7th grade: BRAIN DEVELOPMENT + DECISION MAKING_sandbox

BRAIN DEVELOPMENT + DECISION MAKING TEACHER NOTES

Teacher notes are designed to supplement the slide deck for lessons throughout THAT HEALTH CLASS. At the start of each set of notes is a general introduction for educators – this information does not have a corresponding slide. Following the INTRO FOR EDUCATORS, every slide in the deck has a set of notes including more detailed definitions, extra examples, and ideas for in class exercises. There are no supplemental notes for the LET’S TALK ABOUT IT and SCENARIO conversation starter slides, because these are simply meant to be jumping off points for class discussions if needed.

The goal of these supplemental notes is twofold:

To offer both basic background information for educators who feel less confident teaching a given lesson
To offer a deeper dive into biology, physiology, and data for educators craving more information

Listen to our podcast episode on this topic to learn more. We also have a long list of favorite resources pointing to much more content about any and all of the topics covered in this curriculum.

INTRO FOR EDUCATORS:

By the time a kid hits middle school, their brain is halfway through myelination, a process that doesn’t finish until they’re close to 30.

Myelination and maturation are words used synonymously.
They happen in a specific order in the brain.
Once the prefrontal cortex, the consequential decision-making part of the brain, is mature, the process is done.

Some parts of the brain are fully mature in middle school, namely the limbic system. This part of the brain is the epicenter of pleasure, risk taking, and feel-good experiences. This lesson is all about the imbalances in the tween and teen brain that make it harder – but not impossible – for kids these ages to make consistently good decisions.

ICE BREAKER

Think about a regrettable decision you've made. Was it silly? Dangerous? Irresponsible? Why do you think you did it?

LEARNING OBJECTIVES:

Understand brain development and myelination.
Learn about the limbic system dominance during puberty.
Develop strategies for good decision making.

BRAIN DEVELOPMENT

Brains mature in two ways: through pruning and myelination. These processes change how fast signals can be sent through the brain.

PRUNING

As we get older, we actually *lose* neurons! Pruning is the process of eliminating neurons (nerves) in the brain when they are not used. It's like pruning a tree.

The nerves we use are saved, but the ones we don’t are lost. This is what makes us better at certain skills (like speaking a language or playing an instrument). It’s also what makes it harder for adults (with fewer brain cells!) to pick up a new skill or hobby.

Myelination:

Myelination means the covering of neurons in the brain. When we’re born, the cells in the brain start out as naked neurons, but over time, many of them are covered with an insulating layer of fat cells, called myelin.

The brain sends electrical signals. Those signals move much faster when the nerve is insulated (myelinated). When people talk about “mature” brains, most of the time they are referring to brains that are fully myelinated A fully myelinated brain can send messages the fastest, but that doesn't happen until you're almost 30. Myelinated brain cells send signals 3000x faster than unmyelinated brain cells!

Signal speed matters

Think of unmyelinated neurons like dirt roads, and myelinated ones like paved highways. Cars can travel a lot faster on a smooth paved highway than on a bumpy dirt road. Like cars can travel on boath kinds of roads, nerve signals can travel through both myelinated and unmyelinated neurons---but they'll be sent much faster through myelinated pathways.

Nerves transmit electrical signals. These signals travel much faster when a neuron is myelinated. In fact, myelinated neurons can send and receive messages 3,000 times faster. These signals don't spread to neighboring neurons, so any part of the brain that has myelin around its nerves gets messages much faster than parts that don’t.

This is the same reason that wires like your cellphone charger are coated in a plastic, so you don't get a shock when you touch them.

Here’s the video in the slide: The Remodeling Brain with Dr. Dan Siegel.

BEING PARTIALLY MATURE

It takes three decades for the brain to fully develop. Myelin is laid down in a very specific order. Remember, the parts of the brain that are myelinated send signals more efficiently, so they dominate decision making. Myelination happens from the inside and bottom of the brain and works outwards and towards the top.

Myelination starts at birth. It travels upwards and outwards: starting at the bottom of the brain (near the neck) and in the innermost area (between the two hemispheres). By middle school, myelin has reached the halfway point through the brain. This means your brain won’t be fully covered with myelin for another couple of decades!

The order of myelination is why the limbic system (in the middle of the brain) develops before the prefrontal cortex (at the upper edge beneath the forehead)

THE DOMINANT LIMBIC SYSTEM

Located in the middle of the brain, the limbic system will dominate from until the brain is fully mature (somewhere between ages 25-30).

The limbic system is the feel-good center of the brain. It is the site of motivation, memory, risk taking, emotions, reward seeking, and pleasure. It’s actually a collection of a bunch of different brain structures including the hippocampus and the amygdala. It can drive impulsive (usually not the wisest) decisions. It can also motivate positive behaviors. Example: if you study hard for a test and you do well and that feels good, you will be motivated to study again – thank you, limbic system!

The limbic system is lit up by peers but not adults. So friends might encourage more risk-taking behavior just because the limbic system responds to friend’s being around. This happens both in real life and online.

Meanwhile, the last part of the brain to mature is the prefrontal cortex: because it’s not fully myelinated, the prefrontal cortex sends and receives messages much more slowly than the limbic system. The prefrontal cortex is in charge of consequential thinking, executive function, and planning. It’s the part of the brain that weighs the outcomes of two competing choices: If I do this, this will happen, but if I do that, that will happen… I should do that.

The prefrontal cortex won’t be fully myelinated until a person is in their late 20s (a couple of decades from now!) The prefrontal cortex is designed to balance the limbic system. But it can’t do that job very well when the limbic system is myelinated and the prefrontal cortex is not! If there’s a race between signals inside the brain, the signals going to and from the “feel good” limbic system will move a lot faster than the ones going to and from the “smarter” prefrontal cortex.

Here’s the video in the slide: Brain Development Explained.

YOU CAN MAKE GOOD DECISIONS!

The key is to give the brain time to send signals everywhere. When the brain is fully myelinated, that happens quickly. But when the brain is only partly myelinated, signals reach one part faster than another. When signals have the chance to get to the prefrontal cortex, the brain has a chance to think and then act differently. We’re not talking a lot of time here – just a few seconds is often all it takes.

Here are some hacks to give your brain time to make good decisions:

Count to 10
Do 10 jumping jacks or burpees
Text your parent
Get a drink of water
Go to the bathroom
Whistle happy birthday
What else might work?

Teacher note: Kids often feel really crummy when they make a bad decision. It might seem like everyone is disappointed in them – parents, teachers, friends. But some of the poor decision-making of the tween and teen years has to do with uneven myelination. Signals are getting to the limbic system before they get to the prefrontal cortex. This drives choices to do things that feel good over things that have better long term consequences.

SUMMARY:

It can feel really embarrassing when you make a bad decision, but it’s important to remember that you’re not a finished product – you are a work in progress. No one expects you to be perfect, but they do expect you to try your best to make good choices. Knowing the science behind how you make decision helps you make better ones.

LET'S TALK ABOUT IT

Think about how you make choices differently depending on who you are with...

You parents or a trusted adult in your life?
Your best friends whom you've known forever?
Your new friends or people you want to know better?

Sydney and Dillon are at the pharmacy. Sydney suggests Dillon shoplift some candy. What can Dillon do to take a pause that will give him a chance to make a smart decision?