Here is the full transcript of physiatrist John Rigg’s TEDx Talk: The Effect of Trauma on the Brain and How It Affects Behaviors at TEDxAugusta conference. This event took place on January 30, 2015. Dr. John Rigg is the director of the Traumatic Brain Injury Clinic at Fort Gordon.
John Rigg – Physiatrist
I want to ask you to think back to some occasion in your life when you might have gotten in an argument with someone, particularly someone that you loved, you cared for a lot — a family member, a spouse, a parent and really reacted — really reacted, you got so angry, did things, you said things, maybe broke stuff, said hurtful things and then later on reflected on your behavior and wondering what happened: where did that come from?
I want to look at some of the factors that contribute to that type of overreaction, that mechanism, that hyper arousal that occurs. Hyper arousal, anger, hostility — where does that come from? What generates it?
I’m going to talk about stress, OK. Stress as a factor that can influence behaviors and look at the anatomy of the human brain — we actually have two brains that are contributing to our behaviors. Two brains contributing to our behaviors. And stress is particularly influential on one of them.
Stress is nothing that we think about, right? We don’t come up with stress. It is a reaction to the external environment. So let me talk about the two brains.
I have a diagram here of the cortex of the brain and this structure underneath the cortex of the brain, which is labeled brainstem in here. But I’m really going to talk about the subcortical brain, this entire structure here.
The cortex of the brain is what I’m going to call the human brain, the intelligent brain. It’s where our personality is, our individuality, where we make choices of our mate, what we eat, what kind of music we listen to, what car we drive, where we live, what type of life we live. We take in sensory information and it’s processed in the cortex, and we take actions based on sensory information. That’s where our personality, our individuality, is all centered in that cortical area.
Note in the human brain, it’s actually — by far the largest mass of the human brain is cortex, OK. We rule the world as humans. Why? Not because we perform animal functions better than any animals; we’re not bigger faster stronger than animals. We think better. We have the largest cortex and we rule the world.
But we’re animals. We eat, make waste products and make babies, and that behavior triggered by our primitive animal brain is sometimes responsible for triggering some of the behaviors that we’re not particularly fond of.
So this primitive animal brain, what does it do? Well, the brain reacts to situations whether we want it to or not. Particularly this animal brain which doesn’t think, it just reacts to the environment. So if I said to you, hey let’s all go outside and race across broad street but don’t your heartbeat increase; could you do it? No.
You can think to yourself, hey I’m going to stop my heartbeat for 10 seconds but you can’t do it. The thought exists, the thinking exists in the cortex, the human brain but the animal brain is controlling your heartbeat and won’t let you do it. So you can think all you want about lowering your blood pressure and it won’t happen. That primitive animal brain is maintaining your heartbeat, your breathing, your digestion from the moment that you’re born, I mean even pre-birth as a fetus, that these structures start operating in that central nervous system, primitive animal brain is operating non-stop until your death. Pretty amazing, OK.
I’m going to ask you to look at another way that this primitive animal brain reacts to situations, OK. So let’s picture a bunch of guys hanging out arguing about who’s going to win the Super Bowl, on Sunday talking about cars, whatever men might want to talk about when they’re involved in a conversation. I’m a man, so I look at — you know I only have a male perspective on things. But what you guys are sitting around talking.
And all of a sudden during that conversation, this really attractive looking woman walks by with an inappropriately short miniskirt and an inappropriately tight T-shirt, what’s going to happen to that conversation? The little Snickers in the audience, not me, man, I don’t look. Men will be attracted to that, not because they’re out there searching for mates, married men might react that way, OK, but because of the fact there’s an animal instinct of sexual attraction.