The stress response and the Triune Brain

Yesterday we brought all of our definitions together and discussed the impacts that stress can have on you. While the effects can be severe, the good news is that we can minimise them by implementing some lifestyle factors. We’ll cover those things later in the month.

Today I’d like to discuss the stress response. This takes us back to the in-built survival mechanism we all have in our brains. We are biologically programmed to do everything we can to remain alive for as long as possible. Some guy named Paul McLean introduced us to something called the Triune Brain, which breaks down its complexity, dividing it into 3 parts that make it a lot easier to understand our survival instincts. If you’d like to read more about the Triune Brain you can just google the term, but here is a site to start you off.

So this post is likely to be a little lengthy and technical, so read it at your own pace. Feel free to put it aside and come back to it later. I’ll include diagrams and subheadings to break it into manageable parts. If there is anything you don’t understand, please ask. It’s important that you are able to process and understand this information, because it will help you to implement strategies that work for you.

The Triune Brain

Ok. So as I said, the Triune brain is divided into 3 parts and together they explain our evolutionary processes.

Brain Stem

This part of the brain is the only part that is fully developed at birth. It’s located at the bottom of the brain and runs down into the top of the spine. It’s responsible for our basic human survival. Breathing, heart rate, blood pressure and so on. It also has part responsibility for the stress response, otherwise known as the fight/flight response (which I’ll explain soon).

To paint a picture for you, if you hold your arm up in front of you, your forearm between your wrist and elbow would be the brain stem.

Limbic Region

This is generally fully developed between the ages of 3-5. It sits on top of the brain stem and is responsible for our emotions and plays a big part in our stress response (fight/flight). It also plays a part in anxiety, depression and trauma.

Within the limbic region are 2 key parts that you need to be aware of. The first is a pea-size thing (very technical term) called the amygdala. Its sole job is to make an assessment, which I’ll explain further soon. The other part is the hippocampus, which forms part of our memory systems. I’ll explain this soon too.

As an aside, when a child is abused at a young age, their amygdala becomes enlarged and is activated much more easily.

If you’re still holding your arm up, make a fist. Your fist is the limbic region of the brain.

Neocortex

The neocortex is the last part of the brain to develop. While it starts to grown when you’re young, it really kicks in when you hit your teenage years and doesn’t fully develop until around age 25 (which is why teenagers are so impulsive and don’t think things through. Their limbic regions are fully developed, enabling them to act on their emotions, but their thinking brain doesn’t yet have the capacity to keep up and balance it with the ability to reason things out).

The neocortex is commonly called the thinking brain. It’s responsible for exactly that. Thinking. Which includes reasoning and problem solving.

Going back to your arm, keep your fist clenched, and wrap your other hand over your fist. This hand is the neocortex.

Take a look at this first picture. Hope you like my super artistic ability! It shows the Triune Brain as I’ve described. Hope it makes sense with the colour coding.

Let’s go back to caveman times for a second

I want you to take on the role of caveman for a moment. You’re coming out of your cave to do the hunter-gatherer thing. You’re too far out to get back inside quickly, and you suddenly notice a saber-toothed tiger sitting on a rock to your right. And this tiger is look at you like you are its next meal.

What do you do?

Here is where the amygdala comes into play.

You see the tiger, you hear it, and you may feel vibrations under your feet, smell it and so on. Your brain takes in this information and sends it to the amygdala.

Your amygdala’s sole job is to answer 1 question – is this tiger a threat to my survival?

If the answer is yes, your stress response, or fight/fight response, is immediately activated:

1. The amygdala sends a signal to the brain stem to say, ok, I need all of my resources available to get me out of this situation alive. Your brain releases adrenalin and cortisol (the 2 main stress hormones) to prepare you for either fight or flight. It increases your heart rate, breathing rate and blood pressure to ready your body to respond.
2. At the same time signals are sent to the neocortex (thinking centre) that says “I don’t need you right now, time to shut down”. Think about it. Will the tiger sit around waiting for you to think about things and decide which way to go in case it moves to the left 4 inches or closer to you? Let me tell you, it won’t wait. You need to be able to react immediately. If you take time to problem solve your life could very well be terminated! So, the blood flow to your thinking center gets shut down so you can immediately react.
3. Additionally, you need to be aware that once the crisis has passed, if it happens again you need to be ready to act very quickly. So the memory device I mentioned earlier, called the hippocampus, lays down memories so that next time you see a tiger, the information is processed much quicker. The amygdala does its thing and the stress response is activated.

We can come back to modern times now

So now we’ve explained the stress response, we need to understand that with the really quick advances we’ve had since our caveman times, we’re no longer confronted by saber-tooth tigers. Generally, our lives are rarely threatened. Evolution hasn’t kept up with those developments and unfortunately, the amygdala can’t tell the difference between tigers and finances.

Or any number of other things we have to deal with in our modern society. Families, kids, work responsibilities, traffic and so on.

And because our lives are so fast these days, it’s likely that our stress response is activated over and over again in very quick succession.

But here’s the thing. The stress response is there for a specific purpose. To keep us alive in a crisis. And after the crisis has passed it is supposed to ease. Blood flow is returned to those non-essential systems like our thinking brain. The stress hormones dissipate and leave the body (which is when you feel shaky and fall to bits). And at this point we are supposed to rest and recover and recoup our energy.

I hope all that makes sense. It’s a complex process and can be difficult to understand. We’ll leave things there for now and pick it up again tomorrow, when we’ll talk more about that pea size thing called the amygdala.