficient, more adult brain. We are beginning to prune away.

Most of these changes are taking place in the front of the frontal lobes. Here are your frontal lobes. Your eye sockets are called the orbits. So, this is called the orbital frontal cortex or the prefrontal cortex. And I am going to tell you what that part of the cortex does in a minute. Just be aware right now that this is where a massive pruning and loss of tissue is taking place. That is the first change.

The second change is in myelination. It is not finished. Now, the neurons that you need to survive will myelinate first. So, your neurons for the sucking reflex, for the swallowing, those are going to develop first. And then, eventually -- if you look at the amount of coordination that a one-year-old has versus a four-year-old, you can actually know that in that brain myelination has taken place in the motor cortex of the brain that allows you to be more refined. Think about the child who cannot ride a bicycle and has to have the training wheels, but eventually can do the balance. That is all the myelination of neurons allowing them to work more efficiently.

What do you suppose the last part of the brain to myelinate is? It is the frontal lobes. And myelination is not complete in the frontal lobes of the brain until around 18 to 20. You have a lot of myelination going on again in the temporal lobes, a lot of myelination going on in the parietal lobes, before it happens in the frontal lobes. Now, think for a minute. What does that mean?

They are moving from concrete to abstract thinking, but they are not there yet. In fact, they may not be able to do the higher-level abstract thinking that we are able to do, most of us, until 18 to 20. And that may have some real implications for the curriculum.

Let me show you a brain scan of myelin over time. Unfortunately, this one does not show adolescence, but I think you can still get a picture. This is birth. This is six months. This is five years and this is adult. And the amount of white there shows the amount of myelination that is taking place. And you need myelin on a neuron why? To allow it to operate more efficiently. So, that is your second change.

Now, we are seeing that these changes in myelination and pruning of neurons take place in the frontal lobes, particularly the prefrontal lobes. So, what do the prefrontal lobes do? This is the CEO of the brain. Look at this. This is what the prefrontal lobes are responsible for: your reasoning ability. Is this a reasonable response to the teacher? Is this a reasonable response to the parent? Is it reasonable for me to get every part of my body that can be pierced pierced? Might there be any long-range effects of this?

Reasoning, your ability to reason. Goal and priority setting. One of the reasons we think that adolescents engage in such risky behavior or do not settle down to do their studies, et cetera, et cetera, et cetera, is that they do not set goals. And they have a great deal of difficulty prioritizing. What should I do first? What should I do second?

Now, part of this is style. There are some adults who do not like to prioritize either. So, we are talking as a generalization.

Your ability to make sound judgments. And we are going to see in a little bit that part of your ability to make sound judgments is your ability to send a message from the frontal lobes down to the amygdala, to the fight or flight part of the brain and say, cool it. Hitting this person is not a good idea. It's the principle.

Planning and organization of multiple tasks. They just do not seem to be able to do this. Where, as an adult, you not only can -- and incidentally, women do multitask better than men. That appears to be a genetic difference, and where that came from I am not even going to speculate. But adolescents are just terrible at multitasking. And they get zeroed in on one thing and forget that there are these other things that need to be done.

Impulse inhibition. I don't know how many of you read Daniel Goldman's book, Emotional Intelligence. In that book, he describes the very famous experiment where they took four-year-olds one at a time and set them down at a table. There are three marshmallows on the table and they say to the child, "Do you like marshmallows?" "Yes." "Would you like to eat these?" "Yes." "You can eat these anytime you want to but, I tell you what" -- there is a little bit of playful torture here. "I have got to leave the room and, if you can wait until I come back into the room without eating these three marshmallows, I will give you two more, so you can have five."

Now, this is a test to see if kids at age four can delay gratification. Can they inhibit their impulsiveness? And there is a little bell on the table and, if the kid cannot wait, they ring the bell. The researcher comes back and they get to eat the three marshmallows but they do not get the other two.

In the original experiment, about a third of the kids rang the bell before the researcher got out the door. You know, a bird in the hand. A third of them tried really hard but couldn't do it and rang the bell. And another third of them waited the full five minutes.

And this one little boy especially was just really interesting. He is on videotape and he looks at the ceiling and he does not look at the marshmallows. He puts his hands behind his back and he looks all the way around the room. Pretty soon, he can't stand it, but he keeps his hands behind his back and he leans down and he smells the marshmallows. And then, listen to this. He licks the table all around the marshmallows, but he doesn't eat them. And now he still has some time, so he sees he can see his reflection in the little bell, so he is making faces at the bell. But he did not eat the marshmallows, so he got five. And when they interviewed him, they said, was it hard? And he said, oh, not at all.

This is called impulse inhibition. And it is very interesting that some four-year-olds have developed that ability to delay gratification and to control their inhibition and others have not. Part of that may be genetic, but a large part of that -- what do you suppose a large part of that is? Why could some kids wait? What might have happened in their homes that had formed their connections?

Maybe they had to wait until someone else was through talking before they talked. Maybe they had to eat their vegetables before they got their dessert. Maybe those brains had had some models for delaying gratification while others had not.

So, there is a genetic component to it but there is also this age component, in that if you did this same test with adolescents, they are not nearly as good at controlling their impulses as the adult brain is. And we will see why in a little bit.

Emotional control. And we will look at this in more depth in just a minute.

Determining right from wrong. They just sometimes do not seem to have a sense of moral development. And you think you did a really good job of developing it and all of a sudden it flew out the window.

Determining cause and effect relationships. If I do this, this will happen. How many of you have said to your kids, "Didn't you realize that if you did this, this is what would happen?" "No." "Didn't you think? What were you thinking?" The point is they were not.

This is a laundry list, and researchers suspect that the unfinished cortex, the frontal lobes, and the unfinished myelination is what is responsible for this.

And the third change is going to deal with emotion. And here again we have to do a biology moment. Here is our change three. Have you heard of the cerebellum? In Latin, the word "brain" is "cerebrum." The word "cerebellum" is "little brain." They look like two little brains stuck on the back of your head. They have their own little cortex.

Now, if I asked you, what does the cerebellum do, what would you tell me? What have you heard that the cerebellum is responsible for in brain functioning?

AUDIENCE RESPONSE: Muscle coordination.

PAT WOLFE: Muscle coordination. Right. This allows you to stand on one leg, balance. This allows you to ride a bicycle.

I did a lot of research on the cerebellum and a lot of reading of what people said a year and a half ago, almost two years ago, when I wrote the book. And in the book I wrote this statement, that it is responsible for motor coordination and control and some neuroscientists feel it may also be responsible for coordination of cognitive activities. And indeed, that is gaining more and more credibility.

It appears that not only all the steps you have to go through to ride a bicycle, for example, or to drive your car, that that is coordinated in the cerebellum, but it also appears that in the cerebellum your coordination of social steps that you go through when you greet someone and relate to someone or the steps you go through in solving a mathematical problem, that the cerebellum is also involved in coordination of cognitive events as well as motor events. And I think we are going to see a tremendous amount of research on this. I have read this in several places.

Well, guess what? The cerebellum is not done yet either in the adolescent brain. This is not helping much, is it? It is just telling you what is going on in there.

Now, here is what is a really interesting question. I want you to think about this. Neurons that fire together wire together, right? So, you learn. You strengthen connections. And actually, let me just tell you what it is called. You can use this at your next cocktail party. It is called LTP. And LTP stands for long-term potentiation.

And very briefly, what that means is -- I think most of you know that when two neurons at the synapse, that the electrical impulse comes down the cell, you get to the synapse, which is a little gap between the two cells, and this releases chemicals which flow across the gap. And these chemicals are called neurotransmitters: serotonin, dopamine, endorphins, et cetera. The brain produces probably at least 50, and maybe as many as 100, different chemicals, neurotransmitters, that it uses to communicate. That is how the cells communicate.

The first time you make a connection and learn something, you learn the name of something, like LTP, that just made a connection in your brain. Now, it may not be a very strong connection. It does not have a lot of meaning. And then, let's say, a few days later, you pick up something and you read about LTP. That triggers that connection you made earlier, and it fires again. And then, a few months later, you read something and you then you say, I have heard. I am going to read a paragraph or two. I am going to read what some neuroscientist says about LTP. And what have you done? You have further strengthened the connection.

What is interesting is that it will take less neurotransmitter each time. You have actually strengthened the synapse. And what long-term potentiation is and what scientists believe that learning and memory is, you have increased the potential of that connection to fire a second time or a third time. That is long-term potentiation. This is what learning is.

Well, what do you do to strengthen the cerebellum? What do you do to strengthen the cerebellum? The cerebellum controls coordination and movement. Can you change your cerebellum? What would you need to do? Use it.

Walking, riding a bicycle, engaging in sports, playing the piano, all these things that involve that coordination. Physical activity increases the effectiveness of the cerebellum.

Now, think about this. If it proves true that the cerebellum also controls the steps you go through in social interactions and in problem solving as well as music and art, et cetera, could it be that physical activity could increase the effectiveness of the frontal lobes and our ability to do higher-level thinking?

And what are we doing in schools? We are cutting out recess, cutting back on P.E. This is a "suppose," but actually I read two or three scientists who are suggesting that one of our big problems as we are trying to raise test scores and increase the ability of kids to do higher-level thinking is that we are cutting out the very things that could strongly influence the brain to be better at those things. We are becoming an increasingly obese nation. Our amount of physical activity is going down, down, down, in adolescents and in adults. And we may be working counter to what the brain needs to do its best thinking.

As I said, physical activity influences the cerebellum. What are the implications for cognition in that?

One more little piece of biology. This one is really bad, I have to tell you. I did not know I was going to have an Elmo, so use your imagination here. This is the inside of the brain. And while you can’t see it, I want to tell you a couple of the structures that are down there. One of them is called the amygdala.

How many of you know what an amygdala is? It is Latin for almond. You have two of them, one in each hemisphere. It's a tiny, little bitty, almond-like structure. When information comes into the brain through the senses, it is relayed to the different parts of the cortex for processing, and there is a fraction of a second before you are consciously aware of what you are seeing.

For example, let's say I am out hiking and a light ray off of a curved shape on the path hits the retina of my eye. It will be a fraction of a second before I clearly see it. A very short amount of time. In that amount time, the brain sends the information to the amygdala. And the role of the amygdala, it holds emotional memory. It tells you how you feel about things.

And so the information is sent to the amygdala to see how you feel about it. Is this something I like? Is this something I do not like? Am I going to run toward this or am I going to run away from it? As Bob Sylvester says, does it eat me or do I eat it? This is just what the amygdala does. And the amygdala is going to start off the fight or flight response if that sense that is coming in is dangerous. That is its main role.

Right beside the amygdala is a structure called the hippocampus. Hippocampus stands for seahorse. Somebody thought is looked like a seahorse. And it is the part of the brain that allows you to transfer information from short-term memory to long-term memory. This is the basic memory organ of the brain.

This is the part of the brain that Alzheimer's hits first. It controls not only your memory for events and what you have learned but also for spatial information. And this is why people with Alzheimer's often cannot find their way back and why they lose their memory, because they are beginning to lose connections, and eventually cells, in the hippocampus.

So, what happens is I am out hiking and this light ray off of a curved shape hits the retina of my eye and gets into my brain. Before it gets back to the occipital lobe, so that I really see what it is, it goes to the amygdala. The amygdala and the hippocampus take a look at that and what do they say? What does it look like? It looks like a snake. And it starts off the fight or flight response. I jump and scream, which is my typical reaction.

Now, it gets back to my occipital lobes and what do I see a fraction of a second later? It is not a snake. It is a stick. So, why did I jump and scream? Why do you have a brain that allows you to jump and scream before you even see what it is? Survival. The brain says it is better to be safe than sorry.

So, this is the amygdala, and they can scan it. And what I am going to show you here is some absolutely fascinating research that is being done by a woman named Debra Yurgelun-Todd. And what I want you to do is to take a look. This is the actual test that they were using with the adolescents and adults. So, they show them this face. What do you see in this face? What emotion is this? What is this woman feeling?

AUDIENCE RESPONSE: Fear.

PAT WOLFE: Fear. And you all answered that. And that is what all the adults answer. Half of the adolescents could not figure it out. They said shock. They said sadness, confusion, but not fear. But they do this with all emotions. So, what is going on here? What Yurgelun-Todd has discovered is that the amygdala develops before the frontal lobes develop. The amygdala must be pretty active at birth or you would not be able to survive.

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